Sea Monster's carcass or other aquatic animal?

This photo were published in englishrussian.com showing an unknown animal carcass near the shore. For me it might be the croc carcass or somethin' similar. I've been visiting the PRSG page and really enjoy reading all the info and article submitted. I'm not a researcher or any, just normal reader who loves the mysteries and paranormal things. Hope you guys might explain and gave opinions bout the mysterious carcass. Thanks.





Becky Tan L. Hsia
Penang

Time Travel. Is it Possible?

In 1905, an obscure Swiss patent office worker wrote a paper that caused an uproar in the scientific community. The paper refuted all the Newtonian physics that scientists knew. The writer of the paper was Albert Einstein. Scientists now accept his Special Relativity Theory and General Relativity Theory as the best theories to explain the universe, or as Stephen W. Hawking (1988, p. 175) put it, to "know the mind of God." If someone were to know the mind of God, he would be omniscient like God. If someone were omniscient, he would know how to take control of time and travel forward and backward at his whims.

Since 1895 when H. G. Wells published his book The Time Machine, the idea of time travel has enamored the American public. Large amounts of literature, usually science fiction, have been dedicated to time travel. On the humorous side of that literature, the Calvin and Hobbes cartoon above contains a truth about Einstein's equations that all physicists know: the Mathematics behind travel into the past and General Relativity is extremely difficult. Arthur Buller also used the ideas behind Einstein's theories in a humorous way in his limerick about "Miss Bright:"

There was a young lady named Bright,

Whose speed was far faster than light;

She set out one day

In a relative way,

And returned on the previous night (Davies, 1992, p. 21).

Even though Miss Bright's trip may seem like an idea concocted by Star Trek writers, many respected theoretical physicists have published serious ideas using Einstein's Special and General Theories that may allow travel in time.

To understand how theoretical time travel is possible, one must understand the basics of Einstein's theories. Using Special Relativity, scientists know that time, length, and mass are "not absolute and universal but depend on the observer's state of motion" (Davies, 1992, p. 20). At the speed of light (which, according to Einstein's equations, cannot be reached or exceeded by a body with mass¹), length decreases to zero, mass increases to infinity, and most importantly, time slows to a stop (Macvey, 1990). Therefore, time is not absolute. An event that took two seconds to a stationary observer would seem to take only one second to a person traveling at 0.87c (87% of the speed of light)². Any length would also shrink to half its original length relative to the moving observer and the mass would double.

General Relativity is even more difficult to understand than Special Relativity. In General Relativity, Einstein said that gravity is not a force. Matter distorts and curves spacetime (commonly referred to as the "space-time continuum" by science fiction authors). Projectiles merely attempt to travel in the straightest line possible in the warped spacetime. Using Riemannian geometry (since planar Euclidean geometry does not encompass warped planes), Einstein improved upon Newton's equations of planetary orbit by more accurately describing the path that planets travel³. A mass, such as the sun, warps spacetime as a steel ball stretches a taught rubber sheet. (Theoretical physicists call this type of two-dimensional model of spacetime a "spacelike hypersurface.") The larger the mass, the more the rubber sheet stretches (Gribbin, 1983). The "pit" created by the sun catches the planets, which are trying to travel in a straight line. A black hole, which warps spacetime in special ways, can be described as a lead ball that ripped through the rubber spacetime sheet. Anything that falls into a black hole is compressed into a "singularity." Hawking (1993), who has done intensive research with black holes, defines a singularity as a point in spacetime where the spacetime curvature is infinite and where spacetime ends. Wormholes, another result of Einstein's equations that connect two distant points with a short path through spacetime, are thought to appear to be two black holes ("mouths") connected by a passage (a "throat"). However, the passage is very small and wormholes have not even been proven to exist (Lemonick, 1989).

Fig. 2. An example of a spacelike hypersurface (Parker, 1991, p. 84)

Many scientists in Einstein's day refused to accept his results because the equations led to the possibility of time travel. Theoretically, the Special Theory of Relativity allows travel into the future, while the General Theory, under exotic conditions, allows travel into the past. However, the energy and the technology required to accomplish either of these feats are far beyond what anyone in the foreseeable future can dream to use. Using Einstein's theories of relativity, time travel into the future and past are theoretically possible, but are not feasible.

Time travel into the future is commonplace. Humans have been adept at moving steadily into the future since their creation. However, moving appreciably faster into the future than others is more difficult. As already stated, if a traveler could move at a velocity of 0.87c, time on earth would move twice as fast as his time. Therefore, if he were to leave on his birthday and return on what he thought was his next birthday, two years would have passed on Earth. Although this may be useful as a "fountain of youth," it is not useful to serious time travelers. If this traveler could tweak his engine to get it to travel at 0.999 999 999 9c, or one hundred millionth of a percent less than the speed of light, he could travel to Andromeda and back in 55 years. If he were to return to Earth if it still existed, the Earth would have aged 4.7 million years (Macvey, 1990). Most travelers would not want to go that far into the future. However, traveling a 0.999 999 5c, the traveler would only go one thousand years into the future with one year of travel⁴, which could be extremely useful to potential time travelers.

No physical barriers have been proposed yet to prevent time travel into the future. However, no technology known comes even close to accelerating massive starships to such tremendous velocities. Many scientists look at the advancements that the human race has made in the last forty years and speculate that eventually such a ship could be built eventually. Realistically, even if the vehicle was built, the ship would consume enormous amounts of energy. John Macvey (1990) estimates that for a spaceship weighing one ton, the power needed to attain a velocity of 0.8c would be 215 billion kilowatt-hours. All the power stations on the earth combined would need several months to generate that much power. Also, traveling at such high velocities, the impact of the spaceship hitting even a particle of dust would be enormous. The particle could have the inertia of a planet (Davidson, 1990). The force of the collision would easily rip the ship apart. If the prospective time traveler was able build a spaceship, enslave the workers of the world and force them to produce power for himself for several months, he would probably die in his attempt to travel forward to a time where the people of earth had forgotten his tyranny by striking a speck of dust.

Time travel into the past is much more difficult than into the future. To travel into the past, "exotic conditions" are needed to change spacetime in a way that a traveler can go backwards in time (Freedman, 1989, p. 58). To warp spacetime enough to allow the functions of space and time to interchange, a person must travel at relativistic speeds, because no valid conditions are within a close range of the earth. If a traveler could reach suitable conditions, he would encounter many other obstacles. Many scientists believe that "causality" will prevent anyone from traveling to the past (Davidson, 1990). Causality is the normal relationship between cause and effect. If someone could travel back in time, the effect could influence the cause. For example, if Michael J. Fox in Back to the Future had killed his parents, then he would never have been born, which would render him unable to kill his parents. Some theoretical physicists believe that nature protects itself from time travel because of causality violations. Stephen Hawking (in Travis, 1992, p. 180) believes that since the Earth has not been "invaded by hordes of tourists from the future," time travel will never occur. Whenever a new theory is proposed about traveling back in time, other physicists attempt to prove that each is impossible. By playing with Einstein's complicated equations, scientists also learn more about the properties of the universe.

Fig. 3. A diagram of an Einstein-Rosen bridge system (Parker, 1991, pp. 118)

Black holes have long been of interest since Einstein's theories predicted them. In a black hole, matter collapses to a point of infinite density, called a singularity. Around the singularity is an event horizon. Once a traveler passes the event horizon, the gravitational pull is so great that the traveler cannot pass back through the event horizon without traveling at a speed greater than the speed of light (Gribbin, 1983). However, another exit may be available. In a rotating black hole, an Einstein-Rosen bridge system develops (Parker, 1991). In this "wormhole," a shuttle could enter and, by orbiting around the singularity to avoid it, could arrive in another universe (Davidson, 1990). Scientists are not sure what this other universe might be. The other universe may be our own universe but in a distant location in space and time or it may be another universe, often called a parallel universe.

However, to reach the "other universe," the traveler must survive the hazards of the black hole. According to Barry Parker (1991), a spaceship attempting to travel through the wormhole in a black hole would be crushed by the wormhole passage pinching off, stretched out by the strong tidal gravitational waves, and "literally fried" by extremely high radiation levels. This grim forecast should deter most travelers from attempting to enter a black hole. If, for some foolhardy reason, a traveler attempted to enter a black hole, he would never reach the event horizon relative to an observer orbiting around the black hole. Time slows down in strong gravitational fields (Parker 1991). Therefore, the traveler's ship would at first accelerate toward the black hole. As the ship would approach the event horizon, however, it would slow down to a virtual stop. If the observer were to see a clock on the ship, the clock would slow down so much that it would appear to stop. The traveler, on the other hand, would feel as though he passed through the event horizon almost instantly (Parker, 1991). Unknown to the traveler, an infinite amount of time would have passed outside the event horizon and he would be cut off from the rest of the universe. The traveler would be forced to travel infinitely into the future and then travel back infinitely into the past to accomplish anything. Because of the number of difficulties associated with travel into a black hole, most theoretical physicists have given up on using black holes to go back in time. Hawking (1993) consoles potential black hole time travelers by stating that even though they would be ripped apart to atoms, their atoms may float into a time in the earth's past.

Although the wormholes connecting black holes are not likely to be useful for time travel, other types of wormholes may exist which do not have singularities in the middle of their throats. Scientists who work on the Plank scale (dealing with objects smaller than 10-33 cm long, which is smaller than an atom) have discovered that tiny wormholes lace spacetime, making a "spacetime foam" of millions of tiny wormholes (Davies, 1992). These wormholes connect different spots in time 10-42 seconds into the past (Deutsch, 1994). If one of these microscopic wormholes could be inflated into a macroscopic wormhole by some means, then it could be used to connect two different points in space and time. By taking one of the mouths and moving it at a relativistic speed away from the other mouth, one end of the wormhole would be younger than the other ("Wormholes," 1988). By traveling from the older one to the younger, a shuttle could go back in time (Allman, 1992).

Fig. 4. Diagram of spacetime foam (Davies, 1992, pp. 23)

Problems still arise in a wormhole even without a singularity. Wormholes tend to be very unstable, and the if a spaceship entered one of the mouths, the throat would immediately pinch off, crushing the ship (Clarke, 1990). To keep the throat open, negative energy or "exotic matter" equal to the pressure in the center of a neutron star is needed ("Wormholes," 1989). Madhusree Mukerjee (1994) describes negative energy as a "no-no," meaning that physicists do not know how to produce negative energy. Scientists have no idea how to produce any of these "lozenges" to open up the throat. Also, since enlarging a microscopic wormhole would be extremely difficult, a natural wormhole could be used, but the ends of the wormhole would be separated by large expanses of space. Therefore, to return to earth within his lifetime, a traveler would have to travel at relativistic velocities. Even at those high speeds, he probably could not return before he left.

The most recent theoretical model of a time machine has sparked a great deal of dispute, some of which has been appropriately published in the popular newsmagazine Time. The model, proposed by J. Richard Gott III, involves cosmic strings. Cosmic strings are long, thin strings of pure energy left over from the beginning of the universe (Lemonick, 1991). The energy of a cosmic string converted to mass would yield a density of approximately 40 million billion tons per inch (Travis, 1992). By taking two of these strings, placing them parallel to each other, and accelerating each to 0.999 999 999 92c in opposite directions, spacetime becomes extremely curved. By traveling between the strings and then looping around them, Gott calculates that spacetime would be warped enough that when a traveler took off, he could see himself returning (Peterson, 1992). By repeatedly traveling between the strings, multiple spaceships could all be together at once. Edward Farhi of the Massachusetts Institute of Technology remarked that Gott's idea "was so simple that it was tantalizing" (Peterson, 1992, p. 202).

Many physicists were quick to attempt to prove that Gott's idea is impossible. The team of Farhi, Alan H. Guth and Sean M. Carroll from the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts developed a simplified model called "Flatland" (Peterson, 1992). Ignoring one space dimension and forming a three-dimensional spacetime, Farhi and his colleagues determined that if the universe was open, meaning that it did not contain enough matter to halt its expansion, not enough matter and energy would be present to construct the strings (Travis, 1992).

Gott quickly responded that this analysis may "eliminate his time machine from certain universes, but not necessarily from our own" (Travis, 1992, p. 179). He claims "physicists have a deep-seated belief that things should be causal" and believes that these physicists are saying, "We do not like what [Closed Timelike Curves] imply for physics, so CTCs are unphysical constructs" (Travis, 1992, p. 180). Despite this tirade, Gott himself admits, "Actually, before trying to locate a pair of cosmic strings, it would probably be helpful to locate a single string-something that no one has yet managed to do." He also wistfully states that the speeds that the strings are required travel at are "not any faster than we get electrons to move in the Stanford Linear Accelerator," ignoring that electrons are extremely light while cosmic strings are extremely massive.

