New evidence suggests giant asteroid impacts created Earth’s continents
singularityhub.com
singularityhub.com
I think that intro sentence is implying a lot more than the paper it cites is stating.
Paper cited: https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/GL01...
We see magnetic fields this strong on gas giants, but not on inner planets. I wonder too if we will find that some asteroid impacts and the formation of the moon didn’t goose up the magnetic flux of the core while they were at it. Maybe habitable zones only appear on tortured worlds, like earth and some of the moons of a Jupiter, because normal planets are just too boring, don’t have enough building blocks for life.
That's 10^22 opportunities to get it right. We can't possibly be alone.
Also, the numbers above are based on the observable universe. We have no idea how big the universe is outside that region. It could be infinitely large.
And in fact, you can conclude nothing from your own existence. Observer selection bias.
10^21, 10^22 and 10^23... Whichever number, the point that the parent poster was making doesn't change at all.
>You are implicitly assuming a probability that life can arise.
What are you suggesting? We're all actually not alive? Come on.
Why anger? And will you expand on why this is utter bullshit? In what way does probability not work this way? You are making strong assertions without expanding on why you believe those assertions.
Your assertion also goes against some pretty big names in the field; not that big names are automatically trustworthy, but they do seem to carry more weight than a random HN comment (no offense).
The SETI people making this busted argument are implicitly assuming p, the chance that life arises on a suitable world, is not "too small". And there is no basis for making that assumption.
That is not mathematically rigorous, but it is, from the Bayesian perspective, enough to move the needle.
That is obviously false; zero observations will never cause a Bayesian adjustment.
The argument is generally that scale and probability favor the existence of intelligent life, assuming Earth is not somehow exceptional in the universe.
Assuming Earth is exceptional seems just as problematic.
Welcome to the Fermi paradox.
Why are you holding p fixed and allowing N to increase? You are implicitly assuming N is in that regime where N > 1/p. That's just assuming p > 1/N, and there's no good reason to make that assumption.
The comment that started this thread: "That's 10^22 opportunities to get it right. We can't possibly be alone."
Edit: See https://en.m.wikipedia.org/wiki/Earth
*for humans
I'm supposed to believe the planet's alpha predators willing make themselves subservient to smaller, but more furry beta predators?
So how rare are true earth like planets does matter a lot.
Put it another away, all it takes is about four one-in-a-million chance independent events (or filters) and you're left with Earth being the only planet with life in the observable universe.
This presupposes life can only exist on a planet with several exact characteristics that we have on Earth. Given life on Earth exists quite nearly in every environment that exists, it could be expected that despite significant filters, there is room for several variations which enable life even if quite different.
If you look at the history of earth, there have been several filters that very nearly wiped out intelligent life.
Further, we needed a few extinction events just to have a world where our intelligent life could reach the point of developing science. We wouldn't, for example, have been able to thrive in the Jurassic period. There were simply far too many predators to keep us from doing anything more than hiding in caves and trees.
Then if you look at the evolution of humanity, we very nearly went extinct a couple of times. We were estimated to have been whittled down to 10000 citizens at one point. [1]
Evolution, it seems, doesn't necessarily select for intelligence. It selects for better killers and better hiders. Being smarter than the predators doesn't immediately grant enough benefit. If it did, we'd probably not be the only intelligent species to ever exist.
[1] https://www.npr.org/sections/krulwich/2012/10/22/163397584/h...
What an incredible waste.
It seems to me that the odds of encountering other life forms are vanishingly small, simply because of the scale of the universe, combined with the low odds of finding other life forms. Sure, it might happen, but we're alone until we're not. And we're incredibly likely to remain alone for a very long time.
If never, why is that not a possible future?
There's two scales you can change, yourself, and the tools you use to interact. So how fast can you make a spaceship competes with how long you can make your life.
Time is short. You cannot imagine how vanishingly, briefly, disappointingly short it is. I mean, you might think you have all the time in the world, but to the universe, you're a fraction of a gnat's wingbeat.
