How long did it take modern humans to completely colonize Earth, such that there are few places you can go on Earth and not meet any humans? Less than 10k years for sure.
If we become a space-faring civilization, how long will it take us to colonize the galaxy, such that there are few places you can go and not find evidence of humans around? Not more than a million years or so.
So if intelligent life -- capable of becoming a space-faring civilization -- is common, why is the galaxy not colonized already?
The Milky Way is 100,000 light-years across. So at least that long assuming we can ever attain near-light-speed travel (unlikely). And due to cosmic inflation, many other galaxies are receeding at faster than light speed, so we could never get there.
There could be a lot of intelligent life (as intelligent as us, maybe more so) that can never realistically travel beyond their local star systems, and we'd never notice them.
Earth has had lifeforms for about 90% of its existence. Earth has existed for 33% of the age of the universe. The time it took organisms from Earth from the earliest lifeforms to discovering space travel amounts to 30% of all time was available in this universe.
Sure, it's easy to imagine someone doing it a million years faster than us. But at the same time it's very likely we are just early to the party.
These ideas (just like the "dark forest" concept by Liu Cixin) are based on the fact that every intelligent specie out there is driven exactly by the same instincts as ours. It can be, but you cannot be certain until you meet them. Also, meeting other species might take millions of years, so at every effect we would be safe for a loooong time anyway.
The Romance languages use that name (or something very closely related). English uses "Sun", but just as it borrows a ton of stuff from Latin/French/etc., it also borrows "Sol" for its word "solar".
Also, Captain Archer in Enterprise used the name Sol when making contact with aliens.
And in Germanic mythology the personification of the sun is Sól.
In PIE it's sunnōn. In some languages that evolved to some variation of sun or son, in some to became sol (notably Latin). And many use both variations in some capacity
We are a necessary but insufficient part of the proof of life. One cannot say "no proof" when necessary proof has been achieved. All that remains is a second example -- the first took several billion years to achieve self awareness.
But that is a belief that says it can happen again. It is not a proven belief. And the whole reason we are looking out in space is to prove it.
But I don't think we will find it. Life is special. The earth is special. And all the planets and all the stars and all the solar systems and all the galaxies cannot make something special again. So alas, we are earth. and we are all that is out there. And the rest of the universe is just there for our awe. That is how special we are.
I don't think life is special. I'm interested to understand the range of its generation.
Multicellular life is certainly less common, and sapience is also less common (and may not be only an emergent property of multicellular life) than just replicating chemical structures.
Certain pushes in Earth's history likely shaped and sculpted current state, but the general factors aren't terribly uncommon (water, Goldilocks zone, somewhat stable solar systems, etc.). Moons at our size are less common, and whether that is crucial is unknown. Snowball earth and hell-phase may be common. Plate tectonics may be a limiting factor.
I look forward to humanity discovering this, then finally agreeing that perpetuation of sapience generally or humanity specifically beyond the heat death of the universe is a good goal, much better than the common banal drivel that drives our wars or religions today.
> finally agreeing that perpetuation of sapience ... beyond the heat death of the universe is a good goal, much better than the common banal drivel that drives our wars or religions today.
If you are looking for a goal, then you are looking for a fight or a war.
Instead, a good goal is what comes from the good lessons of religions: the idea that humanity is nothing, that you are nothing, that your plans are nothing, and all that matters is the creator and the rewards he set abound around the problems that you struggle against. Lessons like good vs evil are derived from this paradigm. And the paradigm also inspires studying the universe from obsession with the creator's enigma.
OTOH all ideas that lead to war and conflict grow from obsession with the self. If not the self, then with your people, and if not the people then with your hatred for anyone other than your self and your people.
I mean there is a very non 0 chance that Europa (moon) itself has life in it, it might not be more than very basic life, but there is a non zero chance that it does have it.
Something that involves "thinking capabilities" in a form we would recognise?
That's always what I consider when someone mentions the Fermi Paradox.
Humans tend to barely recognise "thinking capabilities" in other mammals. There is intriguing evidence that plants "communicate" and "remember", and have been doing so around us for at least as long as mammals have existed with humans barely noticing and usually ignoring or criticising researchers who suggest that perhaps plants may be "thinking".