Despite these restraints, Gerard 't Hooft of the University of Utrecht in the Netherlands is determined to grind any hope that cosmic strings may work under his heel. He warns, "Don't try [to go back in time using cosmic strings] . . . You won't just fail-you might destroy the entire universe" (Mukerjee, 1994, p. 32). The dilemma described by 't Hooft shows that in a closed universe, the strings cannot pass parallel to each other. Instead, they begin to orbit each other, moving closer and closer together spinning faster and faster. As the kinetic energy of the strings approached infinity, the universe would begin to crumble and collapse in onto the strings. Mukerjee (1994) described the event from the prospective of a potential time traveler: "A time-machine ticket-holder will see massive walls closing in while being shredded to spaghetti by the strings speeding through. . . The scene sketched by 't Hooft shows how such objects can act as Nature's dragons, guarding time machines from fools who would rush in" (p. 32).

Gott, not to be easily dismissed, has proposed a new theoretical puzzle: a finite, rapidly shrinking cosmic loop. This idea will prove more difficult to prove or disprove, because "Flatland" cannot be used. Complete four-dimensional spacetime is needed to fully analyze the phenomenon. However, Gott admits that the system will probably collapse into a black hole, and any time travelers attempting to travel through would be captured behind the event horizon (Peterson, 1992).

Theoretical physicists have been and will continue to introduce new ways to travel in time. Other theoretical physicists will continue to prove that time travel is impossible. Despite optimism from some prominent physicists and science fiction fans, mankind will never "know the mind of God," and therefore will never be able to control the passage of time. Travel into the future will be restricted by the absence of the technology needed to build vehicles capable of velocities close to that of the speed of light and the enormous energy requirements needed to operate the vehicles. Travel into the past will be more violently restricted. Natural phenomena such as crushing singularities, pinching wormholes and collapsing universe will prevent anyone from attempting to violate causality. Stephen Hawking (in Travis, 1992, p. 180) also believes that time machines in general "sow the seeds of their own destruction by creating a small feedback loop in which small fluctuations in the energy of the vacuum travel back in time" and amplify the distortions to astronomical proportions, destroying the time machine the instant it is created. Presently, Hawking is working on a "Chronology Protection Conjecture," which will rule out time machines altogether. Various parts of the conjecture have been proven, including one which states that unless a ship is surrounded by negative energy while attempting to travel back in time, singularities will form around the ship and cut it off from the rest of the universe (Allen, 1992). If a prospective time traveler ever wishes to enter a time machine, he should carefully take heed of the warning Dante to those entering Hell: "All hope abandon, ye who enter here."

Notes

¹ Using the formula for mass dilation

where M₀ is the rest mass, M_v is the mass of the object in motion, v is the velocity, and c is the speed of light (299 792 458 m/s), the fact that a massive body can only travel below the speed of light can be proven (Macvey 51). By plugging the speed of light into the equation for the velocity,

the rest mass is divided by zero to give the value of the mass in motion, which is undefined and approaches infinity. When a speed greater than the speed of light is used for the velocity, such as 2c,

the rest mass is divided by the square root of a negative number, which produces a complex or "imaginary" number (). Stephen Hawking has proposed an alternate time scale, called "Imaginary Time," or T_i, which may include time, length, and mass in parallel universes (Brief 134). The Mathematics suggests that if the speed of light is exceeded, the travelers may find themselves in another present in a different universe. Tachyons are the only particles thought to travel faster than the speed of light. However, tachyon particles have no mass and therefore the complex part of the result cancels out.

² Using the equation for the dilation of time,

with T_v (time to an observer in motion) equal to one second, and T₀ (time to an observer at rest) equal to two seconds,

the formula yields a result of 87% of the speed of light as the velocity. At this velocity, the moving observer would see things as occurring twice as fast as an observer at rest.

³ Newton's equations stated that planets travel in a perfectly elliptical orbit around the sun. Einstein's, however, took into account that the perihelion of Mercury's orbit rotates around the sun at 43 arc seconds per century. (Macvey 64) The other planets' orbits, while not as observable as Mercury's, follow a similar path.

⁴ Again using the formula for time dilation,

with T_v equal to one thousand years and T₀ equal to one year,

the velocity required is 0.999 999 5c.

Time travel is a concept much loved by science fiction writers, and Star Trek fans, but is it possible within the known laws of physics? To answer the question we shall take another look at quantum theory (Quantum Mechanics) bringing in the ideas of Richard Feynman, and re-examine the theory of relativity. After that we shall consider the difficulties involved in constructing a time machine, if such a thing can be done. But before we do any of this, let's first consider some of the problems that time travel raises. I have to say at this point that if ever a theory was riddled with problems, paradoxes, speculation and possibilities, then this is it, outright winner of my gold medal award!

One of the stock answers to the question of time travel is to suggest that if time travel were possible it would have already happened. By way of explanation let's say that at some time in the future a clever scientist invents a time machine that can travel through time in any direction, just like the fictional time machine created by H. G. Wells. So where is our intrepid time traveller? History shows that no time traveller has ever visited us from the future, therefore it's never going to happen. This appears at first glance to be a good solid argument against the possibility of time travel, but the argument is flawed. It may be that time travellers from the future have visited us, but have not revealed themselves in order to avoid changing the future. Alternatively, time travel may be possible, but only into the future, the past already having been determined. Finally, time travel into the past may be possible, but only into a different (alternative) universe, thus avoiding paradoxes. The fact that we have no record of having been visited by time travellers does not exclude its possibility. Having dealt with that little problem we can now move on the fun part, paradoxes.

Paradoxes

This is where we start to run into some of the problems posed by time travel. The most commonly posed paradox is known as the 'grand parent' paradox. This states that if you could travel back in time you could murder your grand parents and thus prevent your existence, thus rendering it impossible for you to have gone back in time and killed them... no need to draw you a picture. Even more to the point perhaps, you could travel back in time and kill the person responsible for time travel before they discover it! However, popular though the grand parent paradox is, it only reveals the tip of the iceberg. Let's examine a theoretical time travel situation in more detail in order to highlight some of the problems involved.

Imagine that today you travel back in time to August 2001 and warn the authorities that the World Trade Centre in New York is going to be attacked on September 11th. They take the necessary action and as time unfolds the disaster is eventually averted. You are still in August 2001 at this point and the disaster has not yet been prevented, but it will be eventually because of the chain of events that you have put into motion, and you now wish to return to the time you came from. Here comes the Big Question - can you return to where you came from? Where you came from the attack had taken place, therefore where you came from no longer exists! If you do return to your original time, the World Trade Centre will still be standing (because you prevented the attack), so it cannot be where you came from. You will have changed the course of history, not just for yourself, but for the entire world. The question is, will the World Trade Centre still be standing when you return to your starting time? This is a major point of contention. According to one theory it both will and it won't! This is because your actions will have created an alternative possibility and in the process an 'alternative' universe, where we now have one universe with the World Trade Centre intact, and one with it destroyed, and we will all exist in both. The theory is firmly rooted in quantum theory that states that ALL alternative outcomes are possible. However, there is no evidence at this stage that the strange phenomenon found in quantum theory can be applied to the larger world.

Yet another theory suggests that alternative universes will not be created because events will conspire against you that prevent you (as in this scenario) from warning the authorities and changing history. This 'theory' it isn't really a theory as such, more an expression of a desire, because it is believed to be impossible (and very bad manners from the point of view of historians) to change history. The theory has no explanation as to how this 'prevention' could actually come about and has no solid theoretical basis.

The same arguments can be applied to travel into the future. Suppose I travel 24 hours into the future, armed with a loaded gun, (just in case, you never know) and happen to meet myself sitting at my computer, (can you meet and interact with yourself?) also armed with a gun, which would be most unusual for me as I do not own one. I am alarmed to see that the gun is pointed at me and warn my future self to put it down or I will shoot him. He prepares to fire the gun so I shoot him dead at the computer, then return. On my return, when tomorrow comes, I am sitting at my computer and receive a visit from 'me' from my past. He warns me that he will shoot me. I of course knew this would happen and took the precaution of keeping the gun beside me and aimed at the spot at the time I knew 'he' would arrive, and I shoot him first. Can I do that? That isn't what happened in my future, it was the 'me' at the computer that died. Even if I don't manage to shoot 'him' in time and still die at my computer, which one of us exactly is it that is still alive? We have created a nonsense scenario. Now this may sound like nonsense, and perhaps it is, but if the future really does exist then it does raise the prospect of meeting and interacting with yourself.

If we accept the idea that the future does exist, because time is just another dimension as discussed in the previous section, then these paradoxes would be unavoidable. If however, we take the view that only the dimension of time itself exists, and not the events within it, then this would suggest that time travel is impossible. Why? Because if future events do not exist, then it would be impossible to travel into the future to witness them, there would be no 'future' to visit.

We either have to accept that if time travel is possible we will, by our actions , create all sorts of paradoxes, or accept that we will create alternative universes. The paradox problem will not go away. As for alternate universes, the mind boggles!

Alternate Universes

The idea of having alternate Universes very conveniently solves the paradoxes raised by time travel, but is it a serious possibility? It sounds a bit far fetched, like something out of a science fiction paperback, but try not to dismiss the idea out of hand, it has some strong supporters.

The alternative universe theory (also known as the multiverse) suggests that for every possible outcome of an event, an alternative universe is created, with the result that somewhere out there I won the lottery last week, and so did you. If only we knew how to get there! This theory has the problem that there must be an infinite number of alternative universes existing to cover every possible outcome of every event. Which one, if any, is the 'real' one, or are they all equally 'real'? Furthermore, where does all the energy and mass come from that creates all these alternative universes? To try and find answers to these questions we have to return briefly to quantum theory.

We learned from the cat-in-the-box thought experiment that prior to observation the cat is in, what is termed in quantum speak, a 'superposition of states'. In plain talk, it is either dead or alive until the moment of observation, its fate is not determined beforehand. The explanation given for this strange state of affairs was the behaviour of the electron's probability wave spreading through first the box, then the room, and finally collapsing into an electron at the moment of observation. A different approach however, is to suggest that at the moment of observation both (or all, as the case may be) possibilities become realities. This is achieved by the creation of an alternate universe, in which the cat is in the opposite state to the cat in our universe. A refinement of this theory suggests that there are always two universes involved, but prior to the experiment they are identical in all respects. If three different experimental outcomes are possible, then we would have three initially identical universes, one of which would change. In general, we would need an infinite number of universes to cover all possibilities. When we were looking at the section 'can anything real be infinite?' we discovered that if the universe were infinite in size then every possibility of every possible outcome would exist within the universe. Perhaps the universe IS infinite?

We have looked at some of the problems associated with time travel, it is now time to look at the laws of physics.

Quantum theory

We shall now study another aspect of quantum theory, one that is directly related to time travel, and learn that particles can travel backwards in time!

We can look at an event that begins with a photon and an electron, and ends with a photon and an electron. We can say that what has taken place is a photon is absorbed by an electron, the electron continues on a bit, and a new photon comes out. This process is called the scattering of light. When calculations are made for scattering, we must include some peculiar possibilities. For example, the electron could emit a photon before absorbing one. Even more strange is the possibility that the electron emits a photon, then travels backwards in time to absorb a photon, and then proceeds forwards in time again. The path of such a 'backwards-moving' electron can be so long as to appear real in an actual physical experiment in the laboratory. The backwards-moving electron when viewed with time moving forwards appears the same as an ordinary electron, except it's attracted to normal electrons - we say it has a 'positive' charge. For this reason it's called a 'positron'. The positron is a sister particle to the electron, and is an example of an 'anti-particle'. This phenomenon is general. Every particle in Nature has an amplitude to move backwards in time, and therefore has an anti-particle. When a particle and its anti-particle collide, they annihilate each other and form other particles.

We have now learned that time travel is not only possible, it is a perfectly normal phenomenon, at least for particles. But is it possible in the macroscopic world?

Einstein's theory of relativity

Black holes, according to relativity theory, warp spacetime with their enormously powerful gravitation field. The effect of this gravitational field is that if an astronaut were to cross the event horizon of a black hole, time would slow down on board his spacecraft as he approached the singularity and eventually come to a stop. Similarly time slows down in proportion to speed, the faster our astronaut travels the slower time runs. The closer the astronaut travels to the speed of light the more time slows, until at the speed of light, time would stop. Both these effects of time being affected by speed and gravity have been discussed in the previous section, all of which illustrates that time is not a fixed constant, but is affected by gravitational fields and relative speed in the same manner as the other three dimensions of space.

The solutions to particular equations of the Special Theory of Relativity can be expressed mathematically in any direction of time without running into any problems. Does this mean that time travel is possible? There is nothing in relativity that rules out time travel, it would appear to be theoretically possible.

