speed of light

Originally posted by FabianFnas

I get a raise from my boss and anything impossible.

Hey it could happen...I've gotten 2 raises at work since joining this site....I think its from staring hard at the computer screen, and throwing in a little wth and sometimes smacking myself on the forehead.

Originally posted by Restless Soul
Hey it could happen...I've gotten 2 raises at work since joining this site....I think its from staring hard at the computer screen, and throwing in a little wth and sometimes smacking myself on the forehead.

I'll try that too, a good advice.
Staring in a computer screen might be taken for working hard, even if I'm thinking about my next move.
Yes, it might work.

🙄🙄🙄🙄🙄🙄🙄🙄🙄🙄🙄🙄🙄🙄🙄🙄🙄🙄🙄🙄🙄🙄🙄

The entire point of relativity is that light goes the same speed, no matter what speed you're travelling at. So, even if you could travel the speed of light (and we'll ignore the obvious problems with that idea), from your frame of reference, light would still be travelling the speed of light, it would simply be shifted (red if the source was pointing away from you, blue if it was pointing towards you, I believe).

Originally posted by Fwack
The entire point of relativity is that light goes the same speed, no matter what speed you're travelling at. So, even if you could travel the speed of light (and we'll ignore the obvious problems with that idea), from your frame of reference, light would still be travelling the speed of light, it would simply be shifted (red if the source was pointing away from you, blue if it was pointing towards you, I believe).

Even the possibility of going in the speed of light would shake the very foundation of relativity theory.
And math would be shaken to its foundation, due to division by zero implications.
There just aren't any physics that allow a partical with mass to travel in the speed of light. Why even speculate about it?

Originally posted by FabianFnas
Even the possibility of going in the speed of light would shake the very foundation of relativity theory.
And math would be shaken to its foundation, due to division by zero implications.
There just aren't any physics that allow a partical with mass to travel in the speed of light. Why even speculate about it?

You can write the Lorentz transforms in terms of cosh and sinh to avoid division by zero, not that that avoids physical quantities diverging. See http://en.wikipedia.org/wiki/Lorentz_transforms - there's a nice animation of an accelerating entities view of spacetime as it moves between frames of reference on that page.

Fwack was talking about frames of reference for things travelling at the speed of light. Things that go at the speed of light don't have an inertial frame of reference, as if they did you could find a transform to a non-light speed frame of reference and there isn't one (for the reasons you outlined). As far as the photon (or whatever) is concerned it is emitted, passes through all points on its path, and is absorbed at the same instant. You can say things like: in the limit that the speed of x approaches lightspeed, although the point with limits is that you never quite get there...

Originally posted by prosoccer
It's impossible because as you get closer to the speed of light, your mass increases to greater and greater proportions of what it is, so more and more energy is required to accelerate and eventually you will have an infinite mass therefore an infinite amount of energy would be needed to accelerate faster.

Yes, this is when ACCELERATE to the speed of light. Einstein said so. On the other hand, he said nothing about entities traveling at the speed of light or faster. And the question states that the entity is already traveling at the speed of light.

Originally posted by DeepThought
You can write the Lorentz transforms in terms of cosh and sinh to avoid division by zero, not that that avoids physical quantities diverging. See http://en.wikipedia.org/wiki/Lorentz_transforms - there's a nice animation of an accelerating entities view of spacetime as it moves between frames of reference on that page.

Fwack was talking about frames ...[text shortened]... x approaches lightspeed, although the point with limits is that you never quite get there...

Nothing with mass can travel with the speed of light. The photon, massless, can't see other light with a red or blue shift. Therefore the very ansatz is wrong. It's not possible.

So if you say: "Hey, assume it is possible..." then your assumption is wrong and you cannot ever get any reliable result out of it.

It's like assuming that one actually can divide by zero...

Originally posted by FabianFnas
So if you say: "Hey, assume it is possible..." then your assumption is wrong and you cannot ever get any reliable result out of it.

It's like assuming that one actually can divide by zero...

I wouldn't say it's pointless. Einstein found such thought experiments useful when he was formulating the theory. If it's good enough for him...

Division by zero is different. One case is not a logical impossibility, it just happens to contradict a particular theory about how the Universe works (which may well be correct, but we can't guarantee it won't be proved wrong in the future). Whereas the other is about the rules of a self-referential mathematical system. Division isn't defined for zero, so referring to division by zero is like referring to division by parrot - doesn't make sense. Unless you formulate your mathematical system so that it is defined (which can be done if you really want to).

