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Kevinito
2002-Apr-06, 03:48 PM
My wife and I just watched K-PAX last night. Fabulous movie, but we were intrigued about the faster than light possibility. Any comments on this movie or subject?

brian1905
2003-Oct-16, 09:54 PM
hey- looks like i'm the only one to post here...i'm a bit late at that, too!
i will say i enjoyed the movie, but i was confused on how he traveled faster than light. i suppose we are to feel that this technology by the aliens is not understandable to us but my problem is that even if he could travel at the speed of light, he could not ignore time dilation factors. he claimed the trip took him (6?) years. at the speed of light the trip would have been instantaneous in his frame of reference. if he traveled faster... well i don't know what that would mean.

Glom
2003-Oct-16, 10:03 PM
The Lorentz transformation

t' sqrt(1-v/c) = t

where t is the time observed from an observer stationary to the reference frame in question
and t' is the time observed by the observer moving with respect to the reference frame at speed v.

As you see, as v tends to c, the t' tends to t as you say. But, at v > c, the t' is imaginary.

Stephen Hawking introduced the idea of imaginary time on page 59 of The Universe in a Nutshell.

Zamboni
2003-Oct-17, 01:42 AM
I think he (what's the chr's name again? Space Kevin? :lol:) meant six years from our point of view...

For example, one light year would take one year to travel from a standing point of view while the traveller would feel no passage of time (or maybe he would I dunno)

zrice03
2003-Nov-04, 03:31 AM
In the movie, Spacey mentions that Einstein's equations only limit crossing the light barrier, not traveling faster than it, so I would expect some sort of tachyonic radiation to travel. Of course, that raises the question of how would tardyons (which make up Kevin Spacey) would change into tachyons.

It is, however, unlikely that tachyons exist. If they do, they would have to be too massive for our particle accelerators detect yet. (I know that a tachyon's mass is supposed to be imaginary, but that is only rest mass. When it is moving, it has a real number mass.)

wedgebert
2003-Nov-04, 05:08 AM
It is, however, unlikely that tachyons exist. If they do, they would have to be too massive for our particle accelerators detect yet. (I know that a tachyon's mass is supposed to be imaginary, but that is only rest mass. When it is moving, it has a real number mass.)

Actually, I believe tachyons are supposed to have a negative mass, which explains why they travel faster than light. They actually (theortcally) require energy to slow down, and the closer to the speed of light they get, the more energy it takes to slow them down.

Of course, if you think about it, that would mean that most tachyons would travel almost infinitely fast since the faster they go, the less energy it takes to accelerate them.

zrice03
2003-Nov-05, 06:03 AM
nope, tachyons have imaginary(i.e. similar to sqrt(-1)) mass. It is a direct relation to the equation which determines the amount of Lorentz contraction, also known as the Tau factor(not sure of the actual name) which is:
1
_________________
_____________
\/ (1-v^2/c^2)

Let's run through the numbers for two particles, who's masses are 1. One going at .5c(A) and another at 2c(B). If you do the math, particle A has it's mass increased to 1.155. Particle B will be "increased" to 1/sqrt(-3) which is an imaginary number. Since all particles observed will have a real mass, the tachyon must start at an imaginary mass.