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Q & A: energetic baloney

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Most recent answer: 05/27/2013
Q:
http://www.physicscentral.com/experiment/askaphysicist/physics-answer.cfm?uid=20120221015143
Is a refrigerator a closed thermodynamic system? Would a closed universe have negative net energy?
- Mike W
Urbana
A:

This is another answer full of baloney from the American Physical Society, the generally reputable professional society of which most of us here are members.

In a somewhat rambling answer (no need for us to discuss the question) they say "Refrigerators are examples of closed thermodynamical systems" and show a picture of some refrigerators. It's true that the ones shown have closed doors, but they are not close to being "closed thermodynamical systems". When operating, they plug into electrical outlets and draw low-entropy electrical energy from the power company. They dump heat (high-entropy thermal energy) to the environment out the coils, usually mounted in back. And that's with the doors closed.

The answer also discusses the relation between the energy of the universe and its overall geometry. Not only does it get the total energy mixed up with the energy density, it also gets the relation between the energy and the geometry sort of backwards, misses the role of dark energy, and confuses some other issues. Oddly, the link that they give as a source () is fairly good, although it confuses the roles of ordinary energy and dark energy in determining whether the universe will expand forever.

Mike W.


(published on 05/27/2013)

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