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Reading comprehension: The collision with Theia likely had a large effect on Earth once it occurred, but the collision might still have been unlikely to occur in the first place.
Earth was born dry until a cosmic collision made it a blue planet
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Re: Earth was born dry until a cosmic collision made it a blue planet
#32This 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…
I agree. In addition to the chemical elements like water, as mentioned in the article, the impact with Theia also enabled strong magmatic activity at the core of the planet, and that was a critical element as well to sustain life.
Probably the strong magnetic activity of the Earth's core was key to maintaining the atmosphere, but also, the magmatic heat contributed to keeping the planet at a good temperature to support life when a young Sun provided significantly less radiation.
All these elements may suggest that the collision is needed to satisfy the very strict requirements about where the planet is located and about the size and composition of the colliding planet. This makes the probability for life-sustaining planets in the Drake equation extremely low.
As an indirect proof of the tightness of the condition is the fact that the Earth in its history had periods of climate extremes hostile to life, like the Snowball Earth when the planet was completely covered by ice and snow, or at the opposite extreme, the very hot periods when the greenhouse effect was dominating the climate.
Re: Earth was born dry until a cosmic collision made it a blue planet
#33So we're not only made of elements which formed inside star(s) but also ones merged from two different planets. This is weird.
And the remnants of two neutron stars colliding.
Re: Earth was born dry until a cosmic collision made it a blue planet
#34So we're not only made of elements which formed inside star(s) but also ones merged from two different planets. This is weird.
In the scale of the universe this is bound to happen, likely infinite times anyway and this is what feels rather weird to me. Not just the perceived "special circumstances" but that independent of the rarity it will still happen many many times and then any conscious lifeform developing technology to realize this be subject to the definition of survivorship bias.
Re: Earth was born dry until a cosmic collision made it a blue planet
#35This 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 Drake Equation is filled with assumptions, like life must appear on a planet in the Goldilocks zone of a star. The whole equation has only one datapoint to extrapolate from. Tweak the equation's parameters and it will predict universes that only have one civilization per galaxy or worse! We have no way of knowing what those parameters are because we haven't seen other examples.
A major reason we are interested in Europa is because it might have underground oceans. Hypothetically, through tidal forces with Jupiter, the moon's core is hot enough to create oceans under the ice crust. Combined with hydrothermal vents you have the possibility for deep sea life similar to our own deep oceans. The Drake Equation does not predict this possibility.
Re: Earth was born dry until a cosmic collision made it a blue planet
#36Imagine this sci-fi plot twist: Aliens make live habitable by hitting proto-Earth with a planet, so life can sprout there. They calibrated it such a way that angular size of Moon is the same as of Sun.
What if they miscalculated and intelligence evolved when the moon drifted too far to cover the sun?
They regularly smashed asteroids onto earth until intelligent life emerged.
Re: Earth was born dry until a cosmic collision made it a blue planet
#37Imagine this sci-fi plot twist: Aliens make live habitable by hitting proto-Earth with a planet, so life can sprout there. They calibrated it such a way that angular size of Moon is the same as of Sun.
I would say "spoilers" ... but it's the title of the story. The Fermi Paradox Is Our Business Model
https://en.wikipedia.org/wiki/The_Fermi_Paradox_Is_Our_Busin...
https://www.tor.com/2010/08/11/the-fermi-paradox-is-our-busi...
Re: Earth was born dry until a cosmic collision made it a blue planet
#38This 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 Drake Equation is filled with assumptions, like life must appear on a planet in the Goldilocks zone of a star. The whole equation has only one datapoint to extrapolate from. Tweak the equation's parameters and it will predict universes that only have one civilization per galaxy or worse! We have no way of knowing what those parameters are because we haven't seen other examples. A major reason we are interested in…
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.
Re: Earth was born dry until a cosmic collision made it a blue planet
#39Earlier quoted context omitted.
The Drake Equation is filled with assumptions, like life must appear on a planet in the Goldilocks zone of a star. The whole equation has only one datapoint to extrapolate from. Tweak the equation's parameters and it will predict universes that only have one civilization per galaxy or worse! We have no way of knowing what those parameters are because we haven't seen other examples. A major reason we are interested in…
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.
I'm assuming they were referring to this term:
> n_e = the average number of planets that can potentially support life per star that has planets.
The fact that the planet is neither too hot nor too cold would seem to be a major component of this term:
Re: Earth was born dry until a cosmic collision made it a blue planet
#40This 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 100B - 1T galaxies out there and therefore a similar number of such events.