What would happen if something would go immediately from point a to b

  • #1
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the idea of time dilatation is that the light should cross 299 792 458 meters each second relative to all point of views , so when there is two observer that one of them is in rest and the other observer is moving , the clock ticking of the moving observer would be slower(by clock ticking i mean anything that happens over time) . but if something is going through distance after zero time the light shouldn't pass any distance by the time the object is crossing the distance from a to b . (299 792 458*0) d=c*0. so my question is weather teleportation immediately from point a to b is possible theoretically and would it cause time travelling ? ( it also my be related to the EPR paradox even though I don't understand it fully so forgive me if it not related to that at all)
 
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  • #2
Ibix
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If you allow communication faster than light this leads to causal paradoxes. Google "tachyonic anti-telephone".
 
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If you allow communication faster than light this leads to causal paradoxes. Google "tachyonic anti-telephone".
I googled it but I didn't understand why crossing distance immediately means signaling to the past
 
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Ibix
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Because of the relativity of simultaneity. Two spacelike separated events A and B are in the order A, B in some frames and B, A in others. Thus if you signal from one to the other then you are signalling to the past in some frames. The tachyonic anti-telephone exploits that to create a communication loop to your own past.
 
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Because of the relativity of simultaneity. Two spacelike separated events A and B are in the order A, B in some frames and B, A in others. Thus if you signal from one to the other then you are signalling to the past in some frames. The tachyonic anti-telephone exploits that to create a communication loop to your own past.
so now I have two question . one is about EPR,if the signal effect is not carry any data and is not determent anything so you can say it not have an effect on the past, and my second question is how sending signal from difference times frames is like sending signal to your own past,let say clock in point A is ticking 3 times and clock in point B is ticking 5 times . the data you can send from point B is only about information in point B you cant tell your self anything about the feature in point A because there inst any general point of view so the event in point B is not actually happen before the event in point A it just that the events in point B happens slower .
 
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  • #6
Ibix
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I can't understand your first question. The point of the EPR paradox is that no information is transferred.

Your second question suggests you don't understand the relativity of simultaneity. Clocks that are synchronised in one frame not only tick at different rates as measured in another frame, but are not synchronised. It isn't the rate difference being exploited here. It's the different synchronisation - i.e. the different meaning of "now".
 
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I can't understand your first question. The point of the EPR paradox is that no information is transferred.

Your second question suggests you don't understand the relativity of simultaneity. Clocks that are synchronised in one frame not only tick at different rates as measured in another frame, but are not synchronised. It isn't the rate difference being exploited here. It's the different synchronisation - i.e. the different meaning of "now".
can you give me an example for how it worked. assume we have two time frames when new data arrive in point B and it being send to point A how it effect the past of any of the locations ? I mean if information is being created in point B then it not have an effect on point A and if it being send to point B and then back to point A it not being send to it past
 
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Ibix
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can you give me an example for how it worked. assume we have two time frames when new data arrive in point B and it being send to point A how it effect the past of any of the locations ? I mean if information is being created in point B then it not have an effect on point A and if it being send to point B and then back to point A it not being send to it past
The Wikipedia page on the tachyonic anti-telephone has several examples.
 
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but in this example the signal is going back in time and in my first post I wonder about it
That is nearly a sentence!
 
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so now I have two question . one about EPR,if the signal effect is not carry any data and is not determent anything because there inst any general realty so you can say it have an effect only when you measured it , so isn't it like the signal arrive after you notice it which is require sending signal in speed f light ?, and the second question is how sending signal from difference times frames is like sending signal to your own past,let say clock in point A is ticking 3 times and clock in point B is ticking 5 times . the data you can send from point B is only about information in point B you cant tell your self anything about the feature in point A because there inst any general point of view so the event in point B is not actually happen before the event in point A it just that the events in point B happens slower .
You can't expect anyone to make any sense of that.
 
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  • #12
Ibix
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but in this example the signal is going back in time and in my first post I wonder about it
Yes. That's the point. Any faster than light signal is backward in time in some frames. The tachyonic anti-telephone exploits that to violate causality.

That's why faster than light signalling is inconsistent with relativity.
 
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  • #13
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Yes. That's the point. Any faster than light signal is backward in time in some frames. The tachyonic anti-telephone exploits that to violate causality.

That's why faster than light signalling is inconsistent with relativity.
but I am wondering why ,I understand that when the single is traveling in speed that twice bigger then light or something like that , but if it going immediately from point a to b isn't going back in time for zero second which and also logically it doesn't require any time dilatation because the light is not cross any distance in zero second as I wrote in my first post
 
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You can't expect anyone to make any sense of that.
I changed it a bit
 
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Ibix
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immediately
Immediately in which frame? In any other frame, it's either going forwards or backwards in time.

Any faster than light motion is instantaneous in some frame.
 
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  • #16
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Immediately in which frame? In any other frame, it's either going forwards or backwards in time.

Any faster than light motion is instantaneous in some frame.
assume that the clock in location A is ticking 3 times while the clock in location B is ticking 5 times ,then someone in location A press on "send signal button" after three ticks , then signal arrive to point B after zero time and it go through point A and B only it like it teleportation then the signal doesn't have any velocity . it not going to the time clock of location B is ticking 3 times it getting to location B only when ticks 5 times .
 
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Ibix
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assume that the clock in location A is ticking 3 times while the clock in location B is ticking 5 times ,then someone in location A press on "send signal button" after three ticks , then signal arrive to point B after zero time and it go through point A and B only it like it teleportation then the signal doesn't have any velocity . it not going to the time clock of location B is ticking 3 times it getting to location B only when ticks 5 times .
The signal has infinite velocity in this frame. It has finite velocity in others.

I think you need to write down the velocities of all clocks and ##(x,t)## coordinates of all the events you are considering, then apply the Lorentz transforms to see how this looks in other frames. We are just going round in circles here.
 
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  • #18
PeterDonis
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The OP question has been answered. Thread closed.
 

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