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Another "if" I'm often wondering is about the size of the Earth. Had we shown up on something the size of the Moon or Ganymede, the amount of resources we would

Another "if" I'm often wondering is about the size of the Earth. Had we shown up on something the size of the Moon or Ganymede, the amount of resources we would have had at our disposal would have been a lot smaller. We would probably have figured that we weren't the center of the Solar system much sooner though. On the other hand if an intelligent species spawns on a much larger planet they can progress much longer before depleting their resources.

godelski 6y ago
Those bodies are too small to have a real atmosphere. Nor would they have molten cores which provide the magnetospheres essential for their radiation shielding and being able to have an electric ground. While neither of these are necessary, per se, they are extremely helpful (especially having an electric ground) and I think make a big difference when we're talking about advanced life vs microbial.
TeMPOraL 6y ago
Conversely, were we born on a world a bit larger than Earth, we wouldn't be able to reach orbit the way we did, due to limits of chemical rocket propulsion.
- bsder 6y ago
  I thought this, too, but someone did the math and were not as close to the boundary as you think. It's something like the Earth would have to be 10x bigger to prevent chemical rocketry from working.
  - philwelch 6y ago
    From working at all, sure, but how big would those rockets have to be? Rocketry doesn’t exist just because some idealists wanted to go to space. It exists because governments wanted to invent new ways to bomb their enemies. A V-2 allows you to bomb England from continental Europe (and wasn’t even a cost-effective solution for that); nobody was going to build a Saturn V-sized rocket for that use case, and even if they wanted to, it’s not clear that they could get it to work without lots of testing with smaller prototypes.[1] Compounding this issue is that, on this hypothetically larger planet, whatever enemies you’d want to bomb in the first place could also be much farther away! Whereas on Earth it’s not hard to reach any other point on the planet; a little over a decade from the V-2 we had ICBM’s. [1] By way of analogy, Lofstrom loops are theoretically much more efficient than rockets, but to find out for sure we’d have to build a full scale example, and that would be extremely expensive even if we didn’t run into any unforeseen cost overruns or delays—which we inevitably would because this would be the first time we built anything like this. It would be like ITER except at least ITER has a practical application if it works.
- throw0101a 6y ago
  > chemical rocket propulsion. If anyone wants to learn more about the history of this specific/niche topic, there's actually an interesting book (with a foreword by Isaac Asimov), Ignition!: An informal history of liquid rocket propellants by John Drury Clark: * https://www.goodreads.com/book/show/677285.Ignition_ https://www.goodreads.com/book/show/677285.Ignition_ * https://en.wikipedia.org/wiki/John_Drury_Clark https://en.wikipedia.org/wiki/John_Drury_Clark * PDF copy: http://www.sciencemadness.org/library/books/ignition.pdf http://www.sciencemadness.org/library/books/ignition.pdf
  - basilgohar 6y ago
    It's so interesting that you mentioned that because just yesterday I came across a video [0] on Scott Manley's YouTube channel where he discusses this book exactly. [0] https://www.youtube.com/watch?v=_wLk2j7_KB0 https://www.youtube.com/watch?v=_wLk2j7_KB0
- njarboe 6y ago
  We probably would have kept working on nuclear powered rockets and have settled the solar system with the tech by now if chemical rockets hadn't been sufficient for ICBMs.

godelski 6y ago

Those bodies are too small to have a real atmosphere. Nor would they have molten cores which provide the magnetospheres essential for their radiation shielding and being able to have an electric ground. While neither of these are necessary, per se, they are extremely helpful (especially having an electric ground) and I think make a big difference when we're talking about advanced life vs microbial.

TeMPOraL 6y ago

Conversely, were we born on a world a bit larger than Earth, we wouldn't be able to reach orbit the way we did, due to limits of chemical rocket propulsion.

bsder 6y ago
I thought this, too, but someone did the math and were not as close to the boundary as you think. It's something like the Earth would have to be 10x bigger to prevent chemical rocketry from working.
- philwelch 6y ago
  From working at all, sure, but how big would those rockets have to be? Rocketry doesn’t exist just because some idealists wanted to go to space. It exists because governments wanted to invent new ways to bomb their enemies. A V-2 allows you to bomb England from continental Europe (and wasn’t even a cost-effective solution for that); nobody was going to build a Saturn V-sized rocket for that use case, and even if they wanted to, it’s not clear that they could get it to work without lots of testing with smaller prototypes.[1] Compounding this issue is that, on this hypothetically larger planet, whatever enemies you’d want to bomb in the first place could also be much farther away! Whereas on Earth it’s not hard to reach any other point on the planet; a little over a decade from the V-2 we had ICBM’s. [1] By way of analogy, Lofstrom loops are theoretically much more efficient than rockets, but to find out for sure we’d have to build a full scale example, and that would be extremely expensive even if we didn’t run into any unforeseen cost overruns or delays—which we inevitably would because this would be the first time we built anything like this. It would be like ITER except at least ITER has a practical application if it works.
throw0101a 6y ago
> chemical rocket propulsion. If anyone wants to learn more about the history of this specific/niche topic, there's actually an interesting book (with a foreword by Isaac Asimov), Ignition!: An informal history of liquid rocket propellants by John Drury Clark: * https://www.goodreads.com/book/show/677285.Ignition_ https://www.goodreads.com/book/show/677285.Ignition_ * https://en.wikipedia.org/wiki/John_Drury_Clark https://en.wikipedia.org/wiki/John_Drury_Clark * PDF copy: http://www.sciencemadness.org/library/books/ignition.pdf http://www.sciencemadness.org/library/books/ignition.pdf
- basilgohar 6y ago
  It's so interesting that you mentioned that because just yesterday I came across a video [0] on Scott Manley's YouTube channel where he discusses this book exactly. [0] https://www.youtube.com/watch?v=_wLk2j7_KB0 https://www.youtube.com/watch?v=_wLk2j7_KB0
njarboe 6y ago
We probably would have kept working on nuclear powered rockets and have settled the solar system with the tech by now if chemical rockets hadn't been sufficient for ICBMs.