But, yeah, political implications nowadays are a slippery slope.
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
It's a pretty safe assumption that all life requires water.
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.
Right. Silicon dioxide is quartz.
Longer analysis.[1]
[1] https://www.the-ies.org/analysis/does-silicon-based-life-exi...
I for one remember reading about possible silicon/methane based life, etc. Actually, here’s a whole wikipedia article on what you’re talking about.
https://en.m.wikipedia.org/wiki/Hypothetical_types_of_bioche...
Perhaps HN folks will lose your scent now and direct their snark there
https://en.wikipedia.org/wiki/The_Devil_in_the_Dark
https://lweb.cfa.harvard.edu/~ejchaisson/cosmic_evolution/do...
2. joshuahedlund’s reply: Grounds the argument in chemistry and probability.
There are only ~90 stable elements → a finite combinatorial chemistry space.
Among possible solvents, water is the most abundant and chemically versatile (dipolar, wide liquid range, high heat capacity, good at dissolving ions and organics). → So even if other solvents can work (like ammonia, methane, formamide), the odds heavily favor water-based life.
3. caymanjim’s addition: Brings in carbon’s unique valence behavior:
4 valence electrons → can form stable, complex chains and rings.
Bonds are strong but not too strong → dynamic yet stable biochemistry.
Silicon (next best candidate) forms brittle, static lattices and poorly soluble oxides → bad for metabolism. → Therefore: if life is carbon-based, water is the only sensible solvent.
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.
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.
As a reminder, this is the equation: https://en.wikipedia.org/wiki/Drake_equation#Equation
It makes very few assumptions.
> 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:
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 point.
fi = the fraction of planets with life that go on to develop intelligent life (civilizations).
fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space.
L = the length of time for which such civilizations release detectable signals into space.
Edit: the parent post has been edited substantially after I replied.
They are "defined" conceptually, in words, not in physical quantities. It assumes we can assign a known value to any of that when we don't and likely never will. It's like saying "Let X answer the unanswerable question. X is the answer".
> at no point does it assume a planet must be in the Goldilocks zone
You could say it implies it with fl.
> Edit: the parent post has been edited substantially after I replied.
Only for legibility.
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.
Rick Sanchez uses a microverse battery
https://annas-archive.org/md5/4c381ac344506d10037fc8e7747098...
The cheela lived on the surface of a neutron star, and they lived faster because the nuclear physics that powered their metabolism are far faster than the chemical and mechanical physics that power our own.
Anyway, sounds interesting, gunna add that to my list
Also Macbeth was written 400 years ago. Let's not pretend this is a fair comparison. This author has been dead only 20 years - it might be that their partner is still alive and needs that money, or their children.
Amazon is hanging on by a thread, and piracy is stealing their cut.
Anyway, what is copyright expiration in America these days? 100 years?
Also, is it simply a matter of X years after creation? I somehow doubt it's that simple anymore. I wouldn't be surprised if "copyright is extended indefinitely if the work is being actively commercially used" or some such
Which is saner eh! That way people living at the time who are protecting it (copyright and patents are both protections for things otherwise being distributed and which could be copied easily) can benefit from it eventually.
100 years is just rent extraction.
We need more discussion about copyright in our society, and we need it most in front of those who are unaware, inattentive, or would otherwise shirk that discussion. Posting a relevant link in a relevant discussion appears as good an avenue as any to get people talking.
That's a rather severe escalation to me.
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 horizon and forever unreachable."
It's nowhere near a precise estimate of the probability of life. What it mainly shows is that the Fermi "paradox" is no such thing. It can look that way if we guess specific parameter values, but if we fully account for our uncertainty on the various parameters, then the result is a decent chance that we are alone, given the knowledge we have so far.
You can’t have a distribution with one data point.
It’s similar to the arguments about 3I/Atlas being an alien spacecraft because it’s so ‘weird’.
With so few data points, everything is fundamentally ‘weird’ - or normal - we have no way to tell, so making any sort of statistical argument about it is fundamentally useless and misleading, as statistics is based on groups. And we don’t have a group yet.
One of the most uncertain parameters is the rate of abiogenesis events per planet. For that one they used a log-normal with a standard deviation of 50 orders of magnitude. They discuss specific theoretical limits from biology for both ends of the range.
