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I was reading this question and talking about it with my flatmate when a question came up. Ignoring the effects of losing or gaining mass due to cosmic dust, meteorites, and atmospheric losses as described here, has the Earth overall lost mass due to the entropy generated in the chemical reactions since the start of life?

What I'm thinking is that all of life uses resources from the Earth, whether it be plants extracting chemicals from the soil or digging up uranium for use in nuclear reactors. These materials then undergo chemical changes, thus increasing entropy. It could be argued that trash is buried so the mass change neutral but the items in the trash have been chemically altered at some point, therefore they technically weigh slightly less than their constituents.

Even trash that is burned "returns" to the Earth in the form of smoke in the atmosphere, right? But burning is a chemical reaction which again increases entropy. So if life had never developed on Earth and it was isolated from the rest of the cosmos, logically it should weigh more because less mass was converted to energy in reactions. Does that sound right?

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    $\begingroup$ Interesting concept, but don't forget that life can capture & store solar energy, eg in the form of fossil fuels. $\endgroup$ – PM 2Ring May 23 at 10:36
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    $\begingroup$ life also catches energy from the sun, that could be otherwise reflected back into space and perhaps it even conserves energy that would be radiated to space by earth otherwise $\endgroup$ – Umaxo May 23 at 10:37
  • $\begingroup$ Biomass absorbs energy by replacing the surface, not always with a lower albedo. Also life eliminates carbon dioxide, eliminating greenhouse effect. This made the earth turn into a snowball many times, so it would not be logically heavier in that way $\endgroup$ – Sartem Cacartem May 29 at 16:45
  • $\begingroup$ Maybe I should clarify that when I said the Earth I meant the atmosphere too. $\endgroup$ – enea19 May 31 at 9:00

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