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by bill@xoom.org
Mon Feb 15, 2016 12:00 am UTC
Forum: What If?
Topic: What-If 0145: "Fire From Moonlight"
Replies: 157
Views: 72182

Re: What-If 0145: "Fire From Moonlight"

This Winston paper "The thermodynamic limits of light concentrators" from 1990 is full of math, and includes discussion of how thermodynamics support concentrations greater than the surface of the sun through combination of non-imaging and a high dielectric material like sapphire. It also...
by bill@xoom.org
Fri Feb 12, 2016 5:34 pm UTC
Forum: What If?
Topic: What-If 0145: "Fire From Moonlight"
Replies: 157
Views: 72182

Re: What-If 0145: "Fire From Moonlight"

I think an important point is being missed in the explanation: that the transfer of energy from source to target isn't just a matter of how many photons there are, but the angles involved as well. Conservation of etendue tells us that we can increase the photon density only by increasing the angles ...

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