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In special relativity the space-time can be seen as a static four-dimensional picture that contains the entire past and the future of a flat universe. And the patterns in it are subject to several constraints to make it physically feasible. Observers within it observe it by sweeping their plane of simultaneity through it. In this case anything that moved faster than the speed of light would draw a space-like line through spacetime.

And one doesn't even need to have tachyons to have a space-like line of events. For example it's possible to flash a ribbon of lights simultaneously, which can draw a similar space-like line of events. And observers wouldn't notice anything special other than just a regular line of space-like events.

Would tachyons be any different than just a ribbon light flashed simultaneously in a frame of reference?

Emilio Pisanty
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Calmarius
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1 Answers1

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The problem is, that the word simultaneously means that the events are light-like connected. So, the flashing of two lights on your ribbon is not a space-like event.

Tachyons behave very peculiar, i.e. in such a way that they lose energy while accelerating. It takes more and more energy to asymptotically slow them down towards the speed of light. It can never be stopped and thus has no connection to (no interaction with) our side of the barrier that is the speed of light. Therefore the answer is no, we can never notice them, even though they might be there (some string theories have something to say about Tachyons).

Clever
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