Science a GoGo's Home Page Forums General Discussion Physics Forum The Divided Universe

This is an idea that arises out of the consideration of particles that travel, or appear to travel, at superluminal speeds. It looks at some of the possible consequences of this, and asks what kind of universe would allow it to happen. As Far as I am aware, the only proposed superluminal particle is the tachyon, which is a hypothetical particle that always travels faster than the speed of light. Not only does it travel faster than light, it also travels backwards in time. This must mean that the laws of physics, as we know them, are reversed in the reality inhabited by the tachyon.

John Gribbin has this to say about the tachyon: “These ‘superluminal’ particles, if they exist, behave in a way which mirrors the behaviour of ordinary ‘subluminal’ particles, so that they can never, for example, slow down below the speed of light. Whereas an ordinary particle moving at high speed will tend to lose energy and slow down, a tachyon will tend to lose energy and speed up - it is as if both subluminal and superluminal particles are repelled from the speed of light. So if a tachyon were created in some violent event in space, it would radiate energy away furiously…….and go faster and faster, until it had zero energy (and was therefore undetectable) and was travelling at infinite speed”.

Gribbin talks lightly about the tachyon accelerating as it loses energy. Mind blowing as this phenomenon undoubtedly is, it is, perhaps, not the worst problem. It would not occur in isolation; all the other laws of physics would also be reversed. Imagine a blacksmith taking a red-hot iron out of the forge and dipping it in water. Instead of the iron being quenched, it would glow hotter, and ice would form on the water. As you walked in, you might expect the smithy to be hot, but the forge would have drawn the heat from the atmosphere and it would be very cold. Only the circulation of air from outside would prevent the atmosphere inside from rushing towards absolute zero. Wait, though; Gribbin pointed out that the tachyon would go faster as it lost energy, so what would happen to the fire as it gained energy? It becomes increasingly difficult to imagine life, or any ongoing reactions, in a world in which the laws of physics are reversed. Perhaps it doesn’t have to be like that, though.

Let us return to the idea of travelling at infinite speed. For a start, how are we to define infinite speed? Would this not be the speed at which the traveller would be everywhere at once? The dimensions of speed are distance divided by time, but as diagram 1 shows, when light speed is achieved there is no time left by which to divide the distance. Of course, the equations of relativity can be solved in such a way as to show that the tachyon travels backwards in time, and this seems quite in keeping with the time/space relationship illustrated in diagram 1, which would certainly give rise to the idea that the tachyon must be travelling backwards in time. It would seem that beyond the speed of light, continued acceleration takes the traveller into “negative” time. We must look a little more closely, though, at the speed of light. At this point (light speed) travel can be described as being 100% motion through space, and zero motion through time. This seems like a recipe for being everywhere at once, so how does this differ from infinite speed? If the speed of light in a vacuum can be defined as the same thing as infinite speed, then, because nothing could exceed infinite speed, the only way speed can vary beyond the speed of light is downward. This would imply that the tachyon could not be a superluminal particle in its own inertial frame, but would be a mirror image of the photon. Like the photon, it would be repelled from the speed of light by losing both speed and energy. Now we can invert diagram 1, and dispense with such complications as negative time, and negative space, and possibly, also, infinite speed. (William of Ockham would be proud of us!). There is, in fact, no need to dispense with the concept of infinite speed in this instance, because nothing can be accelerated from subluminal to superluminal speed; and those things that may be calculated to be travelling at superluminal speeds, such as distant receding galaxies, would be doing so only in the frame of reference of, and relative to, a distant observer.


Although most scientists are doubtful about the existence of the tachyon, some scientists are searching for it, or rather they are searching for some sort of tachyon precursor, an event that would indicate that a tachyon was about to be formed. This is because the tachyon, if it travels backwards in time would have to be observed before it was formed. The prospect of looking for something that may be travelling at infinite speed, may be undetectable and, in any case, has not been formed yet, does seem to be quite a daunting task. However, even if detecting a precursor is not, in itself, daunting enough, we should remember that, having found it, we must ask if one can really be sure that some yet to be formed tachyon is truly the cause of the precursor. Intuition insists that to claim that something, existing now, will be caused by an event in the future, requires a degree of belief in predestination that some would find unacceptable. Perhaps it is no surprise that the majority of scientists give this area of research a wide berth. It would, of course, be arrogant to suggest that the tachyon does not exist, simply because we cannot see it, and may never do so. Perhaps another frame of reference within which to consider the possible existence and nature of the tachyon would be valuable.

Diagram 1.




This is where the concept of an extended universe comes in. What I am proposing is an idea that involves, not so much another universe, but rather a two-part universe, of which we are aware of occupying only one half. For convenience, I shall refer to each half as a “universe”; our half being the “Universe” and the other half being the “mirror universe”. There is no reason to suppose that the precepts of relativity would not hold good for this extended universe. It seems quite reasonable to suggest that observers on either side of the divide formed by the speed of light would have equal right to claim that they were travelling forward in time, and that the beings on the other side were the ones who were going backwards. As with all motion in the observable Universe, the perception of relative speeds and directions would be bound by the same subjectivity.

