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Let me try to wrap my head around this: Say there is a completely static, black planet. All sunlight that hits it is turned into heat which is dissipated into

by mg 3y ago

Let me try to wrap my head around this: Say there is a completely static, black planet. All sunlight that hits it is turned into heat which is dissipated into the universe. Nothing moves on that planet. The static black inhabitants of the planet are very thankful for the sun that it makes their planet nicely warm and cozy. Now one day, one of them is allowed to travel to planet earth and read Hacker News. He reads this very thread. Are you telling him that they are wasting half of the benefits they could get from the sun? They could have a nice warm planet AND drive around in electric cars all day? For free? Everything else would stay the same? If so, doesn't that make driving a car "free" in that it not even increased the amount of entropy? Since the sunlight would have turned into high entropy heat anyhow?

rimunroe 3y ago
I'm not sure if you're asking actual or rhetorical questions. Assuming they're genuine: > Are you telling him that they are wasting half of the benefits they could get from the sun? They could have a nice warm planet AND drive around in electric cars all day? For free? Everything else would stay the same? Strictly speaking, yeah, they're not using all the energy they could. "Wasting" seems like a weird way to say it though, because it feels like that implies they want to be doing something with it. > If so, doesn't that make driving a car "free" in that it not even increased the amount of entropy? Since the sunlight would have turned into high entropy heat anyhow? On a long enough timescale nothing matters from the point of view of entropy. Net entropy will always increase. This is a pretty useless observation if you're trying to make a value judgement on the much smaller timescale of a civilization or the much smaller physical system of a planet, where having easily harnessable energy is important.
rcxdude 3y ago
Yes, if you are replacing a process which basically just converts low entropy energy into high entropy heat directly with something that does more interesting along the way, the end result is basically the same from an entropy point of view. Generally we as a species are not limited by the entropy available at the moment, but by our ability to harness it and the consequences of doing so in terms of the balances of the systems that it flows through.

by mg 3y ago

rimunroe 3y ago

I'm not sure if you're asking actual or rhetorical questions. Assuming they're genuine: > Are you telling him that they are wasting half of the benefits they could get from the sun? They could have a nice warm planet AND drive around in electric cars all day? For free? Everything else would stay the same? Strictly speaking, yeah, they're not using all the energy they could. "Wasting" seems like a weird way to say it though, because it feels like that implies they want to be doing something with it. > If so, doesn't that make driving a car "free" in that it not even increased the amount of entropy? Since the sunlight would have turned into high entropy heat anyhow? On a long enough timescale nothing matters from the point of view of entropy. Net entropy will always increase. This is a pretty useless observation if you're trying to make a value judgement on the much smaller timescale of a civilization or the much smaller physical system of a planet, where having easily harnessable energy is important.

rcxdude 3y ago

Yes, if you are replacing a process which basically just converts low entropy energy into high entropy heat directly with something that does more interesting along the way, the end result is basically the same from an entropy point of view. Generally we as a species are not limited by the entropy available at the moment, but by our ability to harness it and the consequences of doing so in terms of the balances of the systems that it flows through.