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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 a
by shireboy 1y ago
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 hampering life.
- adverbly 1y agoNo kidding... This would probably resolve the Fermi paradox if proven true...
- OgsyedIE 1y agoUnless collisions like the article suggests are a statistical inevitability, that is.
- dotancohen 1y agoHydrogen is the most common element in the universe. So long as you have elemental oxygen, it will react with things and hydrogen is the thing it will react with the most. So having water is almost a given for any Star system. Additionally, protoplanet and cometary collisions are in fact statistically inevitable. The real question is if water can be delivered at a point after enough gravity has amassed to ensure the water stays there.
- jug 1y agoRight, that's the sticky point? The likelihood of a planet in the Goldilocks zone to be too hot in the early stage of stabilizing its chemistry that it requires seeding with "post-formation" chemistry? Is that likelihood close to 100%, or maybe not even near and we were just set up for a funny cosmic event.
- xbmcuser 1y agoYour assumption we need water for life to exist is in my opinion wrong. We only know Earth so assume that is what is needed for life to exist.
- yosefk 1y agoWhat's the chemistry of life without water? Do you refer to the promising Russian studies of life sustained by alcohol?
- joshuahedlund 1y agoThere is a hard limit on the number of atomic elements, and an even smaller limit on the number of soluble compounds that facilitate chemical reactions, and water is demonstrably both the best and the most common in the universe. So while it may be possible for life to exist without water, any alternatives should be reasonably expected to be even more rare than water-based life
- caymanjim 1y agoThere's a reason life is carbon-based, and it's not random. It's the only element that works, due to abundance; ability to form many bonds; bonds that are just durable enough but not too durable. There's plenty of sci-fi about silicon-based life, but that's infeasible fantasy. And no other elements have any hope. If you have carbon-based life, you need water as solvent and medium. It's a pretty safe assumption that all life requires water.
- marcosdumay 1y ago> due to abundance; ability to form many bonds; bonds that are just durable enough but not too durable Well, the thing is that all of those are environment-dependent. We do have data on a somewhat diverse set of environments, and it's enough to confirm what we knew about the flexibility of carbon. But it's not enough to disprove the alternatives.
- Animats 1y ago> There's plenty of sci-fi about silicon-based life, but that's infeasible fantasy. Right. Silicon dioxide is quartz. Longer analysis.[1] [1] https://www.the-ies.org/analysis/does-silicon-based-life-exist https://www.the-ies.org/analysis/does-silicon-based-life-exi...
- warent 1y ago
- frankohn 1y agoI 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.
- JamesLeonis 1y agoThe 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.
- mr_mitm 1y agoThe 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 https://en.wikipedia.org/wiki/Drake_equation#Equation It makes very few assumptions.
- crazygringo 1y agoI'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: https://en.wikipedia.org/wiki/Habitable_zone https://en.wikipedia.org/wiki/Habitable_zone
- HarHarVeryFunny 1y agoThe 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.
- pavlov 1y agoDo other galaxies matter here? A civilization would need to be incredibly powerful to be detectable from another galaxy.
- ben_w 1y agoAt the moment, rapid and massive expansion seems likely with tech only just on the horizon. Enough AI and robotics for an autonomous factory may be a mirage (such mirages have (metaphorically) happened before), but it seems like it's on the horizon. Even with relatively mundane growth assumptions, that can go from "species inventing writing" to "Dyson sphere completed, is now sending out seeds to every accessible galaxy" on significantly less than the timescale of light crossing a spiral galaxy's disk.
- kingkawn 1y agoCmon the number of hypothetical extrapolations based on no data in these statements is beyond superstition to something like delusion
- ben_w 1y agoIf I put citations into everything I write, I'd be a Wikipedia article, and people would still criticise the conclusions without reading any of them. But contrawise, I do have data, they're broadly categorised as "history", "biology", and "all the stuff cited by Stuart Armstrong that time".
- andrewflnr 1y agoI 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.
- sesm 1y agoYep, mega-impact is a classic example of an ad-hoc hypothesis. For example, Moon formation is much better explained by multi-impact hypothesis, which also requires less assumptions.
- andrewflnr 1y agoDang, I can't post anything in this thread without someone thinking I agree with them that science is BS. Giant impacts aren't actually surprising in an early solar system that hasn't hit steady state yet. If multiple impacts better explain all the evidence for Theia, including the weird patterns of isotopes and possible fragments deep in the mantle, that's news to me.
- II2II 1y agoMultiple 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).
- GWBullshit 1y agoSpeaking 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.
- ctrlp 1y agoThe likelihood of those criteria might be vastly different in a younger universe than in this one, no?
- quotemstr 1y agoPlanetary collisions happen all the time. All of Mercury, Venus, Earth, and Mars in our solar system had them. We can see their signatures in other solar systems too: see https://en.wikipedia.org/wiki/List_of_extrasolar_planetary_collisions https://en.wikipedia.org/wiki/List_of_extrasolar_planetary_c... Whatever the great filter is, it's not planetary-scale collisions during the accretion phase of solar system formation.
