Particles can travel faster than light!

[Qfwfq]

But you don't get fatter, therefore mass doesn't increase with speed!

[goku]

my point exactly

i think alxian is right, i'll call it a photonic boom

[Qfwfq]

A photonic boom is Cherenkov light! :rolleyes:

[goku]

A photonic boom is Cherenkov light! :rolleyes:

thanks! i think photonic boom sounds better, but that's just me.

 

would mirrors work to decrease the CL?

[Qfwfq]

Well, call it the Cherenkov boom!!!! :D

 

I don't see what you mean about mirrors decreasing it. :)

[goku]

mirrors would reduce the amount of light particle drag.

in the sonic boom situation the wings in the swept back position reduced the drag.

[Jay-qu]

so what you affix mirrored wings to particles - :) - you've lost me aswell

[goku]

mirrors reflect light, don't they?

the photons are stoped then reversed.

[Jay-qu]

absorbed / re-emmited I think

[Qfwfq]

No, they are scattered elastically, and just about perfectly, without loss of phase coherence. Otherwise you couldn't really apply the principles of Huygens and co. to justify the basic rule of reflection.

 

Some less trivial cases of elastic scattering are like an absorbtion with re-emmission by near perfect reversal of the absorption but that's a somewhat freakish thing. :)

 

In the case of a mirror the photons are scattered by the free electrons at the metal surface. It isn't even an event for each photon with one electron, it's actually the wave-charge interaction spread coherently over the surface where the wavefront is incident, so wave-optical principles explain the reflection.

[wizzkid67]

just what that person said about mass making u fatter. Mass and weight are two different things

[Jay-qu]

yes they are and as Qfwfq so elegantly stated we now know that mass is no more than rest energy and because when you gain velocity you gain more energy - you therefore gain more mass

[Qfwfq]

you therefore gain more mass

...except that physicists don't call it mass. At least, not mass of the single body in motion, because it isn't rest energy.

 

If it's a moving part of a composite body then, yes, the kinetic energy in the composite body's c. m. frame, as well as the potential energies between the parts.

 

Although it's a matter of terminology, the notion that a moving body's "mass" increases is a non-covariant one that has stick all too much due to historic confusion. The Lorentz-covariant equation for a free particle, in natural units, is this one:

 

m^2 = E^2 - p^2

 

At rest, p = 0, total energy is only m, in motion E > m; E increases and m doesn't change.

[Jay-qu]

ohhhhh, thanks for clearing that up :doh:

[Qfwfq]

:doh:

 

You will long continue to see the formula m = m_0/(RootOfGamma) around, it is still extensively used in introductory courses. I think it should be avoided and that things should be better explained, even for starters. It simply causes too much confusion.

[Jay-qu]

I will look out for that because I will be starting my first university science degree next year :doh: Im sure it will crop up somewhere in the subjects im doing, cant wait

[Qfwfq]

Good luck!!!