Why can't energy or information go faster than light?

  • #1
danielhaish
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as I read here
http://www.bbc.com/earth/story/2016... energy they possess,are already at top speed.
things with mass can't reach to the speed of light because when you get closer to the speed of light the mass of the practical is become bigger and them you need more energy to eccalrate them mv^2/2 but why can't information go faster then the light or energy
 

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  • #2
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If information could go faster than light then according to relativity you could violate causality. Out of relativity, faster than light, and causality, you can only have two. It looks like this universe has relativity and causality, so it cannot have FTL
 
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  • #3
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Experiments show that there is a speed, c, that is not exceeded when the speed of a platform is added to the speed of light and other electromagnetic waves. This forces there to be a trade-off between motion in space dimensions and motion in time. That, in turn, forces the mathematical geometry of space-time where there is no speed greater than c. In that geometry, with that speed/time trade-off, there is no such thing as a speed greater than c.
 
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  • #4
phinds
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... why can't information go faster then the light or energy
How do you propose that information be transferred? By magic? If not, then you have 2 choices to use for transferring the information and they are massless device (such as light) or massive devices (such as electrons). You already state that neither on of those can travel faster than light so why would you think that information should be able to travel faster than light?
 
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  • #5
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but why can't information go faster then the light or energy
If information could move from point A to point B faster than the speed of light then we could arrange things in such a way that in some frames the message arrives at point B before it has been sent. With a bit more cleverness (google for "Tachyonic Anti-telephone") , we can arrange things in such a way that after receiving the message the recipient will be able to destroy the sending mechanism before the message has been sent.

The resulting contradictions and paradoxes are a very convincing argument that the universe operates under laws that don't allow faster-than-light causality.
 
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  • #6
jbriggs444
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If information could move from point A to point B faster than the speed of light then we could arrange things in such a way that in some frames the message arrives at point B before it has been sent. With a bit more cleverness (google for "Tachyonic Anti-telephone") , we can arrange things in such a way that after receiving the message the recipient will be able to destroy the sending mechanism before the message has been sent.

The resulting contradictions and paradoxes are a very convincing argument that the universe operates under laws that don't allow faster-than-light causality.
The techyonic anti-telephone argument depends on the principle of relativity -- that the laws of physics are the same no matter what inertial frame we use. In particular, it makes use of that principle when we argue about the behavior of the outbound leg of the anti-telephone using one frame and then argue about the behavior of the return leg using a different frame.

If a magical undiscovered FTL effect were to exist and were to allow for transfer of actionable information then we could, in principle, salvage causality by sacrificing the principle of relativity. The FTL effect could respect some preferred frame within which the FTL signal never goes backward in time.

However, the principle of relativity is at the core of most of our theories about the universe. Giving it up would require some extraordinary evidence.
 
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  • #7
danielhaish
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The techyonic anti-telephone argument depends on the principle of relativity -- that the laws of physics are the same no matter what inertial frame we use. In particular, it makes use of that principle when we argue about the behavior of the outbound leg of the anti-telephone using one frame and then argue about the behavior of the return leg using a different frame.

If a magical undiscovered FTL effect were to exist and were to allow for transfer of actionable information then we could, in principle, salvage causality by sacrificing the principle of relativity. The FTL effect could respect some preferred frame within which the FTL signal never goes backward in time.

However, the principle of relativity is at the core of most of our theories about the universe. Giving it up would require some extraordinary evidence.
But this signle doest really go through distance becuase you can't catch it in the middle so is valocty is still may be lower then light becuase then let say there is minimal distance you can move when a phenomenon like gravity is expends then it goes through all space so it go from point a to b then to c and so on so it go some distance so you can say that it speed is d/t distance/time but if the signal is coming through only.two point the distance it travels is very small so also the valocty is not necessary faster thenight am I right?
 
  • #8
jbriggs444
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But this signle doest really go through distance becuase you can't catch it in the middle so is valocty is still may be lower then light
You can't weasel out of it that easily. Regardless of what the signal does or does not do in the middle, if it gets to the end of its journey ahead of a light speed signal, if it can convey actionable information and if the laws of special relativity hold good, paradoxes ensue.
 
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  • #9
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But this signle doest really go through distance becuase you can't catch it in the middle so is valocty is still may be lower then light becuase then let say there is minimal distance you can move when a phenomenon like gravity is expends then it goes through all space so it go from point a to b then to c and so on so it go some distance so you can say that it speed is d/t distance/time but if the signal is coming through only.two point the distance it travels is very small so also the valocty is not necessary faster thenight am I right?
Please put some effort into your posts. This is unintelligible
 
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  • #10
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Daniel, your messages are incomprehensible. Whatever language is your first language, it uses sentences. So does English. Second, you got an excellent message in #4. You should read it and think about it.
 
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  • #11
danielhaish
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Please put some effort into your posts. This is unintelligible
Can I try to rewrite it in new thread?
 