I’m not sure how true that is, and reflects a somewhat older view. There was a lot of cooperation involved, particularly in regards to symbiogensis, which the older generation still opposes.
https://en.wikipedia.org/wiki/Symbiogenesis
> In her 1981 work Symbiosis in Cell Evolution [Margulis] argued that eukaryotic cells originated as communities of interacting entities, including endosymbiotic spirochaetes that developed into eukaryotic flagella and cilia. This last idea has not received much acceptance, because flagella lack DNA and do not show ultrastructural similarities to bacteria or to archaea (see also: Evolution of flagella and Prokaryotic cytoskeleton). According to Margulis and Dorion Sagan, "Life did not take over the globe by combat, but by networking"…
This is what I am talking about. This perhaps predates even symbiogenesis or perhaps drove it. Anaerobic lineages died out in the oxygen rich environment that the first forms of photosynthetic life created. Cellular respiration using oxygen, as animals do, probably evolved after the atmosphere was already oxygen rich. There is a huge fitness advantage if you cannot make use of light energy, but can absorb cells that can and maintain them as photosynthetic eukaryotes do today through symbiosis of the cyanobacteria that became cloroplasts.
What I like about this example are the parallels to modern times. The great oxidation event was an extinction event brought on not by external factors, but by a life form producing gas that changes the composition of the atmosphere and leads to dramatic effects across the planet. Not unlike us humans today with our CO2 production.
Traveling with a 1G acceleration for a 100 years could take you to the edge of the universe, though billions of years would pass on earth.
https://en.wikipedia.org/wiki/Space_travel_under_constant_ac...
The universe hasn't always been a habitable place. It's been hotter and more chaotic; life may have arisen and become extinct due to radiation or cosmic-scale collisions a billion times on a million worlds over the universe's early history. We don't know exactly where the lines are, but we're fairly certain at this point that the universe is not static in time and it has had a less habitable period and will probably have a less habitable period again.
We also don't know what the prospects are for long-term life in environments like galactic cores. Of the hundred billion galaxies we've observed so far, maybe only the tiniest fraction of them are capable of supporting life in the long term -- recall, it has taken Earth 4.5 billion years to produce us! -- and of those that are capable of supporting life, perhaps they can only support life out on their edges.
These amount to some pretty significant polynomials added to the Drake Equation, and they can attenuate the result a lot.
But let's imagine the AI swarm, the most popular rebuttal to the unforgiving conditions of time and space. Let's imagine that one arose a billion years ago, and it happened right next door in cosmological terms -- 1000 light years away. Let's forgive that we are now 71 light years farther away from it than we were when it arose [1], it's fun to mention but a rounding error in this imaginary scenario. You still have the incredible problem of maintaining a homogeneous density of AIs over a rapidly increasing volume! Let's figure one lonely AI to a solar system's worth of space in 1000 light years in every direction -- that works out to 2.6 trillion little self-sustaining devices! [2] With "only" a billion years available to cover that volume, 2,600 new AIs have had to come online every single year (on average) and somehow teleport to their proper location. On Earth, it's easy for us to manufacture 2,600 pieces of complicated electronics in a year -- all it takes is the collective efforts of millions of people to mine the raw materials, refine them, design components, manufacture them, and ship all those molecules back and forth across the globe some absurd number of times. In space, this is much harder.
And this is, I think, a very generous treatment of the AI swarm thought experiment. It assumes that each node has an indefinite lifespan, and both communication and travel are somehow instantaneous over great distances, and that all of the necessary raw materials are always nearby, and that the entire thing never goes to war against itself, and that there are no cosmological disasters (like a GRB) over that billion year span, and that it all happened right next door to us in our very own galaxy. This is the best case scenario for an extraterrestrial presence in our solar system!
[1]: Approximation of the universe's rate of expansion * 1 billion years * 1000 light years of distance, https://www.wolframalpha.com/input?i=70+km%2Fs%2FMpc+*+1000l...
[2]: Volume of a sphere 1000 ly in radius * astronomical units per light year / 100 AU, https://www.wolframalpha.com/input?i=%284*pi*1000%5E3%29%2F3...