- kulahan 1y agoDon’t forget this can only happen once, really. You need it to be such a rare event that it doesn’t keep sanitizing the planet with repeated impacts, but one really perfect strike will bring what you need and allow life to form. The number of instances where this (something unreasonably unlikely) happened in our cosmological history is kinda surprisingly high. I’m absolutely convinced there’s no advanced life (and CERTAINLY no technological civilizations) outside of earth. One other example: we gained most of our adaptability, curiosity, and problem solving skills as very tiny mammals while dinos ruled the earth. The only way we ever took over the planet was thanks to an asteroid wiping out all those huge creatures. Suddenly, high adaptability and intelligence and resilience was what mattered, and being big and strong suddenly was a massive disadvantage. Our intelligence exploded largely because that extinction event removed almost all major predators, turning earth into a giant survival puzzle sandbox for mammals to grow in. Edit: our brains only grew big because it was the best means of survival - they’re crazy expensive, so without this “sandbox puzzle” effect, we probably never would’ve grown them.
- tastyfreeze 1y agoEarth has been struck by large comets many times killing the majority of life on the planet each time. In an early solar system it would be more frequent. Once a comet impacts there is one less comet out there. The solar system cleans up over time making impacts less likely over time.
- kulahan 1y agoThere isn’t that much of a difference in the number of comets in space across just 5 billion years.
- mkl 1y agoThere's not much difference between now and 3.5-3.8 billion years ago, but before that there were a lot more: https://en.wikipedia.org/wiki/Late_Heavy_Bombardment https://en.wikipedia.org/wiki/Late_Heavy_Bombardment
- 1y ago
- Animats 1y agoRight. It's discouraging. We now know that many stars have planets, and some of them are even in the Goldilocks zone. But if it takes a planetary collision to get water... And only one planetary collision, because each one wipes out essentially all life. Look at the rest of the solar system. Mars - almost no water. Luna - almost no water. Venus, maybe water[1], but as steam. Too close to the sun and too hot. [1] https://phys.org/news/2025-10-venus-clouds-reanalyzed.html https://phys.org/news/2025-10-venus-clouds-reanalyzed.html
- Kerrick 1y agoI find it incredibly encouraging. I fear aliens existing in sufficient enough quantity to find us more than I fear Earth being the only host to intelligent life until we escape it.
- Animats 1y agoProbably not the only host, but habitable planets are sparse. If Einstein was right and faster than light travel is impossible, the number of planets we can even talk to is not that large. There are only 94 stellar systems within twenty light years.
- nntwozz 1y agoThis also points to panspermia. "The hypothesis that life, in the form of “seeds” or spores, is distributed throughout the universe, traveling between planets, moons, and other bodies via space dust, asteroids, comets, and possibly even spacecraft." I want to think that the water contained life and not the barren earth.
- jcims 1y agoBit of a nit but the Drake equation is intended 'to estimate the number of active, communicative extraterrestrial civilizations in the Milky Way Galaxy' (from the Wikipedia entry for it). Nice thing is that you can drop a few terms to get to origin of life.
- 29athrowaway 1y agoMars is technically in the goldilocks zone of the solar system... but water on Mars boils at 0C or 32F due to low atmospheric pressure, which really sucks.
- renshijian 1y agoA brilliant summary! You've deepened the question from "Does a habitable planet exist?" to "Does a planet successfully complete the complex dynamics of life's origin?" The habitable zone is merely the ticket, while the conditions you mention are the truly demanding filters. Considering this, the probability of our existence truly seems miraculous
- gtowey 1y agoIf Mars contained significant amounts of water in its past as we suspect, that would mean we have n=2 just in our own solar system.
- shaky-carrousel 1y agoNot so much, because both Venus and Mars also have water. So whatever gave Earth water is common enough to also give it to the other inner planets.
- mensetmanusman 1y agoThe Drake equation is whatever math leads to Earth being the only planet with intelligent matter out of infinity planets.
- nebula8804 1y agoI 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 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 https://www.youtube.com/shorts/g-na5x0Kldk What if we dimmed the Sun by 1%: Destruction [2]: https://www.youtube.com/shorts/Cc3DRRJxhB8 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 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 https://www.youtube.com/watch?v=Eg9fPNg00EE
- WalterBright 1y ago> 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.
- snorbleck 1y agoCould a tardigrade withstand these scenarios? If the answer to any of those is yes, could we then say that even with the parameters skewed a bit, there is a chance life exists elsewhere, and under completely different and extreme or (not "normal") conditions? Is the tardigrade here as a "clue" to tell us that life could form potentially anywhere?
- javier2 1y ago
- WalterBright 1y agoEspecially in the context of this, I am baffled by people who go to great lengths to prevent life from Earth arriving on other solar system bodies. Such as all the efforts to sterilize the probes.
- dleeftink 1y agoHistorically to prevent pre-contamination and erroneous biosignature readings. This may ease once we have some solid pointers or confidence there may be none (caution is likely warranted due to the gravity of such a discovery).
- WalterBright 1y agoBut we also lose opportunity. Consider Mars. Endless probes for 50 years going to Mars looking for life. No clue of life has ever been found. At what point do we face the fact that Mars is a dead rock? What we should be doing is collecting samples of extremophiles from the Earth, and attaching a few packets of them to every probe going to Mars, and see what happens. Probably nothing will happen, but it's worth a try.