Constructing a time machine

Research carried out in the late 1980's showed that genuine time travel is not forbidden by the known laws of physics. This means that it may be possible to build a time machine, but not that it may be easy. Help may be at hand though, it is possible there are naturally occurring objects in the universe that act as time machines.

There are at least two ways to build a time machine. Frank Tipler published a possibility in the highly respected journal Physical Review in 1974. This involves making a naked singularity, a singularity that is not concealed from view behind the event horizon of a black hole. To make a naked singularity involves rotating a singularity extremely rapidly, and if rotated sufficiently fast it would fling away the event horizon and exposes the singularity. We know that spacetime is extremely distorted by the singularity's strong gravitational field and the effect of this rotation would be to twist spacetime, and tip it over so that one of the dimensions of the space dimensions is replaced by the time dimension. A carefully piloted spaceship taken close to the singularity would enter the time dimension and journey through time instead of space, although to the astronauts all would appear as normal. When the spaceship moved away from the distorted area around the singularity, it would be in a different time from when they had entered the area.

According to Tipler's calculations, the same effect could be achieved with a cylinder about 100 km long and about 10 km across, made of material compressed to just over the density of a neutron star, and rotating twice every millisecond. It would be like ten neutron stars joined pole to pole and given a strong twist. Curiously, there are objects in the universe which nearly fulfill the other requirements - so-called millisecond pulsars are known which contain almost the right density of matter and spin once every 1.5 milliseconds, at one-third the speed needed to make a time machine. Such objects are so close to being time machines that they hold out the tantalising possibility that an advanced civilisation might be able to tweak them up in the right way to allow time travel.

That such things as naturally occurring time machines exist in the universe, with only a little tweaking needed, raises the prospect that an advanced civilisation may have already done the trick! This raises the interesting possibility that such a civilisation would have the capacity to travel between the galaxies; a journey of a few million light years would be as nothing. Something for the UFO brigade to mull over!

The other possibility for building a naturally occurring time machine involves worm holes - tunnels through spacetime which may, according to relativity, connect a black hole in one part of the universe to a black hole in another part of the universe. Before the mid-1980's physicists believed that such objects as wormholes could not 'really' exist, and that a better understanding of Einstein's equations would prove this. They were forced to change their minds as a result of careful investigation of wormholes carried out by Kip Thorne and his colleagues at Caltech in 1985. It is interesting to note that this research was triggered by Carl Sagan, a well known scientist, who was writing the science fiction novel 'Contact', a best seller that went on to become a highly successful film. Sagan wanted his wormhole to be as scientifically accurate as possible and approached Thorne to check out the idea as presented in the book. What neither Sagan nor Thorne first realised from the results of Thorne's study was that this short-cut through space would also work as a short-cut through time. In 1988 Morris, Thorne and Yurtsever (Morris and Yurtsever were students of Thorne) published their conclusions in the journal Physical Review Letters, that Einstein's equations really did allow for the existence of wormholes that link different times, and could be used as time machines.

We have seen that the laws of physics do not preclude the possibility of time travel, and further, that it may be possible to construct a time machine by tweaking naturally occurring objects in the universe. It would appear that we only need the technology to make time travel a reality.

What do I think?

Regardless of the theories, I cannot believe that time travel will ever be possible. My main reason for this is because we have recorded history and we know what events happened in the past, and in our own recent past we even have our own memories of past experiences. If time travel were possible then we could not have a recorded history because it would be constantly changing. I can remember, for example, the day when Neil Armstrong set foot on the Moon, the first man to do so. If time travel were possible it would be possible to travel back through time and prevent that event from taking place. It would, for example, be possible for a Russian to travel back through time armed with the technical knowledge necessary to land on the Moon and give it to the Russians years before the Americans achieved it. That act would change history. After that it would then be possible for an American to travel back in time and prevent the Russians from using that information, and so on, and so on. History, however, is not subject to change, it remains constant, if it did change then it would not be history! In order to have a past that past must be unalterable, if it were subject to change then we may not be born to observe it, but we are here observing it. The following quote sums it up rather well I think - "This only is denied to God: the power to undo the past." Agathon (448 BC - 400 BC), from Aristotle, Nicomachean Ethics.

It has been argued that perhaps time travellers from the future have visited us, but being aware of the dangers of interfering with the past - that could have dire consequences for their future - they only observe in secret and do not interfere. However, it should be clearly understood that this policy of 'non-interference' does not help the situation at all. Imagine that today no time travellers have yet come back from the future to visit us. Now imagine that at some future time they do come back to today and visit us. Even though they may only be observing for a few minutes and then return to their own time, they have still changed the course of history. In the first instance no time travellers had visited us, but in the second instance they had. This alone has changed history, it doesn't matter whether or not anybody knew they were there, or if they physically changed anything or not, the fact is they were there. So what happened to our 'original' history, the 'today' with no visiting time travellers? It has been removed from history and never happened - but the problem is we know it did happen! Does this mean that when history is changed our memories are changed as well? Perhaps I only think that my memory of Armstrong walking on the moon has never changed, but in reality it may have been changed many times. I don't think so though, because it is recorded history, it is written down in black and white, and how could that change? Unless it has changed every time of course and I only think it is permanent? This is leading us on to the alternative universe theory, as it is beginning to sound a lot like it.

The alternative universes theory was designed to overcomes the problems of altering history, which of course cannot be altered. It is my opinion however, that this theory is an extremely complicated concept only offered up as a way of getting round a very real problem - that of changing history and associated paradoxes - and is based on strange phenomenon found only in the quantum world - which is not at all understood - and for which we have absolutely no evidence for being applicable in the larger world. Furthermore, I have yet to find any explanation of where all the matter and energy would come from that mysteriously creates all these very convenient alternative universes. I am also puzzled as to what would constitute a choice of outcomes that would generate a universe for every possible outcome. I can understand a photon being 'forced' by observation to go through either one slit or another, and this generating two possible outcomes both of which require its own universe, but what of other examples of a choice of outcome? What about my turning left at a road junction instead of right, does that create an alternative universe? Or what if I said 'yes' instead of 'no' when asked if I liked the colour pink, would that create an alternative universe? You can see where I am going here, if every choice resulted in an alternative universe, then the number of alternative universes created would be infinite and ever increasing at an infinite rate as all those alternative universes created their own alternative universes, and so on ad infinitum. All this just to avoid paradoxes! I think not.

I really cannot see how time travel could ever become a reality, for if it were possible it would have already happened, if you see what I mean? The only method I can envisage as workable, or possible, is to put a person into a state of suspended animation in order to arrive, eventually, at the future, because I don't think the future is already 'out there', I suspect it has to develop moment by moment.

Quantum theory is bizarre. In order to try and understand it we need to forget everything we know about cause and effect, reality, certainty, and much else besides. This is a different world, it has its own rules, rules of probability that make no sense in our everyday world. Richard Feynman, the greatest physicist of his generation, said of quantum theory

'It is impossible, absolutely impossible to explain it in any classical way'.

Quantum theory is much more than just bizarre, it is also without doubt the most amazing theory in existence. If after reading this section you are not totally amazed by it, then the fault will be mine, for I will have failed to reveal to you its deep underlying significance. This theory is not just about experiments and equations, it reveals something extraordinary about our very understanding of what constitutes reality.

This is a very complex theory, and in order to fully do it justice it would require at least a fair sized book. However, in order to grasp the basic principles involved it will suffice to study just three key experiments. The three experiments are generally known as: the 'Double Slit Experiment', Schrödinger's 'Cat-in-the-Box Experiment' and the 'EPR Paradox'.

We will start with the famous double slit experiment as it demonstrates beautifully the central mystery of quantum theory. Quantum theory however, needs some introduction before we get too involved in the experiment.

The standard explanation of what takes place at the quantum level is known as the Copenhagen Interpretation. This is because much of the pioneering work was carried out by the Danish physicist Niels Bohr, who worked in Copenhagen. Quantum theory attempts to describe the behaviour of very small objects, generally speaking the size of atoms or smaller, in much the same way as relativity describes the laws of larger everyday objects. We find it necessary to have two sets of rules because particles do not behave in the same way as larger everyday objects, such as billiard balls. We can, for example, say precisely where a billiard ball is, what it is doing, and what it is about to do. The same cannot be said for particles. They are, quite literally, a law unto themselves, and why this should be so is a source of much debate. The classic experiment to illustrate this is the famous double slit experiment, originally devised to determine if light travels as waves or particles. Feynman said of it:

'Any other situation in quantum mechanics, it turns out, can always be explained by saying, "You remember the case of the experiment with the two holes? It's the same thing."'

The double slit experiment.

If light travels as particles we can imagine particles of light (photons) as bullets fired from a rifle. Imagine a brick wall with two holes in it, each the same size and large enough to fire bullets through, with a second wall behind where the bullets will strike. After firing a few rounds you would expect to see on the second wall two clusters of hits in line with the two holes. This is of course precisely what you get with bullets, so if we get the same result with photons we can say they are particles.

Now imagine that instead of particles, that light travels as a wave, we can replicate that with a water tank. As the wave spreads out from its source it would reach both holes at the same time and each hole would then act as a new source. Waves would then spread out again from each of the holes, exactly in step, or in phase, and as the waves moved forward, spreading as they go, they would eventually interfere with one another. Where both waves are lifting the water surface upward, we get a more pronounced crest; where one wave is trying to create a crest and the other is trying to create a trough the two cancel out and the water level is undisturbed. The effects are called constructive and destructive interference.

If we carried out this procedure with light instead of water, and if light travels as waves, then the pattern on the second wall would appear as an interference pattern of alternate dark and light bands across the wall. Particles, on the other hand, would produce two separate areas of light (where the bullets would hit). This experiment has in fact been carried out many, many times, with the same results every time, and the results are nothing less than amazing.

When the experiment is set up as shown in the above diagram, with both slits open, the resulting interference pattern clearly shows that light behaves as a wave. Now if that was all there was to it we could all fold up our tents and go home happy in the knowledge that light travels as a wave; but there is much more to it than that. This is where the word 'weird' can become over-used.

If the experiment is set up to fire individual photons, so that only one photon at a time goes through the set up, we would not expect the same interference pattern to build up; we would surely expect that a single photon would only go through one hole or another, it cannot go through both at the same time and create an interference pattern. So what happens?

If we wait until enough individual photons have passed through to build up a pattern - and this takes millions of photons - we do not get two clusters opposite the two holes, we get the same interference pattern! It is as if each individual photon 'knows' that both holes are open and gives that result. Each individual photon, passing through the set up will place itself on the wall in such a position that when enough have passed through they have collectively built up an interference pattern, when there cannot possibly be any interference!

If we repeat the experiment, this time with only one hole open, the individual photons behave themselves and all cluster round a point on the detector screen behind the open hole, just as you would expect. However, as soon as the second hole is opened they again immediately start to form an interference pattern. An individual photon passing through one of the holes is not only aware of the other hole, but also aware of whether or not it is open!

We could try peeking, to see which hole the photon goes through, and to see if it goes through both holes at once, or if half a photon goes through each hole. When the experiment is carried out, and detectors are placed at the holes to record the passage of electrons through each of the holes, the result is even more bizarre. Imagine an arrangement that records which hole a photon goes through but lets it pass on its way to the detector screen. Now the photons behave like normal, self respecting everyday particles. We always see a photon at one hole or the other, never both at once, and now the pattern that builds up on the detector screen is exactly equivalent to the pattern for bullets, with no trace of interference. As if that was not bad enough, it gets even worse! We do not need place detectors at both holes, we can get the same result by watching just one hole. If a photon passes through a hole that does not have a detector, it not only knows if the other hole is open or not, it knows if the other hole is being observed! If there is no detector at the other hole as well as the one it is passing through, it will produce an interference pattern, otherwise it will act as a particle. When we are watching the holes we can't catch out the photon going through both at once, it will only go through one. When we are not watching it will go through both at the same time! There is no clearer example of the interaction of the observer with the experiment. When we try to look at the spread-out photon wave, it collapses into a definite particle, but when we are not looking it keeps its options open.

What the double slit experiment demonstrates is this: Each photon starts out as a single photon - a particle - and arrives at the detector as a particle, but appears to have gone through both holes at once, interfered with itself, and worked out just where to place itself on the detector to make its own small contribution to the overall interference pattern. This behaviour raises a number of significant problems! Does the photon go through both holes at the same time? How does a photon go through both holes at the same time? How does it know where to place itself on the detector to form part of the overall pattern? Why don't all the photons follow the same path and end up in the same place?