  • #13
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The techyonic anti-telephone argument depends on the principle of relativity
Indeed it does. That's why I said "very convincing argument" instead of "proof". It's not a proof because we haven't excluded the possibility that some of our basic beliefs about the universe (homogeneity, isotropy, principle of relativity, ...) are wrong. There's another assumption as well, namely that the universe doesn't allow causal paradoxes such as the anti-telephone.

I consider any argument that is valid as long as these assumptions are valid to be very convincing.
 
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  • #14
danielhaish
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Indeed it does. That's why I said "very convincing argument" instead of "proof". It's not a proof because we haven't excluded the possibility that some of our basic beliefs about the universe (homogeneity, isotropy, principle of relativity, ...) are wrong. There's another assumption as well, namely that the universe doesn't allow causal paradoxes such as the anti-telephone.

I consider any argument that is valid as long as these assumptions are valid to be very convincing.
They might be both true according to some theory don't they
 
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  • #15
danielhaish
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Not a new thread. Try again in this thread.
Sorry can't edit the thread any more but I will rewrite the post here as another post
 
  • #16
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But this signle doest really go through distance becuase you can't catch it in the middle so is valocty is still may be lower then light becuase then let say there is minimal distance you can move when a phenomenon like gravity is expends then it goes through all space so it go from point a to b then to c and so on so it go some distance so you can say that it speed is d/t distance/time but if the signal is coming through only.two point the distance it travels is very small so also the valocty is not necessary faster thenight am I right?
I was going to nominate this for the most incomprehensible message of the week, but I see that @jbriggs444 could make some sense of it.
 
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  • #17
danielhaish
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I was going to nominate this for the most incomprehesible message of the week, but I see that @jbriggs444 could make some sense of it.
I am working on re write sorry I don't find it so easy
 
  • #18
danielhaish
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But this single doesn't really go through distance because you can't catch it in the middle from location A to location B so is valocity is still may be lower then light because then let say there is minimal distance object can move. when a phenomenon like gravity is expends then it goes through all space so it go from point a to b then to c and so on, so it go some distance so you can say that it speed is d/t distance/time but if the signal is coming through only.two point the distance it travels is very small so also the valocity is not necessary faster then light am I right?
is it batter now ?
 
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  • #19
jbriggs444
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I see that you have corrected the spelling of "because" on the first line. The spelling of "valocity" is still incorrect.

I see you have changed from having you move to having an object move.

I see you have added a period so that we have two sentences instead of one.

So far, this is not a significant re-write.

The first thought I'd had was that you were thinking of something like quantum mechanics. That if a signal goes straight from point a to point b without being intercepted in the middle that it cannot properly be said to have a velocity at all. But it seems that is not what you are trying to express.

My next thought is that you are talking about something like "folding" space up so that instead of going the long way from point a to point b to point c and eventually on to the target at point z, a signal goes straight from point a to point z over a shorter, direct path that does not follow the folded, crumpled up surface.

Assuming the latter is what you have in mind you will have to describe this hypothetical capability in more detail. Is it possible to fold space-time to link any two events that are space-like separated?
 
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  • #20
phinds
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is it batter now ?
No, "batter" is stuff you use to make cakes or cookies. I realize that English is apparently very difficult for you, but still ...
 
  • #21
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is it batter now ?

You're battering the English language, that's for sure.

I used to think the problem was a language barrier. I am coming to the conclusion that the reason you can't express what you are thinking is because it is not clear in your own mind. Not because you dropped a period into the middle of a run-on sentence.
 
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  • #22
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No, "batter" is stuff you use to make cakes or cookies. I realize that English is apparently very difficult for you, but still ...
With traditional British fish and chips, the fish comes in batter (the green stuff is "mushy peas"):

1607096432453.png
 
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  • #23
phinds
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... "mushy peas"
And THAT is a good example of why people say bad things about British food. :smile:
 
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  • #24
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Batter eat it quick before the wife catches you breaking the diet.
 
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  • #25
danielhaish
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I see that you have corrected the spelling of "because" on the first line. The spelling of "valocity" is still incorrect.

I see you have changed from having you move to having an object move.

I see you have added a period so that we have two sentences instead of one.

So far, this is not a significant re-write.

The first thought I'd had was that you were thinking of something like quantum mechanics. That if a signal goes straight from point a to point b without being intercepted in the middle that it cannot properly be said to have a velocity at all. But it seems that is not what you are trying to express.

My next thought is that you are talking about something like "folding" space up so that instead of going the long way from point a to point b to point c and eventually on to the target at point z, a signal goes straight from point a to point z over a shorter, direct path that does not follow the folded, crumpled up surface.

