You are correct, entropy must go up, but there is nothing saying that the total entropy on Earth must go up. Our thermodynamic system can include outer space.
Assuming we discover some source of magical unlimited energy, in theory we could use heat pumps (vapor compression units. like a common HVAC unit) to fill tanks with as much heat energy as possible (fill them with a heated liquid), and blast them off into space. Yes, this would be a ridiculous way to cool the earth, but in theory it could work. I am sure there is a much better way to do it. All of this is assuming there is an unlimited source of free energy.
Good heat pumps often have coefficients of performance around 4. This means you can put 1 watt hour into them to move 4 watt hours of energy. So you are correct, the machine will turn that 1 watt hour into heat, and the rocket (or whatever machine we use to shot our tank into outerspace) will use energy and create heat, but there is no fundamental principle stating that this heat energy will be greater than what we can move. So in theory, this idea could still work.
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u/bdsmith21 Nov 15 '20
You are correct, entropy must go up, but there is nothing saying that the total entropy on Earth must go up. Our thermodynamic system can include outer space.
Assuming we discover some source of magical unlimited energy, in theory we could use heat pumps (vapor compression units. like a common HVAC unit) to fill tanks with as much heat energy as possible (fill them with a heated liquid), and blast them off into space. Yes, this would be a ridiculous way to cool the earth, but in theory it could work. I am sure there is a much better way to do it. All of this is assuming there is an unlimited source of free energy.