# Is speed of light a teleportation?

1. Jan 16, 2013

### mantas29

I thought about an idea that keeps spinning my head around. It's proven that the faster you move the slower the time passes for you and lets assume that speed of light is the limit. So if you had a spaceship that can travel at lets say 99.9% of speed of light wouldn't that be the same thing as what we call a teleportation? Because you would need to break after about 0.01s after your acceleration because time around you flies almost infinite times faster. And another thing - if you somehow manage to reach the maximum limit and travel at the speed of light, does that mean you become forever trapped in a single line of space (lets say space has no edge) for observers and die instantly from your perspective, because space once again shrinks to it's beginning point?

Sorry for mistakes, english is not my first language, and I registered to this forum just to ask what you think about this. :)

2. Jan 16, 2013

### Simon Bridge

No.
AFAIK this is not the case - if you have different information, please provide the citation.

What happens is that a clock moving sublight with respect to you runs slower than clocks stationary with respect to you.

3. Jan 18, 2013

### BenG549

Definitely not teleportation, you do however experience time dilation when travelling at great speeds.

The following is a bit a of a long winded story I took from: http://www.costellospaceart.com/html/time_and_the_speed_of_light.html

"Travelling at speeds close to the speed of light has a great effect for the travellers. You have probably heard or read that at these speeds, time slows down so much for the traveller that when the travellers return back to planet Earth, all their friends and everyone they knew are now greatly aged as many years have passed on Earth since they first took off on their journey. For the travellers, with their ship travelling at speeds close to the speed of light, time had slowed for them according to the clocks of the people who kept track of the ship on Earth. The travellers, according to the people on the Earth, had been on their journey for a thousand years. For the travellers, the trip seemed like they were gone a couple years.

So, Bill and Mary synchronize their watches and then Mary takes off in her space ship and she travels at 99% the speed of light which is 669,600,000 miles an hour. Now for both Bill and Mary, time will seem to be passing at the same rate to each of them. Another way to put it is, let’s say that Mary and Bill are both 30 years old and we know that they are both going to pass away when they are 100 years old. If Bill spent the rest of his life on the Earth, the next 70 years would seem like 70 years to him, right? If Mary spent the rest of her life on her ship travelling close to the speed of light, the next 70 years would also to her seem like 70 years. Remember, time is relative to ones perspective. It’s when Bill and Mary meet again and they compare their watches that time dilation will show its face. In reality, thousands of years would pass between what Bill saw as 70 years and what Mary saw as 70 years.

If Mary was travelling close to the speed of light and she travelled for one year according to her watch before returning to Earth, she would return to find that close to 20 years had passed on Earth. Also, Bill was no longer waiting for her. Relative to Mary, time had passed one year. It just took longer for that year to pass for Mary in her ship than it did for Bill on Earth. Even though 20 years had passed on Earth, for Mary in her ship, she saw only one year had passed because she was travelling much faster than Bill on Earth and time slowed down for her and time passed at a slower rate than it did for Bill."

If this story is making little sense there is a lot of stuff in youtube about this:

this is another example regarding time dilation etc..

Richard Muller has a great series of conceptual physics lectures on there look for "physics for future presidents" on youtube or "Richard Muller Relativity" for lectures specifically on GR and SR:

(to be honest if you are interested in this you are better of just watching the whole lectures)

(Relativity 1)
(Relativity 2)

The lectures are from University California Berkeley, well worth a watch if you have no great mathematical knowledge but want to know about relativity, magnetism or most things physics.

Last edited by a moderator: Sep 25, 2014
4. Jan 18, 2013

### BenG549

The links above I posted explain length contraction at speeds close to the speed of light as well as time dilation.

5. Jan 18, 2013

### nitsuj

why be so specific with the OP's wording by replying "as far as I know this isn't the case". Then go on to describe the exact same thing.

"What happens is that a clock moving sublight with respect to you runs slower than clocks stationary with respect to you."

What he said about time dilation is right , however the title is a false premise as teleportation is with respect to matter. Other than that it is also right, to some degree; as in not being able to observe EM as it traverses spacetime (as opposed to teleportation which is "skipping" spacetime between events).

