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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

#201

Post by II2II »

andrewflnr wrote: post #59
shireboy wrote: post #4

This 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 don't see any reason to believe that giant impact is the only way to get life-supporting amounts of water. We know Mars had liquid water. We know Titan has lots of ice. We're pretty sure Venus at least had noticeable amounts of water. Did all of these come from Theia-type impacts? I don't think we have any evidence of that.

Multiple impacts is the standard hypothesis for a source of Earth's water. If I recall correctly, outgassing from volcanos is another source.

Keep in mind, the solar system formed from a relatively homogenous nebula. It was the formation of the sun that forced lighter elements to migrate outwards, and that only happens if the lighter elements aren't already part of a larger object. There isn't much of a difference between a 10 km chunk of ice and a 10 km chunk of iron gravitationally speaking. Bouancy doesn't play a role here, so density doesn't matter. Outgassing does matter, but that is a slow process for large object, like the Earth, or for smaller objects on Earth crossing orbits that don't get too close to the sun.

It's also worth considering that each planet's situation is unique. There is much more water ice on the moons of the outer solar system because there was more water at the time of formation and the lower temperatures mean the water that was there stayed there. As for Mars, even though it is colder than the Earth, it is much less massive. As such, its atmosphere bleeds away lighter molecules (never mind lighter elements).

Re: Earth was born dry until a cosmic collision made it a blue planet

#202

Post by mensetmanusman »

shireboy wrote: post #4

This 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 whatever math leads to Earth being the only planet with intelligent matter out of infinity planets.

Re: Earth was born dry until a cosmic collision made it a blue planet

#203

Post by hdgvhicv »

runarberg wrote: post #176
pfdietz wrote: post #167

Earlier quoted context omitted.

Your argument shows a lack of understanding of exponential growth. Any given colony has to create only slightly more than 1 additional colony in order to drive exponential growth. There doesn't have to be any coordinated action by a central authority for it to happen. For it not to happen (if it is physically feasible), in contrast, every species has to refrain from doing it at all points in their history, almost wit…

Permanent exponential growth is very rare in nature, and even rarer in biological systems. What we observe as exponential growth is usually only a partial observation of a logistical curve or is missing a system collapse at the end of the curve. We have no reason to believe alien (or even human) civilization will continue to grow and expand forever. Heck even the human population curve has started to slow down and is…

Unless some means of communicating faster than light is found a galactic colonisations is not a civilisation, its multiple ones. A colony ship heading in one direction at 0.1c will never interact with one heading the other way at the same speed. After 10,000 years the civilisations will be very different, after 100,000 years they will barely be the same species.

Even if 99% stop and fail, the 1% will continue and continue expanding.

The only way to stop would be to run out of planets, which would mean every habitable planet and star system has been populated. There wouldn’t be a biological urge to stop, as the successful colonies are ones which have the urge to expand. An environmental need wouldn’t affect every colony and ship short of a galaxy spanning event of some sort which we can’t even conceive.

Re: Earth was born dry until a cosmic collision made it a blue planet

#204

Post by graycat »

mianos wrote: post #187
DennisP wrote: post #154

Earlier quoted context omitted.

One approach is to give each variable a probability distribution. The greater our uncertainty about possible values, the wider the bell curve. Drexler and colleagues did that, and found "a substantial probability that we are alone in our galaxy, and perhaps even in our observable universe (53%–99.6% and 39%–85% respectively). ’Where are they?’ — probably extremely far away, and quite possibly beyond the cosmological…

A probability distribution describes how likely different outcomes are. It requires multiple observations or an assumed model that can represent variability.

Likely are also making a probabilistic independence assumption.

Re: Earth was born dry until a cosmic collision made it a blue planet

#205

Post by 3oil3 »

pinkmuffinere wrote: post #166
poly2it wrote: post #164

Earlier quoted context omitted.

What?

You heard the man! Monkey us from?

