RFTP said:
Can you explain further cuz it's really interesting!
It's a very complicated subject. It would take a book to adequately cover it and I don't feel like writing a book today. Anyway, you would really need to know the math to understand it.
Here: E = m*[1-(v/c)2]-1/2 and E2 - p2 = m2 < 0. Or, p2 - E2 = M2, where M is real. This is a hyperbola with branches in the spacelike region of spacetime.
(BOX + m2)phi = 0
where BOX is the D'Alembertian, which in 3+1 dimensions is just
BOX = (d/dt)2 - (d/dx)2 - (d/dy)2 - (d/dz)2.
The difference with tachyons is that m2 is negative, and m is imaginary.
To simplify the math a bit, let's work in 1+1 dimensions, with co-ordinates x and t, so that
BOX = (d/dt)2 - (d/dx)2
phi(t,x) = exp(-iEt + ipx)
Get it? Good.
Seriously, just look it up on the net. There's many sites that talk about faster-than-light travel. Sure, i can explain it better than most of these sites and i know stuff that's not on them, but for your needs and level of understanding, they'll do just fine.