The photons we see originated in some form in the Big Bang, (in other words, the energy of that photon existed). Photons can hold the record of the past but we see them in the present. All matter and energy existed in the Big Bang and continue to exist today, (though they can be converted from one to the other).

So just what would exist in the past? Everything would have to exist in the past, present and probably in the future as well* at the same time if one is to imagine worm holes that could link two different times such as Thorne describes.

We can experience time at relatively different speeds (proved) but we can't move in or out of present time. I don't agree with the Thorne/Hawking version that the person traveling close to the speed of light and experiencing time at a different speed is indeed in a different time.

Thorne talks about a hypothetical guy on Earth holding hands through a wormhole with another person who is traveling close to the speed of light and is experiencing time at a relatively slower speed. Hypothetically the traveling person returns as a younger person than the person who remained behind. Less time has passed for the traveling person relative to the stationary one.

Assuming relative time experience is true (because it has been tested), it stands to reason if they weren't holding hands through the wormhole, and if they were traveling through time at different rates, the person on the Earth should see the traveling person return before the traveling person experiences the return. But that isn't what happens because if it did, the traveling person would return twice. The two would be permanently out of time sync.

Instead, I think the person on Earth would see the person traveling in sped up motion, and the traveler would see the stationary one in slow motion. But they would both always remain in the present no matter how slowly or quickly one appeared to be traveling in time relative to the other. My first thought was the stationary person would see the other in slow motion and vice versa. But in thinking it through, if I were on Earth and 10 years later the traveler returned having aged only one year, they went very fast and sort of leaped ahead to 10 years later. And, we know they traveled close to the speed of light so they would have appeared to be going very fast.

My interpretation of events is illogical at first glance. If I experience time more slowly than you, when 10 years passes for me and only one year passes for you, it stands to reason I'll see you return before you see you return. But the apparently logical analysis isn't logical because it misses one key point. Regardless of how much time one experiences passing, everyone remains in the present. Just because you are traveling fast and experiencing time more slowly, if we contacted each other at any time, we'd both be in the present time. When the traveler returned it would seem to them only a year had passed while on Earth 10 years passed. But the traveler left from the present time, traveled in the present time and returned in the present time relative to the person who stayed behind.

I fail to see how Thorne and Hawking view the movement through time at different rates as evidence the time dimension is anything other than flat. I emailed Thorne about this but not surprisingly got no reply. Obviously a non-physicist like me couldn't possibly understand this the way great minds like Hawking and Thorne do. So would someone please explain to me what I am missing here?



*(since once one traveled back into the past the present would become the future and would hopefully still exist)

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Are you looking for some ATM ideas ?

I don't understand how your description differs from just plain old 3D space we already understand?

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No you're right, because no matter how fast this person goes they will always return after they leave. It's not possible to accellerate to the speed of light, so time will never stop and time will never go backwards, a finite amount of time will always pass between departure and arrival, be it a nanosecond or 10 years.

Someone posted this hand-holding thing in another thread and I said the same thing.... I think what you said is accurate, and I think what would happen is the person with their hand through the time warp would either die or lose their arm because of the difference in time passing (causing blood flow probelms and all that).. Ignoring that, I think they would see the person in the ship moving very slowly, and the person in the ship would see the person on earth moving very quickly... and they would have a very old hand when all is said and done (or a very young hand, depending on who it was that was through the worm hole)

There's not really any time travel happening, it's just the rate of change has slowed for one and remained constant for the other... I don't know why people would imagine some kind of bizarre continuity errors or anything.

Edit: On a more "realistic" example, I think I've read before that if there were a ship orbiting a black hole (or in this case, travelling very quickly), their signal would have to be blueshifted in order to interpret any communication they send, since it would have been severely redshifted because of the time dilation.

Again, though, it works the same way as what we've both just said....everything exists now...and I'm willing to fight Stephen Hawking to the ground over that. And that's the James Hurley promise.

That's true .. what's the different between 3D to 3T? just to understand "TIME" and "D's" are not a "stable" thing is hard enough, have you read some "Entry level" introduction to Special Realivity ... your know .... cartoon type with a lot of pictures ?

Of course, after your "indepth" understanding of Relativity .. if you buy the concept that "TIME" is a personal thing, then you will eventually buy the concept that "people can age at their own RATE" ... where the rate is depends on their own "whatever !"

But then again, ATM doesn't sound like a right place for your question, have you tried Q & A ?

Best regard.

I was thinking about this earlier tonight....Maybe it has something to do with quantizing time. Does time need to be quantized? Maybe that's why they tend to think that there are different time lines or whatever they call them.

[Note: I took the liberty of removing the [i] tags from the title.]