Compared to this approach, the usual method is to just pick particular values out of a hat. This paper at least improves that by directly representing our vast uncertainty for some of the values.
It doesn't tell us how many alien civilizations there are. But it does tell us the range of possibilities, given what we know and don't know.
Life, once established, is about competition for niche resources. Established life would kick the polypeptides out of a protocell quite easily (with certainty > 99%).
Protocells could be evolving right now at vents in the ocean, with zero of them managing to escape their birthplace due to being outcompeted by things with fully developed organelles.
If you're willing to concede that in fact, that doesn't happen, then you're putting a limit on that parameter, just like the paper did.
The underlying model is just:
N*f
How many planets are there, and what proportion of them have detectable life?
The f does not have to be structured as fl->fi->fc, although we can see why you'd assume that kind of structure. It's simple to calculate the PI(series) when the model is just a funnel. Like the Million Dollar Money Drop gameshow.
But you could imagine a more complex model of probabilities that branches and merges. There could be events on the bayesian tree that amplify downstream events. For instance, suppose there is some pathway that if reached will leave certain minerals that future civilizations could use. This has happened already on earth at least once: lignin bearing plants could not be easily digested for a long time, and that led to coal formation during the carboniferous period.
You could imagine many such potential trees, but we only have one iteration.
With sublight velocities achievable today, I recall it would only take around a million years for a Von Newmann probe to cover the entire galaxy. Such a probe is quite conceivable, so why isn't there more evidence of such probes everywhere?
Another point I feel is that proliferation of life should be an self-reinforcing affair, for intelligent life even more so. A spacefaring nation may terraform or just seed planets, and these in time will replicate similar behaviors. At a certain point, a galaxy teeming with life should be very hard to reverse given all the activity. A life itself isn't necessarily evolved from biology, AI machine lifeforms should also well suited to proliferate, yet we don't see them anyways.
Time, not space, is your answer here.
Two reasons -
(1) civilizations might not survive long enough to do this.
(2) 13 billion years is a long time. So you have the reciprocal of that as the chances to be in the right year to see such a probe. And with results from the new telescope we now have hints that the 13 billion number is bogus, the universe is likely far older.
What are the incentives to build and deploy such a thing though? We as a civilization fail to fund things that have a ROI of more than a few years, how are you going to fund something that pays off after a million year?
Consider that in some countries on Earth, we can't even get consensus that obtaining energy directly from the Sun via solar panels is a good idea.
First of all it's going to be massively more expensive than any housing we've ever built on earth so only a very small elite could afford living there.
But then again, space is a very hostile environment: it's super dangerous (any incident will almost certainly snowball into a dramatic accident), very unhealthy (billionaires are currently funding longevity research, so I don't think they'd like to go in a place where they would age up significantly faster than on earth…), and life is just worse up there on all respect…
"Extremely improbable" would be a better assessment.
Even ignoring the project complexity, difficulty, and energy budget, which can't simply be handwaved away by "robotic automation", one reason is simply that such colonies don't solve any problem that we're likely to have, that can't be solved much more cheaply, safely, and effectively.
But even the idea that we'll eventually have the technology to build such structures is debatable. Will this be before or after we solve climate change, for example? Because that issue is likely to severely impact our technological capabilities over the timescales involved. And as of today, the most technologically advanced nation is doubling down on atmospheric carbon production.
The fundamental problem with the Drake equation is that it's frequentist, not Bayesian
Hence why you get too high sensitivity to parameters you have no way of having an estimate with a small margin of error
We "don't care" about how many civilisations are out there, we care to the point where we can interact with them.
As mentioned, it has several assumptions. "Rate of birth of sun like stars" means nothing. You can "always" have an exception for life that will throw the data off: "star too bright but with a hot Jupiter tidally locked in front of your moon, shielding it" etc
It seems unlikely that such exceptions would amount to more than part of a reasonable margin of error.
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.
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.
But contrawise, I do have data, they're broadly categorised as "history", "biology", and "all the stuff cited by Stuart Armstrong that time".
What’s the probability that a radio-capable civilization becomes a galactic type 3 one? Looking at the only example we have, it appears very unlikely. It seems much more probable that we’ll destroy ourselves within the next centuries.
