Question about travelling at speed of light

[bloodhound]

WHICH one of these is right

 

1) its not possible to travel at speed of light

2)its not possible to travel at or greater than speed of light

 

if 1) is right. then does that mean theoretically u can travel greater than speed of light

 

dont laugh at me pls. i am a mathematics student and i haven't done anything of relativity.

[jordan]

http://www.scienceforums.net/forums/showthread.php?t=2743&

 

http://www.scienceforums.net/forums/showthread.php?t=2743&

 

Mr.L's posts are the ones to read carefully. Basicly though, it is possible to travel at both the speed of light and greater than the speed of light, just never crossing from one side to the other. Particles traveling faster than the speed of light can't slow down below it and those below it can't speed up above it.

[AntiMagicMan]

Massless particles can (rather, MUST) travel at the speed of light. Particles with mass, i.e. us, cannot.

 

Tachyons, proposed particles that travel faster than the speed of light would be able to travel faster than light, and also backwards in time. But they have never been observed experimentally, so they aren't of much use to us.

[Crash]

You mean all virtual particles. Why must they travel at the speed of light? or above?

 

Why does time travel at the speed of light? It may seem like a stupid question but i really dont know.

[swansont]

You mean all virtual particles. Why must they travel at the speed of light? or above?

 

Why does time travel at the speed of light? It may seem like a stupid question but i really dont know.

 

I don't think "all virtual particles" is right - lots of virtual particles are not ones with zero rest mass.

 

Particles with zero rest mass travel at c because that's the solution to the equations. Particles with rest mass travelling at either v<c or v>c are also solutions to the equations, but they are different solutions from each other. So tachyons, if they exist, can never travel slower than c.

 

What do you mean by 'time travelling at the speed of light'?

[Crash]

well the whole idea of , if you travel faster than c theres moving backward in time.

So time must travel at "c" ?

So ya mean virtual particles dont nessecarily travel at the speed of light? (or above?)

[AntiMagicMan]

Technically all particles travel at the speed of light through spacetime.

 

Ahem, er, time doesn't have a speed, that would be meaningless, what units would you measure it in.

[Sayonara]

Technically all particles travel at the speed of light through spacetime.

Why?

 

Also, what does "technically" mean in this context?

[Crash]

Well why, if you travel at less than, but close to the speed of light you are moving foward in time. If you move at light speed, time stops. And with superceeding light you travel back in?

I always imagined time as a vector..........Time has got direction right? fowards?

[swansont]

well the whole idea of ' date=' if you travel faster than c theres moving backward in time.

So time must travel at "c" ?

So ya mean virtual particles dont nessecarily travel at the speed of light? (or above?)[/quote']

 

Time isn't an object, so saying it travels at c (or faster or slower) is nonsensical.

 

Not all virtual particles are massless. They are still constrained be the Heisenberg uncertainty principle, and the implication of that is that the massive virtual particles don't travel at c.

[AntiMagicMan]

Why?

 

Also' date=' what does "technically" mean in this context?[/quote']

 

Technically means according to the special theory of relativity.

 

The speed of light through spacetime, means something different to the speed of light. Basically light has speed only in spacial dimensions, according to the theory it experiences no time. While it is wrong to talk of it's speed through time, if you account for the change in units then you can show that the faster objects travel through space, the slower through time. So when you sum them up, their "speed" is invarient and is equivalent to the speed of light through spacetime.

[Dave]

I believe we've had a rather large thread about that, and it was quite hotly debated. I believe there's a proof on this page of the thread.