most recent 30 from physics.stackexchange.com 2025-08-05T23:23:52Z https://physics.stackexchange.com/feeds/question/856868 https://creativecommons.org/licenses/by-sa/4.0/rdf https://physics.stackexchange.com/q/856868 7 Matt Schoolfield https://physics.stackexchange.com/users/536271 2025-08-05T16:44:52Z 2025-08-05T19:26:57Z

<p>As the universe is expanding is work being done? If so, where is the energy coming from?</p>

https://physics.stackexchange.com/questions/856868/-/856877#856877 14 Dale https://physics.stackexchange.com/users/204834 2025-08-05T18:51:42Z 2025-08-05T18:51:42Z

<p>Work is the transfer of energy from one system to another. Energy, in turn, is a conserved quantity associated with the time translation invariance of the physical laws.</p> <p>At cosmological scales the time translation invariance is lost so there is no conserved energy. With no energy there is nothing to be transferred and with the universe there is no other system to transfer from.</p> <p>So the concept of doing work on the universe doesn’t make sense as it stands. Of course, you could modify/generalize those concepts to make them apply. But in the course of doing so you could probably arrive at any answer you like. There isn’t currently a standard generalization that would serve.</p>

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