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 without exception. And those that do the colonization will seed additional colonies with a mindset that led to colonization; such mindsets will be selected for for further expansion.
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 now revealing it self to be a logistical curve.
But regardless of this, space is very very very big. And there are a lot of extremely hostile worlds out there. Any civilization will experience biological limitation to which worlds they can (and will want to) colonize. Likewise they will experience both economical and physical limitations to how far they will send their machines. Lets say an alien species is lucky and has a habitable world inside their solar system which they will colonize. I think this is likely. They also spot another world in a nearby solar system which takes them 200 years to travel to, eager colonists travel in a generational ship, and 600 years later the colony is thriving. Now they run out of nearby habitable worlds. There is a world of questionable quality 500 years away and they are unable to persuade enough people to fill a generational ship. Also they learned the stories of the passengers in the generational ship, their lives kind of sucked, we have it much better on this world. So it is better to just stay here. This might happen after 1 or 100 successful colonizations, but I think space is so freaking large, it will happen to all civilizations. At some point they will run out of worlds to colonize, and they will never expand far outside of some local area near their home world.
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.
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.
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.
I also think fast space travel (like 0.1c) is rare among civilizations, and may only happen in the order of hundreds of time in the history of some civilizations. And most of these fast space travel will scientific instruments for curiosity and exploration, not for colonization. And that a technologically advanced civilization would favor doing their explorations with telescopes, not probes. So probes would only be sent long distance for rare occasions.
This would mean that almost no civilizations will be expand beyond their solar system, and those that do, will only do it a handful of times, and the expansion will finally stop.
Especially once you reach the “hundreds” level then given the technology exists and the people exist why would it stop, until there’s nowhere else to go.
There is the light cage issue where a civilisation can only spread so far with exponential growth before internal pressures overwhelm it (the leading edge never gets a chance to continue as it is overwhelmed by trailing edges)
Even in that situation though you’d still have self replicating probes - likely at a far lower tech level than biological. Once you reach the tech to send one probe which can duplicate itself more than once using resources in a new system then its game over.
Send 50 probes to each of the 50 stars within 15 light years at 0.01c. If 10% make it they then use local materials and send 50 more, that’s 250 out in 1500 years. Then it’s 1250 out in 3000 years. Within a few millennia years you’ve got millions of probes spreading in an unstoppable way. The ones heading back “inwards” will fail, but those heading outwards will reach each new star dozens of times, only one will need to get there. Within 10 million years you’ve reached the entire galaxy.
To stop it you’d have to make a self replicating probe which was faster and did exactly the same thing and caught the earlier probe, but then when would that probe itself stop, it would have no way of knowing if there were any other “bad” probes to find without becoming the bad probe itself.
Living beings are the same. Once a few dozen have made it and passed on, it’s inevitable it will continue. It may leave out a hollowed husk in the origin point with all resources having being consumed in the centre, but that doesn’t matter as the centre has no way of affecting what happens on the edge, and one edge has no way of affecting another edge.
I think you may be expecting an exponential growth when population dynamics almost always favor logistical growth. At some point your machines, or your colonial behavior hits a limit and your growth starts to slow down. I suspect that limit is within the solar system for the vast vast vast majority of civilization. And even if one escapes their own solar system and starts anew on a new home world, they most likely will not colonize another. The space is just so big, and habitable worlds so far away from each other that I find it extremely improbable that any civilization (and their ancestor civilization) will survive more than 5-6 colonization (by far most will see 0).
> Living beings are the same.
They are not. You are describing living beings like viruses (fair enough; viruses are worthy to be considered lifeforms) that spread from host to host until they infect everybody. But viruses don‘t behave like that. The vast majority of them only infect their closest neighbors, and those that do spread towards the limit of all members of the species (like Covid) still fall short and eventually start to slow down their spread in a logistical manner. Growth only looks exponential while you are at the initial stages of spread. This behavior is not only common among viruses, but in fact most population dynamics can be described with logistical growth.
Well pack it up folks, we've been told what would be possible for any alien civilization, even given millions of years of effort.
The only argument for von Neumann probes that I can think of is as a specific answer to the Fermi paradox. The universe should be filled with these probes, but since it obviously isn’t, we can infer that no civilization has reach the interstellar age.
