information sending

[`hýsøŕ]

I've learned through many youtube videos on things like special relativity and just general physics that there is no way to send information faster than light, because objects cannot move faster than light.

 

This feels like a bit of a naive question but.. surely in the future it's possible for some loophole around the speed barrier to be found, or some kind of particle that does go faster (maybe a tachyon) to be found, and then could you send information faster than light?

 

Just saying it seems like a pretty useful thing to do if it could be done

[Spyman]

I've learned through many youtube videos on things like special relativity and just general physics that there is no way to send information faster than light, because objects cannot move faster than light.

Correct.

 

This feels like a bit of a naive question but.. surely in the future it's possible for some loophole around the speed barrier to be found, or some kind of particle that does go faster (maybe a tachyon) to be found, and then could you send information faster than light?

We don't know what the future holds for us, but if anything it's far from sure that there could be a usable loophole, more likely constraints against FTL will be harder.

 

Just saying it seems like a pretty useful thing to do if it could be done

Yes, but if it could be done then you could also in principle send a message back in time to before you sent it, which could cause problems.

 

If one were able to move information or matter from one point to another faster than light, then according to the theory of relativity, there would be some inertial frame of reference in which the signal or object was moving backward in time. This is a consequence of the relativity of simultaneity in special relativity, which says that in some cases different reference frames will disagree on whether two events at different locations happened "at the same time" or not, and they can also disagree on the order of the two events (technically, these disagreements occur when the spacetime interval between the events is 'space-like', meaning that neither event lies in the future light cone of the other). If one of the two events represents the sending of a signal from one location and the second event represents the reception of the same signal at another location, then as long as the signal is moving at the speed of light or slower, the mathematics of simultaneity ensures that all reference frames agree that the transmission-event happened before the reception-event.

 

However, in the case of a hypothetical signal moving faster than light, there would always be some frames in which the signal was received before it was sent, so that the signal could be said to have moved backwards in time.

http://en.wikipedia.org/wiki/Time_travel#Via_faster-than-light_.28FTL.29_travel

[swansont]

We might expect loopholes to be exploited already in systems we can observe, which means we'd already be seeing contradictions that FTL travel causes. But we don't.

[`hýsøŕ]

Thanks for the replies, @spyman Ah I see, that does sorta makes sense (would make a lot more sense if i'd have finished special relativity by now)

@swansont I'm guessing you mean a similar thing to what spy said, where it'd cause problems with causality and things would be going back in time, so we should see things going back in time but there isn't any evidence for that so far

[SamBridge]

Would it be ok to go from point A to point B faster than light as long as no one could observe you doing it? Like with hyperspace or space-time expansion?

Edited April 21, 2014 by SamBridge