As a possible explanation it could perhaps be said that this is just one more example of the extraordinary nature of light, after all it does have some very unusual properties. Photons have no rest mass for example, a very odd property! Light is also unique in that it always travels at the same speed. However you move, and however the light source moves, when you measure the speed of light you always come up with the same answer. By way of comparison, two cars approaching each other and each having a speed of 30 mph will be approaching each other at a speed of 60 mph. Two light beams, both travelling of course at the speed of light, will be approaching each other at the speed of light, not twice the speed of light. Perhaps the weird behaviour of photons in the experiment is due to the weird nature of light. Unfortunately further experiments have demonstrated that this is not the case. Electrons have been used instead of photons, and they not only have mass, they have an electric charge, and furthermore they move at different speeds depending on circumstances, like normal everyday objects. The double slit experiments still gives the same result using electrons as it does using photons; electrons also alter their behaviour depending on whether or not they are being observed. The experiment has even been performed using atoms, again with the same result, and atoms are large enough to be individually photographed, they are very real solid objects. This odd behaviour of particles is a very real phenomenon.

The double slit experiment is not simply an oddball theory that has no application in the real world. This strange behaviour of particles lies at the very heart of our understanding of the physical properties of the world. Quantum theory is used in many applications, including television and computers, and even explains the nuclear processes taking place inside stars.

One possible explanation for quantum weirdness is a theory concerning the nature of the wave that is passing through the experiment. The key concept of the theory, which forms a central part of the Copenhagen Interpretation, is known as the 'collapse of the wave function'. The theory seeks to explain how an entity such as a photon or an electron, could 'travel as a wave but arrive as a particle'. According to the theory, what is passing through the experiment is not a material wave at all, but is a 'probability wave'. In other words, the particle does not have a definite location, but has a probability of being here or there, or somewhere else entirely. Some locations will be more probable than others, such as the light areas in the interference pattern for example, and some will be less probable, such as in the dark areas. In this theory, an electron that is not being observed does not exist as a particle at all, but has a wave-like property covering the areas of probability where it could be found. Once the electron is observed, the wave function collapses and the electron becomes a particle. This theory rather neatly explains the behaviour of the particles in the double slit experiment. When we are not looking at the particle, the probability wave, of even a single particle, is spread out and will pass through both slits at the same time and arrive at the detector as a wave showing an interference pattern. When we observe the electron by placing detectors at the slits, it is forced into revealing its location which causes the probability wave to collapse into a particle. If the theory is correct, its implications are staggering. What it suggests is that nothing is real until it has been observed!

Nothing is real until it has been observed! This clearly needs thinking about. Are we really saying that in the 'real' world - outside of the laboratory - that until a thing has been observed it doesn't exist? This is precisely what the Copenhagen Interpretation is telling us about reality. This has caused some very well respected cosmologists (Stephen Hawking for one) to worry that this implies that there must actually be something 'outside' the universe to look at the universe as a whole and collapse its overall wave function. John Wheeler puts forward an argument that it is only the presence of conscious observers, in the form of ourselves, that has collapsed the wave function and made the universe exist. If we take this to be true, then the universe only exists because we are looking at it. As this is heading into very deep water I think we will have to leave it there and move on to the next experiment.

Schrödinger 's 'Cat-in-the-Box Experiment'

According to the Copenhagen Interpretation, the probability wave of an electron requires the act of observation by a conscious observer to collapse it into a definite particle, and thus have a definite location. We can imagine a closed box containing just a single electron. Now until someone looks in the box, the probability wave associated with the electron will fill the box uniformly, thus giving an equal probability of finding the electron anywhere inside the box. If a partition is introduced into the middle of the box that divides it into two equal boxes, still without anyone looking inside, then common sense tells us that the electron must be in one side of the box or the other. But this is not the case according to the Copenhagen Interpretation; that says that the probability wave is still evenly distributed across both half-boxes. This means that there is still a 50:50 chance of finding the electron in either side of the box. When somebody looks into the box the wave will then collapse and the electron will be noticed in one half of the box or the other, but it will only at the moment of observation 'decide' which half it will be in. At the same time the probability wave in the other half of the box vanishes. If the box is then closed up again, and the electron no longer observed, its probability wave will again spread out to fill the half box, but cannot spread back into the other half of the box that was empty.

The way that a quantum wave moves is described by Erwin Schrödinger's wave equation and describes the probability for finding a photon, or electron, at a particular place. Schrödinger did not however, go along with the 'collapse of the wave function' theory, he thought it was a nonsense, and designed 'thought experiments' to prove his point. In an attempt to demonstrate the foolishness - as he saw it - of quantum theory, Schrödinger devised the cat-in-a-box thought experiment.

In Schrödinger 's original thought experiment he used radioactive decay because that also obeys the rules of probability. We however, shall use our box with the partition and electron again, as we are now familiar with it.

Imagine we have our box with the partition in place, and the electron's probability wave evenly spread between both halves of the box. We have now added a device that will, at a given time, automatically open up one half of the box to the room. There is a 50:50 chance that when opened the box will contain the electron that is now free to enter the room. The room is sealed and has no windows that would allow any outside observations to be made. Inside the sealed room there is a cat, a container of poisonous gas, and an electron detector. The experiment is so designed that if the electron detector detects an electron it will release the poisonous gas into the room, which would prove very unfortunate for the poor cat. If, on the other hand, that half of the box does not contain the electron, the poisonous gas will not be released into the room and our cat, henceforth known as Lucky, will continue to enjoy good health, providing it keeps away from busy roads.

Taking a common sense view of the situation, we would say that when the experiment has run its course, and an observer enters the room, they will find the cat either dead or alive. But we already know enough about quantum theory to realise that common sense doesn't apply here, and instead we have to turn to the Copenhagen Interpretation for an explanation.

According to the Copenhagen Interpretation, when the lid of one half of the box is opened, it is not an electron, or not as the case may be, that is released into the room, but the probability wave of the electron as it has not yet been observed. This raises the question of whether or not the cat can be regarded as a conscious observer. If it can be then where do we draw the line? Would a fly or an ant count? How about a bacterium? As this is again getting into rather deep and murky water, we will skip over this problem and continue with our experiment, otherwise we run the risk of becoming seriously side-tracked. So the probability wave spreads into the room, not an electron (or no electron). The electron detector is itself composed of microscopic entities of the quantum world (atoms, particles and so on) and the interaction of the electron with it would take place at this level, so the detector is also subject to the quantum rules of probability. Taking this view, the wave function of the whole system will not collapse until a conscious observer enters the room. At that moment the electron 'decides' whether it is inside the box or in the room, the detector 'decides' whether it has detected an electron or not, and the cat 'decides' whether it is dead or alive. Until that moment, according to the Copenhagen Interpretation, the cat is not either dead or alive, it describes the situation as a 'superposition of states'. Only the act of observation will cause it to become one or the other. Schrödinger described the situation as 'having in it the living and the dead cat mixed or smeared out in equal parts.' The Copenhagen Interpretation does not allow for the room to actually contain a cat that is both dead and alive at the same time, or a cat that is neither dead nor alive, suspended in limbo. But contains either a dead cat or a live cat, until someone looks, and it is then that the actual reality of the situation is determined.

Cat lovers please note. This experiment has never been carried out, and never will be. This is not only because it would be a very cruel thing to do, but because it wouldn't prove anything. An observer upon entering the room would find either a dead cat or a living one, but could not observe what processes preceded this event. Any previous observation would of course defeat the object of the experiment.

The problems highlighted by the cat-in-a-box experiment raise some very deep questions. What for example are the requirements needed to qualify as a 'conscious observer'? Do the probability waves of particles spread out again when not observed and particles somehow become less 'real', as described by the Copenhagen Interpretation? Does the universe exist only because we are here to observe it? Could a cat really be in a 'superposition of states', either dead or alive until the moment of observation? This goes entirely against all our common sense experience of life, we would naturally conclude upon finding the cat alive that it had 'obviously' been alive all the time. Quantum theory is telling us that we could be very wrong in our thinking regarding what reality really is.

Quantum theory has yet another surprise in store for us, and this time it's not simply another bizarre phenomenon that challenges our common sense. This time it contradicts one of the central principles of Einstein's theory of relativity, that nothing can travel faster than the speed of light. As you can imagine, Einstein was not amused.

The EPR Paradox.

The experiment is so named because it was a thought experiment devised by Einstein, Boris Podolsky and Nathan Rosen. As with Schrödinger's cat-in-the-box experiment, its purpose was to expose the 'foolishness' of the Copenhagen Interpretation. The experiment focuses on the phenomenon of quantum theory known as 'non-locality', which concerns communication between particles. A pair of protons, for example, associated with one another in a configuration called the singlet state will always have a total angular momentum of zero, as they each have equal and opposite amounts of spin. Just as we have seen in the other experiments, the protons will not collapse their probability wave and 'decide' which spin to adopt, until they have been observed. If you measure the spin of one proton, according to quantum theory, the other proton instantly 'knows' and adopts the opposite spin. So far so good, we have come to expect this sort of behaviour from particles, so what is the problem with this particular experiment?

It is possible, and has been carried out in laboratory tests over a short distance, to split the particles apart and send them in opposite directions and then measure one of them for spin. The instant it is measured, and the spin determined, the other particle adopts the opposite spin. The time interval is zero, the event takes place instantaneously, even though the particles are separated, and theoretically would still do so even if they were separated by a distance measured in light years. This is what upset Einstein, the implication that particles could communicate at faster than light speed, as it is impossible for this to happen according to Einstein's theory of relativity.

At the time this thought experiment was proposed, in the early 1930's, just about the time of Schrödinger's cat-in-the-box thought experiment, it was not actually possible to physically carry out the experiment. Einstein did not live to see it turned into practical reality, which is probably just as well in light of the results produced. This experiment has now actually been carried out over a distance of 10 kilometres and confirmed as correct. Something here is taking place at faster than light speed, although exactly what seems to be a matter of some debate. Regrettably, due to its very nature, no meaningful communication could be made using such a device. Whether or not it will ever have any useful application remains to be seen, but that is not the point. The point is the experiment has proved Einstein wrong, faster than light speed, at least in the quantum world, is a reality. However, in classical physics - at sizes above that of atoms - relativity still remains unchallenged, nothing has been detected at faster than light speed.

As I said at the outset of this section, these three experiments highlight the basic principles involved in quantum theory. I also said they would amaze you, and I hope that you feel that I have kept my word. If you are not amazed by quantum theory, then blame me, for the theory is truly amazing and any disappointment you may have with it can only be due to my inability to do the theory justice.

One last thing you need to know about quantum theory, and that is Heisenberg's Uncertainty Principle. Heisenberg said that the electron was a particle, but a particle which yields only limited information. It is possible to specify where an electron is at a given moment, but we cannot then impose on it a specific speed and direction at the setting-off. Or conversely, if you fire it at a known speed in a certain direction, then you are unable to specify exactly what its starting-point is - or its end-point. The information that an electron carries is limited in its totally. That is, for instance, its speed and its position fit together in such a way that they are confined by the tolerance of the quantum.

The principle of Uncertainty fixed once for all the realisation that all knowledge is limited, that there is no such thing as absolute certainty.

What conclusions can we draw from these experiments?

We need to be very careful in drawing any conclusions from the results of these experiments. All we can say with any confidence is that if we set up the apparatus in a certain way it will produce a certain result. How we interpret those results, the meanings that we attach to them, is nothing more than our way of attempting to make sense of them, and need have no relationship at all to the actual reality of the situation. To imagine that a probability wave passes through both slits in the double slit experiment helps us to understand what may be happening, but it is in fact nothing more than proposing an idea that meets the criteria of what has been observed; there may be no such thing as a probability wave. It may be the case that we are completely missing some fundamental property of particles, a property that as yet remains undetected by our equipment and experiments. There may be things going on that we are completely unaware of.

What quantum mechanics tell us is that nothing is real and that we cannot say anything about what things are doing when we are not looking at them. In the world of quantum mechanics, the laws of physics that are familiar from the everyday world no longer work. Instead, events are governed by probabilities. Einstein was so disgusted by the whole notion that he made his famous remark, "Quantum mechanics is very impressive. But an inner voice tells me that it is not yet the real thing. The theory produces a good deal but hardly brings us closer to the secrets of the Old One. I am at all events convinced that He does not play dice".

What do I think?

It seems illogical that we need two completely different laws to explain the behaviour of objects, dependent on how large or small the object is. Why is it that the laws of cause and effect, that work so well in the everyday world, breakdown in the world of the very small, when everything in the everyday world is made up of the very small?

It just does not make any sense, but like it or not, until a theoretical physicist comes up with a theory that incorporates both Quantum Mechanics and Relativity we just have to admit that we do not really know what is going on. However, one thing I am absolutely clear on is that an electron, or photon, doesn't 'know' anything, anymore than a frozen pea does. When you remove a frozen pea from the freezer and place it in a warm room you do not gasp in amazement when it defrosts and ask how did it 'know' to defrost. You do not try and trick it into not defrosting by leaving it in the freezer and turning off the freezer. This is of course because we understand the laws of thermodynamics. Particles do not 'know ' anything!