I reject this framing, the Fermi paradox is only a paradox if you assume that space colonization is a thing that is not just possible, but inevitable. My solution to the Fermi paradox simply rejects this assumption. Civilization will not colonize definitely, they will do their space explorations with telescopes and targeted probes, and they won‘t build any von Neumann probes (at least not ones continue to replicate for dozens millennia).
Aside: I am aware of the irony that my description of civilizations outside of our solar system is also a fantasy.
In either case it's a statistical question of how common is life, and intelligent life, but of course there's the human interest in potential contact with another intelligent life form.
But numbers can go arbitrarily low.
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 eyes, having actual energetic gasses on land...
Maybe life is easy, but intelligence is hard. Maybe civilization is hard.
Maybe technology development can only happen on dry land, because aqueous chemistry is hard in water. Sorry mollusks and cetaceans: you'll probably never be able to do chemistry or materials science.
Maybe you need water and carbon and other chemistries aren't robust enough.
Maybe you need lots of fossil fuel deposits to develop industry. And that requires growth without bacteria and decomposers for millions of years, implying a certain order to evolution.
Maybe you need a certain sized gravity well to escape.
Maybe surviving the great filter is hard and still ahead of us. Maybe every species can build tech where a kid in their garage can extinct the entire species by 3d printing grey goo.
There's just so much we don't know about how life could happen. Let alone intelligent life. We don't even know where we're headed.
This forced some apes to climb down the trees and depend on a diet of scavenging for meat, which happened to both increase brain size AND require improved intellect to survive, forcing the evolution of our hypertrophied symbolic brain.
Had this not happened however, other intelligent species could have filled the niche. There's no shortage of other intelligent species in our planet, not just other mammals but octopus and some birds. And then you get hive intelligence, which could equally be forced to evolve into a high problem-solving organism.
[0] Unless that episode of Voyager was right on the mark https://memory-alpha.fandom.com/wiki/Distant_Origin_(episode...
I suspect that any evolutionary environment will eventually create enough variety and instability that some generalists emerge, creating a reward for intelligence. The rise in intelligence from early water-bound life to later forms was likely all driven by more complex and diverse environments.
Basically I fear we’re the universe’s only shot of appreciating and populating the galaxy (or beyond) and we’re on the brink of throwing that away.
On the flip side, that could also be plausibly a blessing, avoiding them to fall into the same trap of becoming too powerful before they get wise. These comics illustrate it: https://www.badspacecomics.com/post/grounded
Having coal/oil is pretty irrelevant in terms of whether a civilization can build spacecraft.
Successor. Whoever comes along after we've done ourselves in.
There will be no successor civilization to humans. Earth won't be able to support multicellular life in a few hundred million years due to the sun becoming gradually more luminous over time, resulting in higher surface temperatures that will eventually culminate in a runaway greenhouse happening, as it already has on Venus. Due to human-driven climate change effects this event will certainly happen much sooner (<100m years) as well, which is simply not enough time for another intelligent species to evolve after a large-scale extinction event.
Even if life evolving on earth was an incredibly rare event the chance of such circumstances not happening elsewhere even in our own galaxy is infinitely small - there are trillions of planets and 100b+ stars. On top of that there are 100s of billions of galaxies within the observable universe as well.
No, it will not. Human driven climate change is drastic, but the Earth has seen far worse events than our anthropogenic carbon emissions. For instance, the Chicxulub impactor at the end of the Cretaceous changed atmospheric conditions overnight, and to a much greater degree than whatever we have cooked up. It was the equivalent of detonating the world's entire nuclear arsenal about a million times over.
Sure, it finished off the dinosaurs. But 66 million years later, we, the descendants of tiny rodent-like mammals, are still here, as are the dinosaur's own descendants, the birds.
Additionally, during the Carboniferous about 300 Mya, both carbon dioxide and oxygen levels were considerably higher than they are today, and life actually thrived. I would say that with the increasing luminosity, there will be at least a decent period on Earth where life returns to that sort of diversity. We are actually still only in an interglacial of an ice age—this has effectively sterilised large tracts of our planet by covering them with ice sheets, or locking permafrost into the soil and making them unavailable for large trees.
