If we were to build a machine that could take
a snapshot and record the exact position of every atom (say, in my fishbowl), wait ten minutes and then re-position every atom to
where it was when it was recorded, will we have built a time machine?
Is there a discipline that regards time as an instance of space and space as an expression of time?
By most reckoning time and space are not two different things. Describing where you is and where you ain’t usually refers to the space-time continuum. Putting all the particles back in place would be more time travel than if you rearranged your furniture the way you had it last year.
There is also the bugaboo of quantum mechanics. Little things, atoms and smaller, don’t behave according to the same rules as big things. The act of observing a particle changes it.
Pardon my garble, I should have said:
Putting all the particles back in place would no more be time travel than if you rearranged your furniture the way you had it last year.
Furthermore, you couldn’t build the snapshot part anyway. The Heisenberg uncertainty principle means that you can’t know both an object’s position and momentum at the same time – that is, the better you know the object’s position, the worse you know it’s momentum (mass * velocity).
Hey, we’re getting off the track here. OP doesn’t need to know whether its possible or not–the question is, what if it were possible.
What the OP describes is a Uni-Duplicator ™, whose patent is held by IBM, I think, but it’s manufactured by Hasbro. It is not a true time-machine, but it is only so limited for marketing purposes. Some backyard quantum mechanics have actually taken them apart and modified them to be a “poor man’s” time machine. It involves isolating the operator from the rest of the transformation. If you want a real time machine, you have to cough up the big bucks for the Time-N-A-Have, by Sony.
rocks
Maybe if you used one of those new digital cameras?
Call it what you will (time travel or not), but if you were able to exactly reproduce the location and velocity of every atom (including location and velocity of the electrons of each atom) in your fishbowl, you would at least get to see duplication of the past. Upon recreation, your fish would be thinking (?) exactly the same thing it was thinking when the snapshot was taken. Any water currents would be pushing on him and annoying him in exactly the same way as when the snapshot was taken. This is assuming that the fishbowl is an isolated system. If you took the snapshot when your room was brightly lit, and then recreated the fishbowl later, when it was dark, the fish would notice the difference upon recreation and this could change any action the fish may have otherwise taken. The temperature difference in the room between snapshot and recreation could affect the water currents. So, this duplication of the past would be dependent on keeping everything outside of the fishbowl EXACTLY the same as when the snapshot was taken. This would involve taking a snapshot of the fishbowl’s surroundings, which could be recreated in sync with the fishbowl snapshot. Maintaining the fishbowl’s surroundings would involve taking a snapshot of the fishbowl’s surroundings surroundings… etc… You get the picture… err… snapshot… whatever.
If you just took a snapshot of the fishbowl, and then recreated it in merely similar surrounding conditions as when the snapshot was taken, you would probably see a duplication of the past for a short period of time. After some time has passed, the minor differences in the surroundings would cause a change from the past. The further out from the fishbowl you could recreate the surroundings at the time of the snapshot, the longer the duplication of the past would last.
This also discounts the possibility of spontaneous (random) matter creation. I don’t know much about it, but have read a theory that matter randomly and spontaneously appears and disappears in the voids between other matter. If this is true, it could disrupt everything mentioned above unless you could somehow recreate this effect also.
Things are random only insofar as we don’t understand them.
I think the argument is only valid if the fishbowl is completely isolated from every other particle in the universe. Interactions with surrounding particles would ensure that the traveled fishbowl would not travel down the same quantum path it did the first time. In fact, <<warming to subject>> thanks to quantum physics, it probably wouldn’t work even if it were totally isolated. Dang, having trouble remembering, but if each particle is a superposition of several possible quantum states, then in the repeat situation, there’s no guarantee that the same state will prevail. In other words, this isn’t like pool, where the ball does the same thing whenever it encounters the same situation. It’s like each particle chooses its own path, and there’s no guarantee that the same path will be chosen the second time around.
Wow. That was well-written. Not.
Oh, and thank’s to Heisenberg, the very act of taking that photograph will completely screw up the whole thing. So we’ll need one of the Star Trek transporters’ “Heisenberg Compensators”.
Ignoring the uncertainty issue (for the moment): What you are doing is not travelling back in time, but taking the fish forward in time. There is no problem travelling forward in time. I’m doing just that right now. If you want to move the fish bowl forward in time faster than you are travelling, you can accelerate it. Due to the time dialation(sp?) time will move more slowly for the fish.
