The surface is too small and you only get like 4% of the energy you need (Assuming you like being naked under full sunlight all day long. The article is for cows, but I guess the number is similar for humans.) 4% of 2400 kcal is almost 100 kcal, that is the content of a small diet treat or 2 apples.

These sea slugs can survive because they move very slowly. For a human, I think it's not enough energy to survive even if all the activity is to watch TV inside a hot swimming pool.

eigenspace 2 days ago | parent | next [-]

Dietary need scales with volume, whereas incident sunlight would scale with surface area.

Assuming a spherical cow and a spherical human, the calories needed would scale with the radius cubed, whereas the calories gained from sunlight would scale with the radius squared. So while I agree this wouldn't be very many calories, even if you sat under the sun all day, I think the 4% figure is probably quite pessimistic.

	▲	gus_massa a day ago \| parent \| next [-]
		Mmm... Cows weight like 5 persons, 5^(1/3)=1.7, so 4%*1.7=7%, so 170 kcal that is still less than a single cheeseburger.
	▲	KnuthIsGod 2 days ago \| parent \| prev \| next [-]
		Marvelous... Finally a good reason to assume a spherical cow!
	▲	pfdietz 2 days ago \| parent \| prev [-]
		The square cube law pops up all over the place, my favorite being in fusion reactors, where it is a two edged sword.

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2 days ago | parent | prev [-]

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