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@michael_nielsen | |||||
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A wonderful little fact about the maximum power density inside the sun (spoiler: about the same as inside a compost pile!) ht @nattyover twitter.com/chris_w_walter…
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Timothy Gowers
@wtgowers
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31. sij |
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There must be some nice scaling-law explanation for why I'd be instantly fried if I dived into the sun but not if I dived into a compost heap. If the radius of a spherical compost heap doubles, what happens to the temperature at its surface? (Is that even the right question?)
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michael_nielsen
@michael_nielsen
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31. sij |
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Suppose you have fixed power density, and the sun is of (variable) radius r. The energy flux at the surface - the thing frying you - scales as power density * volume / surface. That's proportional to the radius. The Sun is just a really, really big compost heap!
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1/(1 - 1/(1 - 1/(1 - Dan Piponi)))
@sigfpe
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31. sij |
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I usually make the comparison with the power density generated by human muscle. I guess it makes me feel like Superman or something.
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michael_nielsen
@michael_nielsen
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31. sij |
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Stronger than a shooting star! (Oops, wrong comparison...)
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David Deutsch
@DavidDeutschOxf
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1. velj |
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And a nuclear fusion reactor will have many millions of times that power per unit volume. So much for its being merely an "artificial sun"!
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Pradyumna Singh
@pradyu_singh
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31. sij |
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Indeed, and humans typically have > 10^4x W/kg than the sun. With bacteria etc. that number gets even higher!
There's a nice talk on cellular energetics by Rob Phillips:
youtu.be/9NgT1z1Kcbs?t=…
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John Carlos Baez
@johncarlosbaez
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31. sij |
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I like it when on a cold day I dig into my compost pile and warm steam comes out. Now I'll think about the Sun.
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Vladbot 5013
@Radegund
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31. sij |
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Maybe it's just a large collection of space reptiles.
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Paul F. Dietz
@PaulFDietz
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31. sij |
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Now compute the thermal energy of a cubic meter of the Sun's core.
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