I don’t think so. Bell’s theorem says that if there are hidden variables (That is if the position and velocity are defined but unknown at present) then we must allow faster than light transfer of information. The uncerainty principle is not a limitation of our present technology, but a fundamental limitation. And don’t get me started on “just a theory, and has not been proven.”
Virtually yours,
DrMatrix
“Feynman was wrong.
I understand Quantum Physics completely.
Anybody seen my drugs?” - WallyM7
That’s only for <i>local</i> hidden variables, I believe. Global hidden variables are still in the realm of possibility.
rocks
For an ongoing, and generally quite cogent, discussion of Bell’s Theorem you might check out the following:
http://news3.news.wisc.edu/cgi-bin/nf/twf/a/8–8.1088.0.1
KarlGauss
Cogent? It sounds like the barbeque pit! But, except for poster ix, who doesn’t seem to understand the math, it’s worth looking at. I think it makes the overall point that hidden variables are still in the realm of possibility–and even discusses the possibility of local variables (there, I think I got the UBB right this tiem).
rocks
What about hidden local static variables? What about automatic variables?
I’d give my left buns-cheek for a Wally sig.
As regards the Heisenberg uncertainty principle, it IS in fact proven, both in the observational sense that any physical theory is “proven” (prove to me that the Sun will rise tomorrow), and in the mathematical sense as well. It follows from the wave-particle duality: The position and momentum of a particle are related in the same way as a wave is related to its Fourier transform, and it can be mathematically shown that the product of the characteristic widths (i.e., errors) of a wave and its Fourier transform must be greater than a certain number. All clear now?
“There are only two things that are infinite: The Universe, and human stupidity-- and I’m not sure about the Universe”
–A. Einstein
In defense of “Perhaps someday, we will be able to measure both the position and velocity of subatomic particles”, and “just a theory, and has not been proven”, I would say that I agree that it is not very likely that Heisenberg will be proven wrong… but I will not say that it is impossible.
I’m just suggesting that we not be so arrogant and confident in what we “know” as to think that we couldn’t be wrong about our accepted rules of nature. Look at what we have learned in the last 100 years, and how drastically our views of nature have changed over that time. Don’t think it impossible that our current “knowledge” of the rules of nature will not change over the next 100 years… and the 100 years after that… and the next…
After all… we used to “know” that the world was flat.
Things are random only insofar as we don’t understand them.
It is so ulikely that the Heisenberg uncertainty principle is not a fundamental limitation that we might as well just accept it as fact. Intellectually we should accept that it may be refuted, but don’t expect to make money beting on it. We have indeed learned a lot in the past 100 years. Would you care to name an example of the refutaion of a supposedly fundamental understanding in the last 75 years?
jrf
JonF
I wouldn’t take that bet either.
If you will read my post again, I think we are arguing the same point. I think it highly unlikely that Heisenberg will be proven wrong, but it is not completely out of the question. I cannot think of any examples of refuted basic principles over the last 75 years off the top of my head. There may not have been any, but that does not mean that it could not happen in the future.
Things are random only insofar as we don’t understand them.
Also, if no one ever questions the world being flat, it will never be proven wrong.
Sure, Heisenberg’s principle works for us now, and we should use it, but let’s not simply “accept it as fact”, and never question it. Never testing theories that “alwlays work” is a bad road to travel down.
Things are random only insofar as we don’t understand them.
This is almost like asking if I stir a glass of milk and chocolate syrup clockwise to blend, will they unblend if I stir backwards? I searched, and it seems to me that no one yet mentioned that entropy has changed. Just like the suggestion by one about rearranging furniture, you will spend energy to achieve what you propose and increase entropy in the process. Thus, your proposal may be a bit intriguing, but you simply “can’t get there from here” as they say.
“They’re coming to take me away ha-ha, ho-ho, hee-hee, to the funny farm where life is beautiful all the time… :)” - Napoleon IV
I think the correct answer to the OP was given somewhere up-thread; you aren’t moving backwards in time, you are moving the fishbowl into the future.
Suppose I come up with the Ronco Stasis Machine ™. I flip the switch and everything inside of it “freezes” in position, down to the subatomic particles. (Yeah, I know. Just go along with me here.)
I put the fishbowl inside and flip the switch. A few years later I flip it off and take the fishbowl out. All the particles in the fish bowl at the time I flip the switch off are exactly the same as when I flipped it on. This is the same effect as moving every particle “back to where it was”. But, the fish didn’t move bacwards into the past. From the fish’s point of view, it suddenly jumped several years into the future.
“Sometimes I think the web is just a big plot to keep people like me away from normal society.” — Dilbert