If we don't even recognise "thinking capabilities" in the plants that have been around us for as long as we've been around as a species, what're the chances that we would notice and recognise "conclusive evidence of advanced extraterrestrial life" when we saw it?
What is the probability that two raindrops land at the same time?
It is pitch dark. Could one raindrop survive long enough to at least hear the sound of another landing before it disintegrates?
Is the time between the drop striking the plane and the drop smashing apart so short that no drop ever hears another, or even sees evidence that any drop other than itself ever existed?
I think at the scale of the universe life even thinking capabilities life is almost certainly inevitable.
What's not inevitable is that it can thrive, and survive to a galactic scale. That's not even yet certain for us.
Universe is too big, we're all too far apart. Civilizations come, civilizations go. Some may not be on a planet where even rocket travel may be possible - no source of energy dense enough. Some can get wiped out by disasters. Asteroids. It's happened on this planet a bunch of times.
It's like the Birthday paradox. It's likely 2 people have the same birthday. It's not likely that someone else has YOUR birthday.
See even here there's no reason to be this doomery.
Yes, climate change is a massive problem, and humanity is ignoring it to our own peril.
But peril here means the unnecessary deaths and displacement of hundreds of millions of people - a civilization-defining tragedy no doubt, but ultimately nothing so serious as to cause our extinction.
We have the technology and knowledge to adapt, change course, finally get of fossil fuels, and enter into a new age of sustainable renewable energy.
We're gonna do it too late, and whole ecosystems, species, and far too many humans are all going to perish. Sea life may become extinct.
But at no point is our survival as a SPECIES in question.
Trying not to be negative, but statements like this completely disregard the degree of thought and evidence that needs to be accounted for to make a reasonable statement that isn't just pulling an ungrounded opinion out of the air. I mean why exactly is it doubtful? It doesn't seem doubtful to many other very intelligent people, so perhaps you should back it up with a bit of reasoning or evidence.
We're multiplying a very large number (number of planets) with a very small number (chance of intelligent life). The margin can make the answer go either way.
Why do you think the chance of intelligent life is a very small number? Considering we know of several million species, the chances are that we are right in the middle of the curve, and can't recognize the vastly more intelligent species the way an ant can't recognize our intelligence.
How is the number of known species correlated to the probability of life emerging? As far as we know, life emerged only once on earth, and all species evolved from a single common ancestor.
There may be countless other planets with intelligent life right now, but... if it took them millions of years to evolve... and they're millions of lightyears away... we might have to wait millions of years for signals to reach Earth from the eldest civilizations in the closest galaxies.
Why would we have to wait? Why would you assume that they're only sending signals now? Why would you not assume that they had a head start on sending signals before us?
My guess would be that there are millions of other intelligent species out there.
Maybe these species are distributed evenly throughout our 90-billion-lightyear-in-diameter universe.
Maybe half evolved to our current level of sophistication in less time than it took us.
So... what is the minimum duration of time, after the big bang, that some lineage of creatures might take to evolve from sludge into a life form capable of emitting data via radio waves? It cannot happen instantaneously... first conditions need to cool down enough to be amenable. Beyond that, it seems to require a little time for evolution to get to human-like level, it took us 13+ billion years.
So given the lack of meaningful signals we have detected so far, Occam's Razor says the nearest intelligent life that currently exists out there is too young and far away for its transmissions to have yet reached Earth.
Earth is 4.5 billion years old, but the milky way is only 105 thousand light years across. So even if you assume an earth like planet couldn't have formed any earlier than ours, other intelligent life in the galaxy only has to go through the geological processes and evolve a tiny tiny fraction of a percent faster to have tons of time to send all the signals they ever want. Nearest other galaxy is only a couple million LYA which ain't too bad either.
My guess, again based on the lack of cosmic signals we have detected, is that intelligent life is rare enough - at this age of the universe, at least - that we have no company yet in the Milky Way. That leaves a lot of room though - there might already be simpler forms of life.
But I won't go to the mat arguing my impression; we only have evidence from one planet to go by, so any view here lacks empirical evidence.
Given the timescales involved and brevity planetary conditions perhaps life is unlikely to observed nearby a star system.
Perhaps instead it is to be observed in energy preserving vessels (i.e. emit nothing) in transit to the next fuel stop (a planetary system). Perhaps dark matter can be explained by the congested highway of these unobservable vessels.
