21–30 of 106 posts
"It is not apparent yet that such Rogue planets are regularly traded between star-systems and subsequently participate in serial evaporative events and the proposal may seem like a long shot, but on astronomical time scales the unlikely can become commonplace." It sounds a bit Velikofskian.
Yes, Michael Lund of CalTech updated the Velikofskian hypothesis: https://arxiv.org/pdf/1903.12437.pdf
Earlier quoted context omitted.
I think you may be mixing up the causation. How probable our universe is, we'll never know (until we can see other universes). We do know that in this universe, life exists. Thus our universe has to be "fine-tuned" for us to exist because we do. As for the universe "favor"ing life, that doesn't really make sense either. I think it's safe to say the universe favors stars, gas giants, black holes but it's pretty hard t…
I suppose if the anthropic principle is correct that would mean there are many examples, it's just our problem that we are only familiar with one.
"It is not apparent yet that such Rogue planets are regularly traded between star-systems and subsequently participate in serial evaporative events and the proposal may seem like a long shot, but on astronomical time scales the unlikely can become commonplace." It sounds a bit Velikofskian.
Yes, Michael Lund of CalTech updated the Velikofskian hypothesis: https://arxiv.org/pdf/1903.12437.pdf
Earlier quoted context omitted.
According to wikipedia, Venus' atmosphere is about 3.5% nitrogen and its pressure is about 91 atmospheres. So, technically Venus doesn't have a lack of nitrogen (it appears to have about 3 times as much as Earth), it has an extreme abundance of carbon dioxide. Something interesting I didn't know is that apparently Venus has almost no plain oxygen. Mars, on the other hand, doesn't have much nitrogen. Perhaps that's at…
Earth atmosphere is 0.04% CO2. Why does Earth have such little CO2? Is maybe used by life on early Earth?
Earlier quoted context omitted.
Is there a succinct explanation of why some terrestial bodies in the solar system (Earth, Titan, Triton, Pluto) have mostly nitrogen atmospheres, but others (Mars, Venus) are mostly carbon dioxide instead? I mean, aside from specifics about each, what's the pattern that you would apply to an arbitrary planet?
According to wikipedia, Venus' atmosphere is about 3.5% nitrogen and its pressure is about 91 atmospheres. So, technically Venus doesn't have a lack of nitrogen (it appears to have about 3 times as much as Earth), it has an extreme abundance of carbon dioxide. Something interesting I didn't know is that apparently Venus has almost no plain oxygen. Mars, on the other hand, doesn't have much nitrogen. Perhaps that's at…
Earlier quoted context omitted.
Is there a succinct explanation of why some terrestial bodies in the solar system (Earth, Titan, Triton, Pluto) have mostly nitrogen atmospheres, but others (Mars, Venus) are mostly carbon dioxide instead? I mean, aside from specifics about each, what's the pattern that you would apply to an arbitrary planet?
According to wikipedia, Venus' atmosphere is about 3.5% nitrogen and its pressure is about 91 atmospheres. So, technically Venus doesn't have a lack of nitrogen (it appears to have about 3 times as much as Earth), it has an extreme abundance of carbon dioxide. Something interesting I didn't know is that apparently Venus has almost no plain oxygen. Mars, on the other hand, doesn't have much nitrogen. Perhaps that's at…
Earlier quoted context omitted.
Yes, Michael Lund of CalTech updated the Velikofskian hypothesis: https://arxiv.org/pdf/1903.12437.pdf
The fact that this paper appeared in April 2019 in a journal called "Acta Prima Aprilia" should give you a clue to how seriously to take it.
"The Chthonian process effectively selects for retainment of water and carbon dioxide, which are heavy and tend to rain back down upon condensing in the upper atmosphere." So earthlike planets would be more plentiful than otherwise. This could be a boon to scifi plots that entail conveniently breathable atmospheres. It would also tend to support the strong anthropic principle.
But can they outgrow the trope of every alien being a human-in-a-mask?
AFAIK Nitrogen in the initial atmosphere rules this out.
Is there a succinct explanation of why some terrestial bodies in the solar system (Earth, Titan, Triton, Pluto) have mostly nitrogen atmospheres, but others (Mars, Venus) are mostly carbon dioxide instead? I mean, aside from specifics about each, what's the pattern that you would apply to an arbitrary planet?
For Earth, the answer is simple: life. In the absence of life, a nitrogen-oxygen atmosphere is thermodynamically unstable. Our best current understanding is that the atmosphere of the early Earth, before life developed, was mostly methane and ammonia, which are commonly observed in the atmospheres of the outer planets and their satellites. Once life developed, the methane and ammonia were gradually chemically converted by life to water and nitrogen.
For the others you mention, oxygen is not present, and the nitrogen is combined with methane (plus traces of carbon monoxide or carbon dioxide). I have not seen detailed thermodynamic calculations, but if there are very few oxygen atoms present, nitrogen plus methane should be thermodynamically stable. The unique feature of Earth as compared with these others would be the presence of a sufficient quantity of oxygen atoms to oxidize the nitrogen to ammonia in the early atmosphere before life developed.
For Mars, it is close enough to the Sun and small enough to make its temperature too high for it to retain significant amounts of nitrogen or methane (it has traces of both, IIRC), so CO2, which is significantly heavier, is the only significant component left.
For Venus, a significant amount of nitrogen gas is present (about four times as much as in Earth's atmosphere--Venus is significantly larger than Mars so its gravity can keep the nitrogen from escaping), but this is masked by the enormous amount of CO2 present (about 95 atmospheres worth), which AFAIK is believed to be due to all of the calcium carbonate in the surface rocks having been driven into the atmosphere due to a runaway greenhouse effect raising the temperature.
"The Chthonian process effectively selects for retainment of water and carbon dioxide, which are heavy and tend to rain back down upon condensing in the upper atmosphere." So earthlike planets would be more plentiful than otherwise. This could be a boon to scifi plots that entail conveniently breathable atmospheres. It would also tend to support the strong anthropic principle.
> This could be a boon to scifi plots But can they outgrow the trope of every alien being a human-in-a-mask?