When physicists ask the question, 'how does a particle 'know' something'? they are of course using the term loosely. What they are really asking is 'what are the forces acting upon the particle that we have not detected? What interactions are taking place that we have not detected?'

That is the problem. Something is going on at a level that we are completely unaware of. However, the idea of probability waves as an explanation is nothing more than an attempt to describe what is observed in the quantum world by the Copenhagen Interpretation, and is of course a purely theoretical concept.

It may be possible that we need to develop a new form of logic to be able to describe what is happening at the quantum level. It may be that it is not enough to say that a statement is either true or false, we may have to introduce a three-valued quantum logic which allows the additional status of 'undecided'. This would mean that a statement that is not true need not be false.

Reference research

Allen, B. & Simon, J. (1992, May 7). Time travel on a string. Nature, 357, 19-21.

Allman, W. F. (1988, December 19) Playing fast and loose with time. U.S. News and World Report, 105, 62.

Clark, C. J. S. (1990, November 22). Opening a can of wormholes. Nature, 348, 287-88.

Davidson, M. (1990, January). Is time travel possible? U.S.A. Today, 118, 60-67.

Davies, P. (1992, January). Wormholes and time machines. Sky & Telescope, 83, 20-21.

Deutsch, D. & Lockwood, M. (1994, March). The quantum physics of time travel. Scientific American, 270, 68-74.

Freedman, D. H. (1989, June). Cosmic time travel. Discover, 10, 58-64.

Gribbin, J. (1983). Spacewarps. New York: Delacorte.

Hawking, S. W. (1993). Black holes and baby universes. New York: Bantam.

Hawking, S. W. (1988). A brief history of time. New York: Bantam.

Lemonick, M. D. (1991, May 13). How to go back in time. Time, 137, 74.

Lemonick, M. D. (1989, January 16). Wormholes in the heavens. Time, 155, 55.

Macvey, J. W. (1990). Time travel. Chelsea, MI: Scarborough.

Mukerjee, M. (1994, February). Time-trippers beware. Scientific American, 270, 32.

Parker, B. (1991). Cosmic time travel. New York: Plenum.

Peterson, I. (1992, March 28). Timely questions. Science News, 141, 202-03.

Travis, J. (1992, April 10) Could a pair of cosmic strings open a route into the past? Science, 256, 179-80.

"Wormholes and Time Machines." (1988, November 5). Science News, 134, 302.

"Wormholes, Time Machines and Schrödinger's Cat." (1989, February). Sky & Telescope, 77, 132.

GnomeXGurl
ParaCrypt RSG

Dejavu from other perspective

THREE TYPES OF DEJA VU

By Arthur Funkhouser, Ph.D., Bern, Switzerland

The term 'deja vu' has been around quite a while, now, and, in the last few years has become practically a
buzz-word, being often found in books, newspaper accounts and magazine articles concerned with a wide variety
of topics (I have amassed quite a collection, should anyone wish to see them). The problem is, though, that while
many see fit to employ it in their writing and conversation, just exactly what is meant by the words 'deja vu' is
pretty vague. Many, based on their own experience, believe it must refer to what they encountered and/or felt,
while others, having never had such experiences, have a very foggy notion of what is meant, if at all. As such, it
has become a sort of catch-all label for any number of hard-to-explain, sometimes upsetting occurrences of
unexpected recognition, in which the person involved has trouble identifying an antecedent for the events and/or
places which seem so strangely and intensely familiar.

In addition, the term 'deja vu' has become encrusted, over the years, with a number of unfortunate associations,
ranging from reincarnation to temporal lobe epilepsy, which hinder further research. These 'explanations' along
with others such as delayed intra-hemisphere transmission over the corpus callosum as well as an astonishing array
of psychoanalytical theories lead people to believe that all that one needs to know about such experiences is
already known and that there is nothing of interest still to be done.

I believe the time has come, therefore, for our terminology, especially in educated discourse, to become more
differentiated (in fact, if I had my way, we would get rid of 'deja vu' altogether as over-worked and entitled to a
well-deserved rest). To this end, I would like to draw attention to three forms of 'deja' experience, defining each
as we go along, and plea that these be used when discussing the experiences they refer to. Upon reflection,
readers may come up with other, better terms for these experiences or propose terms for other, related
experiences which are not the same as the ones described in the following. Since French scientists and thinkers
were the first to investigate these phenomena, it seems fitting to retain French names for these intriguing
experiences.

1. Deja vecu (already experienced or lived through)

A fairly well-known quote from David Copperfield by Charles Dickens can be used to introduce what is meant by
deja vecu,

We have all some experience of a feeling, that comes over us occasionally, of what we are saying and doing
having been said and done before, in a remote time - of our having been surrounded, dim ages ago, by the
same faces, objects, and circumstances - of our knowing perfectly what will be said next, as if we suddenly
remember it! (chapter 39)

This describes the feeling that many people know as deja vu (if they know a name for it). A number of surveys
have shown that about one third of the general population have had such or similar experiences. Moreover,
surveys have indicated that such experiences tend to occur more frequently and possibly more intensely when the
respondents were young, say between ages 15 to 25. In addition, such experiences are frequently, if not always,
connected with very banal events. They are so striking, though, that they are often clearly remembered for years
following their occurrence.

Anyone having had such experiences knows that they normally involve more sense modalities than just sight. As in
the Dickens quotation, they can easily involve hearing, tasting, touch and/or proprioceptive perceptions as well.
This is why referring to such experiences as simply deja vu is inadequate.

Another feature of deja vecu that most would agree with is the amazing detail involved. When you are in the midst
of such an occurrence, you are conscious that everything conforms with your 'memory' of it. This is why
explanations which suggest that the person has read about or experienced something similar in the past cannot be
valid. Moreover, this is why explanations based on reincarnation and past lives can also be ruled out. A typical
deja vecu experience can easily involve clothing or even a PC, but styles of clothing change practically every year
and it is rather unlikely that someone had a PC on his or her desk in a previous life!

If incidences of deja vecu can be taken as being real, our notions of causality may have to be revised in some
ways. It does not seem to be difficult, though, for modern physicists to entertain notions of time loops, tachyons
(particles that can travel backwards in time) and multiple universes. That our unconscious would then be able to
avail itself of such anomalies and present us with precognitive knowledge via visions and dreams, is then not so
farfetched as it might seem at first glance.

2. Deja senti ('already felt')

I would like to turn now to a phenomena that is often confused with deja vecu. To introduce it, I would like to
quote from an 1889 paper by Dr. John Hughlings Jackson, one of the foremost pioneers of modern neurology. In
the words of one of his patients, a medical doctor suffering from what has come to be known as temporal lobe or
psychomotor epilepsy, he wrote:

What is occupying the attention is what has occupied it before, and indeed has been familiar, but has been
for a time forgotten, and now is recovered with a slight sense of satisfaction as if it had been sought for. ...
At the same time, or ... more accurately in immediate sequence, I am dimly aware that the recollection is
fictitious and my state abnormal. The recollection is always started by another person's voice, or by my
own verbalized thought, or by what I am reading and mentally verbalize; and I think that during the
abnormal state I generally verbalize some such phrase of simple recognition as 'Oh yes - I see', 'Of course -
I remember', &c., but a minute or two later I can recollect neither the words nor the verbalized thought
which gave rise to the recollection. I only find strongly that they resemble what I have felt before under
similar abnormal conditions.

This state, which sometimes appears in the aura of temporal lobe epilepsy attacks, Jackson termed 'reminiscence'
and I believe could be best termed deja senti. Three features are evident from this description, however, that
distinguish it from deja vecu: a. it is primarily or even exclusively a mental happening; b. there are no precognitive
aspects in which the person feels he or she knows in advance what will be said or done; and c. it seldom or never
remains in the afflicted person's memory afterwards.

A book has recently appeared which has temporal lobe epilepsy as its main focus. In it, the author mentions deja
vu as being a symptom of psychomotor epilepsy, a contention that also persists in most medical and psychiatric
textbooks and which would seem to be based on this and other remarks by Dr. Jackson. The book quotes a
neuropsychologist named Paul Spiers who told students at a lecture that if they had had deja vu experiences, they
were epileptics! This sort of nonsense continues at least in part because, up till now, our terms have been so
poorly defined and this has hampered making adequate surveys which distinguish between the various deja
phenomena.

3. Deja visite ('already visited')

There is another phenomena which is also often confused with deja vecu. It seems to occur more rarely and is an
experience in which a person visits a new locality and nevertheless feels it to be familiar. He or she seems to know
their way around. C. G. Jung published an interesting account of it in his paper on synchronicity. To distinguish it
from deja vecu, it is important to ask whether it was purely the place and location of inanimate buildings and/or
objects that were familiar, or did the situation that the person was in also play a role. Deja viste has to do with
geography, with the three spatial dimensions of height, width and depth, while deja vecu has to do more with
temporal occurrences and processes.

Deja visite can be explained in several ways. It may be that the person once read a detailed account of the place
and has subsequently forgotten it. This happened to Nathaniel Hawthorne on a visit he made to the ruins of a
castle in England. He 'recognized' the place but didn't know how or why. Only later was he able to trace it to a
piece written two hundred years earlier by Alexander Pope about it. The incident ofdeja visite described by Sir
Walter Scott in his book, Guy Mannering, is also based on this hypothesis. Reincarnation might also offer a way of
explaining some instances of deja visite. A third possibility are so-called 'out-of-the-body' experiences in which a
person is apparently able to travel abroad, leaving his or her body behind.

It is possible that mixed versions of these three forms of 'deja' experience may occur. There are also several other
phenomena which resemble these in various ways, but space does not permit going into them here. Those wishing
to know more and explore the various aspects of deja phenomena more deeply are referred to the excellent
overview in the book by Neppe.

References

FUNKHOUSER, AT (1983) 'A historical review of deja vu'. Parapsychological Journal of South Africa, 4:
11-24.

CHAPMAN AH, MENSCH I.W. (1951-52) Deja vu experience and conscious fantasy in adults'.
Psychiatric Quarterly Suppl. 163-175.

RICHARDSON T.F., WINOKUR G (1967)'Deja vu in psychiatric and neurosurgical patients'. ,Archives
of General Psychiatry 1 7: 622-626.

PALMER J, DENNIS M (1979) 'A community mail survey of psychic experiences. Journal of the
American Society of Psychical Research VON FEUCHTERSLEBEN, E. Freiherr (1845) Textbook of
Medical Psychology, 255-256.

DEUTSCH D, LOCKWOOD M (March, 1994)'The quantum physics of time travel'. Scientific American,
2 7 0: 50-56.

CHESTER M (1978) Particles:,An Introduction to Particle Physics. MacMillan, New York.

DEWITT B.S., GRAHAM N (1973) The Many-Worlds Interpretation of Quantum Mechanics. A
Fundamental Exposition. Princeton University Press.

RYBACK D, SWEITZER L (1988) Dreams That Come True, Ballantine Books, New York.

FUNKHOUSER AT (1983)'The 'dream' theory of deja vu'. Parapsychological Journal of South Africa, 4:
107-123.

JACKSON J.H. (1888) 'A particular variety of epilepsy "intellectual aura", one case with symptoms of
organic brain disease'. Brain 11:179-207.

LAPLANTE E (1993) Seized, Harper Collins, New York.

JUNG CG (1966) On synchronicity. Collected Works, Bollingen Series, Princeton University Press, Vol.
8, para. 973.

HAWTHORNE N (1863) Our Old Home. Houghton Mifflin & Co., Boston.

SCOTT, W (1815) Guy Mannering or The Astrologer. J. Ballantyne & co. Edinburgh. Chap. 4 1.

NEPPE V (1983) The Psychology of Deja Vu. Witwatersrand University Press, Johannesburg.

This article originally appeared in the Scientific and Medical Network Review, 57:20 - 22, 1995 and is
republished here with permission.

APA Reference
Funkhouser, Arthur (1996). Three types of deja vu.

Dejavu- The theory behind the phenomenon

A physiological explanation of the deja vu phenomenon may exist. The optical and neural paths from the two eyes may be slightly different, or the processing of such signals might be delayed in one path due to some variant structure. Or, alternately, a "newer" and "older" brain processing method might be responsible.

For many years, psychologists have known of the phenomenon of Deja Vu, where a patient is absolutely convinced that a first visit to an area seemed like a place already familiar and known. (Deja vu is different from various similar phenomena such as Precognition [where a person has a premonition of some future event] or Clarivoyance [where a person comes to know about some simultaneous event a long distance away] or assorted other unusual phenomena. Modern science does not have adequate explanations for ANY of these apparent phenomena. I am only considering Deja vu here!