If it is a machine that can reproduce itself, growth, collect energy, use energy, do actions based on events, etc, then animals match this profile (perhaps even plants), and also, at some point computer will probably reach that goal.
Despite that, computers won't have a "soul", so where this soul comes from is a big mystery.
I'm not even sure that two humans can prove with certainty that the other ones has a soul, this is still an unsolved problem.
Unless the "soul" or the feeling of self is a property of the universe itself and could apply to computers given enough computer power and "free will".
"Astronomer Frank Drake created a formula to estimate the number of extraterrestrial civilizations in the Milky Way. Adam Frank and Woodruff Sullivan modified the equation to calculate the odds that Earth was the first intelligent life in the universe. They concluded that the odds of Earth being the first are less than one in 10 billion trillion, which suggests that other intelligent species have likely evolved."
1 in 10 billion trillion is some pretty serious odds.
It does get more complicated if we factor in life happening quickly enough without an extinction event.
But after looking at images like this there is just NO WAY we are the only ones.
The Drake Equation is a fun idea and all but I think it should go up there with Sagan's Nuclear Winter work as more thought experiment than reality.
It's just too arrogant to think we currently can place odds on all the important events necessary for us or something like us to come into being. At the time this equation was devised, I'm not even sure they understood how crazy lucky the development of mitochondria was.
In reality, we just don't know the many factors that might've affected our outcome. Also, it's just pure lottery falacy to reason about the statics that specifically "we" exist. If the odds for some strange reason settled out around about 1 of there being a single sentient species in our universe, that species would come to reason about itself and produce the same long odds of their existence. It's a longshot that a specific someone wins the lottery twice. It is a statistical inevitability that someone will win twice.
Whoever they are, they can't alienate themselves from being the one despite all the statistical huffing and puffing they can conjure. We will only know how special we are when we find another or once we have surveyed enough planets in depth.
I don't really doubt that life with human-level (or greater) intelligence has evolved at least a few times.
What I'm more pessimistic about is how long such intelligence might live. How many civilizations reached a point of harnessing nuclear power and then wiped themselves out with nuclear war?
I think even that's perhaps a warped anthropocentric view of intelligence?
Think about other earth-centric scenarios, and try and imagine if dolphins or octopuses or fungus or maybe even insect colonies or plant ecosystems had "won" and become the apex lifeforms on earth instead of humans. I wonder just how different concerns like "civilisations" and "war" and "nuclear power" would have played out in those cases? I wonder if assumptions like "industrial revolutions" and the inevitability of scientific discovery being used in detrimental ways like we have done with nuclear science actually correlate with "intelligence"?
That 600 times zoom-in on 1% of the eventual survey of 1/3rd of the non milky way sky... Shows a couple of galaxies, which if the milky way is "typical" represent a couple of billion stars.
Suddenly 1 in 10 billion trillion odds doesn't seem so (and I apologise in advance for this) astronomical...
Typical galaxies the size of the Milky Way have 100 to 2,000 billion stars and could have as many as ten trillion planets.
That’s about 100^5, so one way to think of this is that if you categories these by any four properties (temperature, stability, hydration, day length) then you’d expect about 100 samples for any point in that 4D space.
So even if you believe Earth is unique along four critical metrics, there are about a hundred planets per galaxy that also have those attributes within a percentage point. If you allow some wiggle room then you have tens of thousands or even millions.
We know conditions here on Earth varied significantly more than 1% over billions of years and life survived and even thrived.
But it spent 1.5 billion years trapped in a low energy trap. Only the unusual process that brought proto-mitochondria inside bacteria made it interest. The branches that didn't follow have remained trapped with a severe limit upon their complexity.
Then use that as one of the four critical parameters.
E.g.: You might believe that some variability in conditions (hot-house Earth, iceball Earth) is required to "kick start" evolution. Okay, then simply pick out the subset of the parameter space with that amount of variability.
But we literally don't know the variability. Unlike the numbers of stars in the universe or the number of planets, which we have some statistically board observational evidence for, we have no such statistical evidence for the development of high energy microbiology. We have 1/1 examples. And we don't know if that's because it was inevitable and the eukaryotes have just outcompeted everything else or if it was exceedingly rare. It could be a coefficient of effectively 0 on the whole the thing.