Hey that bit was for the lols, although it is quite valid to say, just missing plural and a comma. Innacurate in some ways -mainstream theory is not about coming from apes, rather is about sharing a, yet undiscovered, common ancestor. I mentionned the pigs because of promising advancement in organ transplantation, notably kidneys that reached a milesone recently, and I mentionned the hips because human hips and ape hips have an evolution-breaking distinction. I could go on and on, but let's wait for more science, it wouldn't surprise me that what knowledge we discovered and took for granted back then, when 80% of the world population did not know how to read, might be developped today.

Re: Earth was born dry until a cosmic collision made it a blue planet

#206

Post by 3oil3 »

poly2it wrote: post #164
3oil3 wrote: post #163

We humans are not from Earth, what more signs need those who can't see? Humans,from all the species, the unique without a natural habitat. Humans, can not live on this planet unless we all get together and start adapting the environment. Otherwise, we can only survive and it's not fun. We have to wear clothing, cut downn trees. We get ill and stuff. Monkey us from? We closer to the pigs and not just the hips.

What?

Yes.

Re: Earth was born dry until a cosmic collision made it a blue planet

#208

Post by nebula8804 »

shireboy wrote: post #4

This 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 recently became addicted to the SpaceSimsx and SimulaVerse. My takeaway is that so many just slight deviations can extinguish life on earth. I used to think of possibility of life in other worlds just in the lens of statistics. There are so many combinations and possibilities that it seems inevitable. But seeing just how perfectly aligned our solar system is makes me really reduce the probable number of chances of other habitable scenarios in my mind.

These channels helped me realize just how important all the planets in the solar system are to our continued existence. Its as if we have an entire family thats just perfect to make our existence possible. An entire family each one quietly doing their part without fanfare or credit.

What if we had 2 moons with half the mass?: Destruction [0]: https://www.youtube.com/shorts/v3xxaTkKGTQ

What if we moved Earth 5% further from the Sun?: Destruction [1]: https://www.youtube.com/shorts/g-na5x0Kldk

What if we dimmed the Sun by 1%: Destruction [2]: https://www.youtube.com/shorts/Cc3DRRJxhB8

What If We Delete the Biggest Planet from Our Solar System?: Destruction [3]: https://www.youtube.com/watch?v=kHJpIWoksKw

What If We Delete All Gas Giants Except Jupiter?: You guessed it...Destruction [4]: https://www.youtube.com/watch?v=Eg9fPNg00EE

Re: Earth was born dry until a cosmic collision made it a blue planet

#209

Post by runarberg »

pfdietz wrote: post #183
runarberg wrote: post #176

Earlier quoted context omitted.

Permanent exponential growth is very rare in nature, and even rarer in biological systems. What we observe as exponential growth is usually only a partial observation of a logistical curve or is missing a system collapse at the end of the curve. We have no reason to believe alien (or even human) civilization will continue to grow and expand forever. Heck even the human population curve has started to slow down and is…

It's rare in biological systems because it's terminated by running out of some resource. But you're saying galactic colonization would terminate without running out of new systems to colonize. There would be a slowdown due to geometric constraints -- only so many new systems adjacent the boundary of the colonized zone -- but that hardly solves your problem.

My speculation is that the size of space is an obvious geometric constraint which will limit the span of any civilizations almost immediately.

If we look at humans, we have both the space, technology, and the resources to expand even further on earth, yet our span only marginally larger then it was 10 000 years ago. We can have permanent settlements on Antarctica, floating on the ocean, etc. but we don’t. We can increase our population by another order of magnitude, but again, it looks like we won’t. This follows the same population dynamics as most other species on earth. I think aliens will be no different.

Re: Earth was born dry until a cosmic collision made it a blue planet

#210

Post by WalterBright »

nebula8804 wrote: post #208
shireboy wrote: post #4

This 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 recently became addicted to the SpaceSimsx and SimulaVerse. My takeaway is that so many just slight deviations can extinguish life on earth. I used to think of possibility of life in other worlds just in the lens of statistics. There are so many combinations and possibilities that it seems inevitable. But seeing just how perfectly aligned our solar system is makes me really reduce the probable number of chances of…

> perfectly aligned

No matter what the circumstances, live will evolve to perfectly match the conditions it is under. There are many species so perfectly adapted to their ecological niche, they are in great danger of extinction. Like peacocks, who are stuck in a local optimum with no way out.

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