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Comment by DINKDINK | Hacker News Reader

>The entire sky would be about as bright, and as hot, as the surface of the Sun.

Not so according to “The Inverse Square Law”.[1] If one measures the light flux through a hypothetical sphere drawn around a light source and then doubles that spheres size, the light density must decline or you've broken conservation of energy. [2]

[1] http://bccp.berkeley.edu/o/Academy/workshop08/08%20PDFs/Inv_...

[2] http://www.compuphase.com/electronics/candela_lumen.htm

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Yes, but as you look deeper into the night sky, you see more and more stars (proportional to the square of the distance). These two factors cancel exactly.

Remember parallel plate capacitors from Electromagnetics class? They're infinite in size for a reason, to get around not having to worry about the inverse square law. An infinite amount of stars would produce an infinite amount of energy...

If you reduce the power of infinite stars, you still have infinite stars producing infinite light.

x * infinity = infinity (so long as x > 0; even if x is infinitesimally small)

But you can't have infinite stars in your field of view since they'd get in each other's way; blocking radiation. Using the tree example from the article, you wouldn't see infinite trees, you'd only see the pieces that are directly in front of you.

No, infinity times infinitesimal is undefined, you have to define your infinities more carefully to get an answer.

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