Originally posted by kbaumen
...On the other hand, he said nothing about entities traveling at the speed of light or faster. And the question states that the entity is already traveling at the speed of light.

Yes, he said. If anything with a mass travels with the speed of light, nature will not permit it because m=m0/(1-sqrt(v2/c2)) gives a division by zero when v=c.

Nothing with mass cannot be born at the speed of light, so you have to accelerate (or decelerate) it to speed of light, which simply cannot be done.

Originally posted by mtthw
Unless you formulate your mathematical system so that it is defined (which can be done if you really want to).

No, it cannot be done. Division by zero is not possible in any number system.

If you define an division operator where you can divide by zero, math as we know it breaks down completely.

(This is interesting! If I am wrong on this one I would gladly be proven in that. Math would be a lot funnier then! Do you have a definition somewhere where division by zero is possible, perhaps a link of some sort?)

Originally posted by FabianFnas
Yes, he said. If anything with a mass travels with the speed of light, nature will not permit it because m=m0/(1-sqrt(v2/c2)) gives a division by zero when v=c.

Nothing with mass cannot be born at the speed of light, so you have to accelerate (or decelerate) it to speed of light, which simply cannot be done.

I'm just foolin' around. There is a similar quote from the movie "K-PAX". Nice movie. If you haven't seen it, I recommend you to do so. Check it out at IMDB - http://www.imdb.com/title/tt0272152/

And here is the quote I mentioned.

Dr. Mark Powell: What if I were to tell you that according to a man who lived on our planet, named Einstein, that nothing can travel faster than the speed of light?
Prot: I would say that you misread Einstein, Dr. Powell. May I call you Mark? You see Mark, what Einstein actually said was that nothing can accelerate to the speed of light because its mass would become infinite. Einstein said nothing about entities already traveling at the speed of light or faster.

Originally posted by FabianFnas
No, it cannot be done. Division by zero is not possible in any number system.

If you define an division operator where you can divide by zero, math as we know it breaks down completely.

(This is interesting! If I am wrong on this one I would gladly be proven in that. Math would be a lot funnier then! Do you have a definition somewhere where division by zero is possible, perhaps a link of some sort?)

It would have to be defined within a particular number system, which wouldn't be the number systems we use (R, Q etc), so any results wouldn't apply to these systems. So maths as we know it would still be fine.

Whether the new system would have any practical applications is debatable, but as long as division in this new system behaved in the same way as division in the systems we're used to when not dividing by zero it might.

I don't have a link, but I thought I remembered a link to a paper doing something like this on these pages some time ago.

It's just a matter of definition, so you can't say it's impossible. (In a particularly trivial way I could swap the definitions of division and subtraction - division by zero is fine then!). You can say it's possible in a particular framework.

Originally posted by FabianFnas
Nothing with mass can travel with the speed of light. The photon, massless, can't see other light with a red or blue shift. Therefore the very ansatz is wrong. It's not possible.

So if you say: "Hey, assume it is possible..." then your assumption is wrong and you cannot ever get any reliable result out of it.

It's like assuming that one actually can divide by zero...

Please point out to me the part of my posts where I said that particles with non-zero mass could get to the speed of light. On a point of extreme pedantry the mass is defined as the pole of the propagator and so noone in the field ever talks about equivalent (or rest) mass these days.

You can take the limit, you can always take limits. And in the limit that v --> c, the frequency of light from a source moving away from us at that speed goes to zero. To say that the limit exists is not to say that you can get there. Aside from anything else once you've pumped all the energy in the universe into one particle then you've run out of energy to make it go faster.

Incidentally the corrolory to all this is that massless particles are condemned to never slow down beneath the speed of light, they are created, travel, and are then destroyed at their destination.

Originally posted by DeepThought
Please point out to me the part of my posts where I said that particles with non-zero mass could get to the speed of light. On a point of extreme pedantry the mass is defined as the pole of the propagator and so noone in the field ever talks about equivalent (or rest) mass these days.

You can take the limit, you can always take limits. And in the ...[text shortened]... ath the speed of light, they are created, travel, and are then destroyed at their destination.

Ah, then we're agree. Massless particles is the only ones that can travel in the speed of light. Particles with mass cannot.