Let us see if this idea of a dual universe might help to provide an alternative way of looking at the scenario of multiple universes. It is important to remember that it is not only speed that is relative, but that the seemingly fixed and constant values of time and space are also such that their measurement is related to the viewpoint of the individual observer, and is therefore variable.

As indicated earlier the dividing line between the two halves of this proposed universe is formed by the speed of light in a vacuum. Viewed from our side of this division, the situation is as we see it: nothing can be accelerated to the speed of light. The more energy one puts into a moving particle the faster it travels through space, and the faster it travels through space the slower it travels through time. If we could look across the divide it might be easy to see that the first and second of these conditions would be reversed, (nothing could be decelerated to, or below the speed of light, and the more energy you put into a system in motion the slower it would go), the third, however, would not be so easy to establish. What would be the relationship between speed through space and speed through time? Diagram 2 shows the situation from the point of view of the photon, and the tachyon. For the photon, the arrow of time points from left to right and the photon travels forward in time in the same left to right direction. Also, from the photon’s perspective, speed increases up the diagram, seemingly continuing beyond the speed of light, such that the tachyon appears to be travelling at superluminal speed, and backwards in time. However, since we have no direct experience of superluminal velocities, do we have any real evidence that the speed of light in a vacuum is not the terminal velocity for the Universe, and for this proposed extended universe? If this were the case, it would be reasonable to invert diagram 2 and see the situation from the point of view of a tachyon which, if it were able to make observations, would observe itself as travelling forward through time at subluminal speed; with its maximum being set at the speed of light, in its frame of reference. Because it would perceive speed as increasing up the inverted diagram, it would assume the photon (which it would probably not be able to detect for the same reason that we cannot detect the tachyon) to be a superluminal particle. Although Diagram 2 seems to suggest that the photon may travel at less than the speed of light, this should not be interpreted as making any claim other than that, in different media the photon may appear to an outside observer, to travel at less than “c”, the speed of light in a vacuum.

Diagram 2



Diagram 1 looks at this proposed situation from a slightly different perspective. Here we are plotting speed through space against speed through time, taking the view that the combination of these two speeds will always equal the speed of light in a vacuum. The “curve” of the graph in Diagram 1 is a straight line. It passes through the zero point of speed in space (at the bottom left of the diagram), through the point of intersection with light speed (centre), and beyond, but what is beyond light speed? The temptation is to think it that it must be superluminal speed. However, let us look back at John Gribbin’s comments about the speed of the tachyon. He described it as “going faster and faster, until….(it) was travelling at infinite speed”. Again we return to the question: what is infinite speed? Indeed, what is infinity, and how does it fit into calculations? Here I quote a passage from Brian Greene (2005) on the subject of using infinity in calculations. Talking about the incompatibility between general relativity and quantum mechanics, he says: “If you use the combined equations of general relativity and quantum mechanics, they almost always yield one answer: infinity. And that’s a problem. It’s nonsense. Experimenters never measure an infinite amount of anything. Dials never spin round to infinity. Meters never reach infinity. Calculators never register infinity. Almost always, an infinite answer is meaningless”. As with Diagram 2, we can invert Diagram 1 and have both photon and tachyon travelling at subluminal speed, each in its own frame of reference. This situation would seem to fit well with relativity, which tells us that speeds are relative and that they correlate directly only within individual frames of reference. It also tells us that nothing can be accelerated from subluminal to superluminal speed. Obviously, the concept of the tachyon as a superluminal particle, which always travels at speeds in excess of that of light in a vacuum, does not violate either of the above mentioned tenets of relativity, but, somehow, the fit seems a little more comfortable if superluminal speed can be “detected” or inferred only in someone else’s frame of reference.

What does all this have to do with multiple universes? If scientists can suggest – even insist – that there are trillions of other universes around us that we cannot detect, then the idea that there might be just an extra half of a universe that we cannot observe directly seems to be quite a modest suggestion. It is, of course, reasonable to ask where this other part of the Universe might be. It could be beyond the effective range of our telescopes and other devices; perhaps beyond that horizon which, in an expanding universe, marks the absolute limit of what we will ever be able to detect, because light from beyond it will never have time to reach us. It could also be that it occupies the same space as our Universe, but is hidden from us because we cannot experience the dimensions in which it exists. There are many scientists who accept the possibility that trillions of universes might occupy the same space, so the idea is not so far divorced from current scientific thinking. There are, in fact, scientists working on the possibility that dark matter may be some form of “mirror matter”, which could have interesting implications for the divided universe idea.

We might well ask what, if any, advantage this idea of a two-part Universe has over the conventional multiverse. One answer must be that according to the precepts of Ockham’s razor we should not “invent” trillions of universes if half a universe will do. Of course, it could turn out that an extra half will not do, perhaps we really do need trillions of other universes, but perhaps the best we can say about that at present is: “tot homines quot sententiae”.

