Is time travel possible?
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As noted in my introduction, the answer is yes. The important part is knowing what to take with you.
Backward: a stick for fending off cavemen and scientists, newspapers from the present to blow people’s minds, photographs of your parents so you can recognize them and not accidentally kill them, ROCK AND ROLL!
Forward: For traveling forward in time one needs to consider the speed of forward travel. I have a modified PDA that allows me to travel 60 minutes forward in time over the course of one hour. For this slower-rate time travel some pocket change and your house keys should be sufficient.
Fast-forward: anti-Morlock spray, feathered hair, and a unitard (cream-colored with gold trim is expensive but indicates high caste and makes it less likely that you will be eaten).
Very Fast Forward: Take a big stack of magazines and a good mp3 player: You won't have much to do if you overshoot the end of the universe in the form of the Big Crunch and are floating around after the universe has dissappeared.
Of course, first get an answer to the question Is time an illusion?
Return to Big Questions: http://www.wired.com/42
Tbe science fiction author LarryNiven famously demonstrated that, if time travel is possible, it will never be invented.
Simply, assume that time travel is possible. Then every trip backwards in a time machine will alter the state of the universe until by one chance or another that time machine is not invented.
Today's WikiWord is PhaseSpace.
If time travel - in the sense that a human can activate some device and be transported back to some earlier moment - is possible, then we'd know about it by now. If you think about all the possible historical events that future humans would want to see in person, I'd pick Apollo 11 above all. People might pick the birth of some religious figure, or technological advancement, but if you think about it, Armstrong's small step is the first moment that a man walked on another world - surely it'll survive any social upheval of the future.
Since there were no time traveling tourists present, either it's not possible, or humanity doesn't survive long enough to discover it. (And don't get all Star Trekkie and mention some sort of temporal prime directive - over the stretch of the future, there have to be some rogues who would ignore such an edict.)
contributed by on Jan 23 9:42pm
As far as I know, time travel is only possible in one direction, and that is the same direction towards which times flows: the future. Also, there's no time travel machine other than a fast moving vehicle: it wouldn't work just pressing a button, you would have to travel thru space at fast speed and then come back to Earth to check that, because you've been traveling fast and your local time has slowed down, the difference between Earht's time and yours, that will be the amount of time you have travelled into the future.
contributed by on Jan 24 4:06am
If traveling back in time were possible, it would never be noticed by "us" because the traveler is still moving forward in time relative to himself. According to the Multiverse theroy, at the exact moment that he travels back, a branch parallel universe would be created, and thus, we move along unaltered, with the exception that the traveler disappears from our timeline. At the same time his/her travel may seem like an accidental death or non-event to us (think Contact). The point is that the traveler never get's a chance to alter our common timeline/universe.
contributed by on Jan 24 10:01am
"Time is what keeps everything from happening at once."
(I don't know who said it first, but I first heard it on The Real Ghostbusters, the Saturday-morning cartoon.)
contributed by on Jan 24 12:57pm
I'm sure you all jest in assuming time travel is possible. Consider my mom's dick.
contributed by on Jan 24 1:54pm
Consider the possibility that time is not serial, but omnipresent. That is, that time does not resemble a finite line on which we start at one point and stop at another. Rather, what we believe to be the serialized past or future might simply be extensions of the singular moment referred to by numerous existentialists such as Gurdjieff and Rajneesh. In such a case, time travel would be one's ability to become aware of the other arms of existence going on simultaneously with what we consider to be the present. Rajneesh admonishes to "be in the moment," that is, to become aware of a singular moment of the present. One who becomes aware of those other "times" we call past and future would essentially experience the physical and emotional presence of multiple "places" and "selves" while at the same moment experiencing oneself.
contributed by on Jan 24 3:00pm
Current theories state that as one approaches the speed of light time begins to slow down. This concept was best explained to me with classic 'train traveling away from the clock tower' example. If you're sitting on the back of a train, traveling away from said clock tower, approaching the speed of light, the radiation (light) leaving the tower will be passing you slower and slower until you reach the speed of light, at which point you are traveling at the same speed as the photons leaving the face of the clock tower so it would appear as if time has stopped.