Let me be very clear: our emissions—if unchecked—will make life very difficult for us as the rising seas and temperatures scatter millions of people out of coastal cities in the tropics further north and south and cause war, division, strife, and discord like we have never yet seen. But actually bring forward the planet's overall demise? Nearly impossible.
Let's not have the hubris to think we puny humans could remotely affect the planet's geological timeline. If we somehow all disappear simultaneously, most direct evidence that we ever lived will disappear with us–perhaps within a hundred thousand to a million years of erosion and weathering. Our emissions will similarly lurch to a halt and will reach equilibrium within a similar time span. That's all it takes to remove our direct creations from the geological record.
Modern humans have only been around for < 1 millions years, and all the technology we have invented is incredibly recent. 200 years ago we had neither electric light or bicycles.
Over the course of 100s of millions of years, as the sun's increasing luminosity becomes an issue, I'd have to assume we could create some sort of atmospheric solar shield to reflect or absorb a lot of the energy. Of course you can only postpone the inevitable (red giant).
Assuming the evolutionary lineage of our species survives a few hundred more million years (which seems rather doubtful), then it's not going to be homo sapiens any more - we'll have evolved into successor species that may be barely recognizable. If you go BACK in time 100M years, our ancestor was some mouse-like animal.
Intelligence has evolved three times independently on earth - dinosaurs/birds (raptors, covids), mammals, and cephalopods (Octopus)
> Maybe you need water and carbon
Maybe so, but Oxygen and Carbon are only behind (albeit far behind) Hydrogen and Helium as the most abundant elements in the universe
Which begs the question, why 1, and not zero? I can buy zero, or a very large number. But 1 exactly? Nature doesn’t do that.
But in seriousness, I agree.
I doubt water (H2O) is actually that rare. The most common elements by far, both in our own galaxy and the universe as a whole, are Hydrogen and Helium, but the next two most common are Oxygen and Carbon.
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).
Right, which is why it's baffling to me that everyone in this thread seems to be losing their mind over this result, thinking it affects the Drake equation and rewrites solar system dynamics. The multiple impacts thing might not have actually happened to earth, but there's still no reason to believe it wouldn't work.
If you appreciate technical things, you'd be in for a treat.
Whatever the great filter is, it's not planetary-scale collisions during the accretion phase of solar system formation.
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.
Maybe it was just being small, puny, and having a tendency to cower in burrows was what saved us. Our ancestors may not have been much smarter than squirrels, and squirrels aren’t very bright.
Hominids brains didn’t get big until long, long after the KT extinction. A Tigers brain is not that much smaller than that of an an Australopithecus.
It may be more correct to say that growing a larger brain (larger than a lizard’s, I mean) was only realistically possible because of the sudden loss of predators.
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
"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.
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
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.
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.
(Also Mars could have been also hit.)
(As is the claim from the article)
The article doesn't say no planets can have water, but just that originally Earth was too close to the Sun to have liquid water. Theia, according to this hypothesis, was not.
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.
https://www.goodreads.com/book/show/939760.Music_of_Many_Sph...
I recommend folks read it in reverse chronological order, starting at the back, then working to the front and bailing when things get too quaint/old-school/golden-age.
https://en.wikipedia.org/wiki/The_Fermi_Paradox_Is_Our_Busin...
https://www.tor.com/2010/08/11/the-fermi-paradox-is-our-busi...
So the angular size has matched the Sun only for 450 million years.
In 50 million years it's angular size will be smaller and total solar eclipses will be impossible.
Note: Due to the Moon's orbit, the whole story is more complicated.
It's the weirdest filter: you need a giant sign that points you where to look for answers. Without it, you're less likely to find what the universe is all about.
The Earth has a nearly perfect circular orbit. Any collision with another planet would have pushed it off its orbit and caused it to at the very least created a more elliptical orbit that likely would have made the swings in temperature more deadly for life on Earth.
This entire article is science fiction.
It's also ignoring the fact that we likely did have additional planets, but after interactions with other planets with nearby orbits, they would have been either ejected out of the solar system entirely, caused to collide, or herded into more circular (non-overlapping) orbits.
This is why Pluto is not a planet.
The reason is that it was observed "too soon" because of its interaction with Neptune's orbit. Once we realized there were plenty of such objects in the range of Neptune's orbit but we also realized that these were not fully formed planets, we invented the term of dwarf planet, so Pluto was demoted to that status, which it shares with many other objects in the far out orbit.