6. Jan 18, 2013

### Simon Bridge

What tends to happen is that people try to explain things like relativity in terms of more familiar classical mechanics. This does not work - all that happens is that the weirdness gets emphasized and the audience gets more confused. Why? That's easy: relativity is a superset of classical mechanics: it contains all of the classical motion and then adds stuff for things that are not explainable otherwise.

So when we try to give a lay impression of relativity, we need to be careful with our language to avoid misconceptions or being self-contradictory.
Time does not slow down for the traveller in this story - when you are the one leaving the earth and returning - you do not notice your clocks going slowly. Time passes in the normal way for you. In fact, you would see the Earth-side clocks running slowly.
(my emph. [the author] got it right here but kept contradicting [himself] later - see below)
It didn't just seem to take a few years - it actually took a few years. To put it another way - it is equally correct to say that, to the people on the Earth is seemed to take thousands of years.
... it is probably because the wording has got garbled. i.e.
...that one year of Mary's passed very slowly for Bill, not Mary.

It is quite accurate to say that Mary's year "appears" longer to Bill in the same way that lengths closer to you appear to stretch out more than lengths far from you. We can say that "distant lengths look short". It's got a special name: perspective. Lengths that are altered by perspective appear shorter. Special relativity says that relative speed alters perspective as well, and time also gets altered by perspective. Time periods that are altered by perspective appear longer.

That one year for Bill also passes slowly for Mary - because Bill is moving in Mary's reference frame - and perspective works both ways.

If Mary and Bill were a few hundred yards apart, then Mary would notice that Bill looks shorter than if they were standing next to each other ... for the same reason that Bill notices that Mary appears shorter. It is the same physics here only for time.

To get a consistent understanding - have a look at:
http://www.physicsguy.com/ftl/html/FTL_intro.html
... it is in four parts and serves as a quick primer on the important aspects of special relativity that you tend to hear about and familiarizes the reader with the specialized language that goes with physics where time is another dimension of space. It also deals with the problems that must be overcome for FTL travel.

(Note: the talk about perspective works from relativity to classical but not very well the other way around. i.e. a distant clock does not run slow like a distant length looks short ... recall: relativity replaces classical.)

Last edited: Jan 18, 2013
7. Jan 18, 2013

### BenG549

Not sure I said anything to the contrary, I understand that this is the case, that passage was copied and pasted from the web site that I cited, sorry if was worded badly, maybe I should have read it more carefully before posting. I provided the other links to clarify, in case the story was confusing in the way you suggest.

Last edited: Jan 18, 2013
8. Jan 18, 2013

### Simon Bridge

Um - perhaps I wasn't clear enough: my apologies. I'll try again.
OP described the moving observer's time passing slower with respect to the moving observer.

... "time passes slower" for who?

i.e. as you go faster, you see your watch tick slower.

I wrote:
... i.e. your clock runs slower for some other observer - not you. Or: the faster you move the slower your time passes for someone else.

It is possible that was not what was intended, but it is what was written down and it is a very common misunderstanding. It is a misunderstanding that gets reinforced by common descriptions of the Twin's Paradox.

When someone is learning relativity, it avoids a lot of confusion if we are particular about the language we use. It is very easy to slip into a kind of shorthand and confuse people. Even the kind of care I'm advocating will have it's limitations - in the end, you have to explain and adopt the language of relativity. Please see the link in the previous post for clarification.

Last edited: Jan 18, 2013
9. Jan 18, 2013

### Simon Bridge

I did notice - My commentary should be considered to be directed at the message and not the messenger.

The quoted section was a very good example of how confused impression can be set up and reinforced by well-meaning attempts to describe the less intuitive parts of physics. I wouldn't be surprised if some parts of the videos repeat the error. You should see how badly I trip up sometimes :)

(In fact - I tripped up in the comments by referring to you instead of "the author" as if these were your statements - apologies and corrected.)

10. Jan 18, 2013

### BenG549

Do you suggest I remove that section of my post, to save any confusion? To be honest the videos are really very good. Professor Muller is a very well respected physicist, his lectures are a really useful resource for people without a good mathematical background.

11. Jan 18, 2013

### nitsuj

Moving observer compared to the moving observer?

The sentence you quoted was

"It's proven that the faster you move the slower the time passes for you."

This is not an overly complicated situation. It's a comparison of proper times in between accelerations..i.e. going faster.

