On Wed, Jan 14, 2015 at 7:54 PM, Anthony Jackson <ajackson@iii.com> wrote:

From: Richard Aiken

> (Although I honestly still don't understand why his sunbeam weapon has to have a ceiling on effective damage . . .)

Because no possible arrangement of mirrors can focus sunlight to an intensity greater than the intensity at the surface of the sun (this is true for concentrating light from any surface that emits light in a non-directional manner). If it were possible to do so, all kinds of second law of thermodynamics violations would become practical.

I can see that. For one thing, I imagine any conceivable focusing mirror for any significant fraction of that amount of light would melt well below that level.

But I'd think you could get up a spot temp high enough to vaporize a battleship while also still well below that same level.

(googling . . . .)

The black body temp of the sun's surface is 5777 K.

The vaporization temperature of steel is 3273.15 K.

So if the sunbeam array can focus 57% of the sun's effective surface temp on one spot . . . POOF!

Or am I missing something?

Richard Aiken

"Never insult anyone by accident." Robert A. Heinlein

"A word to the wise ain't necessary -- it's the stupid ones that need the advice." - Bill Cosby

"We know a little about a lot of things; just enough to make us dangerous." Dean Winchester