Just move the Earth to a new orbit. In a billion year, our terraforming technology will advance enough for us post-humanoid species to do complex orbital adjustments. — Problem solved.
Lord Ruler!
The future lifespan of Earth’s oxygenated atmosphere
71–80 of 90 posts
Re: The future lifespan of Earth’s oxygenated atmosphere
#72In all candidness: can someone tell me what the point of these studies is?
Re: The future lifespan of Earth’s oxygenated atmosphere
#73Earlier quoted context omitted.
I think we can all but rule out a dead, ancient planet-spanning civilization on Mars now. We have medium resolution imagery of the entire planet and high resolution (meter or submeter) imagery of a lot of the surface, in a wide distribution. Mars hasn’t had enough volcanic activity to hide evidence of a planet-spanning civilization unless it occurred while large asteroid impacts were much more common. Venus, however,…
A planet spanning civilization on Mars is less likely. However, there are still ways it could be found, depending on how long ago it was. I list three ways below, and suspect there are more. First, there is the possibility of a civilization dying and evidence being erased by tectonic plate recycling. Mars is approximately 4.6 billion years old. We know it has volcanic activity, and most consider it to have inactive t…
Mars has volcanism but not tectonic plate recycling. That’s an Earth thing. There are large parts of the surface of Mars that are MUCH older than any significant surface areas of the Earth for this reason. And that’s my point.
Re: The future lifespan of Earth’s oxygenated atmosphere
#74In all candidness: can someone tell me what the point of these studies is?
Completely uninformed speculation:
* Provide more information to the search for habitable planets/extra-solar life
* Better understand how the Earth's atmosphere and overall ecosystem evolves over time, which may inform our understanding of long-term risks of climate change (and perhaps contribute to our ideas of how to manage terraforming on Earth, if we need to mitigate climate change).
Re: The future lifespan of Earth’s oxygenated atmosphere
#75Earth will not host complex plants in 600 million years. So that’s also a problem - https://en.m.wikipedia.org/wiki/Timeline_of_the_far_future
Please post non-mobile links to wikipedia when you can [0] [0]: https://en.wikipedia.org/wiki/Timeline_of_the_far_future
Separating presentation by subdomain feels like a relic from the 2000s or earlier. Wikipedia is one site that could do to be modernised with dynamic formatting or whatever it's called. Even BBC moved news.bbc.co.uk to bbc.co.uk/news although that is not quite the same thing.
Re: The future lifespan of Earth’s oxygenated atmosphere
#76Earlier quoted context omitted.
I think we can all but rule out a dead, ancient planet-spanning civilization on Mars now. We have medium resolution imagery of the entire planet and high resolution (meter or submeter) imagery of a lot of the surface, in a wide distribution. Mars hasn’t had enough volcanic activity to hide evidence of a planet-spanning civilization unless it occurred while large asteroid impacts were much more common. Venus, however,…
I always wondered what it would be like if Mars and Venus were swapped. Would Mars be warmer, or would it be even more devoid of atmosphere? And would Venus (with its greenhouse gas) be a more livable temperature if it was in Mars's orbit? It still wouldn't be survivable due to the atmospheric composition, but I was just wondering about raw climate.
Yes, mars is too small to hold its atmosphere at its current distance from the sun, moving it closer would only make the problem worse. Like our moon, the bright side would be hot during the day, but it would be cold at night with very little atmosphere to retain heat, and even in temperate regions at the poles liquid water would not be stable.
We're not really sure what kicked off Venus' runaway greenhouse, so it's possible that would still occur, though it does seem less likely. Without the runaway greenhouse, Venus' atmosphere would likely remain primarily nitrogen. Its atmosphere would still be significantly thicker than Earth's but by a factor of 5 instead of a factor of 100. With the additional atmosphere, it might remain quite temperate even at the greater distance.
Of course had Venus and Mars developed in eachother's places, Venus would have developed as a smaller world with a thinner atmosphere (generally more mars-like) and Mars would have been larger with a thicker atmosphere (generally more venus-like), so the whole point is somewhat moot.
Re: The future lifespan of Earth’s oxygenated atmosphere
#77They provide the fortran code too! Sweet
Re: The future lifespan of Earth’s oxygenated atmosphere
#78Earlier quoted context omitted.
Why do we think the origin of intelligent life requires a few hard steps and not just a continuous progression or perhaps one hard step and otherwise a steady progression?
I think the hard steps are sharp divisions that had a long time in the status quo, then a sudden random development. Single-cell to multi-cellular. Development of nerve tissue that can collect information, make decisions, and influence the organism. Centralization of a bundle of nerves into a decision making center. Then you get to higher order steps that probably aren't as complicated, such as communications and org…
I think any step which occurred independently on multiple occasions is probably not a hard step. The origin of multicellular life from unicellular life occurred on at least three separate occasions independently.
However, I think at the very least that the origin of the first cells, as well as perhaps the transition from Archaean/Prokaryotic cells to our symbiotic Eukaryotic ancestor may qualify.
Re: The future lifespan of Earth’s oxygenated atmosphere
#79Phytoplankton is responsible for 50-80% of all oxygen in the atmosphere. The World wide phytoplankton population has been in decline since the 50’s, down almost 40%. As the population continues to decline it will hit a tipping point and the population will crash, when that happens, we’ll get to witness what happens when oxygen levels decline.
Re: The future lifespan of Earth’s oxygenated atmosphere
#80Earlier quoted context omitted.
This is predicted by the hypothesis that the origin of intelligent life requires the occurrence of several hard steps, each of which take at least several billion years (but with no upper bound) in expectation. If that hypothesis holds, then conditional on all the steps having completed on a given planet, they will have done so roughly equally spaced in the time allotted, regardless of their relative difficulty. So,…
Why do we think the origin of intelligent life requires a few hard steps and not just a continuous progression or perhaps one hard step and otherwise a steady progression?
We don’t necessarily think that from first principles. But the hypothesis does make certain predictions which are consistent with what we see.