Re: Want to prove E=mc²? University labs should try this!

On Tue, 19 Nov 2024 16:06:10 +0000, gharnagel wrote:

On Tue, 19 Nov 2024 9:41:32 +0000, ProkaryoticCaspaseHomolog wrote:

Nope. Physics limits their application.
You can achieve 99.999% reflectivity only at one specific angle
(which is dependent on the mirror design). If the mirror reflects
99.999% of light normal to the surface, it won't reflect 99.999% of
the light at other angles.

>
Exactly.  I didn't realize how complex the LIGO optical train was,
nor the "power recycling" concept:
>
https://arxiv.org/pdf/1105.0305
>
I'm still quite certain, however, that when you throw 750 kW
into a 10 cm ball with walls that are 0.999999 reflective,
the losses will, as you say, cause serious problems.
>
For one, that's a loss of 0.75 W/bounce, and bounces will happen
c/0.1 = 3x10^9 times per second -- IF one could supply the power
to keep it operating.  In which case, the whole thing would make
a beautiful incendiary display.  With only 5 W input to drive
the system, however, it would heat up to about 300 C, according
to my radiation slide rule.

No. Your loss per bounce calculation is off.
Think conservation of energy.
At steady state, 5 W input equals 5 W output, which is not incendiary.
It _is_ warm enough, however, that the whole shebang needs to be run
in ultra-high vacuum to avoid convective effects.