Crowded or Lonely? The Statistics of Alien Life

[@CoolWorldsLab]

FAQs (keep ‘em coming!): 1. "We’re here, so that proves/implies intelligences are common", or "sets a lower bound on lambda_B (the birth rate)". Sadly not! We only observe ourselves because we exist, it couldn’t be any other way. This is a product of the weak anthropic principle. For example, you might naively conclude that 1/lambda_B ~ 4 billion years, since thats how long it took on Earth to get to us. But Brandon Carter’s paper (arxiv.org/abs/0711.1985) exemplifies why this thinking is wrong with an analogy of hard locks. If a lock takes 100 years to pick, on average, but only 10 minutes have passed by thus far, one might guess no-one could have possibly succeeded. But, in fact, given enough independent lock pickers, someone will luckily pick the lock very quickly. That person would then be in error to conclude their lock pick time was typical. The basic issue is you just can’t use “us” as a data point, because we *are* the observers and thus “us” is not a fair, representative sample from the distribution. I've also written about this extensively before, see arxiv.org/abs/2005.09008 and kzbin.info/www/bejne/n33Fk6OIjreKa7s 2. "You said the flasks are all nearly similar, but planets could be very different from one another!" True, good point. I somewhat regret emphasizing the similarity between the flasks, I used that analogy to make things easy to follow but it adds a confusion with deeper thought. In fact, the flasks could be wildly different and the conclusion is the same. Let’s make some boiling, some acidic, some salty, etc. In doing so, we make some choices as to how to diversify them. The thing is, it’s very unlikely that the choices we make here will just so happen to split the sample 50:50 between dissolving and not dissolving. Because remember we made those choices in the absence of any information about compound X, so why should they happen to divide the sample evenly like this? Another way of thinking about it is that there is some logistic function which acts like a switch between dissolving and not dissolving, with the x-axis being the conditions of each flask. The neck of this logistic, the switch point, occurs at some unknown position, A. To get a 50:50 split, the conditions would have to saddle the neck of the logistic curve event on each side, but the logistic extends very far in both directions, so it’s pretty unlikely we’d happen to choose a set of flasks that land 50:50 either side of the unknown switch point A. Hopefully this extra analogy helps, but at the end of the day it might be helpful to look Jaynes’ paper (ieeexplore.ieee.org/document/4082152)

[@holographic_red]

Just such a great video, thank you, it really widened my perspective on this. And thanks for the FAQs

[@johnbennett1465]

I agree with the first point. The second is a very simplistic analysis. Solubility is not a binary function. Also the solubility in the mixture is not a single variable linear function. It is a multivariable nonlinear function. So while 50-50 is not likely, neither are 100-0 or 0-100. While has-life may seem binary, there is a huge range from barely supporting single cell life to comfortable supporting a space faring civilization. So, properly analyzed, the analogy is reasonable.

[@lotuschamp7796]

Isn't there a paradox wherein the more technologically advanced we become, the more easily we might extinct ourselves by accidents and the complications of such events? If that would hold true in a grander scale, then the universe being mostly empty would actually make sense - that life could be common enough, but that survival (or more to the point, civilizations surviving themselves) would be extremely rare.

[@holographic_red]

@@johnbennett1465 So... we just don't know because we don't have the data?

[@johnbennett1465]

@@holographic_red correct. That is my current understanding of the situation.

[@JohnMichaelGodier]

Absolutely compelling and a fresh take on the Fermi Paradox that's going to give me pondering material for a good long while. For anyone interested in the possibilities of other life in the universe, this is a gem. And also, exomoons! We want exomoons!

[@CoolWorldsLab]

Thanks JMG!

[@gorbachevdhali4952]

JMG you are the GOAT man. You and Dr. Kipping are shining beacons on the hill of what is the internet.

[@timewstr]

I can't wait to hear this conversation on Event Horizon!

[@EllyCatfox]

♥️💜

[@joshf9074]

John Michael GOATier

[@visvivalaw]

Drake never meant the equation to be used. He meant it to be an agenda for discussion at the astrophysics conference where he presented it.

[@peachypietro9980]

Boy, how successful that turned out to be, though.

[@ronin4713]

It was meant to simply get the proverbial ball rolling on merely *thinking* about how many variables there are to consider in this search. The beginnings of life on our *own* planet are still veiled in mystery, though we've made some headway. If we can't even define how many miraculous coincindences needed to occur here on the world we are most familiar with, how likely are we to figure it out for a world on the other side of the galaxy!?🤯😵

[@yvindwestersund9720]

I think it was only ment as a thought experiment A what if scenario if you will Now I have no idea what to say or think about this But to me that is what I would take from it Q fun way of thinking about the galaxy and the possibility of life elsewhere And as always a great video from a great Channel 👍 Just saying 🇳🇴

[@ahmetmutlu348]

Not actually. Original big bang theory clearly indicates there is life put there certainly... statistically this theory assu,es anything os part of only one function therefore mathe,aghically its certain there is lofe put there tough todays researchers do not use math/statistics analysis prorocols by simplifying comples logics... so thats wjy they assume life is only on visible spectrum :P😂😢😮😅😊

[@holographic_red]

Seems human, it checks out.