It also assumes a level of technological sophistication not too different from our own, depending on advances in AI and automation this could feasibly be us in 200 years. We hobble ourselves by only considering an alien species to be somewhat more advanced than us, it's a forgivable fault because we want to keep things realistic but it prevents us from asking the harder questions about what would be possible in 1,000 years or 1,000,000 years of continued technological development. Kardashev dared to dream when he proposed his scale. What if we could convert our entire solar system including the sun into usable energy? an entire galaxy? It's akin to the hunter gatherer asking "what if we could harness the power of lightning?" he may be very far from that dream becoming a reality but it did eventually give way to man's ingenuity. We should ask those questions: What if we could control gravity? What if we could move faster than light? What if we could create any kind of matter or field from scratch out of the raw stuff of spacetime? What is beyond space itself and could we ever access it? Dreams maybe, for today at least but perhaps not forever.
This doesn't come close to being true. That just isn't how infinite quantities work. You can have an infinite sequence of numbers that doesn't include 3 at any point.
*life on Earth
It seems that it would have to be. If a planet has had life for a large number of generations, that life will have evolved to fit the conditions.
Well, of course Earth life is optimized for Earth's environment. Otherwise it wouldn't exist.
I bet somewhere out there an intelligent lifeform with radically different chemistry and biology is posting on their online forums, "It's pretty amazing our planet has exactly the liquid argon-cadmium oceans we need to survive, really makes you think."
That’s how it works. Life adapts to the conditions it faces or it goes extinct.
I like Nick Lane's description of abiogensis as a process born in the chemical reactions at early alkaline hydrothermal vents. Again, a process that could only happen on a very specific kind of planet with active tectonics combined with a (at the time acidic) liquid water ocean.
If we are the only living planet then it is out duty to life on this planet to expand outwards.
If not then it is our duty to meet the others.
Life here will eventually die regardless of what we do. We should start working on spreading the seeds as far as possible. Otherwise we would have lived for nothing as a species.
We haven't even figured out how to be good to each other. That's far more important than worrying about how to get a civilization on Mars. If most people die, that's a tragedy. If everyone dies, that's nature and no real value is lost.
You are right re being good to each other.
Scarcity of resources leads to a lot of bad things. People and all life are programmed to compete for resources in order to survive. Most wars are caused by the struggle to control these resources. And that causes misery to those on the losing side.
Near space has endless amounts of everything we need so that competition can be more relaxed.
If anything, expanding to space will make life better here on earth, by keeping our planet cleaner and safer, and will give us the time we need to learn how to move beyond our basic instincts. We progressed a lot but we need to do more.
Mars shouldn't even be the immediate goal. We should harness the energy of our star at its full potential and extract nearby resources as first steps. Mars will be a byproduct of these two.
Else we are stuck arguing over -isms and tribal wars at scale over who owns what part of the planet.
The very fact that we push electrons writing here shows that we humans have moved beyond the natural, so simply stating that “that's nature and no real value is lost” is not in our … nature.
People with actual freedom seem to reproduce beyond replacement rates:
https://www.statista.com/statistics/299077/billionaires-chil...
https://qz.com/1125805/the-reason-the-richest-women-in-the-u...
From what I've read a certain number of people do say that financial constraints cause them to have fewer children than they'd like, but stated preferences are not far enough above revealed preferences for that to change the result. In Hungary Orban is virtually throwing money at people to have more kids but the population is still declining. Countries with robust social safety nets are doing no better than those without. The only exception I'm aware of is Israel, primarily due to the Orthodox community.
Having explored this question for a long time, I think we have figured it out, quite a long time ago, actually. But the answer is very difficult to accept. Huxley recognized this, and used the answer to show how it could be used to both create a dystopia ("Brave New World") and a utopia ("Island").
Reality has always been a mix of sudden and long-running processes.
Current information indicates that most of the Earth’s lithosphere ended up in the Moon.
BTW, George Gamow wrote about the “birth” of the Moon back in the ‘50s.
I would also like to invite some aficionados and scientists to spend some time watching olive oil floating on simmering water. Lots of weird stuff happens, and if subduction and aduction zones aren’t cause by plate separation but instead caused it as I suspect, then there’s probably some food for thought to be had in a pot of noodle water.