Have I shocked everyone into silence, or do the intellectuals consider this such a silly idea that there is nothing to say about it.

Could be it needs a push!


What do we have to look for as evidence of a “mirror universe”. Would evidence for “mirror matter” be a step in the right direction?

Let’s start by looking at “handedness”. In biochemistry, there is, I believe, a strong tendency to left-handedness. No doubt Bryan will be able to tell us how strong that tendency is.

A recent study of 15,158 spiral galaxies showed a preference for left-handedness.

Even in the subatomic realm, where the concept of symmetry has been regarded almost as sacrosanct, neutrinos seem to be consistently left-handed.

Could this be taken to suggest that there might be a dominantly right-handed “universe” out there, somewhere?

Perhaps it requires a spot of theology, philosophy or mythology to get a thread going. How's this for a start?


THE BOLTZMANN DIVINITY

In the beginning was the Void, and the Void was without form or content. Thus was the Void utterly empty from all eternity. The Void did contain neither space nor time; nor was there any possibility of any matter or energy existing within the Void. The nature of the Void was total emptiness because there was no observer who could give reality to anything that the Void might otherwise have contained; and so it was, for the vastness of eternity.

In the fullness of eternity there appeared within the Void the Boltzmann Brain. Only for the most unimaginably minuscule instant did the Boltzmann Brain remain in existence in the Void, but that was sufficient for it to become an observer. As the only observer of the Void the Boltzmann Brian was, perforce, the typical observer. So it was that the observations of the Boltzmann Brain did become the reality of the Void.

In order that the Boltzmann Brain could be within the Void there had to be space for it to occupy, moreover, there had to be time during which it could occupy that space within the Void and thus make its observation. For this reason was the Void filled entirely with time and space, but as there was no observer, once the Boltzmann Brain had vanished whence it had come, there was no change within the Void throughout the vast expanse of time that followed, which has been designated as the first era.

That has nothing to do with the O P!
A bit like mythology and reality, then!
Cool, that should bring the philosophers out of hiding!

I just finished reading a three-paged artucle from the NEW YORK TIMES http://www.nytimes.com/2008/01/15/science/15brain.html?pagewanted=1
Big Brain Theory: Have Cosmologists Lost Theirs?
By DENNIS OVERBYE
Published: January 15, 2008
Here is how it opens:
===================== Here is how it concludes:
========
Ordinary science? Is this supposed to be ordinary science?

Bill S, may I ask: Does this article strike you as "ordinary science"? If so, does it grab your attention? In what way?
BTW, thanks for your thoughtful response to my last post in the "Philosophyof Religion..." thread.

Thanks Rev. Looks interesting. I've printed the article to read at leisure (what ever that might be).

I would love some comments on the OP. You seem to have the knack of getting people going.

OP? What is it?

OP=original post. I have trouble with some of these abbreviations, but my son is usually on hand to help. Have you looked at A Little Cornucopia of Conundrums? Needs a translator.

I'm posting in this thread in the hope that bringing it to the top of the list might encourage a comment from anyone who was not on the forum as far back as April. Mentioning no names, of course.

I have never got into tachyon studies Bill S for a few simple reasons.

If they exist there universe is completely incompatable to ours it's like discussing the living conditions on a planet 50 billion light years from Earth to me.

Remember in there own universe I suspect time would move completely normal to them its only in our world that time would appear to go backwards. Thus the want to reverse the laws of physics is almost certainly incorrect. My guess would be they will be the same in there own world I mean if we simply rewite a new speed for C = 100x10E8 m/sec rather than 3x10E8 as the speed of light no real physics changes.

The speed of sound sort of shares this relationship with speed of light on earth you see a lightning bolt long before you hear it.

I think you are overcooking the reality it shouldn't be much more complicated than the speed of sound versus speed of light.

I worded that badly. What I meant was: "This must mean that the laws of physics, as we know them, would appear to us to be reversed in the reality inhabited by the tachyon."

A little further on I reach the conclusion that: "It becomes increasingly difficult to imagine life, or any ongoing reactions, in a world in which the laws of physics are reversed."

the point of having the diagrams invertable is to argue that the denizens of either "half" of the universe would see time etc on their own side as normal, and on the other side as reversed.

Yes then if you put it like that I would say your perceiption of what you would see would be very close.

It's really hard to work in your head because time effects are very difficult.

I once tried to make a film in which I did everything backwards like the short film balancing point (http://www.youtube.com/watch?v=9ci-BecLfJI) its really hard.

Interesting film, Orac. Its not until you think about making it, which obviously you have done, that the real difficulty becomes evident.

Returning to the divided universe; when I hatched the idea it appeared to present less problems than any of the multiverse scenarios I had met. These things always seem to have hidden snags, though, which was why I was looking to run it past some others.