Assuming the latter is what you have in mind you will have to describe this hypothetical capability in more detail. Is it possible to fold space-time to link any two events that are space-like separated?
actually it is what I am trying to express
 
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  • #26
jbriggs444
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actually it is what I am trying to express
All right. So you have decided that we have this hypothetical capability to send objects or signals between two arbitrary events in space-time. And just so we are not cheating too outrageously, we will require that the points be "space-like separated". That means that you cannot directly link one event with another that is unambiguously in its past. In other words, you can't send a signal directly to an event from which you could then hand-carry a response back the other way.

The point you seem to want to make is that this capability does not count as "Faster Than Light travel" because you can divide distance covered (on the hypothetical short-cut non-folded path) by elapsed time (on a wrist watch carried on the short-cut non-folded path) and arrive at a figure less than the speed of light (c).

That's true. You do not need to call this faster than light if you do not want to. But that's just word choice. It does not affect the physics. If you can get a signal from point a to point b and the signal can get there faster than light could (following the normal long-way path) and if you can do this for any pair of space-like separated events then that is all that is needed to construct a tachyonic anti-telephone and start generating paradoxes.

You could also Google for "closed timelike curve". A path that goes from point a, FTL to point b, FTL to point c and then snail mail back to point a counts as a closed timelike curve.
 
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  • #27
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actually it is what I am trying to express
This does not negate the problem identified above at all. Even with this type of spacetime with a shortcut you still wind up with the possibility of closed timelike curves and hence a breakdown of causality.
 
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  • #28
danielhaish
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All right. So you have decided that we have this hypothetical capability to send objects or signals between two arbitrary events in space-time. And just so we are not cheating too outrageously, we will require that the points be "space-like separated". That means that you cannot directly link one event with another that is unambiguously in its past. In other words, you can't send a signal directly to an event from which you could then hand-carry a response back the other way.

The point you seem to want to make is that this capability does not count as "Faster Than Light travel" because you can divide distance covered (on the short-cut non-folded path) by elapsed time (on a wrist watch carried on the short-cut non-folded path) and arrive at a figure less than the speed of light (c).

That's true. You do not need to call this faster than light if you do not want to. But that's just word choice. It does not affect the physics. If you can get a signal from point a to point b and the signal can get there faster than light could (following the normal long-way path) and if you can do this for any pair of space-like separated events then that is all that is needed to construct a tachyonic anti-telephone and start generating paradoxes.
can you explain the paradox in the fallowing example , I am a little confused . let assume that there is two location with difference time frames and in each location there is one quant , and the two quant are entanglement to each other . let's take a look at the properties of the location of each quant . each quant have a possibility to be in every location but when you put measure device on one quant it like sending a signal to the past that change the wave function of the quant . but no one can tell that the measured has taking place in the other location according to the No-communication theorem . and also it not like the location of the quant has changed because before the measure of the location of the quant it still could be where the measurement took place (the result of the measure). so the past didn't practically changed till you reach to the future . I meant that the observer can see the signal only after some time and adter data about weather the other quant has been measured so it not effect him and also the location of the quant is not necessarily changed . let assume there is two people in each location and one should jump to the pool when signal arrive according to the paradox it not possible that the signal is being send faster then the light because then it would change the past and make one man jump to the pool in the past but the other person can't tell that the signal have change in the past
 
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  • #29
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can you explain the paradox in the fallowing example , I am a little confused . let assume that there is two location with difference time frames and in each location there is one quant , and the two quant are entanglement to each other . let's take a look at the properties of the location of each quant . each quant have a possibility to be in every location but when you put measure device in one quant it like sending signal to the past that change the wave function of the quant . but no one can tell that the measured has taking place in the other location according to the No-communication theorem . and also it not like the location of the quant has changed because before the measure the location of the quant still could be where the measurement took place. so the past didn't practically changed till you reach to the future . I meant that the observer can see the signal only after some time and adter data about weather the other quant has been measured so it not effect him and also the location of the quant is not necessarily changed
I thought I had a prayer of understanding what you were talking about this time.

The prayer was not answered.

Probably it has something to do with quantum entanglement not transmitting actionable information due to the no-communication theorem. [I was careful to use the phrase "actionable information" in my posts up-thread in order to avoid discussions like this about quantum entanglement]
 
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  • #30
danielhaish
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I thought I had a prayer of understanding what you were talking about this time.

The prayer was not answered.
I add something in the end . I am referring to the pardox that changing the past can't change the future
 
  • #31
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I am a little confused

That is clear.

t assume that there is two location with difference time frames

That is not.

and in each location there is one quant

Nor is that. What is a "quant"?

but when you put measure device on one quant it like sending a signal to the past

I understood that! But it is not correct.
 
  • #32
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when you put measure device on one quant it like sending a signal to the past that change the wave function of the quant

No, it isn't. The measuring device only affects the thing being measured at the spacetime location of the measurement. It doesn't affect anything to the past.
 
  • #33
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@danielhaish I am sorry but your posts simply do not meet our quality standards. I am closing this thread. I don’t know that we will be able to help you at all here. You may want to find a forum in your native language where the others may have a chance to understand what you are asking.
 
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