Does this mean that the perception of time equates to the passing of radiation?
My other question is: what if one was to travel at the speed of light in a circle around the clock tower?
contributed by on Jan 25 12:58pm
If traveling at the speed of light around the clock, your speed away from the clock is no longer sufficient to overcome the speed of the photons radiating from the clock because you are introducing a curve into the equation. In fact, if you traveled in a circle where you distance was constant from the clock, the clock should look to operate normally because you are not increasing your distance from the clock at all and therefore not outpacing the photons. You would need to travel in a very large spiral above the speed of light (theoretically impossible) in order to achieve what you are asking about.
contributed by on Jan 29 9:32am
Back From The Future
There has been a lot of flurry on retrocausality in the media (see URL below) that got me thinking about that issue once more. I suspended belief and for a few brief moments on champagne thought I really had it. But I was wrong ...
OK folks I woke up this morning realizing why my particular scheme without the coincidence circuit won't work. Very simple, same reason as usual. The noise from the receiver photons entangled with those sender photons that are absorbed by the stencil barriers will destroy the local signal. Of course, in the usual way of nonlocal interferometry the signal can be reconstructed after the fact with a proper design using data transmitted from the sender in the usual way. The only other loop hole would be if there were advanced EM signals, but if there were we would not have to go to all this trouble.
On Jan 28, 2007, at 4:11 PM, Jack Sarfatti wrote:
http://qedcorp.com/APS/SignalNonlocality.pdf
now online is a bigger file with references, illustrations and some more corrections and clarifications. This file will be continually updated expanded clarified and will be presented at Quantum Mind Conference in Salzburg and at the ISST Time Conference in Montery in summer 2007.
I discuss time travel in my books on Amazon. UFOs are evidence for time travel.
Wouldn't the time on the clock stop - not because you are moving at the speed of light away from it, but because you are moving at the speed of light relative to it?
contributed by on Feb 2 6:43am
The answer to the question of whether time travel is possible depends very much on how one defines time travel and to what cosmological model one subscribes. For instance, if the question is, "Can one travel into one's own past, change events in the past, and return to an altered present" then the answer is probably that time travel is not possible. If the question is "Can one travel into one's own past, change events in the past, and observe how one WOULD HAVE reacted" then the answer is probably yes.
This second account of time travel is predicated on a cosmology that views our universe as a "Multiverse". In the simplest sense, this means:
1) The universe is infinite
2) An infinite universe contains every possible combination of matter
3) Some combinations of matter in an infinite universe will resemble eachother
4) Somewhere there exist worlds just like ours, except with all possible permutations of historical events
Under this account, if it were possible to identify alternate worlds of interest, and travel efficiently to them, then time travel would be possible.
contributed by on Feb 2 7:02am
a thought experiment on time travel and the nature of time:
i believe the minimum requirements for time travel are:
1. a copy of the universe for each point in time.
for each Planck unit of time, there must be one copy of the universe. thus for each second, there must be 1/Planck time copies, i.e. approx. 5 x 10e44 copies.
2. the state of each copy must be fixed.
that is, it must be static in all respects, e.g. no radioactive decay, no change of particle spins, no change of etc.
3. the copies must pre-exist (to allow travel to the future) and be retained (to allow travel to the past).
4. each copy contains all the matter and energy of the universe.
Conclusions:
1. we don't observe the universe increase it's mass by a factor of approx. 5 x 10e44 times each second, therefore there is no past and no future, there is only the present.
2. past, future and the passage of time are illusions, they have no objective reality, they exist only because of the reaction of neurons to sensory input, i.e. they are totally subjective.
Why the illusion of time? There is survival value in having a nervous system with memory. Even the primitive nervous system of flatworms displays memory (as evidenced by their ability to learn) this memory is really the persistence of a state of a neuron. A sense of the passage of time comes from comparing current sensory input with the existing state (memory) stored in the nervous system. The survival value comes about by the ability to recognize a pattern of state changes and calculate a future state based on the pattern and the state currently in memory. Humans perceive state changes of neurons in response to events as the passage of time.