And thats just how life on earth happened to iterate in recent terms. For most of the history of life on earth, it was unicellular. It could have just as easily remained a planet of unicellular life for another few billion years if it weren’t for a few chance mutations that happened to be slightly more competitive over the background.
I think there's a pretty compelling argument that could be made that matter assembling itself into conscious beings follows pretty naturally from life itself, given a long enough time horizon and assuming the properties of basic elements holds constant throughout the universe which seems pretty likely.
I’m no physicist/biologist, but I always find it odd when they look for water on other planets to see “if life could exist”.
Sure, maybe that’s a requirement for the type of life we on earth know about, but I don’t see why other elements couldn’t have also formed in just the right way to be able to reproduce, and maybe eventually “think”.
It's a matter of water being a great place for carbon based chemistry to occur. Why carbon? Because it is so dynamic. It readily forms complex molecules which interact in interesting ways.
Looking at other forms of chemistry we don't see much as naturally varying as carbon. Though I have heard some chemists and biologists hypothesize about sikicon based life. At high temperatures it forms the kinds of dynamic connections that carbon does.
I think you fail to see the sheer probability just from the number of galaxies and the timeline itself where life can form and extinguish in even few million years. Every planet in the universe gets various amount of tries over eons
That’s hardly proof considering these examples all share a common ancestor. I ask you, can you communicate with a slime mold? Even the slime mold is more similar to ourselves than any potential life we’d find elsewhere, as we share a common ancestor.
What's so important about "sharing a common ancestor"? It doesn't say anything about the spread of different types of life that could evolve, considering we have a sample size of one, and it also says nothing about how difficult it is for any particular form to evolve intelligence.
Because there are probably an uncountable number of different turns life could have made instead to lead to dramatically different outcomes. Life iterates on itself. Mutations on top of mutations. Mitochondria could have just as easily never been enveloped by our eukaryotic ancestors and life would look a hell of a lot different today.
Knowing physics is roughly same every where in the universe, same rules of biology will apply elsewhere where if conditions meet, maybe earth is one of many conditions that can form life.
Within those rules are a lot of things that can get by under them. Take two points in earths history bound by the same physical laws and life can look dramatically different. You can think of it like how we all use the same microsoft word but that doesn’t lead to the same exact book being written independently twice or more often. The amount of permutations to be taken along the way is a countless number probably far larger than the number of habitable star systems in the universe.
I agree. There is a huge bias in our culture that we imagine a human supremacy. We are the top of the food chain we think. The masters of our world we argue, despite simple bacteria being superior in all environments compared to fragile sickly humans. We not only assume that aliens would think like us, we think they would even look like us with more or less the same body plan. We think they would have the same cultural sensibilites of exploration aboard a ship, of making treaties and even sharing technology. Even in this thread you get pushback from replies and downvotes from people who are almost offended that this would not be the case.
If you ever study evolution on the other hand, you would realize how fantastical these assumptions all are. No, life elsewhere if anything is far more likely to look like how it did for most of the history of life on earth: unicellular. People forget that even multicellularity, let alone an organism with an entire bodyplan, emerged from pure chance, and could have easily been wiped out or outcompeted for resources as soon as it came if it didn’t have sufficient fitness. How lucky it was for us that our ancient eukaryotic ancestors enveloped that first mitochondria. How different life would look today if that never happened and we never had such an energy source to actually support these later iterations, considering all life that exists today are directly descended from this single line. How supremely unlikely it all is to tread even close to the same path. How many potential paths are lost along the way and how many paths only emerged as a result of previous paths.
What we know about mathematics can't prove or disprove things we simply don't have any idea of. Think as if other beings would live in a different frequency plane (outside of our 3 spacial + 1 time), our instruments and theorems can't detect that.
To not have doubt, we need to have a reasonably high confidence that such life is there. However, the estimates are so wild and range from very unlikely to no-doubt. Thus, there is doubt (to the best we understand).
If you read through the link, the estimation for.probability of finding life elsewhere ranges from practically none to very high. When the former is also a.part of that range, could it not be that we actually do not have life anywhere else? I think it's not a question of when or a 'no doubt' case. We simply do not know enough.
If the calculations were to say there's very high chances of the universe teeming with life at many places, but life is not 'found' yet, then I would say it like 'no proof but no doubt'.
