Going FTL ... because the light is not going at c

[Fritz_Brown]

Well, here is an interesting article about slowing down light. Essentially, with a holey waveguide, they have gotten light to slow to .003c . They can supposedly slow it more by applying an electric field.

What happens (relativistically speaking) when you slow light? Does it make it easier to achieve c, or does your limit just get lower? If you can crack the lower limit, does it change anything above that? Anyway, discuss amongst yourselves quietly....

[Fritz_Brown]

<chirp, chirp, chirp>
Not that quietly...

[parmasson]

Relativity and the Internet

Slowing light this way doesn't violate any principle of physics. Einstein's theory of relativity places an upper, but not lower, limit on the speed of light.

www.news.harvard.edu/gazette/1999/02.18/light.html

[Falkayn]

IIRC the speed limit just gets lower too. C is unpassable in Einsteinian physics ... it is THE limit, no matter hos fast or slow that is.

[parmasson]

So if we were to travel in that tank at 30mph we would experience relativistic effects?

[daibaka]

As I understand it, technically speaking you would. They are just so small as to be unnoticeable. Wasn't there an experiment done with two synchronised atomic clocks and a supersonic jet that proved the relativistic effects of travelling at high speed?

[veltyen]

Cherenkov radiation.

Cherenkov radiation occurs when an object is travelling faster then light. Note that this is not travelling faster then C, just faster then light.

C is the speed of light in a vacuum. The speed of light through other materials is often slower. C is the limit.

See http://en.wikipedia.org/wiki/Cherenkov_effect

So if we were to travel in that tank at 30mph we would experience relativistic effects?

You experience relativistic effects constantly already. Mostly the effects are too small to measure though. Decent time-dilation and curvature twisting generally only happen >> 0.1 C

[Fritz_Brown]

Right you are, veltyen, about C. (Continue discussing, however....)

[Anthony]

In terms of the original question: FTL should really be FTC -- relativistic effects occur based on velocity relative to C, not velocity relative to light.

[veltyen]

A couple of days ago the local TV had a BBC special on a similar issue (speed of light and time travel).

I think the synopsis is here: http://www.bbc.co.uk/science/horizon...metripqa.shtml

If you can find it it is worth checking out. Specifically the material on how to travel faster then C, and more importantly why this is a bad idea.

Of course travelling faster then C requires bending the universe more then normally allowed.