3. each state of the universe is a consequence of the previous state. that is, one "present" leads to the next "present" and so forth.
my approach of looking at the minimum requirements for time travel is to provide clarity. the common approach, e.g. asking what would happen if we could go back in time and kill our grandfather, results in insoluble paradoxes and does not illustrate clearly the nature of "time", "past", "present", "future".
Paul Sagi
contributed by on Feb 4 6:53am
America Jones said:
The answer to the question of whether time travel is possible depends very much on how one defines time travel and to what cosmological model one subscribes. For instance, > if the question is, "Can one travel into one's own past, change events in the past, and return to an altered present" then the answer is probably that time travel is not
possible. If the question is "Can one travel into one's own past, change events in the past, and observe how one WOULD HAVE reacted" then the answer is probably yes.
This second account of time travel is predicated on a cosmology that views our universe as a "Multiverse". In the simplest sense, this means:
1) The universe is infinite
2) An infinite universe contains every possible combination of matter
3) Some combinations of matter in an infinite universe will resemble eachother
4) Somewhere there exist worlds just like ours, except with all possible permutations of historical events
Under this account, if it were possible to identify alternate worlds of interest, and travel efficiently to them, then time travel would be possible.
I don't think this is correct.
First, it should be noticed that there isn't only one degree of infinity. Even in common mathematics and logic different degrees of infinity are used:
infinity^2, infinity^3, etc. All the possible combinations of events (even the tiniest, like a thought of a man in 1521) that could happen probably are not
only an infinity, meant as infinity^1, but infinity^infinity. I don't think this could be said of the possible combinations of matter in the universe.
Second: if it could be possible for someone to go back and forth time and create new timelines, than there would be not only one Time,
but multiple ones, meaning that you would have to enter a fifth dimension to manage multiple "4d objects", as you must be in 3d to view multiple 2d
figures that are in the same position (you can't see the difference between a square and a cube if you're not in 3d). So the multiverse theory
needs a 5th dimension to function, which is not acknowledged by current science. Besides, what would that dimension be? Speed, maybe?
contributed by on Feb 4 7:57am
Am I the only one who thinks that the answer to the question should be NO instead of YES? Time-travel as stated in the article, as perceived by the average person and displayed in the average Sci-Fi tv-show/movie is just magical thinking. What is/may be possible according to some scientific theories probably shouldn't be called time-travel.
contributed by on Feb 6 5:11am
There are multiple interpretations of the Multiverse hypothesis; I only stated the simplest. According to Max Tegmark, professor of physics and astronomy at University of Pennsylvania:
"The simplest and most popular cosmological model today predicts that you have a twin in a galaxy about 10*10^28 meters from here...The estimate is derived from elementary probability and does not even assume speculative modern physics, merely that space is infinite in size and uniformly filled with matter, as observations indicate."
Furthermore, the notion that there is "not only one Time, but multiple ones" is I believe fairly well accepted. Beyond Einstein's assertion that time does not pass uniformly at all locations, Stephen Wolfram in A New Kind of Science discusses some interesting mechanisms from which time as we know it can be deduced from non-traditional underlying causes (simple network structures that update nodes according to definite rules).
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contributed by on Feb 7 10:30am
I consider time a multidimensional relationship not a physical measure within any single/group-limited dimensional
relationship. It would be very hard to time travel, maybe impossible, because we must unlock a point in existence (all/entirety-
dimensions) that is not present, but locked in a relationship to all other dimensions. I view these relationships as multiple/many
spheres changing shape and color as interactions occur at different energy types/levels (like canvas on silk or diamond on milk).
To time travel is a poor phrase. It is more like taking a single point in existence, then changing enough dimensional
relationships that the single point is now located where it has not been before (no small feat). IOW, if it were an I, me, or you we would be relocated to a specific single point in existence or vise-versa by moving dimensional existence states. We would be unlocking a single point in existence and moving another specific single point in existence to a co-incidental point. It is far more complex than just meeting yourself in time, but the results would be the same I suspect.
Time as a multidimensional event sequence relationship with infinite combinations possible. I suspect a unique combination for each single point in existence ... where is our cosmic safe-cracker.
!HAVEFUN! Reality is self-induced hallucination (for most, maybe all).
contributed by on Feb 8 10:00am
