Can something move faster than light?

[Qfwfq]

I had forgotten to mention it, a very simple and easy way to see a superluminal velocity:

 

Stand up, turn around a few times. In your coordinate frame a lot have things have travelled very far, in a few seconds... B)

[paultrr]

Good example.

[Qfwfq]

...there is also an amplitude for light to go faster (or slower) than the conventional speed of light.

Of course.

 

But a QM amplitude for something isn't quite the same as something. Not yet...

 

If you work out functional methods, or whatever, with the requisite of Lorentz covariance then you get a Lorentz covariant solution. That's why I hadn't really counted the example although I had thought of it.

[sanctus]

When is group velocity superluminal?

Yes, I confused was thinking about phase velocity. I don't know group velocity being FTL.

[paultrr]

The only thing I have seen really interesting was an article done by a guy named Cahill on Lanl, which covers only the results of all the retests of the original M&M experiment. He reports, and does offer the references for such, that the actual results where not null. What makes such interesting is the average results which he quotes are the same for the sunward deceleration noted with Voyager. However, he, since he did not consider Voyager data into this, suggests that Aether drift was the cause. When you add in Voyager data or findings thus far such a suggestion is out of the question because real aether drift would not be sunward in every direction unless the sun somehow pulls the aether inward. However, and do not get me wrong, none of this has enough evidence either way yet to really speculate, but it would be suggestive that perhaps things are not always equal in all frames. Such might suggests ways around C. But as I said there is simply not enough data from different perspectives to really figure anything out yet. Even here at the worst it simply suggests a modification to SR/GR.

 

One solution, and well within both SR/GR is that our figures on vacuum conductance might be off a bit. Another, is that perhaps spacetime should not even locally be considered ever flat to begin with. A lot of models including Hal's PV modeling that attempt to get equal results with GR rely upon a flat spacetime model as the background. But even here not all models do and something should have suggested this before now.

 

I do have the Lanl link on that article if anyone is interested. Try Physics/0501051 if memory serves me right.

[Nismoskyline]

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[Jay-qu]

think of this:

If you had a sufficiently long pole, say 1 light year long, and you gave it a nudge

-would the other end move instantaneously?

-if it does then you could use morse code to send messages faster than light!

[Qfwfq]

-would the other end move instantaneously?

What material is your pole made of?

[bumab]

Doesn't matter. Force is transmitted along the pole through particle interactions, which cannot happen faster then the speed of light, because it involves the motions of the particles (collision theory)

[Jay-qu]

i didnt think of that...? do you think there is a material dense enough that it would be instantaneous or at least faster than light?

[bumab]

No, because we are really talking about the transmission of force, which is still limited by the speed of light

[TeleMad]

"Can something move faster than light?"

 

I found the question ambiguous too.

 

First, I assumed it implied "... faster than light in a vacuum".

 

"Can something move faster than light in a vacuum?"

 

Second, I took "something" to refer to something with mass...rest mass.

 

"Can something with non-zero rest mass move faster than light in a vacuum?"

 

Third, I assumed the motion was through space.

 

"Can something with non-zero rest mass move through space faster than light in a vacuum?"

 

So I voted NO.

[Aki]

I briefly read this month's Scientific American, and it says that galaxies can recede faster than the speed of light, and that this does not violate special relativity.

[paultrr]

Galaxy recession is brought about by the expansion of spacetime itself. Now while true that galaxies have rest mass, their own local motion is never FTL. So as far as inertia goes there is no problem since its only spacetime itself that is causing the effect. If you expand any system or geometry over time it grows faster and faster. Eventually such growth results in its size increasing faster than light can travel. But such geometric growth does not violate anything out of relativity. If anything it only sets a limit on how much of spacetime we can view at anyone point in the history of the universe. With accelerated expansion eventually only things very local will be able to be viewed.

[Qfwfq]

do you think there is a material dense enough that it would be instantaneous or at least faster than light?

It would have to be a material in which the particles are bound by a field that could propagate faster than light. The fields we know of don't.

 

In essence, if you can't find a field that propagates faster that light, you won't find a material that get's around the limitation.

 

If you do find one, hope remains for that jackpot... now stands at €53 million.

[TeleMad]

I briefly read this month's Scientific American, and it says that galaxies can recede faster than the speed of light, and that this does not violate special relativity.

 

Right, because the galaxies are not moving through space faster than c; they're "riding" the expansion of space (and with so much intervening space between them and us that is expanding, they are receding from us superluminally). To avoid this possibility is why I added as my third qualifier "Third, I assumed the motion was through space."

[Jay-qu]

but that assumes you take space as only the three spatial dimensions that we spend every day life in. Because the universe is expanding it has to be expanding relative to something - say the 5th dimension (taking the forth as time) - So could you then say it is possible for something to travel faster than light if higher dimensions are included...