Hyperluminal Spaceship, Tachyons and Time Travel
June 27, 2010 21 Comments
Einsteins theory of relativity suggests that none can have hyperluminal speed. Negative mass or tachyon are the particles which always travel at superluminal speed and had a negative time frame means time run backward for them. What if a spaceship is travelling at hyper light speed? Would time run backward for that space ship? These are questions which are to be solved here by Earnst L Wall.
To depart somewhat from a pure state machine argument for a moment, we will consider a more general discussion of the argument that an object that moves faster than the speed of light would experience time reversal. For example, the space ship Enterprise, in moving away from Earth at hyperluminal velocities, would overtake the light that was emitted by events that occurred while it was still on the earth. It would then see the events unfold in reverse time order as it progressed on its path. This phenomena would be, in effect, a review of the record of a portion of the Earth=s history in the same manner that one views a sequence of events on a VCR as the tape is run backwards. But this does not mean that the hyperluminal spacecraft or the universe is actually going backwards in time anymore than a viewer watching the VCR running in reverse is moving backwards in time.
Further, it must be asked what would happen to the universe itself under these circumstances. To illustrate this, suppose a colony were established on Neptune. Knowing the distance to Neptune, it would be trivial, even with today’s technology, to synchronize the clocks on Earth and Neptune so that they kept the same absolute time to within microseconds or better. Next, suppose that the Enterprise left Earth at a hyperluminal velocity for a trip to Neptune. When the crew and passengers of the Enterprise arrive at Neptune, say 3 minutes later in Earth time, it is unlikely that the clocks on Neptune would be particularly awed or even impressed by the arrival of the travelers. When the Enterprise arrives at Neptune, it would get there 3 minutes later in terms of the time as measured on both Neptune and Earth, regardless of how long its internal clocks indicated that the trip was. Neither the Enterprise nor its passengers would have moved backwards in time as measured on earth or Neptune.
The hands of a clock inside the Enterprise, as simulated by a state machine, would not be compelled to reverse themselves just because it is moving at a hyperluminal velocity. This is because the universal state machine is still increasing its time count, not reversing it. Nor would any molecule that is not in, or near the trajectory of the space ship, be affected insofar as time is concerned, provided it does not actually collide with the space ship.
In the scheme above, reverse time travel will not occur merely because an object is traveling at hyperluminal velocities. Depending on the details of the simulation, hyperluminal travel may cause the local time sequencing to slow down, but a simulated, aging movie queen who is traveling in a hyperluminal spacecraft will not regain her lost youth. Simulated infants will not reenter their mother’s wombs. Simulated dinosaurs will not be made to reappear. A simulated hyperluminal spacecraft cannot go back in time retrieve objects and bring them back to the present. Nor would any of the objects in the real universe go backward in time as a result of the passage of the hyperluminal spacecraft.
The mere hyperluminal transmission of information or signals from point to point, nor objects traveling at hyperluminal velocities from point to point, does not cause a change in the direction of the time count at the point of departure nor at the point of arrival of these hyperluminal entities, nor at any point in between.
Based on concepts derived from modern computer science, we have developed a new method of studying the flow of time. It is different from the classical statistical mechanical method of viewing continuous time flow in that we have described a hypothetical simulation of the universe by means of a gigantic digital state machine implemented in a gigantic computer. This machine has the capability of mirroring the general non-deterministic, microscopic behavior of the real universe
Based on these concepts, we have developed a new definition of absolute time as a measure of the count of discrete states of the universe that occurred from the beginning of the universe to some later time that might be under consideration. In the real universe, we would use a high energy gamma ray as a clock to time the states, these states being determined by regular measurements of an object’s parameters by analog-to-digital samples taken at the clock frequency.
And based on this definition of time, it is clear that, without the physical universe to regularly change state, time has no meaning whatsoever. That is, matter in the physical universe is necessary for time to exist. In empty space, or an eternal void, time would have utterly no meaning
This definition of time and its use in the simulation has permitted us to explore the nature of time flow in a statistical, non-determinate universe. This exploration included a consideration of the possibility of reverse time travel. But by using the concept of a digital state machine as the basis of a thought experiment, we show clearly that to move backward in time, you would have to reverse the state count on the universal clock, which would have the effect of reversing the velocity of the objects. But this velocity includes the not only the velocity of the individual objects, but the composite velocities of all objects composing a macroscopic body. As a result, this macroscopic body would also reverse its velocity, providing the state was specified with sufficient precision.
But if you merely counted backward and obtained a reversal of motion, at best you could only move back to some probable past because of the indeterminate nature of the process. You could not go back to some exact point in the past that is exactly the way it was. In fact, after a short time, the process would be come so random that there would be no real visit to the past. A traveler would be unable to determine if he was going back in time, or forward in time. Entropy would continue to increase.
