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Author Topic: Can you use light to time travel?  (Read 7429 times)

Offline Fluid_thinker

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Can you use light to time travel?
« on: 31/03/2009 13:16:57 »
If light is affected by Gravity and Gravity can distort time.

Could you use light says lasers etc to time travel?


 

Offline yor_on

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Can you use light to time travel?
« Reply #1 on: 31/03/2009 14:45:10 »
« Last Edit: 31/03/2009 15:24:18 by yor_on »
 

Offline LeeE

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Can you use light to time travel?
« Reply #2 on: 31/03/2009 18:49:30 »
You are already travelling in time, forward, at the speed of one second per second, local time(frame).  To travel backwards in time, you'd have to be travelling both forwards and backwards at the same time; backwards to get to when you're going, and forwards so that you go back after you've been forward, instead of before, which is the normal way of things.

Travelling back in time is a bit problematic.
 

Offline Fluid_thinker

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Can you use light to time travel?
« Reply #3 on: 01/04/2009 15:54:10 »
Maybe I was trying to think of alternatives to the concept of wormholes that take huge galactic amounts of energy. If blackholes distort time by frame dragging, could you not create a similar framme dragging froma rapidly rotating light. Would it equally use galactic amounts of power?
 

Offline LeeE

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Can you use light to time travel?
« Reply #4 on: 01/04/2009 20:36:05 »
Wormholes aren't so much distortions of spacetime due to frame-dragging but rather hypothetical openings in spacetime where you can leave our set of spacetime, and possibly re-enter it somewhere else.

Imagine representing our universe by the letter 'U'.  Normally, to get from one tip of the 'U' to the other, you would have to travel down from one tip, around the bend at the bottom, and then back up to the other tip (in this scenario, the bend at the bottom of the 'U' is like the curvature of space associated with gravity).  If you had a wormhole that linked both tips though, you'd be able to travel directly between the two tips without having to go all the way around.

Wormholes shouldn't be confused with closed universes; this would be like representing the universe by the letter 'O'.  In this case, you'd come back to where you started, but you still have to go the long way around to get there.

It's generally thought, however, that the universe is open and not closed.
 

Offline yor_on

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Can you use light to time travel?
« Reply #5 on: 01/04/2009 23:41:39 »
I'm not sure how one would make light spin at that speed. Does there exist some such known natural mechanism, spreading waves or photons while spinning near 'c', somewhat like a rotating cosmic garden hose :) If there was, your idea might be tested. We seem to have them macroscopically in our universe, but they are harder to find in our labs :) I've also wondered if you could test time by using light? It's interesting.
 

lyner

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Can you use light to time travel?
« Reply #6 on: 01/04/2009 23:54:06 »
All these ideas may be worth considering when dealing with 'particles'. It is not suitable to consider as a mode of personal travel!
On the subject of wormholes; where / when could one plan to have the 'other end' of the worm hole located? Luggage and air travel come to mind - only worse.
 

Offline DoctorBeaver

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Can you use light to time travel?
« Reply #7 on: 02/04/2009 03:10:11 »
You are already travelling in time, forward, at the speed of one second per second, local time(frame).  To travel backwards in time, you'd have to be travelling both forwards and backwards at the same time; backwards to get to when you're going, and forwards so that you go back after you've been forward, instead of before, which is the normal way of things.

Travelling back in time is a bit problematic.

Is anyone else confused by that or is it just me?  ???
 

Offline justaskin

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Can you use light to time travel?
« Reply #8 on: 02/04/2009 03:49:23 »
You are already travelling in time, forward, at the speed of one second per second, local time(frame).  To travel backwards in time, you'd have to be travelling both forwards and backwards at the same time; backwards to get to when you're going, and forwards so that you go back after you've been forward, instead of before, which is the normal way of things.

Travelling back in time is a bit problematic.

Is anyone else confused by that or is it just me?  ???
Perfectly understandable Dr B its the classic case of not knowing if you are coming or going. ;D

Cheers
justaskin
 

Offline DoctorBeaver

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Can you use light to time travel?
« Reply #9 on: 02/04/2009 03:56:30 »
You are already travelling in time, forward, at the speed of one second per second, local time(frame).  To travel backwards in time, you'd have to be travelling both forwards and backwards at the same time; backwards to get to when you're going, and forwards so that you go back after you've been forward, instead of before, which is the normal way of things.

Travelling back in time is a bit problematic.

Is anyone else confused by that or is it just me?  ???
Perfectly understandable Dr B its the classic case of not knowing if you are coming or going. ;D

Cheers
justaskin

Thanks. That really helped.  ::)

If LeeE had said "backwards to get to when you're going, and forwards so that you get back after you've been back, instead of before," I would have understood it.
« Last Edit: 02/04/2009 03:59:21 by DoctorBeaver »
 

Offline yor_on

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Can you use light to time travel?
« Reply #10 on: 02/04/2009 12:34:04 »
Let's say that LeeE once and for all presented (nailed?) time's two-faced nature. I can't but wonder if we are required to fill up our temporal niche (aka place and time) at all 'times' as this suggests though? We never seem to have any problem jumping back and forth when traveling backwards, in them books, at least:). What about it. Can we 'jump over a year' in our present frame and then just continue? In a Unbothered whistling sort of way?
 