During the time while this web-page has been on the Internet, more than two thousand people (up to Nov 2006) have e-mailed to say that they have Deja Vu experiences. That is interesting, but their descriptions have virtually always described some different phenomenon. If a person has any pre-knowledge of something that is yet to happen, like in a dream, it cannot be Deja Vu, and is likely to be some type of Precognition. (Even if the Precognition is only seconds before the event.) A person cannot know that a Deja Vu experience is coming, and also, it is also always sensed as INSTANTANEOUS, as being a sudden realization that an experience "was somehow familiar". This last part eliminates Deja Vu from occurring in any place that the person has already been! (Again, such experiences are probably Precognition instead, or even something as mundane as much as a simple forgotten memory from a year earlier.)

Here is a hypothetical example of Deja Vu, assuming that you are not an Eskimo! On your first trip EVER to some desolate village in northern Alaska, you are invited into an igloo. The moment you are inside, and see everything, you suddenly feel that you "already knew" where everything was. Specifically, you notice something that you consider unusual, but sense that you somehow were familiar with that elk leg or whatever. You obviously could not have known, but you have an instantaneous sensation that you "must have already been there" even though you know that was impossible. Notice that you do NOT know what is in the next room, before you actually go there. (If that occurs, it would be Precognition.)

Here is another potential example of what an actual deja vu might be. You are driving cross-country, and have never been to Utah before. You stop for gas, and need to use their restroom. As you enter, you find a full-size fireplace INSIDE THE BATHROOM! Now, no one expects to see a fireplace inside a public bathroom, so it would be an experience that you probably had never experienced in any OTHER bathroom! And you had certainly never been to THIS one. And yet, immediately AFTER this experience, you have the sensation that you had "been there before". THAT would be a Deja vu. Notice that you did not "predict" seeing anything unusual, EVEN A SECOND AHEAD, and that you only had the Deja vu sensation AFTER actually seeing it. And that you could not possibly convince anyone that you had previously experienced that, because any listener would insist it was impossible. (If you had ANY pre-knowledge, even a second earlier, it could not actually be a Deja vu, and would probably be some sort of Precognition).

In order for it to be a credible Deja vu experience, it needs to be some experience that is clearly different from any forgotten memory you might have had, which generally also means something truly surprising. (Our brains have millions of such forgotten memories, like of smells or songs or old friends, which seem to be able to get triggered sometimes, and that is NOT Deja vu.)

Also, since, by definition, there can be no external confirmation of a Deja vu experience, no one else could possible know and there is no actual evidence, it turns out that "credible" Deja vu experiences have only been believed when the witness had a character that was beyond any question. If that person had EVER been known to have told a lie, or even bent the truth, it is likely that no one would believe any claim of a Deja vu experience!

Because of all this, Deja Vu is actually a LOT more rare than everyone seems to think it is! When people casually say that they have many Deja vus every day, or even several each week, their credibility pretty much goes to zero as to regarding Deja Vus! (It is certainly true that movies and the news seem to describe Deja vu as something rather different than it actually is!) They may certainly be describing Precognitions, and probably nearly always are. Of the billions of people who have ever lived, only a few handful may have actually had experiences that are credibly true Deja vus! And I am not aware of ANYONE who has ever credibly claimed to have had more than two Deja Vus in their entire life. Interestingly, some e-mailers then inform me that I am completely wrong! They apparently think that they are authorities on Deja vu! Interesting! I tend to doubt it though, if they cannot even get their definitions of phenomena straight!

Please note that this is distinctly different from when you go up to a vending machine and you somehow "know" that a pop can will get jammed or will be dented or something (which is probably Precognition). Also note that ANY experience that involves more than a fraction of a second cannot be Deja Vu (and is likely to be Precognition or Clairvoyance). For clarification purposes, here are some generalized comments about several paranormal phenomena.

• Precognition. (pre = before; cognition = knowing). This is probably the most common paranormal experience that people claim to have. It is usually where a person "watches" a scene, sometimes in a dream or a daydream, which then later, usually within hours or days, and sometimes within seconds, seems to match an actual event. When the event involves an airplane crash or other disaster, such stories sometimes get in the news.

  However, from a scientific perspective, there is usually very little "data", evidence or documentation, to confirm that a Precognition had taken place. If a person learns about some disaster and THEN tells people that he/she had foreseen it the day before, that may or may not be true, because there is usually no corroborative confirmation of what the person claims. There are certainly notable exceptions. Around 2001, I think, a woman who had become known for such insights was being interviewed on a live radio call-in talk show, when she suddenly got a Precognition regarding an airliner crash. On the air, live, she described a number of details that she saw. I believe that around six hours later, an airliner crashed in a manner extremely similar to what she had described. From a scientific perspective, THAT represents a documentable event, and it is valuable toward some future understanding of the phenomenon. (If she had been able to see an actual identifying number on the aircraft's tail, it would have been even more impressive!)

  When an individual puts money in a vending machine and the pop can comes out upside down, and he/she then tells friends that he/she had "seen" that was going to happen in a dream, it has virtualy no scientific value toward understanding the phenomena. About the only way it would, would be if the person woke up from the dream, wrote down specific details seen in the dream, signed and dated the notes, and immediately gave a copy of the notes to some respected person (NOT a family member or friend!) (like maybe a Doctor or a Lawyer or a Police Officer) to also sign and date upon acceptance. THEN, if the events later came true, there would be some credible confirmation that a Precognition had occurred. All this is pretty involved, and busy respected people would quickly tire of being given such notes several times each day! But, otherwise, the only "evidence" that would exist would be the word of the person who had the dream or daydream. In scientific terms, that is called "anecdotal evidence", un-corroborated statements that something had occurred, and it is considered to be of virtually zero scientific value.

• Clairvoyance (clair=clear; voyance=seeing). This paranormal phenomenon is somewhat similar to Precognition, but rather than seeing a scene earlier in time than it actually happens, it is usually seeing a scene at a location that is distant, and quite possibly at the exact same time. If Clairvoyance occurs alone, the awareness (vision) seems to sometimes be occurring at the exact same moment (corrected for time zones) when some real event is occurring. Clairvoyance seems to also sometimes be combined with Precognition, where a distant, future scene is seen in a dream or daydream.

  There have been many "somewhat documented" examples of Clairvoyance. In many cases, close relatives, particularly twins, seem to be sometimes capable of an awareness that science has not yet figured out. An example would be where a twin in Ohio might get an instantaneous sensation of sadness, and might even feel that something terrible has happened, only to learn two days later that the other twin had been in a serious car accident in Italy, essentially at the exact same moment of the sensation or vision. Since the person having such a sensation often has hours or days to worry about such a possibility, it is relatively common to mention it to others, which represents a certain level of documentation (for scientific purposes). For true scientific value, writing notes, signing and dating them, and immediately giving the notes to a respected person, like above, would really be the only really valuable scientific evidence, because that would represent corroboration of the otherwise anecdotal evidence.

  There was a very impressive example of a pretty well documented case of Clairvoyance. And it was somewhat accidental! In August 1883, a Byron Somes worked for the Boston Globe newspaper, in Boston, Massachusetts. He was sleeping in his office at the newspaper (after heavy drinking) on a Sunday night. He woke up due to a terrifying dream that he just had. It was such an unusual dream, and he was a reporter, that he wrote down all the details that he had seen in it. The dream/nightmare was about a horrendous scene of explosions, earthquakes and screams of countless dying people. Somes wrote the word IMPORTANT on his notes and left them on his desk and went home to sleep. He did not report for work the next day, Monday, still suffering from the heavy drinking.

  In 1883, there was not yet any radio or television, and news traveled fairly slowly around the world, even for newspapers. Geological people (there were not really yet any experts) were puzzled by a seismological disturbance that had just been recorded, which was identified as being on the other side of the Earth, in the Straits of Sunda. Someone at the newspaper apparently found the notes on Somes' desk, and the word IMPORTANT, and assumed that it was a report on that disturbance. On August 29, 1883, the Boston Globe ran an excellent story based on the details of those notes. Other newspapers across the country picked up the story and almost immediately, the entire country "knew" of what had happened to Krakatoa, a volcano that erupted so violently that an entire island disappeared in the process!

  The management of the Boston Globe wanted more information on this remarkable, and very popular, story, which was selling a lot of newspapers! So they found Somes, wanting more details. Somes soon admitted that it was not a news story at all but merely notes on a terrible nightmare. He was fired immediately. The Boston Globe was preparing to issue a public confession that the story was not true, that it was a mistake, just a dream. But as they were about to do that, huge tsunamis (incorrectly called tidal waves) started hitting the California coast, and actual news of the disaster began to arrive as survivors of the disaster got to cities with telegraph stations that had not been destroyed. Somes was re-hired as the incoming (real) news was amazingly identical to what Somes had written down in his nightmare notes.

  Other newspapers were curious as to how the Boston Globe could have scooped them so remarkably. The Boston Globe declined to admit the actual truth, and made up several stories to try to explain their unusual access to information that they obviously couldn't have gotten!

  Somes had his nightmare late on Sunday night in Boston. Because of time zones and the International Date Line, it was actually Monday morning at Krakatoa at that time, essentially the identical time that was later confirmed as when the volcano erupted so violently. Since that story (accidentally) got published Nationally before any actual evidence was even available, it represents an excellent example of the sort of documentation that is valuable for scientific research regarding Clairvoyance.

• Telekinesis (tele = distance; kinesis = moving) This is a rather different paranormal phenomenon where a person is apparently able to cause (small) objects to move without actually touching them. The only really well documented example I have heard of involved a very young Russian girl who, with apparently very great exertion, could make small objects move on a table in a laboratory, with various scientists present. Other claimed examples seem to have tended to all involve young girls, and the ability is apparently lost by the later teens. (There have been many people who have known how to fake such displays by trickery, as part of entertainment for audiences.)

• Deja Vu Deja Vu is different from these other phenomena, by definition. A person who experiences Deja Vu does not have any clue whatever that something is GOING to happen (like Precognition), but merely has the sensation (during and afterward) of having already experienced the scene.

  I am personally only aware of one incident that seems to qualify as a Deja Vu event. My half-brother grew up in the Midwest, near Chicago. When he enlisted in the Marines, he was shipped to Fort Pendleton in southern California. He had never been anywhere in California before. When he got a three-day pass, he drove north into central California just to explore that area. In one of the small towns there, he stopped for gasoline. As he looked around the town, he KNEW that he had been there before! But, of course, he couldn't have been! He sensed a real familiarity with the town and where stores were and even small details.

  If you think about it, you can see how impossible it is to document such Deja Vu experiences to be of value to any scientific investigation. He did not know that something surprising was about to happen, so he could not even have written down any notes, as might be possible for Precognition or Clairvoyance. And no other person could even confirm the "feeling" of familiarity he had, so there is no way to advance such an experience beyond merely being anecdotal evidence. As a result, there is virtually nothing of scientific value to even confirm that the phenomenon of Deja Vu even exists! Except from the words of those people who have experienced it! And, my acceptance of that as being a "real" experience is very dependent on the fact that I had great respect for him as being my "big brother"!

• Combinations There are a LOT of experiences that people have described that seem to possibly be some combination of these para-normal phenomena, or they might be entirely distinct phenomena. Here are a few examples that I find interesting!

  What is generally called Reincarnation sometimes seems to be too selective to me. There are modern people who are convinced that they are reincarnated Civil War soldiers, and some of them seem to know details about the death of some Civil War soldier that would not easily be learned. That certainly suggests that some paranormal phenomena is at work. But if it was actually a Reincarnation, why doesn't the modern person remember what the soldier had for lunch that day? Or the names and descriptions of brothers and sisters and parents? The entire basis for a claim of Reincarnation seems to be some bits of very specific knowledge about events associated with the MOMENT of the death of the soldier. I am tempted to think that these cases might actually be examples of a combination of Clairvoyance and Precognition (or, actually, Post-cognition) and probably not actually evidence of anything like Reincarnation.

  There definitely have been some remarkable cases that seem to suggest Reincarnation. The most famous is Shanti Devi, a girl who was born in Delhi, India in 1926. As a very young child, she concerned her mother by constantly seeming confused and bewildered. When she was seven years old, she told her mother than she had lived before, in a distant town called Muttra, and she described the house and people of that life. Her parents were very concerned about such strange statements, and they took her to a Physician, who carefully interviewed her. The Doctor did not provide any answers, and merely recommended that the father write down her various statements.

  She never changed her story. Her parents sadly concluded that she was mentally defective, and had little hope for her. When she was nine, in 1935, she told her parents that she had lived in Muttra, been married, and had three children. She described the children, including their names, and said that her own earlier name had been Ludgi. Her parents humored her, but did nothing.

