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The 250 W/m^2 is measured sunlight, not the amount reflected by the atmosphere. I absolutely would not confine ourselves to land as oceans provide a large area

The 250 W/m^2 is measured sunlight, not the amount reflected by the atmosphere. I absolutely would not confine ourselves to land as oceans provide a large area available for solar energy capture and there's no reason to think we might not be able to use it. Photovoltaics, or whatever technology we use to capture sunlight, will get better but even at a modest 20% still gives us a lot of headroom. Whether its 2.3% or 2.5% energy growth per year, the calculation gives us a timeline of 200-400 years. For some reason this is used as a countdown to oblivion instead of a rallying cry about where we're headed. Mars is great but there's a *lot of space in space*. Besides pushing solar panels into orbit, either the earth, moon or sun directly, there's also tons of asteroids, ripe for mining. Forget a second earth, we can make a Dyson swarm. What you take as a countdown timer to a bomb, I take as a timeline for us to go up the Kardashev scale. These reduction to absurdity arguments about the temperature of the earth assume we're not going to space. I don't understand why you reject this idea outright. All the above calculations about the energy available to us are from a tiny pin-prick sliver of how much energy the sun deposits in all directions, every day, all day, for the 4 billion years. Once we have access to a significant fraction of the suns energy, going to other stars and repeating is well within feasibility.

breuleux 1y ago
> These reduction to absurdity arguments about the temperature of the earth assume we're not going to space. I don't understand why you reject this idea outright. Most people just want to stay home, they don't want to go anywhere, let alone space. Regardless of whether some humans or manmade probes go to space, inhabited regions need their growth to be checked in order to maintain a stable, long-term steady state, lest we want to keep shipping billions and billions of people from the center to ever-farther reaches of the galaxy (a logistical and humanitarian nightmare).
stouset 1y ago
> These reduction to absurdity arguments about the temperature of the earth assume we're not going to space. I don't understand why you reject this idea outright. Not just going to space, but transitioning to a primarily space-based civilization. We'll need to terraform Mars within 400 years, and even then that will only buy us thirty years of sustained growth. Even if we slow down to 1% growth, once we exhaust Earth, we'll exhaust Earth-2 in just seventy. Further, this doesn’t actually solve much because all the growth is happening on the outer planets. Earth is definitionally full in this future, so it needs to stay steady-state. Unless we forcibly ship off half the population every doubling period. Is it going to happen? Maybe. But I'm not sure we should be playing brinksmanship with the one planet we know we've got on the idea that the overwhelming majority of humans will (and must) live in space on every rock in the solar system in the same amount of time it took us to go from the Renaissance to the Internet. > All the above calculations about the energy available to us are from a tiny pin-prick sliver of how much energy the sun deposits in all directions, every day, all day, for the 4 billion years. Exponential growth is a bitch. In roughly the same time it took us to go from the dark ages to now, we'll need to be consuming 100% of the sun's total energy output. I think it's far more likely that either: a) we won't stop using more energy and literally cook ourselves off the planet, or b) we'll stop exponential growth of energy use Based on our approach to the economy vs. climate change, I think it's pretty clear which of those two choices humanity will opt for. If we even make it there, thanks to the aforementioned climate change.

breuleux 1y ago

> These reduction to absurdity arguments about the temperature of the earth assume we're not going to space. I don't understand why you reject this idea outright. Most people just want to stay home, they don't want to go anywhere, let alone space. Regardless of whether some humans or manmade probes go to space, inhabited regions need their growth to be checked in order to maintain a stable, long-term steady state, lest we want to keep shipping billions and billions of people from the center to ever-farther reaches of the galaxy (a logistical and humanitarian nightmare).

stouset 1y ago

> These reduction to absurdity arguments about the temperature of the earth assume we're not going to space. I don't understand why you reject this idea outright. Not just going to space, but transitioning to a primarily space-based civilization. We'll need to terraform Mars within 400 years, and even then that will only buy us thirty years of sustained growth. Even if we slow down to 1% growth, once we exhaust Earth, we'll exhaust Earth-2 in just seventy. Further, this doesn’t actually solve much because all the growth is happening on the outer planets. Earth is definitionally full in this future, so it needs to stay steady-state. Unless we forcibly ship off half the population every doubling period. Is it going to happen? Maybe. But I'm not sure we should be playing brinksmanship with the one planet we know we've got on the idea that the overwhelming majority of humans will (and must) live in space on every rock in the solar system in the same amount of time it took us to go from the Renaissance to the Internet. > All the above calculations about the energy available to us are from a tiny pin-prick sliver of how much energy the sun deposits in all directions, every day, all day, for the 4 billion years. Exponential growth is a bitch. In roughly the same time it took us to go from the dark ages to now, we'll need to be consuming 100% of the sun's total energy output. I think it's far more likely that either: a) we won't stop using more energy and literally cook ourselves off the planet, or b) we'll stop exponential growth of energy use Based on our approach to the economy vs. climate change, I think it's pretty clear which of those two choices humanity will opt for. If we even make it there, thanks to the aforementioned climate change.