FTL communication

[Moontanman]

Lets do a thought experiment...

 

Lets say that in some lab somewhere (don't matter where or what kind of lab it was) an effect was discovered that indicated that during or as a result of some experiment a connection was made with aliens doing a similar experiment somewhere in the Andromeda Galaxy. Lets just say for the sake of argument a device meant for something else started vibrating in a non random way and it turned out to be aliens with a similar device making our device vibrate. It turns out to be a code based in math and we are able to decipher it and it not only turns out to be from another galaxy but the communication between devices is instantaneous.

 

Would such a device and the knowledge to build them result in me calling my past self and telling me not to do something that turned out disastrous or would the effect on modern life be just a curiosity that impacts modern technology in more subtle ways much like time dilation is not part of our normal experience?

[swansont]

Once your thought experiment defies known physical laws, you can justify just about any answer you want.

[Moontanman]

Once your thought experiment defies known physical laws, you can justify just about any answer you want.

 

 

Didn't the discovery of radioactivity defy the known physical laws of the time? Did that discovery justify any answer they wanted? Why would the discovery of instantaneous communication justify any answer i want?

[swansont]

Radioactivity was part of new physical laws. The constancy and finite value of the speed of light has been well-tested via relativity.

[Moontanman]

Radioactivity was part of new physical laws. The constancy and finite value of the speed of light has been well-tested via relativity.

 

 

When radioactivity was discovered it was not part of any new physical laws, it resulted in new laws being written. I am not trying to predict or support FTL communication, i was just wondering if such a discovery would change or how it would change our daily lives. I am quite sure current laws would have to be amended at the very least but what would such a discovery really allow? I have heard all sorts of causality problems that would occur but would they be real enough to actually change our perception of reality on a personal man of the street way. Radioactivity did but it took many years for the changes to filter down and once the cause of radioactivity was discovered those changes held together and were not just arbitrary stuff someone thought up.

 

If it became possible to communicate with zero time lag would how we live really change significantly? Or would it just result in being able to "for instance" report a super nova before we could detect it with visible light? On shorter distance scales i see no reason to expect any changes, if the time lag between new york and Australia became zero would we really notice?

Edited May 17, 2011 by Moontanman

[swansont]

FTL communication would not be an instance of "we didn't know that could happen." It would be "this contradicts what we have observed to happen for the last 100 years of experimentation." Almost on par with an overunity perpetual motion machine being developed.

[Moontanman]

FTL communication would not be an instance of "we didn't know that could happen." It would be "this contradicts what we have observed to happen for the last 100 years of experimentation." Almost on par with an overunity perpetual motion machine being developed.

 

 

Radioactivity was a case of contradicting everything we thought we knew and observed about matter but what i want to know is that if such communications was possible, if we must lets say it is still within what we already know some how but was missed. Would being able to contact anyplace with no lag time really result in anything different in our current methods of communication except no lag time? Would being able to transmit to the moon with no lag time really cause things to happen we would think of as weird or unusual? Or would talking to some one on mars not be any different than talking to some one next door. Would everyday cause and effect be disrupted somehow?

[lemur]

It would cause me to wonder why light was so slow relative to the FTL signal.

[Iggy]

You have to define "instantaneously".

 

In relativity the present instant changes with velocity. If a transmitter, A, instantly sends a signal to another transmitter, B, and B is moving towards A and it relays the signal right back to A then A will receive the signal back before it sent the original which is a problem for causality. A gets its own signal from the future.

[lemur]

You have to define "instantaneously".

 

In relativity the present instant changes with velocity. If a transmitter, A, instantly sends a signal to another transmitter, B, and B is moving towards A and it relays the signal right back to A then A will receive the signal back before it sent the original which is a problem for causality. A gets its own signal from the future.

I didn't get the impression that the thread-premise was that a signal can go faster than causation, just light-causation. I think the assumption is that there is something else that could travel faster than light and cause events even more simultaneously.

[Iggy]

I didn't get the impression that the thread-premise was that a signal can go faster than causation, just light-causation. I think the assumption is that there is something else that could travel faster than light and cause events even more simultaneously.

 

I really don't know what 'even more simultaneously' means.

 

In relativity FTL communication would make sending signals into the past possible and pretty trivial.

[lemur]

I really don't know what 'even more simultaneously' means.

 

In relativity FTL communication would make sending signals into the past possible and pretty trivial.

Generally I agree that it makes no sense that some other aspect of something could arrive at you before you see the cause of it happen; but I think what the OP is postulating is that there is some simultaneity between events that occurs before the light from one reaches the other. I think the OP thinks that, for example, you could discover a supernova by some other signal before seeing it occur.

[Moontanman]

Ok, I am the OP and I totally understand that current theory forbids any FTL effects that could transfer information (or matter for that matter ) So I will try to explain what I am asking, I'll have to use a few Science fiction terms, for want of better words, to describe some of this. Swansont is quite correct in his summation of the idea of instantaneous communication, if current theory is correct it's not worth thinking about. BUT if it was discovered I'll bet anyone here $50 to a donut that someone will be able to include it as a subset of the knowledge we already have... be that as it may i am not asserting such a thing will ever be possible, or that it should be possible. I am genuinely curious about what the effects of "Instant" communication would be.

