Faster than light travel impossible

[com]

Jesus had long hair b/c he was a Nazarian (sp?), they can't cut their hair.

[James S]

No, Jesus had short hair because he says in the Bible that long hair is disgraceful on men. How could he say that then have long hair himself?

If you want to start your own thread then go ahead, but we're talking about faster than light travel here, not religion. Now everyone is going to miss my long winded post at the bottom of the last page!

Paul, do the starships in Star Trek actually travel in subspace? How do they see the stars outside their windows then? I never did understand how subspace was different or how they entered it in Star Trek.

[Paul]

i saw him on tv the other day. he had long hair. nuff said.

[Paul]

http://www.ex-astris-scientia.org/warp.htm

http://www.ananova.com/news/story/sm_538441.html

i found a really great page last year that had all the diagrams and stuff to go with it. hmm.

[David Horn]

If you stand on the back of a train that's moving at the same speed as a bullet leaves a gun, and fire a gun backwards off the train, two things happen.

1) To you, the bullet moves away from you twice as fast as if you were standing still.

2) To an observer, the bullet just drops to the ground.

Here's a riddle I just want the moose, I mean, Moose, to have a go at.

If I fire a gun horizontally from 1 metre, how much longer will it take to hit the ground than if the bullet was just dropped from one metre? Speed of bullet from gun: 300m/s

Neglect air resistance and any lift given to the bullet as it travels through the air.

[James S]

well, none. No difference. Horizontal velocity plays no role in vertical velocity. But it's been a year since I last did any kind of calc problem so I'm not sure. I just recall that horizontal velocity is not taken into account.

[Guest]

But if you're in a ship, let's say with no windows, just for clarity, how can you tell if you're moving or not? You can't (unless you're accelerating) So, no matter what your speed you see the light emitted from a lightbulb travel at the speed of light. Also, if you're in a car, with a walkie talkie, and you send out a signal, that signal travels at the speed of light away from you, no matter how fast you're going. The speed of light is always a constant, not to the "rest frame" of the universe.

People used to believe that light travelled through an "ether" and then wondered how fast the earth was travelling through this ether, since, yes, the earth goes around the sun, and the sun goes around the centre of the galaxy, the earth must be travelling at some speed through the ether and the speed of light was thought to be relative to this ether. Then, after some experimentation (michelson-morley) they couldn't figure out how fast the earth moved through this ether, so Einstein suggested, what if there was no ether? The speed of light was constant no matter what your frame of reference.

And, correct me if I'm wrong. But modern physics does not allow for speed of light travel of particles with mass, so how can one determine what will happen when travelling at super-luminal speeds, since there is no physics for such a case?

Now, I apologise if what I've said has already been said. But the foundation of special relativity is that the speed of light is constant to ANY and ALL observers in an inertial frame of reference (i.e. not accelerating)


Cheers,
Brad

[James S]

I was going to point that out, that we don't have any clue how fast the earth is actually travelling because we don't really have anything to relate it to, but it seemed just an unimportant "ooh, ahh" statement.

But... did your comment just affirm or deny my lightbulb in the spaceship question? Will the light being emitted from a lightbulb be able to reach the front of the spaceship if the spaceship is moving faster than light, theoretically (regardless of whether mass can travel faster than light).

[Brad]

Moose: If you're in the spaceship, then yes, the light will hit the front, just as if the spaceship were at rest. If one is observing the spaceship from the outside, then no, the light will not.

Brad

[James S]

alrighty then, horray for relativity!

[Chris Edwards]

[Jadam]

[James S]

[Warren]

[Jadam]