Is SR-allowable time travel future-only ?

[bcrowell]

I find that URL actually a bit pathetic in explaining tachyons. Since no material particle can go faster than the speed of light in a vacuum (cf above), the only real way to define tachyons is material particles that go faster than light in their medium. Such tachyons have been observed in nuclear reactors.

The WP article is correct and you're incorrect. The c in special relativity cannot be interpreted as the speed of light in a medium. Nobody uses the word "tachyon" to describe particles emitting Cherenkov radiation.

 

[Frame Dragger]

The WP article is correct and you're incorrect. The c in special relativity cannot be interpreted as the speed of light in a medium. Nobody uses the word "tachyon" to describe particles emitting Cherenkov radiation.

I love it... if this guy was correct there wouldn't BE any Čerenkov R!

kg4paep The famous 'blue glow' known as Čerenkov Radiation is a RESULT of normal particles experiencing the termination shock of one material's c into another. I'm curious how you think we'd be able to observe an FTL phenomena as a UV+ bandwidth emission? I can't even follow your train of thought here, sorry.