Offline LeeE

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Can you use light to time travel?
« Reply #11 on: 02/04/2009 18:08:12 »
...What about it. Can we 'jump over a year' in our present frame and then just continue? In a Unbothered whistling sort of way?

Well, we can jump forward a year using time-dilation, but there doesn't seem to be any way of going backwards whilst being aware of it.
 

Offline yor_on

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Can you use light to time travel?
« Reply #12 on: 02/04/2009 21:52:51 »
Absolutely LeeE, as compared to another frame of reference we can and do time travel :) But can we 'jump' forward one year in our own 'frame of reference', leaving a 'spacetime' gap between those two events compromising one year without us? The question, if taken down to 'basics', is if there would be any way to 'operate' outside of time. And that doesn't seem to be possible for any type of matter, dead or living. Although light might have that 'possibility',  probably not as 'information' though?
 

Offline LeeE

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Can you use light to time travel?
« Reply #13 on: 03/04/2009 18:04:00 »
But can we 'jump' forward one year in our own 'frame of reference', leaving a 'spacetime' gap between those two events compromising one year without us?

That's an interesting question.

If I'm interpreting that correctly, you're asking if you could become a year older in your own reference frame without actually taking a year in your own reference frame to do so i.e. without living through all the time between then and now.

In some respects, this seems to be equivalent to travelling in space, from point A to point B, without passing through all the points between; instead, you simply cease existing at point A and resume existing at point B.  However, it seems to me that changing your position from point A to point B must take a discrete period of time because if the transfer were to take zero time you'd end up being in both places simultaneously.  This in turn means that when you then move from point B to point C, still having taken no time to do so, you'll have to be at all three points at the same time.  Following this to it's illogical conclusion suggests that you could be everywhere in the universe at the same time.

Trying this with time doesn't seem to work though, and there are a couple aspects to it that I can't reconcile.   Probably the biggest problem I have with it is that if you suddenly become a year older but haven't taken a year to do so, in your own reference frame, where has that year, which defines your increase in age, gone?  It almost feels as though, just as with energy, there should be a conservation of time law.

Having said that though, if we move in discrete 'ticks' through time, possibly due to the nature of our movement through time being different to the nature of our movement through space, as we were discussing in another thread, then we are already aging in discrete jumps, except that the jumps appear to be incredibly small, possibly/probably even smaller than the Planck time unit, instead of years.
 

lyner

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Can you use light to time travel?
« Reply #14 on: 04/04/2009 00:48:26 »
...What about it. Can we 'jump over a year' in our present frame and then just continue? In a Unbothered whistling sort of way?


Do we have a definition problem here?
You (your experience) can hardly jump 'within' your present frame of reference because that's what you are experiencing - body chemistry, brain, the lot.
You can only jump in someone else's frame - in which case you could emerge next Tuesday and no one on Earth would have seen you whilst they were experiencing the weekend. You would just turn up on that day, but not be aware of any time having elapsed - just the time taken for the machine to gurgle and make a Dr Who noise.

Your  consciousness can always 'jump forward' relative to your body chemistry when you are unconscious. That's a daily experience for most people. Your reference frame would correspond to your body chemistry, and an observer by your bedside would agree.
« Last Edit: 04/04/2009 00:49:59 by sophiecentaur »
 

Offline yor_on

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Can you use light to time travel?
« Reply #15 on: 05/04/2009 22:27:40 »
Yes and no SC, it would still be 'timteravel' as it happened in the same 'frame of reference' like me f ex. doing it here on Earth. It all falls back to how one define 'frame of reference' it seems to me. I can't see it happen though :) It's alittle like asking if a photon ever can 'time travel' as seen from its own 'frame of reference', it seems an impossible question, as the only time travel it will do is in its final interaction with spacetime. Wasn't there a known physicist that once got the idea that all photons was one, a friend of Feynman I think?
 

lyner

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« Reply #16 on: 06/04/2009 00:24:01 »
OK. What we mean, conventionally, by time travel is moving about in someone else's time space reference frame (the frame of the rest of the World, in fact). There would be a continuous flow, as far as you, the time 'traveler', are concerned during your experience of walking up to your time machine in 2009, tonight and stepping out of it in, what is for the rest of the World, 2010.  Your life will appear to be 'discontinuous' to people in the World frame but, in your frame, everything is continuous.