  One evening, during meal preparation, there was a knock at the door, and Shanti went to answer it. Her mother soon found her staring at the stranger on the steps, who she claimed was the cousin of her previous husband! And that she knew that he lived in Muttra, the same town she claimed to previously live in. The man DID live in Muttra, but he had merely come to talk business with Shanti's father. He did not recognize the little girl Shanti, but he told her parents that he had a cousin whose wife, named Ludgi, had died in childbirth ten years earlier.

  Her parents then described the stories Shanti had long told, and the stranger agreed to get his cousin to come to Delhi to see if Shanti could recognize him. Shanti knew nothing of this plan, but when the new stranger arrived, she immediately threw herself in his arms and cried! The man was obviously very confused! Soon, the government of India appointed a special committe of scientists to investigate the whole matter, and suddenly, a little nine-year-old girl became very famous in India!

  The scientists took Shanti to the town of Muttra. She immediately pointed out and named many people. Interestingly, she spoke to them in a dialect that was local to Muttra, and which she would not have learned in Delhi (where she only understood and spoke Hindustani). Shanti demonstrated to the scientists that she was completely familiar with the town, many of the people, and many of the houses and stores.

  There is FAR more remarkable documentation regarding Shanti Devi, and many books have been written about her. No one yet has any answers, although lots of people make guesses, and Reincarnation is the primary hypothesis. Given all the evidence, it is hard to argue against! But the jury is still out, until some day science understands how such things could occur. My point of including Shanti Devi here is to demonstrate the sort of documentation that is of great value to science. She had made very specific statements for several years, and her parents and a Doctor had been witnesses to those statements. Later, a team of scientists also witnessed and documented many amazing things regarding her.

  One additional incident that might qualify as paranormal has long intrigued me! A man named David Lang lived with his family near Gallatin, Tennessee in 1880. He was a respected and known man. On a bright sunny afternoon of September 23, 1880, he was walking across his front yard, in clear view of his wife and two young children. In addition, a carriage was arriving, of a friend, noted Judge August Peck. David turned around to return to the house to greet his guest, and after a few steps, just vanished! Five people witnessed this event, the Judge, his driver, Mrs. Lang and the two children. His wife screamed.

  All five immediately ran to the place where Mr. Lang had just disappeared, in the middle of a normal lawn, with no trees nearby and no holes to have fallen into. The adults searched and searched and found no clue. Mrs. Lang becme hysterical. Neighbors soon joined the search and dozens of people were soon looking for David Lang.

  Afterwards, Mrs. Lang never really recovered, and all but one of the household servants soon left. The county Surveyor carefully examined the field. Interestingly, the following Spring, a circle of yellowed grass around 15 feet in diameter had formed where Mr. Lang had disappeared, and on a quiet evening in April 1881, the two children were playing nearby when they heard what they said was their father's voice, faintly calling for help, over and over, until it faded away.

  No one has the slightest clue about what happened regarding David Lang! Even good guesses are hard to come by! He was apparently never seen again by anyone. Since he had seemed to have been a happy and successful person, and with a wife and children, it hard to imagine that he would have just "run away" and even if he did, how could he have done it? It represents to me another example of a type of event that is currently still beyond our understanding.

Deja Vu

Of the five human senses, it appears that the deja vu phenomenon only occurs to the sense of sight. Whether the other senses can be affected is unclear. Since deja vu is such an undocumentable experience, even this is not a certain statement.

Going under the assumptions that it is exclusively a visual phenomenon, that it only seems to occur to certain people, and that there must be a physiological cause for the phenomenon, we consider the following possible explanation:

Hypothesis A

Any scene perceived by a normal person, is actually seen independently by each of the two eyes. That is how we accomplish three dimensional vision. Let us speculate for a moment that the signal path to the brain has a slightly different length from the two eyes. If this was the case, then the brain would get the signals from the first eye, and promptly process them and record them into memory. A moment later, the signals would arrive from the other optic nerve. The brain would then receive this signal, and immediately note that it seems very familiar, being very similar (virtually identical) to an image already in memory. But it wouldn't be a memory from months or years earlier. It would have only been from a memory recorded a fraction of a second earlier! (The brain's memory does not keep "time stamps" on individual memories and has no way of identifying when they first were recorded there. Under normal circumstances, other related experiences that include time-information usually give a person a cue as to when a memory was from.)

Psychological experimentation has solidly established that the human brain can only distinguish two individual visual events, with respect to time, if they occur more than about 25 milliseconds (0.025 second) apart. Since, in normal people, the signals from the eyes, through the two optic nerves, arrive at the brain and are processed well within this time interval, the brain interprets them (properly) as two slightly different views of the same scene, giving us the impression of a single event, which includes depth perception.

Let's consider if a person had a physiological impairment in one optical signal path, such that one optic signal arrived at the brain more than the 0.025 second after the other. The brain would not necessarily know it to be the same scene and might interpret it as the Deja Vu phenomenon. An alternative way this could occur would be that the optic processing centers of part of the brain had a flaw or temporary impairment (maybe electrolyte imbalance or other biochemical deviation) that caused a delay in processing one of the signal trains.

Such an impairment could be a congenital condition, in either the optic nerve or the brain. It could also be a temporary condition due to a viral infection or an injury effect or from any other cause.

The brain's processing of optic information is actually far more complicated than this, but the basic premise can still apply. The terminal ends of the optic nerves arrive at the optic chiasma, where half of the fibers from each eye cross over to the other hemisphere. The thalamus is then involved to get the signals to the primary visual cortex in the occipital lobe. However, the premise of a signal delay in either optic nerve, or in the brain hemisphere's processing of the signals it has to work with, or in the corpus callosum, is still valid. Whether the 'raw' data in the optic nerve is delayed or the brain's processed image is delayed, the result would be two separate images arriving at the memory, at slightly different times. If that time differential is great enough, the only noticeable result could be a Deja Vu experience.

Hypothesis B

Recently, (late 2001) I have become aware of the research being done by Vilayanur Ramachandran. In his investigations of the so-called "blind sight" condition, he has discovered something that seems to fit in well with this premise. Blind-sight is a rare condition where an individual is completely unable to see at all, and yet seems to experience awareness of some things that could only occur due to sight. Dr. Ramachandran has discovered that humans actually have TWO totally separate brain processing methods regarding visual information.

His research has indicated that the thalamus-centered pathway mentioned above is the standard processing method that our brains use today. However, he has found that there is a second, much more "primitive" processing method for visual information in the brain. He interprets this brainstem-centered as an earlier evolutionary stage of vision, which has largely been overshadowed by the newer thalamus-centered pathway.

I find his research into blind-sight quite interesting, but I see an additional possibility. IF the newer thalamus-centered pathway has taken over because of higher efficiency (a seemingly reasonable conjecture) in order to better react to more complex and changing environments that humans found themselves in, then it seems possible that this suggested higher efficiency might be associated with a quicker processing time for the visual information.

This could easily then imply that the newer thalamus-centered pathway might be more than 0.025 second faster in processing time than the older brainstem-centered pathway. Thus, in individuals where the older pathway is still relatively active, the brain could then receive two images of a scene, which it would interpret as separate experiences, as described above.

In this case, individuals who have substantial functional activity in the brainstem-centered pathway could very regularly experience the deja vu phenomenon. Individuals with lesser functionality of that pathway might only experience rare deja vu events. This would imply that most individuals probably have very well developed thalamus-centered pathways, where the brainstem-centered pathway has greatly degraded due to lack of use, and they would never experience deja vu.

A slight variation of this could involve the timing delay involved. If, in most individuals, both pathways were well functional, but where the two sets of visual information arrives at the cortex within the 0.025 second time interval, the brain would perceive it as a single event, and everything would seem normal. If such individuals had slightly longer time differentials, say 0.026 second, they could have a vague awareness of deja vu type sensations, while individuals who had longer still time differentials could conceivably almost continuously experience deja vu. For such individuals, and possibly for the rest of us as well, it seems likely that as very small children, if such confusing situations initially existed, the baby's brain would soon establish that "time-window" of 0.025 second or whatever else was necessary in order to allow the world to appear logical. And so, there are probably no (surviving!) individuals who continuously experience deja vu, but such people with unusually long time differentials might be especially subject to having occasional deja vu experiences, especially in moments of emotion or rapid activity.

I have noticed a phenomenon that seems to support this conjecture. During late dusk, when the (clear) sky was still barely lighted, I regularly drove past a radio transmitting tower. At the top of it was mounted a white strobe light, for warning to low flying aircraft. The physics of how a strobe light works is important here. A capacitor gradually charges up electrically. Once there is enough charge in the capacitor, it is possible to suddenly discharge all of the accumulated charge to the strobe light, which then creates a SINGLE, extremely bright, extremely brief, flash of light. It is NOT possible for a normal strobe light to rapidly flash twice, since the capacitor needs time to recharge. The flash length is VERY brief, on the order of a millionth (0.000001) of a second.

One time as I approached this tower, I happened to notice an interesting looking bird flying across the sky in front of the tower. As I panned across, focused on and watching the bird fly across, the strobe light flashed. I was aware of the sensation of two distinct flashes! Since I knew that this was physically impossible for the strobe light to do, I was puzzled for quite some time. I later tried to duplicate the experiment. At other times of the day or night, there was minimal success, but at dusk, the phenomenon was often easily repeatable and noticeable.

If no bird was present, the phenomenon while panning across was also often easily obvious, but there might be a mundane explanation for that situation. It is easily reasonable that without a specific focus of attention, while panning, the two eyes might not be directed in the same direction (They might not track together). If that were the case, it could appear that a single actual flash might appear as though there were two discrete flashes (not at different times, but in different apparent locations) due to the eyes being momentarily pointed in different directions. When a bird was present, I believe this possible explanation is eliminated. The existence of the bird certainly causes both eyes to register together on it. Since both eyes are then looking in the exact same direction, the only apparently remaining explanation for the apparent appearance of two flashes where only one could have actually occurred seems to be by the process described above, where the two optic pathways to and in the brain have different response times, thereby slightly delaying the processing of the optic information received by one of the eyes (or the brainstem-centered pathway) until the head had panned to a different location. The strobe could not actually have flashed twice, and this seems to be the only remaining explanation for the sensation of two flashes.

Several possible follow-up studies seem to be available.

Statistical

A possible way to prove or disprove this premise would be to survey a large number of people who have experienced the Deja Vu phenomenon and check if any of them only have sight in one eye. Whether due to accident or illness, if only one eye sends a signal to the brain to be processed, my initial premise implies that Deja Vu could not occur. If even a single one-eyed person experienced the deja vu phenomenon, that would suggest that that premise may be erroneous. If the sample is large enough, and there are NO one-eyed people that have ever experienced the Deja Vu phenomenon, statistical support might be established for this premise.

If any one-eyed people experienced deja vu, that would seem to imply that the second (thalamus vs. brainstem) premise would apply instead.

(Note: October 2005. A person who has long had a permanent physical flaw in one eye has described what seem to be valid deja vu experiences. He has described having MANY of them, which has never otherwise been credibly claimed, so I am not completely sure about this. The fact that deja vu experiences can never be confirmed or proven false by anyone other than the person experiencing them, is a real complication in such cases. But if he is correct, then my theory would have to be wrong, as there are not two separate optical paths operating in him.

Experimental - Low-Expense

A volunteer is seated along one wall of a dimly lit room, which has very plain walls (no patterned wallpaper, no hanging pictures, no furniture along the opposite wall of the room. Just in front of that opposite wall, a horizontal four-foot long rod acts as a radius arm, with one end attached to a vertical rotating shaft and the other (free) end supporting a small, dim light bulb, like the small version of Christmas lights, or a grain-of-wheat light bulb. As the shaft rotates, the small, dim light bulb moves in a large horizontal circle, which has a four-foot radius. If the shaft turns once every two seconds (30 rpm), the bulb will be traveling at about 12.5 fps (about 8 mph). It will move one inch in about 0.0065 second. This moving light is meant to be the center of attention of the viewer's eyes, so that the vision will track the moving light.

From the volunteer's perspective (in the plane of that motion), the light will appear to move horizontally back and forth. As the radius arm crosses the point nearest the volunteer, it triggers a switch that flashes a fixed position strobe light a few inches below where the small moving light then happens to be.

In one experiment, related to the first premise, the volunteer would wear a pair of glasses similar to one type of 3-D glasses, where one lens (RIGHT) is red and the other (LEFT) is green.

This is how the experiment would be performed. The volunteer would follow the movement of the moving dim light, usually by "panning" the head back and forth. When the strobe flashes, the volunteer's brain will receive two images of the strobe, one reddish and one greenish. If the two signal paths are identical, to within about 0.001 second, the brain will receive both images simultaneously and the light will be perceived as a single white (red + green) light. However, if either optical signal path is delayed in the optic nerve (as compared to the other), the observer would see two separated images, one red and one green. If the delay was about the 0.025 second mentioned earlier, the two images would appear to be around 4" apart (because the viewer's center of attention is panning at one inch during each 0.0065 second). The observer would see two images, somewhat duplicating the effect I witnessed with that strobe tower and the bird.

