Probing Question: Can anything travel faster than the speed of light?

PhysOrg.com ^ | 23 March 2006 | Joe Anuta

[reagandemo]

If two objects pass by each other each traveling .75% of the speed of light would then a each object in relation to one another be traveling faster than the speed of light?

[gomaaa]

To me it seems to be a possible or impossible but unprovable in either situation.

At this point I guess travel to distant stars will come in the form of another method.

It's VERY provable, though not in the sense that we can actually build a spacecraft and accelerate a person in it to relativistic velocities, which is what you're picturing. We usually have to settle for subatomic particles, and we do this EVERY DAY. We simply would not be able to run a particle accelerator without accounting for special relativity. So if you have a proton travelling at 99.99999% of the speed of light (as opposed to a train) and it emits a photon (as opposed to turning on a flashlight) you get an independent confirmation of what WOULD happen if you were to be on a relativisitic train. The math is the same, and in physics that's what counts.

[gomaaa]

Nope, we even had a thread about this question not too long ago... although I can't seem to find it.

You can't just ADD speeds that way when dealing with relativisitic velocities. It works fine for slower relative velocities (like two cars passing one another on a racetrack) but not at all when the velocities approach light speed (like two particles passing one another in an accelerator).

The math is different, and in physics that's what counts. This website explains more, but is not really written for the layman, sadly.

http://math.ucr.edu/home/baez/physics/Relativity/SR/velocity.html

[reagandemo]

Humm... I just remembered a Scientific American magazine article back in the late 60's where they talked about theoretically making a time machine with two spinning disks travailing in opposite directions at a high rate of speed and achieving higher than the speed of light and time travel.

[gomaaa]

It might have just been science fiction, but there has been a lot of speculation that time travel is possible if you can manipulate matter and energy to the point where you could create and manipulate worm-holes and things like that. So perhaps the disks you refer to could lead to time travel if they were, say, the density of neutron stars and rotating at relativistic speeds. Such things are so far beyond our capabiltity to test that it's easy for theorists to come up with crazy ideas that are mathematically possible but completely impractical.

The short answer is, don't hold your breath for real time travel, but it's cool to think about anyway!

[BlueMondaySkipper]

For you, perhaps. But to an outside observer, you would never get up from your seat.

With that line of reasoning, you're never actually moving at all since you're staying stationary relative to your pants...

[gomaaa]

Of COURSE you're stationary with respect your pants! I mean, I HOPE they're not flying away from you right now...

[BlueMondaySkipper]

Of COURSE you're stationary with respect your pants! I mean, I HOPE they're not flying away from you right now...

They aren't flying away from me right now. but it has happened before... :-)

[Buffettfan]

YES, illegals streaming across our unprotected southern border.

[LogicWings]

Thank you, you answered my question. Bell's inequality doesn't say that determining the polarity position of A doesn't magically determine the position of B, which is what I have read time and time again.

What the correlation represents is the limits of information. The reason why the two measurements get the correlated answers is because they're extracting the same piece of information...and this despite the fact that the information wasn't in a definite state until it was measured. (If it were in a definite state, it would have to obey Bell's Inequality; this is what sank Einstein's interpretation well after his death.)

I have seen it explained in the past is that if one changed the polarity filter Left for A then by observing that fact it 'magically determined' what the state of what B would be. If one reversed the polarity for A to Right, the B would magically become Left.

"correlation is not causality"

That is not the way I have seen Bell's Theorem presented time and time again. Why is it a "Theorem" anyway if it isn't univerally true?

If it were in a definite state, it would have to obey Bell's Inequality

I thought it did, that was the problem. The contradiction between this and Einstein's Theory.

and this despite the fact that the information wasn't in a definite state until it was measured.

Do you know that it was definitely wasn't in a 'definite state until measured?' How do you know? If you can't measure it in an "indefinite state" then you have a theory with no possible evidence. Therefore, how do you know?

Pardon my ignorance on the subject. I have followed this for years. It makes no sense. I personally think QM is wrong and hope to live long enough to see it dethroned. It is based upon a fallacy of reification (the Copenhagen Interpretation.) I think Bell's Theorem is wrong also.

But then, what do I know?