So, it was just a classification thing. We could have also said all those others are also planets.
How can it be science fiction if most scientists currently believe this?
[0] https://en.wikipedia.org/wiki/Giant-impact_hypothesis#Possib...
Let me give you a pro life tip. When someone comes up with an extraordinarily complicated scenario or hypothesis and it can’t answer a very simple straightforward question, it most certainly means that the the hypothesis is wrong.
It’s all science fiction.
Sure, there are still questions. But the questions for all the other explanations of the Moon's origin at even bigger. You can be skeptical, but until you have a better theory that accounts for all the evidence, you don't get to dismiss it as "science fiction". Not if you want to be taken seriously anyway.
Here's a life pro tip: The correct guideline for a theory is "as simple as possible and no simpler. The real world is complicated. Complicated things happen all the time.
There is a lot of evidence of a big collision, but that's a very good question anyway!
I guess the interactions with other planets and asteroids change the orbit to a more circular one. I couldn't find a serious source that confirm, and not even a non-serious, so I'm still curious, very curious.
Anyway, there is a good theory that Jupiter formed at 3 AU and moved later to 5 AU and (very slowly) caused havoc in all the outer solar system https://en.wikipedia.org/wiki/Formation_and_evolution_of_the... So the initial orbits are not fixed in stone.
https://www.bnl.gov/newsroom/news.php?a=111648
I wonder how this ties in with the submitted link about Theia. And it will be interesting if we ever get similar trapped water discovered in martian rock.
https://www.newscientist.com/article/2400567-bits-of-an-anci...
(I'm not saying the article is wrong, just trying to understand.)
(But yes, Venus is hard to satisfactorily explain, regardless of whether you accept the article's conclusions at face value.)
Venus doesn't have liquid water, which is needed for the reaction of silicates with CO2 ("weathering"). Without that reaction, CO2 just accumulates in the atmosphere. Most of the carbon on Earth (and there's a lot) is locked up in rocks.
There's also a biological effect. Here on Earth, silica in the ocean is scrubbed out by microorganisms that create silica shells; these tiny shells fall out into sediments, where (in deep ocean) they eventually form a kind of biogenic rock called "chert". Elsewhere, typically in shallow water, carbonate rocks are formed from the remains of other kinds of animals. Without these effects, the dissolved silicon concentration in seawater would be orders of magnitude higher, and the silica would react to form clays. This reaction would acidify the ocean and prevent carbonate formation.
Just such "reverse weathering" has been hypothesized to occur after the Permian-Triassic boundary, where CO2 levels stayed elevated for 5 million years. The extinction event was so severe it disrupted chert formation (a "chert gap").
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 released.
(The real questions are "Why does Ganymede not have an atmosphere?" and "What's up with Venus, really?")
* that the planetesimals that formed Earth had the same orbital characteristics (notably eccentricity), rather than being averaged out.
* that planetesimals formed from dust in largely the same manner as planets form from planetesimals
>Our Solar System formed around 4,568 million years ago. Considering that it only took up to 3 million years to determine the chemical properties of the Earth
sounds suspiciously precise. You'd imaging the proto Earth would have formed gradually over millions of years from rocks and dust merging rather than suddenly there 4,568 m years ago and then shortly after crashed into?
> "...this is surprisingly fast," says first author Kruttasch.
So they don't entirely disagree that it's weird.
But why are you replying to me with a quote from the article I already called a mess? Try your hand at the paper if you want real answers. :D Like I said, tough going, but they sure seem to think they have the sigfigs to back it up.
It's that. Just one more in a long line of wild-eyed 'the Earth collided with' theories.
> Scientists have shown that Earth’s basic chemistry solidified within just three million years ...
They haven't 'shown' anything. They may have evidence to support part of one model ... if they can demonstrate that a Theia probably existed in the first place.
Try to read it? Thick going. https://www.science.org/doi/10.1126/sciadv.adw1280. Quoting from that:
"Today’s element abundances of the BSE and isotope constraints strongly suggest that the bulk Earth comprises ~90% PE, ~10% Theia, and ~0.4% late veneer material... Other models suggest that Earth formed from ~60% PE and ~40% Theia ..."