The explanation is as follows. The brain knows that the two eyes are registering together, because of following the dim moving light. The actual light entering the lenses of the eyes, strikes specific rods or cones, identical to how the system works every moment of every day. However, while the 'slower' processing is still occurring (after the 'faster' signal has been processed, the volunteer's head will have rotated due to the fast panning action. Now, if there were background guides or patterns or benchmarks, the brain would recognize the similarity of the two images and laterally adjust the images to align, during the processing action. Again, this occurs all the time for us, in the instant before our eyes can adjust their tracking of moving scenes at different distances from us. But, without such necessary background clues (a plain background), the brain has no way to make such a 'software' adjustment. The result is that the vision's attention remains following the moving light (bird) yet the brain knew which rods or cones were stimulated, and it knows what direction those rods or cones NOW represent (after the slight turning of the head), so the delayed image seems to appear in a location shifted horizontally from where it actually should appear. The amount of that horizontal shift is directly proportional to the difference of time or signal processing for the two eyes and also directly proportional to the rate of panning of the head.

The dim moving light in the experimental apparatus establishes and defines the panning rate, so the horizontal shift would be exactly proportional to the processing time difference we seek. The horizontal shift would be identified by the volunteer seeing two separate strobe flashes (one red and one green) which appeared to be a certain distance apart. If the red and green flashes appeared to be one inch apart, that would imply a differential time of 0.0065 second (with the apparatus as described above). They appear to seem simultaneous, but they are separated in distance due to the panning of the head. If the red and green images appeared four inches apart, that would represent 0.025 second, approximately the time distinction threshold of the brain. This might then be implied as a method of distinguishing people who could have the Deja Vu phenomenon and those who could not.

This simple experiment also has value regarding the second premise. If the effect should be due to a thalamus vs. brainstem time differential, our observer with the colored glasses would always see white images, but still possibly two. Now, the apparent separation of the two would represent the time differential between the two processing pathways in the brain. Again, the premise here is that, by the time the second set of information is received into cortical memory, with no obvious background identifying information, the brain would use the direction of visual attention AT THAT INSTANT (actually due to the other processing pathway!) to try to determine exactly where it actually was, and so it would appear shifted off to the side, as before.

Given the variability of life structures, it seems certain that some amount of this time differential must be present in all of us, whichever of the two premises might be valid. It is inconceivable that both images always arrive at and are then processed by the brain and then placed in cortical memory at the same nano-second. The only question that remains is just how large those differences are in various people, and whether they are ever large enough to explain the experience of the Deja Vu phenomenon.

This experiment has additional value. If two flashes are seen but they are not necessarily red and green, but nearly white, this still supports this premise of explanation for the Deja Vu phenomenon, but it might imply that much of the delay occurred in the brain processing. Since each hemisphere of the brain receives optic signals from both eyes, a delay here would delay both the red and green image processing (in that hemisphere) resulting in a basically white image that is shifted from the white image from the faster hemisphere. In other words, slightly tinted red and green images might suggest the first premise, and even suggest the proportion of delay attributable to the optic pate and the brain processing. (The second premise should always cause completely white images.)

In the first premise, if experimental results show that the two 'whitish' images could be distinguished somehow by the volunteer (maybe by colored fringes on the leading and trailing edges), another area of knowledge could be gained. If the image processed by the right hemisphere is always behind that processed by the left hemisphere (in right-handed people), that also supports the general concept suggested here but also implies that there might be a specific mechanism responsible for the delay, and might be associated with the corpus callosum. Such a consistent pattern would be different from that seen due to individual differences in the optic nerves (or diseases they might experience) [distinctly red and green images] or in the visual cortex [white identical images]. Such a preference would seem to only be possible if a major part of the recorded delay is due to the passage of the processed signal from the visual cortex in the non-preferred hemisphere, through the corpus callosum, to the preferred hemisphere. If such a pattern of results is noted, an analysis might establish the actual signal transfer speed between the hemispheres through the corpus callosum. (I am not familiar with any research that has examined that.) On the other hand, if the results show no such preference pattern, the implication is that the corpus callosum processing is faster than the error factor of the experiment.

Experimental - High-Expense

An extensive EEG monitoring of brain activity would be used. Only a single, fixed strobe light would be used. The EEG output would need to be either extremely high speed paper or a dual-trace oscilloscope. With the normal paper speed of EEG equipment, the few millisecond differences we are looking for would be unnoticed. Either a high-speed paper output or a dual-trace oscilloscope could display and quantify the time differentials involved. Identifying the two separate traces would allow all of the above analysis including the possible contribution by the corpus callosum activity. The time differences could be established much more accurately than by the subjective opinion of the volunteer as to how many inches apart the two images appeared to be.

Such experiments might also shed light on apparent feedback loops that seem to occur in the brain. Conditions like Epilepsy and Parkinson tremors may represent a signal processing situation where a delay is somehow included, as in the premise above regarding the Deja Vu phenomenon. Possibly, without such a delay, the brain would sense a single stimulus and react normally, but if a delay appeared in the processing action, the brain might perceive two or more separate stimuli, and then activate muscles in convulsive tremors.

There is a peculiar thing in my own experience that is not Deja Vu, but nor does it seem to be any other phenomenon that I have ever heard of. I guess it might qualify for an odd version of a Precognition.

I am open to any assistance to locate what should be really easy to find evidence!

George W. Bush became President in January 2001. I didn't think he seemed especially smart but otherwise I had no opinion of him good or bad. But then during June of 2001 I was with a couple friends visiting while a TV was on. There was a TV interview of George W Bush, in itself a rather rare incident. In THAT conversation with some reporter on a National Network, we all heard Bush say regarding Saddam "He tried to kill my daddy!" I immediately said "My God! We are going to attack Iraq!" And then all three of us laughed about a President referring to his "daddy" as really a strange thing to say in that way.

Notice that this was THREE MONTHS BEFORE the 9/11 attacks. Within a few days of 9/11, Cheney and Bush were already referring to invading Iraq, and reporters would ask, "Did Iraq even have anything to do with the 9/11 attacks?" Of course, they didn't.

OK. None of this should seem strange, right?

EXCEPT for the fact that news reports of more than a year later (2002) are the first ones that seem to be findable on the Internet, which refer to a slightly different wording of the "daddy" comment.

SO! Did my friends and I see some event that never actually happened in June of 2001? It seems inconceivable that the Internet would not have both a transcript and the actual Network video of something as rare as a televised News Interview of President Bush (NOT a Press Conference). I don't see how it could have gotten DELETED from all records! I could easily imagine that the Bush people would have wanted to delete it, but I cannot imagine any of the News Networks agreeing to do that.

It seems fairly certain that the interview was with either ABC News, NBC News, CBS News or FOX, as I don't think I watched any other networks at the time. (I later added the BBC News to my interest.) (I admit that someone else might have turned on that TV and it may have been some other network.)

Now, I KNOW that interview occurred, and so do my friends! But IF that interview occurred, how could it be possible that no one else seems to be aware of it? There couldn't have been ten Presidential Interviews in all of 2001! But, IF such an interview had not really ever happened, how could the three of us have discussed it? And how could I/we have already known when the comment was repeated late in 2002?

I suppose this is not a world-shaking problem, as it may just be something inside my brain and those of a couple friends! However, IF that interview actually took place, the implications are incredible. The fact that comment was made BEFORE 9/11 really made extremely clear to me that Bush really was hoping for some excuse to invade Iraq, and 9/11 then just happened to provide it. However, if my memory was totally wrong (which for a research Nuclear Physicist would be rather unusual!), and the findable references were correct, then Bush seemed to just be adding to an existing (alleged) WMD issue with his personal feelings a year afterward. That is incredibly different!

So, if there is anyone who can figure out how to find any record of a rather rare Presidential Interview in June 2001 on a major Network, I feel that I can guarantee that that interview contains the exact sentence, rather casually said: "He tried to kill my daddy." I also remember that the reporter had a very surprised expression, while Bush had essentially none, except that strange smile he usually has.

I would really appreciate if anyone can confirm this either way! If it can be confirmed that Bush gave NO individual interviews in June 2001, I guess I would have to accept it. Except I and others SAW it

I guess while I am on this sort of thing, there is another thing I saw that I guarantee that I actually saw! Nothing weird here, just a little bothersome. And it has absolutely NOTHING to do with Deja vu! There is a product that started being advertised for men to grow hair, called Rogaine, in the early 1990s. It achieved some success (and is still being sold). Around 1995 or 1996, they clearly decided to start advertising to women, to try to sell even more products. Here's the interesting part. For maybe a little over a month, the new ads included a statement where women were losing hair BECAUSE OF THE STRENGTH OF SHAMPOOS. I remember thinking, wow, the shampoo industry can NOT be pleased with that! But I think they were actually noting that long ago, virtually no woman lost her hair, that virtually all women still had all their hair in extremely old age. It was even called "male pattern baldness" because it only happened to men!

Well, now, that concept was quite interesting! Clearly, they had only invested hundreds of thousands of dollars for the new advertising toward women if they KNEW that there was a large enough market, that is, that a lot of women were now losing their hair! You can probably figure that those ads quickly disappeared from all TV advertising, and a different reason was put in its place, that of a genetic disposition because a woman's mother had been susceptible to losing her hair. However, this new reason seemed rather silly, as virtually no older women had ever lost much hair, until fairly recently.

SOOOO! Does this mean that their initial ads were correct? That women are now losing hair because the modern hair care products they buy are so strong? If so, shouldn't women be provided this information? However, we note that the sales of billions of dollars of hair care products would plummet! Are the ethics of modern business so profit-centered that they are willing to cause millions of women to lose their hair just to get greater profits in hair care products? Boy, I hope not, but I wonder!

Specifically, I discovered that there seems to be no record of those early TV ads that exist anywhere, nor even any reference to any such thing. There is little doubt that the hair care corportations would have tried to delete that from history. Did they succeed? As far as I can tell, they did!

The implications of both these things are really terrifying. Can our government or a giant corporation really totally delete some undesirable incident from the entire world's memory and knowledge? If so, we should all really be very, very scared!

So, if someone with far better Internet search skills than me can locate references to these two things, I would be greatly comforted!

Now, some people seem to read this as though I am some sort of "conspiracy theorist". That is NOT the case! I really have no personal reason for thinking such things go one way or another. But as a good scientific researcher, I do NOT EVER rely on speculations or silly concepts, but instead always attempt to pursue whatever is the actual truth in any situation. When things "don't seem to add up right", I tend to notice such lack of logic and I try to investigate. If somebody would get reliable evidence that gravity sometimes did not work right, I would be similarly interested in investigating!

Some additional comments will be added here, primarily to show how scientific research progresses. It turns out that the great majority of scientific experiments tend to prove that some hypothesis or theory is WRONG rather than right! Non-scientists do not seem to realize that! But that is progress, in a scientific sense. When Edison kept finding hundreds and hundreds of failures as he was trying to develop the light bulb, he kept eliminating wrong directions and gradually wound up narrowing it down to an approach that eventually resulted in the light bulb. If Edison had given up after the first failure, or the hundredth failure, or the eight-hundredth failure, we might not have light bulbs today!

Regarding this premise (of the different optical path lengths for the two eyes), there are two recent additions. there have been three e-mails received that seemed especially interesting. Two of the three said that they were born with just one functioning eye, and the third is the one already mentioned above. Those three people each presented credible descriptions where they feel that they had Deja vu experiences. If so, then my theory must certainly be either wrong or incomplete. However, noting that a truly remarkably few people seem to have ever actually had Deja vu experiences, I wish there was some way to actually confirm that these three had! It just seems really remarkable that the three of them would have had the experience, while virtually all other humans never have it.

There is actually another area that is even more compelling. We noted above that the brain only senses two experiences as distinct if the sensation arrives more than 0.025 second apart. I have not found the specific speed of propagation of optic signals along the optic nerves, but in general, nerve signals travel through our nervous system at around 200 mph or 300 ft/sec. In order for a mechanically different path length to be responsible for a differential of 0.025 second, that path would have to be about 7.5 feet longer for one eye than the other! So a MECHANICALLY different path length is not realistic. However, much of the speed of the passage of a nerve impulse is involved in the chemical events that occur at, around and in the synapse where the signal is transferred from one nerve to the next. If there were still to be any value in my hypothesis, it would have to be in a flaw in the synapse structure related to one eye, where signals could be delayed long enough to account for the 0.025 second. A significantly different local chemical environment might materially speed up or slow down the transmission of such nerve impulses by that amount of time. It could also happen irregularly as the chemical environment might change, maybe even due to specific foods eaten???

C Johnson, Physicist, Physics Degree from Univ of Chicago