In that specific sentence they described a situation like the twin paradox, but as an only child .

Oddly those sentences are more loosely worded (make more assumptions about understanding of SR) than the OP one you said was wrong.

Absolutely, but you didn't explain the definition of proper time and coordinate time.

If you want to help clarify the OP thoughts, ask what is meant by

"...you would need to break after about 0.01s after your acceleration because time around you flies almost infinite times faster."

In that we'd see what the OP means by "time around you flies by faster."

Or address the issue of even idealizing about going the speed of light.

Last edited: Jan 18, 2013
12. Jan 18, 2013

### PAllen

I share Simon's view that this quote is wrong, pure and simple. Simon's rewording is correct. As long as you are moving inertially, you consider all other clocks to run either slower than yours or the same speed (if they are stationary with respect to you). Earth moving away from you at near c does not make your clock run slow.

13. Jan 18, 2013

### Simon Bridge

Either way - I'd expect OP to correct me if I misunderstood :)
@PAllen: thanks.
@Mantas29: any of this any help to you?
Welcome to PF BTW.

14. Jan 18, 2013

### SJBauer

I am going to take a different approach to your question. Light travels at the speed of light because it is relatively massless (or zero mass) relative to the SpaceTime continuum. Therefore for anything to travel as faster or faster than the speed of light, it would need to be able to dimensional transition between being mass conditions of positive and zero, and maybe even negative. So the problem with considering this a viable illusion of teleportation is one of warping the fabric of SpaceTime. Per the Equivalence Principle, it doesn't matter how you accelerate; you become a victim of your own increasing gravitational acceleration (and its not a pretty picture).

15. Jan 18, 2013

### Simon Bridge

There is always the definition of "teleportation" of course.
"this" meaning "dimentional transport" or "this" meaning "light-speed"?

Teleportation, in the common SF sense of repositioning something from one place to another instantly, without passing through the intervening space. I have seen it used to refer to quantum entanglement events where "information" is the thing "repositioned".

I think the reference to everyone being infinitely time-dilated in the speed-of-light limit best refers to this kind of thing... translation in zero time. i.e. if light gets everywhere it's going in zero time on it's clock - is that teleportation?

The answer each time is "no" because light also measures zero distance between positions. It no more teleports than you do when you go from sitting in your chair to sitting in your chair in the same instant.

(... I have been pinged before about trying to talk in terms of the photon-frame - it is not really all that helpful.)

Not that dimension warps and FTL are not interesting.

FTL could, in principle, (iirc - it's been a while) get you to the state where you arrive at your destination before you left (i.e. a causality violation ... unsolvable paradoxes ... fancy hypothetical space-time geometries notwithstanding) I suppose that would be a kind of teleportation. Since you approach before you left, you could always go sub-light to time your arrival to coincide with the proper-time of your setting off from your origin. Which is where most of us break out the whiskey. Part IV of the last link I posted discusses these things in, what I hope people will find, more understandable terms.

In light of the previous discussions - I think basically what all this means is "the first post needs clarification".

16. Jan 19, 2013

### SJBauer

Per your statment - "Teleportation, in the common SF sense of repositioning something from one place to another instantly, without passing through the intervening space." The concept of Time dilation still involves intervening space, or the relativity within the SpaceTime continuum.

In my opinion, true teleportation requires the disntegration of matter in one SpaceTime position and the reintegration of like matter in another SpaceTime position. So while speed of light travel is the illusion of teleportation, there are theoretical equivalences that show more promise. Quantum Teleportation, from a SF sense, provides a better vehicle for the sense of teleportation because it relies on quantum entaglement to allow the information of the disintegrated matter to be passed on for the reintegration of matter in a different SpaceTime position. However, even this procedure lack the mechanism for the actaul disintegration and reintegration process.

17. Jan 19, 2013

### Simon Bridge

Yeah - most speculative teleportation schemes are duplication + destruction schemes.
It is usually unclear why there needs to be a destruction.

This is getting highly speculative though.