>a later collision with Theia likely delivered the water
Etc. If water was so hard to get ... where in the hell did this hypothetical, no evidence 'likely' get the water it 'delivered'?
They're not here to "demonstrate" the Theia impact theory, because there's already tons of other work doing that.
How Earth Got Its Water: A Cosmic Detective Story
The Big Question: How did Earth become a planet with oceans and life, when it formed so close to the hot Sun?
What Scientists Did:
- They used a "radioactive clock" made from two elements: manganese and chromium - Manganese-53 breaks down into chromium-53 over time (like ice melting at a steady rate) - By measuring these elements in meteorites and Earth rocks, they figured out WHEN Earth's basic chemistry was locked in
Key Finding: Earth's chemical recipe was set within just 3 million years after the Solar System formed (that's super fast in space terms!)
The Problem: At that point, early Earth was missing the ingredients for life—especially water, carbon, and other "volatile elements" (stuff that evaporates easily when hot)
Why Earth Was Dry: Close to the Sun, it was too hot for water and other volatile stuff to stick to the rocks that built Earth—they stayed as gas and floated away
The Solution: About 70 million years later, another planet called Theia (which formed farther from the Sun where it was cooler) crashed into Earth:
This collision created our Moon It also delivered water and other life-essential ingredients to Earth
The Big Takeaway: Earth needed a cosmic accident to become livable. Without that lucky collision bringing water from the outer Solar System, we wouldn't be here!
Why This Matters: If Earth needed such specific, lucky events to support life, habitable planets like ours might be much rarer in the universe than we thought.
We don't. It's usually within a range. My illustrated book shows the timeline with more context and detail. Note that the events are provided on a timeline with some uncertainty (e.g., ± 1 million years):
Btw your book is AMAZING!
The resulting radiation pressure clears out the debris from the solar system’s accretion disk, and this process surely is not instantaneous but is relatively fast.
[edit, benefiting from convo: mechanisms on atmospheric escape, to varying degrees of verification)
• https://en.wikipedia.org/wiki/Atmospheric_escape
• https://en.wikipedia.org/wiki/Hydrodynamic_escape ]
Absent that, our treasured atmospheric molecules would have to autonomousy achieve escape velocity, some 22 km/sec , with no outside assistance. A difficult feat. And so, resident atmosphere.
https://en.wikipedia.org/wiki/Atmospheric_escape
https://en.wikipedia.org/wiki/Hydrodynamic_escape
As a layperson I see our current epistemological state as long on models, and short on empirical verification (because we're talking about a difficult phenomenon to verify).
I think I mostly wanted to offer counterpoint to the original comment that 'this atmosphere can't stay long' i.e. even under elevated temperatures.
(I'll probably update my prev comment with those wikipedia links.)
Today years old on learning that 'carbon' is a 'volatile element'. (I come to learn that astrogeology has a unique definition of volatile).
• The summary's own source article points makes no reference to carbon being volatile.
• The wikipedia article for 'volatiles' in the astrogeological sense makes no reference to carbon being volatile https://en.wikipedia.org/wiki/Volatile_(astrogeology) . Similarly, the wikipedia article for 'refractory', posed as the astrogeological opposite of volatile, does not place carbon at all in the spectrum of volatile to refractory.
• Contra: at least two papers do refer to carbon being a volatile element. https://www.nature.com/articles/s41586-022-05276-x and https://arxiv.org/abs/2311.18262
[shrug]
https://sentinelmission.org/astrophysics-glossary/metallicit...
What is thought to be likely is used to frame conventional wisdom as truth, making the new viewpoint "extraordinary, until, over and over again, the new viewpoint becomes conventional wisdom. So "extraordinarily improbable" is really just an overton window framing (what we accept/don't accept), rather than a statement based in logic. Though your overall framing reminds me so much of historical phrases that I wonder if you are being intentionally ironic.
Just out of curiosity: you do realise that illness is not specific to humans, but also occurs in animals, right?
Exoplanet surveys that I've seen in popular press can see rocky, dry planets. I'm not sure if that's just a selection bias in our current technology or if Earth with ocean and atmosphere is relatively rare.
alexey-salmin•4mo ago
rd07•4mo ago