Excuse me? I have to read some entry level intro to special relativity? I don't mean to be rude but I don't think so. You need to better explain your position rather than assuming you are making a clear point. I understand space time. I don't think my ATM idea implied total ignorance of Einstein's work. You are claiming there are multiple universes just because a person is spatially separated from another. You describe only 3D space then leap to some conclusion about 4D space time. Try again.

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Thank you. I tried to edit the title which I thought we could do before anyone posted to the thread but it only edited the subtitle.

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I reviewed the NOVA transcript of the time travel episode. And I looked at a few of the physics pages describing Thorne's ideas on time travel. The physics is beyond my area of expertise but I get the gist of it. Essentially Thorne and Hawking were delving into the physics equations surrounding travel near or exceeding the speed of light while maintaining some 3D spatial connection between the time traveler and others still on Earth. I don't know how the physics allowed the wormhole but it isn't relative () to my discussion. The following site had a brief summary that better suits what I am talking about.

Kip Thorne's Wormholesemphasis mine.

Here is my point exactly. If the time traveler were to pass through the worm hole, he would not be in a different time, he would be in the present time. He might now experience time more slowly relative to those still on Earth, but he would not be in a different time.

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LOL. That's one of the first things I do, too.

Here's an observation from special relativity that might be relevant: If Alex is moving differently from Beyonce, then the following situation is possible. Courtney kills herself because of her love for David, and David kills himself because of his love for Courtney. From the point of view of Alex, Courtney killed herself first, before David. From the point of view of Beyonce, David killed himself before Courtney. The events in Alex's past do not line up in the same fashion as the events in Beyonce's past. That may seem weird, but if you understand special relativity, it's not weird.

"Present Time" is puzzling, that's why that site was refered to you.... according to my book, TIME would leak 'in/out' when you are under some form of dec/acceleration ... could that be right ?

Have you read thru the whole thing in that web site ? it's not my idea, it's just an ATM ... excuse me for my ignorance ..... I learn't relativity thru comic books.

Check Where is 'Objectivity'? .... there, KG., Nd , CM, Bb etc. are real good at this thing called SPACE TIME.
Hope that helps.
My own BS about TIME in this ATM .
Where is 'Objectivity'?
Where is 'Objectivity'?

Learning is the responsibility of the learner ... oh well, alright :

• Time-Space with 4 degree of freedom is NOT the same as Multiple Universe
• It's 3D 1T vs. 3T 1T ... if you can't see the difference , you are normal

Can your question be reshaped as such ?

If you and your twin Measured the the Universe ... 14B year,
Sent your twin out
he returned 2B years later,
say he's only 1B Year older ... and you 2B ,
Now both of you sit side by side and look into the Universe .....
Hmm ... Will he find it as 15B old ?, while to you .... the size of it would be 16B ....
How does it sounds ? .... my guess ? .... 16B.

I am still contemplating the sequence issue and the idea of no absolute time. I had to print up a page or two of link material so I could think about it more in regards to the present time I described. So I haven't lost interest in this thread but contemplating the Universe is very time consuming.

I'll try to get to your links as well, John and bump the thread back up once I've got something intelligent to post.

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4T is indeed very different from 3D 1T .... it's not a easy task to change the concept ..... the following link may help.... since you know relativity, it's a worthy challenge !

John Tsang's ideas about time etc
John Tsang's ideas about time etc

Sincerely yours.

johntsang, you have been previously warned twice by the forum staff not to hijack other discussions in order to promote your own ideas. Your posting privileges here have been revoked for continued rules violations and ignoring the moderators' warnings in that regard.

If only Shakespeare had known that then the ending to Romeo and Juliet could have been so much more climatic.

If they could both see the other commit suicide first and then commit suicide themselves as a result of the observation then we could have a very interesting trajedy indeed.

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If logic doesn't work, then surely it does.

You have to go beyond special relativity to do that

Sometimes, it's too bad Shakespeare isn't writing today, about this stuff.

Beskeptical, I think the Light Cone model is useful when considering these causality questions. The diagram implies that all frames of reference (i.e. the physical reality) belong in the 'hypersurface of the present'. A spaceship accelerating to near c won´t escape this surface into a 'parasurface of the present', or into a 'surface of the future'.

I confess that Thorne´s idea sounds somewhat silly to me, not to mention this passage, worth of a cheap sci-fi story: "The electrical field created by the plates (the Casimir effect) creates a tear in spacetime." But maybe I´m missing something.

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I'm missing something.

Every programmer should know lsz.s(z) or lsz.s(s(z)) things about lambda.

I'm a programmer and I don't know what you're talking about. (I didn't get very far with Lambda Calculus)

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If logic doesn't work, then surely it does.

I saw the light cone model when I was trying to figure out the two viewers seeing events in different time frames. One sees the entire event before the second sees the beginning of it if I am reading things correctly. If I am on the train I can see the same things as someone not on the train so that should hold no matter what speed I am going. In other words we should be able to see the same events at the same time. Yet for one person the events are occurring slower.