18. Jan 19, 2013

### mantas29

Yes, thank you all, I learned a lot from what you all said. :) I just compared speed of light with teleportation because they seemed similar for me, I understand that teleportation is nothing about speed but it's some kind of form of instant reach of destination for the traveller. Sorry if the title wasn't clear enough. :) But the final answer is still a mystery for me. I'd like to concentrate on the second part of my question and be more specific about what I want to know. Well lets say I reach the speed of light. Would that mean that time stops for me in respect of the stationary surrounding? In that case I would still move at the speed of light but I would be frozen in time forever, so I would be everywhere in a straight line at the same time from my perspective (everyone else would see me moving away or towrds them but inside my ship i would be frozen and everything i do would take infinite time). Is this true?

19. Jan 19, 2013

### Simon Bridge

You won't... and the math does not say anything sensible for that sort of speed. What you can do is talk bout what happens as your speed approaches the speed of light.

In special relativity - the observer is always stationary. Your surroundings do the moving. Time always continues at the usual rate for the observer - it is everyone else who has the slow clocks.
Thus: as you approach the speed of light, you do not notice anything special about the way time passes, and you'd notice that everyone else is moving, and you'd notice that the distances between objects is smaller, and everyone elses clocks are running slower.

From the POV of everyone else, you'd be going real close to the speed of light - but your clock would crawl by... maybe taking centuries to tick off one second. You'd appear to be frozen with respect to your spaceship. But to you, while you are not accelerating, everyone else appears to be frozen... this is because they are all moving with respect to you just like you are moving with respect to them.

The link I gave you covers this situation... also shows you what happens when you are accelerating.

20. Jan 19, 2013

### mantas29

Now I understand! I didn't realise that everything around me would be moving at the same speed. That explains everything :) Thank you so much for explaining this. Now I can continue thinking more impractical questions that no one really care about! :D

21. Jan 19, 2013

### Simon Bridge

Just to be clear - when you change speed, in relativity we say you changed reference frames.
As far as you are concerned, as the observer in your new reference frame, you are stationary.
An observer in your old reference frame will say you are moving with velocity v, then you will see them moving with velocity -v. All the other objects that are stationary in your old reference frame will also be passing you with velocity -v.

22. Jan 20, 2013

### SJBauer

Per your understanding, "Now I understand! I didn't realise that everything around me would be moving at the same speed. That explains everything :) Thank you so much for explaining this. Now I can continue thinking more impractical questions that no one really care about! :D"

True, due to our understanding of special relativity, SpaceTime is relative to the observer. As Simon Bridge explained, "Time always continues at the usual rate for the observer." Ergo, the speed of light is same within your speed of light (SOL) reference frame as it would be for someone who was traveling much slower. But then, what of Space?

Getting back to a portion of your previous question, "In that case I would still move at the speed of light but I would be frozen in time forever, so I would be everywhere in a straight line at the same time from my perspective." There are multiple perspectives to consider. A) If as actual rate of Time changes with respect to his acceleration, his reality became part of this slower rate of time, then it would appear to him that his Earth-bound counterparts were milling about at incredible speed in relation to his own. OR B) Consider the SOL traveler is moving at the same rate as he would on Earth, but only the rate of Time changes with respect to his acceleration. In this respect the rate of Time is slowing down consistent with his acceleration, but his movements are still relative to his Earth-bound rate of Time; ergo, he is moving more in less time, or moving faster. Consistent with this notion, he is also able to process more information in less time, or he is thinking faster. Somewhat like a housefly that is able to react and move much faster relative to his frame of reference, the SOL traveler would perceive his Earth-bound counterparts to be moving more slowly or not at all.

The Theory of Relativity favors selection ‘A’ as the SOL traveler’s reality, allowing him to be younger when he returns to Earth. The logic behind this is that as the SOL is measured the same, relative to one’s frame of reference in the rate of time, so must the relative relationship among all of its participants. Subsequently the perspective relationship of man’s speed relative to the actual SOL should remain the same within any reference frame. Consequently if the rate of time slows with acceleration, then so must everything else in that frame of reference do likewise.

But one cannot consider Time without Space, so this brings up another aspect of relativity; i.e. mass increases with acceleration. This would suggest that the mass of the photon becomes greater upon acceleration, as well as everything else in this reference frame. Therefore to suggest that the SOL travelers would age less during the time of their acceleration and would be younger than their Earth-bound counterparts, one must also agree that the SOL travelers should have also retained their increased mass upon return to Earth. Since the most likely form of increased mass would be due to increased density, rather than increased volume, the SOL traveler would be a veritable superman upon his return.

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