 

I'm not talking about "subspace signals" or some sort of tachyons or anything that takes time to reach it's destination. I am talking about an effect that if two such "Instant radios" were tuned to each other there would be no time elapsed between pressing the key on one and the key depressing on the other (I am thinking of the old Morse code transmitters used back in the 1860s to communicate across the US.) Those transmitters of course used electricity which is slower than light by quite a bit. But back to my madness, if five such "radios" were on five different places, the nearest star, Andromeda, Magellanic clouds, USA and Australia. The signal would not have a travel time, if all the "radios" were tuned to the same signal all would receive the signal at the precise same time. Any return signal would also be received with no travel time, would this cause paradoxes or would it just appear to be paradoxes if we look at it from the point of view of arriving light signals? BTW a signal, to be sure, suggests travel time but I don't know a better word to describe what i am thinking of.

[Iggy]

I'm not talking about "subspace signals" or some sort of tachyons or anything that takes time to reach it's destination. I am talking about an effect that if two such "Instant radios" were tuned to each other there would be no time elapsed between pressing the key on one and the key depressing on the other (I am thinking of the old Morse code transmitters used back in the 1860s to communicate across the US.)

 

You say "two transmitters" and "no time elapsed". If the two transmitters are not in the exact same frame of reference then they will disagree about the idea of no time elapsing. If the one transmitter found that no time elapsed for the transmission of a signal the other transmitter could find that the signal landed before it was sent.

 

Those transmitters of course used electricity which is slower than light by quite a bit. But back to my madness, if five such "radios" were on five different places, the nearest star, Andromeda, Magellanic clouds, USA and Australia. The signal would not have a travel time

 

If the signal had no travel time according to one of those frames then it would have a travel time according to the others -- either positive or negative.

 

, if all the "radios" were tuned to the same signal all would receive the signal at the precise same time.

 

In relativity, "at the precise same time" depends on frame of reference. It is not something that everyone agrees about. If A sends a signal to B and A thinks that it takes no time for the signal to get there then B sends the signal directly back to A and B thinks that it takes no time for the signal to get back to A then A can get the return signal before he sent the original. He can get his own signal from the future. Causality is violated.

[Ophiolite]

Radioactivity was a case of contradicting everything we thought we knew and observed about matter ...?

Not so. Radioactivity solved one of the biggest problems science was facing at that time. The evidence from geology was, as Hutton so eloquently expressed, of an Earth with "no vestige of a beginning,–no prospect of an end." The indications from evolution were that enormous lengths of time were necessary to achieve the observed diversity and complexity of life.

 

This flew in the face of calculations of the planet's age based upon rate of cooling. Radioactivity resolved these contradictions and supported the observations from biology and geology. That is quite different from what is being proposed in this thread.

[Moontanman]

You say "two transmitters" and "no time elapsed". If the two transmitters are not in the exact same frame of reference then they will disagree about the idea of no time elapsing. If the one transmitter found that no time elapsed for the transmission of a signal the other transmitter could find that the signal landed before it was sent.

 

 

 

If the signal had no travel time according to one of those frames then it would have a travel time according to the others -- either positive or negative.

 

 

 

In relativity, "at the precise same time" depends on frame of reference. It is not something that everyone agrees about. If A sends a signal to B and A thinks that it takes no time for the signal to get there then B sends the signal directly back to A and B thinks that it takes no time for the signal to get back to A then A can get the return signal before he sent the original. He can get his own signal from the future. Causality is violated.

 

 

Iggy and every one else, i guess i am just not capable of wrapping my mind around the concept that there cannot be a time frame consistent with everyone in the universe, some sort of universal time = T with time as we experience it being a subjective time = t caused by the distortion matter and speed. I understand that gravity and speed slow time down but to me that indicates that such distortion is a local phenomena and that instant communication is just that "Instant" if i called Australia with instant communication i would not expect to see a reply before i sent it, but is that what you are saying or does this only apply to distant objects?

[Klaynos]

A universal frame does not exist. Sorry.

[Moontanman]

A universal frame does not exist. Sorry.

 

 

I know that is the current theory... sorry I couldn't help myself..... so much male bovine excrement is touted here i didn't think mine would be all that bad but it smelled pretty much the same

 

Not so. Radioactivity solved one of the biggest problems science was facing at that time. The evidence from geology was, as Hutton so eloquently expressed, of an Earth with "no vestige of a beginning,–no prospect of an end." The indications from evolution were that enormous lengths of time were necessary to achieve the observed diversity and complexity of life.

 

This flew in the face of calculations of the planet's age based upon rate of cooling. Radioactivity resolved these contradictions and supported the observations from biology and geology. That is quite different from what is being proposed in this thread.

 

 

Thanks Ophiolite, your post reminded me of the stuff i did learn in school, my bad....

Edited May 18, 2011 by Moontanman

[swansont]

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Moderator Note

"There is no time" split off into new topic http://www.scienceforums.net/topic/57227-there-is-no-time/

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