So there two people experience time differently, yet they still remain in and return to the same 'present' time. When time dilates for one person, again, there is something happening but it isn't time travel. If it were we'd all be out of sync. I cannot view one second before or one second after the present time. If a person is experiencing time a few seconds slower than I they are still in the same present time. If they weren't, they would return to an earlier time than I was in and I wouldn't see them any more in my present time.

So if one person sees an event before the other, then what happens if that person joins the person who hasn't yet seen the event? It would appear the person would have to be traveling in time if they subsequently saw the event a second time. But that can't be so there is something wrong with the model.

We always discuss this model as the two people having aged at different rates. But we don't usually discuss what would happen if the guy on Earth joined the guy in the space ship. There is still something which doesn't make sense that I have to think about here.

Think of the events this way. I see an event. I leave the planet and orbit it at 9/10 the speed of light. I am not going to see that event again.

You leave the planet. You orbit the planet at 9/10 the speed of light. I see an event but you haven't seen it yet. I jump in my ship and join you before you see the event.

That can't happen. And it shouldn't make any difference whether you are there ahead of me.

I'm going to have to keep working on this.

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You´re right. It happens that the "surface of the present" for a traveller at near c is 'skewed' in relation to the surface of the observer at rest (as in here - scroll to the bottom of the page). That´s the geometric analogy to time dilation for this model . This causes both to disagree as to the synchronism of events. But since the two surfaces intersect, both will share a point in the present; one will always be somewhere in the 'present' of the other. At the end of the trip, as the traveller starts to decelerate, the angle between his surface and that of the observer at rest will begin to diminish, and when the traveller is decelerated enough both surfaces will coincide, and they´ll continue to share the present (although they may be separated by a large distance in space). This corroborates your impression that no matter how fast one travels, all the action unfolds in the present.

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In fact, that was inspired by your sig.

As you know, lambda calculus treats everything as (recursive) functions, including integers. In the ambit of this formalism, those function prototypes in the sig are called "Church integers". The Church integers are generated by function recursion. lsz.s(z) stands for the integer 1 (the function is applied one time). lsz.s(s(z)) stands for 2, since the function is applied two times (it calls itself recursively). The process can go on infinitely. Thus, the meaning of that phrase is:

Every programmer should know one or two things about lambda.

Lambda is handy in understanding certain formalisms. It expresses computation via anonymous functions. It´s akin to LISP (which drew from it a lot).

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What brings us together is stronger than what pulls us apart

OK by the model, but explain how the person who saw the event before the other, then joins the other will be viewing the event. Or any events for that matter. You talk about deceleration, I'm talking about acceleration.

When the two meet up in the fast moving ship, time will be synchronous for both, in the ship. But if they were looking back at the Earth, where things were moving at a different rate relative to them what happens?

Person on the space ship sees events more slowly (or quickly I'm getting confused but nonetheless at a different rate.) Person on the ground sees events sooner. As long as one returns to the ground, they end up in the dame times with the traveler having aged less.

But if the Earthbound person joins the traveler and both are now looking at the Earth, and they had viewed events on the Earth at different times relative to each other, how would they now both be viewing the events at the same time. One saw an event before the other. He joins the other who has not yet seen the event. But that can't be because then he would see the event twice or they would be out of sync in what they were seeing.

For some fixed amount of time I could see their event view come back into sync. But if the traveler orbited the planet at 9/10ths the speed of light for years, they would be seeing something quite out of sync with those on the planet. Since they are orbiting, the person on land need only catch up to their speed. That person need not exceed their speed for the time it takes to overtake them. The traveler's view must not be getting further and further behind the planet person's view.

So if that's the case, they only have an illusion of difference between them. A real difference would accumulate. But if it is only an illusion, then how are they aging more slowly.

See, no matter how I try to think it out, it doesn't work.

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Ah, I thought it might be the successor and zero functions, but the "lsz." threw me. I actually use LISP occaisonally to tweak my .emacs file - but I don't really get it.

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If logic doesn't work, then surely it does.

I'm not sure if I'm on the right track here, but I think the thing to remember here, beskeptical, is that disagreements about what are simulatenous events can only happen when there is spatial separation.

If two observers are in the same place at the same time but one is moving relative to the other then the degree to which they will disagree about what is now at a particular point in space will be proportional to how far away that point is in the direction of the relative motion. But we must remember that we are talking about what they would deduce is happening now when the light from there has reached them. At the instant when they coincide they would both see the same distant event occur from the past, but they would both deduce that it happened at a different time in the past.

I hope that's helpfull (and correct). I, too, am still trying to get my head around all this stuff

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If logic doesn't work, then surely it does.

No, but thanks for trying. I'll contemplate some more.

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