Not buying it, Mars had water with no major collision.
Earth was born dry until a cosmic collision made it a blue planet
71–80 of 279 posts
Re: Earth was born dry until a cosmic collision made it a blue planet
#72This could mean in the Drake equation ne -number of planets capable of life- is very small. A planet has to be hit with a comet big enough to deliver a large amount of water but not so big or fast to destroy it. And be in the Goldilocks zone of the star. Also the mass of the planet would play a part - gravity of more massive ones would be more likely to capture a comet. But again, too massive and I could see that ham…
The thing is that even for a super low probability event, the size of the universe is so huge and such events must be happening all the time. e.g. Say chance of a random planet ever being hit by a water-carrying comet is one in a billion, then with 100B - 1T planets in the milky way it'd happen here 100-1000 times. If chances are only one in a trillion, and we're the one in the milky way, then there are still another…
Just as easily as we can multiply planets times systems times galaxies times cluster groups we can multiply multiple small probabilities of each chemical being present at the right time and right type, temperature ranges, gravity ranges, etc
Re: Earth was born dry until a cosmic collision made it a blue planet
#73Earlier quoted context omitted.
The Goldilocks zone doesn't enter the Drake equation at all. As a reminder, this is the equation: https://en.wikipedia.org/wiki/Drake_equation#Equation It makes very few assumptions.
The equation itself makes no assumptions. But anyone trying to calculate something with it must. The last five factors in the equation will be filled in by assumptions based entirely on one data point, life on Earth. From your link: ne = the average number of planets that can potentially support life per star that has planets. fl = the fraction of planets that could support life that actually develop life at some poi…
Those variables come with embedded assumptions they are essential and meaningful to discovery of life and civilization elsewhere in the universe.
For all we know civilization exists inside our car battery. Why assume it only exists on planets.
It's not explicit in it's assumption but implicit assumption the equation is meaningful.
Re: Earth was born dry until a cosmic collision made it a blue planet
#74Earlier quoted context omitted.
> The thing is that even for a super low probability event, the size of the universe is so huge and such events must be happening all the time. But numbers can go arbitrarily low.
And you have to have multiple low probability events. These probabilities multiply. We had a good start. A Jupiter to clear the debris, a Theia impact to create tides and contribute to tectonics, a magnetic core, a shielded atmosphere. We had water delivered to us. Maybe even panspermia. Maybe cell walls and mitochondria are hard. Maybe multicellular is hard. Maybe life on land is hard. Building lungs, rebuilding eye…
Even on Earth, the only reason humans exist is because the “local maximum” of the dinosaurs was wiped out by a meteor. Perhaps comparably intelligent dinosaurs would have eventually evolved - but it’s not a given!
Re: Earth was born dry until a cosmic collision made it a blue planet
#75I've tried reading the paper, which is obviously less hand wavy than this mess of a blog post but pretty tough going for a layman. I still don't see how they conclude that the water arrived all at once instead of in a bunch of comets... https://www.science.org/doi/10.1126/sciadv.adw1280
I also don't see how they disprove the contribution of gravity. Remember that Earth is composed of fifty Titan-sized bodies. Titan, and probably Uranus and Neptune, probably have their methane etc. as a result of outgassing - initially, the volatiles are embedded in the inner rocks, but as they gravitationally differentiate and heat - and are subject to tide-like interactions with other bodies - the volatiles are rel…
I believe the idea is that the water was all cooked out of Earth's protoplanetary disk material before it even formed large chunks. So gravity never got a chance to "contribute" on that front.
Re: Earth was born dry until a cosmic collision made it a blue planet
#76Earlier quoted context omitted.
The Goldilocks zone doesn't enter the Drake equation at all. As a reminder, this is the equation: https://en.wikipedia.org/wiki/Drake_equation#Equation It makes very few assumptions.
The equation itself makes no assumptions. But anyone trying to calculate something with it must. The last five factors in the equation will be filled in by assumptions based entirely on one data point, life on Earth. From your link: ne = the average number of planets that can potentially support life per star that has planets. fl = the fraction of planets that could support life that actually develop life at some poi…
It does assume that life must be associatable with a planet. It's a plausible assumption, but you could also hypothetically have life develop on a star itself or its remnants, comets, clouds of interstellar gas. Maybe even something more exotic than that (dark matter? some weird correlated statistical properties of the quantum foam?)
Re: Earth was born dry until a cosmic collision made it a blue planet
#77[flagged]
Re: Earth was born dry until a cosmic collision made it a blue planet
#78This could mean in the Drake equation ne -number of planets capable of life- is very small. A planet has to be hit with a comet big enough to deliver a large amount of water but not so big or fast to destroy it. And be in the Goldilocks zone of the star. Also the mass of the planet would play a part - gravity of more massive ones would be more likely to capture a comet. But again, too massive and I could see that ham…
Speaking of Drake equations, you should (1) see the other comment here with this account name (2) check out the top Pirate Bay rip of Dark City (which predated that other movie) and turn on the English subtitles and count the number of times the characters look at or make gestures pointing to certain alignments of the text in the subtitles and, if you're true "hackers", try to figure out the encrypted messages in the text alignments that the characters are looking at/pointing to at key moments – and then when/if you figure out what the encrypted messages mean, try to figure out how the director worked together backwards so that they could have a script that aligns a certain way using subtitles and then make the scenes so that the actors are looking/pointing to key spots at just the right time.
If you appreciate technical things, you'd be in for a treat.
Re: Earth was born dry until a cosmic collision made it a blue planet
#79Is this the same collision theorized to have created the moon?
Yes
Re: Earth was born dry until a cosmic collision made it a blue planet
#80The article says the light elements hydrogen, carbon and sulfur (and oxygen?) were only able to condense on the outer planets (and their moons). And the original article specifically says "the inner Solar System planets Venus and Mercury are largely devoid of volatile elements". If that's the case, why does Venus have so much carbon dioxide? (I'm not saying the article is wrong, just trying to understand.)
Keep in mind that carbon dioxide is almost 3x heavier than methane. Part of the reason Venus has "so much" CO₂ is because all the lighter gasses have been depleted.
(But yes, Venus is hard to satisfactorily explain, regardless of whether you accept the article's conclusions at face value.)