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Just taking since life developed, our planet has been being hit by sun for 4.2bn years. If Earth had no way of dissipating heat, we’d have burned to a crisp by
by r3trohack3r 3y ago
Just taking since life developed, our planet has been being hit by sun for 4.2bn years. If Earth had no way of dissipating heat, we’d have burned to a crisp by now. No?
- Brusco_RF 3y agoEarth is a blackbody[1]. We receive heat from the sun in the form of radiation. We also radiate heat out to space. [1] https://en.wikipedia.org/wiki/Black-body_radiation https://en.wikipedia.org/wiki/Black-body_radiation
- Timon3 3y agoNo, the earth is not a black-body. As your link says: > Of particular importance, although planets and stars (including the Earth and Sun) are neither in thermal equilibrium with their surroundings nor perfect black bodies, black-body radiation is still a good first approximation for the energy they emit.
- Brusco_RF 3y agoAll models are incorrect, but some are useful. Fine, you win Timon3, earth is not a blackbody because blackbodies don't actually exist.
- Timon3 3y agoThank you! Party this evening at my place. It's fine to say "the earth behaves similarly to a black-body" or "a black-body is a good approximation for the earth". But that's different from "the earth is a black-body".
- bitcurious 3y agoThought experiment - you could look at life itself as a form of heat management. Consider oil: crudely speaking, it's energy that could have heated some bit of the ocean, but instead was captured by a cell via photosynthesis which died and got buried underground.
- PheonixPharts 3y agoYou can take it further and even argue that complex life is ultimately just a tool for increasing entropy (which the universe seems to enjoy doing). Digging that oil up from the ground and the burning it does a tremendous amount to free up all that energy stored in a low-entropy system. The book Into the Cool makes an interesting case regarding this overall concept.