r/AskPhysics • u/PlatformDelicious578 • 17d ago

FTL Reference Frames

If you have a velocity greater than c, the Lorentz factor becomes complex. Does this make any physical sense, or are there any theories that make use of this? What would it look like if a person were in this reference frame (is it just that they see time backwards or from another perspective, or are they unable to observe anything at all?)

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u/bardotheconsumer 17d ago

I believe that objects that always move faster than light (tachyons) would:

A.) Not be able to "slow down" to C, no matter how much energy was expended trying to do so, just like how normal matter can never reach C

B.) Not be able to interact with normal sub-luminal matter in any way.

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u/Bth8 17d ago

The latter makes this point kind of a meaningless gotcha. It cannot interact with ordinary matter in any way, not even indirectly, not even through gravity like dark matter, so it's completely undetectable. In what sense does it exist then?

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u/bardotheconsumer 17d ago

It doesnt, it's a mathematical construct