But doing even this in the real universe, of course, would present a problem because you would need naturally occurring, synchronized, discrete states (outside of quantized states, which are random and not universally synchronized). You would need to be able to control a universal clock that counts these transitions, and further, cause it to go back to previous states simultaneously over the entire universe. Modern physics has not found evidence of naturally occurring universal synchronized states, nor such an object as a naturally occurring clock that controls them. And even if the clock were found, causing the clock to reverse the state transition sequence would be rather difficult.
Without these capabilities, it would seem impossible to envision time reversal by means of rewinding the universe. This would not seem to be a possibility even in a microscopic portion of the universe, let alone time reversal over the entire universe.
But aside from those difficulties, if you wished to go back to an exact point in the past, the randomness of time travel by rewind requires need an alternative to rewinding the universe. This is true for the simulated universe, and a hypothetical rewind of the real universe. Therefore, the only way to visit an exact point in the past is to have a record of the entire past set of all states of the universe, from the point in the past that you wish to visit onward to the present. This record must be stored somewhere, and a means of accessing this record, visiting it, becoming assimilated in it, and then allowing time to move forward from there must be available. And, while all of this is happening in the past, the traveler’s departure point at the present state count, or time, must mover forward in time while the traveler takes his journey.
Even jumping back in time because of a wormhole transit would require that a record of the past be stored somewhere. And, of course, the wormhole would need the technology to access these records, to place the traveler into the record and then to allow him to be assimilated there. This would seem to be a rather difficult problem.
This then, is the problem with time travel to an exact point in the past in the real universe. Where would the records be stored? How would you access them in order just to read them? And even more difficult, how would you be able to enter this record of the universe, become assimilated into this time period, and then and have your body begin to move forward in time. At a very minimum our time traveler would have to have answers to these questions.
Still another conundrum is how the copy of the past universe would merge with the real universe at the traveler’s point of departure. And then, if he had caused any changes that affected his departure point, they would have to be incorporated into that part of the universal record that is the future from his point of departure, and these changes would then have to be propagated forward to the real universe itself and incorporated into it. This is assuming that the record is separate from the universe itself.
But if this hypothetical record of the universe were part of the universe itself, or even the universe itself, then that would imply that all states of the entire universe, past, present, and future, exist in that record. This would further imply that we, as macroscopic objects in the universe, have no free will and are merely stepped along from state to state, and are condemned to carry out actions that we have no control over whatsoever.
In such a universe, if our traveler had access to the record, he might be able to travel in time. But he were to be able to alter the record and affect the subsequent flow of time, he would have to have free will, which would seem to contradict the condition described above. We obviously would be presented with endless recursive sequences that defy rationality in all of the above.
This is all interesting philosophy, but it seems to be improbable physics.
Therefore, in a real universe, and based on our present knowledge of physics, it would seem that time travel is highly unlikely, if not downright impossible.
We do not deny the usefulness of time reversal as a mathematical artifact in the calculation of subatomic particle phenomena. However, it does not seem possible even for particles to actually go backwards in time and influence the past and cause consequential changes to the present.
Further, there is no reason to believe that exceeding the speed of light would cause time reversal in either an individual particle or in a macroscopic body. Therefore, any objections to tachyon models that are based merely on causality considerations have little merit.
For the sake of completeness, it should be commented that the construction of a computer that would accomplish the above feats exactly would require that the computer itself be part of the state machine. This could add some rather interesting problems in recursion that should be of interest to computer scientists. And, it is obvious that the construction of such a machine would be rather substantial boon to the semiconductor industry.
We already know from classical statistical mechanics that increasing entropy dictates that the arrow of time can only move in the forward direction . We have not only reaffirmed this principle here, but have gone considerably beyond it. These concepts would be extremely difficult, if not impossible, to develop with an analog, or continuous statistical mechanical model of the universe.
We have defined time on the basis of a state count based on the fastest changing object in the universe. But it is interesting to note that modern day time is based on photons from atomic transitions, and is no longer based on the motion of the earth. Conceptually, however, it is still an extension of earth based time.
But finally, history is filled with instances of individuals who have stated that various phenomena are impossible, only later to be proven wrong, and even ridiculous. Most of the technology that we take for granted today would have been thought to be impossible several hundred years ago, and some of it would have been thought impossible only decades ago. Therefore, it is emphasized here that we do not say that time travel is absolutely impossible. We will merely take a rather weak stance on the matter and simply say that, based on physics as we know it today, there are some substantial difficulties that must be overcome before time travel becomes a reality.