If you did the experiment on a mouse in the lab, then the mouse might disappear and then appear ten seconds later - but its heart would have been going continuously - just by one beat, perhaps. The harder scenario would be the mouse running along a line and the same mouse appearing just behind the first version of itself. Finally, the 'first version' of the mouse would disappear, leaving the 'older' version of the mouse running. The latter scenario is the one which introduces all the paradoxes but I suggest that there could be 'permitted situations'  in which the two mice could be present at the same time (our frame) as long as the 'later' mouse didn't take an action to terminate its own existence or modify its behaviour regarding going into the time machine. The 'loop' could only be there if it satisfied all the logical requirements. Under any other circs, the machine could not / would not actually work.
A daft idea on the macroscopic scale but, on the quantum level, possibly?
 

Offline yor_on

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Can you use light to time travel?
« Reply #17 on: 09/04/2009 02:02:25 »
Nice idea SC but no :) at least not as I see i it. You wrote "I suggest that there could be 'permitted situations'  in which the two mice could be present at the same time (our frame) as long as the 'later' mouse didn't take an action to terminate its own existence or modify its behaviour regarding going into the time machine."

The reason to that is not possible, according to my view, is that you can't be at two places in the same 'spacetime' at the same time. What you introduce here, thinking of it, shouldn't even be possible in a 'many worlds scenario" In such a scenario you might be able to timetravel but only to an alternative 'timeline'.

Well, not by anything made of 'fermions' like matter in any way. When it comes to 'bosons' like photons they are a 'unknown' property to me, I'm still not sure how, or even if, they 'travel' in spacetime :) They are so strange ::))

---
Edit for edits sake, no not really, just need to find them glasses.
If now only I could see them?

------------

Reading myself I find I need to clarify what I see as some subtleties here making me choose one idea before another. My view springs out of thist that we all are 'originals'. Imagine another 'timeline' in another 'spacetime'. Although that time line may contain a 'you' too it will not belong to your original 'spacetime' and therefore won't create any 'super positioning' of fermions if I may express it so (loosely:).
So to my eyes the idea of traveling backwards finding yourself in another 'spacetime' is in that manner explainable, but the other idea.

That you somehow would be able to travel backward inside your own spacetime introduces such a lot of paradoxes to me.To do so seem to imply crosscut's of spacetime being stringed one after each other and then somehow taking out one 'slide' putting in a new with two of you instead. How would that be done? The 'many worlds scenario' is a way to come around this problem although it introduces a new one. Did those other timelines, if so, exist before you time traveled, or are they the created as a direct result of your time traveling? If they are created then you would probably only find one 'you' there even that timeline would contain a history of there being another 'you' before that moment it came into existence. Crazy ain't it :)
« Last Edit: 10/04/2009 14:08:14 by yor_on »
 

Offline Mr. Scientist

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Can you use light to time travel?
« Reply #18 on: 09/04/2009 21:49:39 »
If light is affected by Gravity and Gravity can distort time.

Could you use light says lasers etc to time travel?

Yes, it was hypothesized by a scientist in the 1990' (don't ask me his name or his rference papers because i don't have them any more in memory or literature), however, his experiment consisted of having lazers around a central core which would move at very high speeds; the hope was to ditort the spacetime in the interior of the dwelling of barred lazers and find a gravitational ditsortion.

I am not aware how his project is now working out unfortunately.
 

Offline Raghavendra

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Can you use light to time travel?
« Reply #19 on: 10/04/2009 08:49:54 »
good question but simple answer, can you run in time with light speed?
 

Offline LeeE

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Can you use light to time travel?
« Reply #20 on: 10/04/2009 21:21:13 »
...What about it. Can we 'jump over a year' in our present frame and then just continue? In a Unbothered whistling sort of way?


Do we have a definition problem here?
You (your experience) can hardly jump 'within' your present frame of reference because that's what you are experiencing - body chemistry, brain, the lot.
You can only jump in someone else's frame - in which case you could emerge next Tuesday and no one on Earth would have seen you whilst they were experiencing the weekend. You would just turn up on that day, but not be aware of any time having elapsed - just the time taken for the machine to gurgle and make a Dr Who noise.

Your  consciousness can always 'jump forward' relative to your body chemistry when you are unconscious. That's a daily experience for most people. Your reference frame would correspond to your body chemistry, and an observer by your bedside would agree.

Sorry - a bit late on seeing this post.

Using Dr Who's Tardis to move forward in time isn't really much different to using time-dilation to achieve the same results except that in the Tardis you'd appear to vanish from the universe for the duration rather than remain in it.  Actually, now I think of it, the Tardis doesn't travel instantaneously does it?  The Dr. and his assistant appear to experience a passage of time during their journeys.

Either way though, using either the Tardis or time-dilation, you don't skip any time in your frame of reference.

Your point about our consciousness skipping time relative to our bodies when, for example, we sleep, is a very good one.
 

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Can you use light to time travel?
« Reply #20 on: 10/04/2009 21:21:13 »

 

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