[@nikidino8]

I'd like to mention that it's really nice that you do not use background music. It helps me to concentrate on what you say and your voice is so soothing too.

[@jensenat]

Dr. Kipping's voice is the music.

[@rikimarizard]

He does use background music in some videos but subtly and it's very effective. Here it works best without it because it's a discussion of their latest paper.

[@AquaticAbomination]

I'm so tired of content creators who either don't have trust on their own material and have to fill with music- or consider their audience as infantiles who need constant noise. Thank you for not using empty filling music

[@jeff__w]

It’s an excellent observation with which I agree. I also appreciate how the visuals actually have _some_ connection with what is being said on the screen, as opposed to just being random stock videos of stars, nebulae, galaxies, and anything else that might look “astronomical.”

[@RonaldMcDonald519]

I would like to second this

[@reiki-guy3894]

As an uneducated layman, I'm genuinely grateful for the way you explain your theories to the likes of me. Thank you, my friend.

[@DavidGS66]

The fact that we took 4 billion (with 1 Billion years left before life dies out entirely) years to evolve, 1/3 the age of Universe is a serious issue. Prokaryotes evolve very quickly; however, eukaryotes unambiguously evolved 1.6 bya, multicellular life evolved 0.6 bya, so combination evolution of eukaryotes, multicellular life, & intelligence is a great filter. We're lucky to be here.

[@camerontatro9447]

One thing to consider is life may take much longer, or barely any time at all to get where we are. Arguably, life never needed to take the leap to eukaryotic multicellular organisms. They were trucking on for 3 billion years without any issues. But a catalyst eventually made that happen. Be it from Arobic organisms surviving the great oxygenation events. To an early eukaryotic cell engulfing a bacteria and utilizing it as an ADP factory instead of a meal (mitochondria). And then when multicellular life took over it was FAST. But the evolutionary advantage of intelligence didn't take over. There very well could be a scenario where shortly after the earths oceans formed eukaryotic organisms took over and multicellular life was on the scene 2 billion years ago. And then there would be a reason that a sentient species popped up in 200 million years vs 500-600 million years like it did here. Etc. There is no reason that intelligent organisms couldn't have arrived during the jurassic for example. Plenty of time to develop intelligence during that period. So there could have been organisms walking on the moon 1.5 billion years ago. And the inverse of that is true. Life could have just stayed a prokaryotic sludge to this day.

[@JonnoPlays]

"Cool Worlds searched for aliens and what they found was TERRIFYING" What the title would have been if this was not a real science channel 😅

[@jimmyzhao2673]

Omigosh, too funny. 😆

[@mikejwheatley]

Like most of KZbin click bait. 😢

[@PremierSullivan]

Believe me, an empty universe is the good outcome.

[@andyf4292]

or that guy with Londo Morali's hair

[@Greippi10]

With JWST and NDT in the thumbnail.

[@CoughSyrup]

The irony that Jaynes' initials are E.T. was not lost on me.

Its tripppin me out, was he an alien?

[@Skraeling1000]

Hehe, I was trawling comments to see if anyone else noticed!

[@justadildeau]

An illegal one

[@javierolazaran7227]

The problem is that people think of the Drake equation as an actual attempt at prediction when it was just meant to organize a meeting agenda to discuss SETI.

[@christopherdaffron8115]

Yeah, well Fermi simply posed a question in passing to some of his colleagues and we can now see what came of that.

[@tonib5899]

One thing that has always struck me is, we are looking, but we have only been looking for maybe a few hundred years in the optical, maybe 100 years using radio telescopes. This is out of 13. Billion years. Aliens would have to be relatively close, technologically advanced and be existing at roughly the same time to have overlap with ours. It’s that overlap I think will be the most important factor.

[@djsarg7451]

We have studied 20 million stars, and not one can support life as they are ALL too unstable, we are alone. The Sun is the only stable star. Of the 4,100 solar systems studied, not one looks like our solar system, able to support life. Almost all the 4,100 solar systems studied have Hot Jupiters. In normal planetary systems giant planets form beyond snow line and then migrated towards the star. A small percentage of giant planets migrate far from the star. In both types of migrations, any rocky planet like an earth is lost in these planetary migrations. Most stars do not have planets. Many stars are in bi-star systems, thus no earth-type planets. Have not found another galaxy that can support life. Must have stable arms for life. Thus we are alone. The odds are currently at 1 to 20 million. Only a fool would say the odds will be better next year. 10 years ago this was 1 to 1 million and back then people were saying that is only 1 million. Finding more stars will not change the odds, it will be soon, 1 to 30 million and on and on. The normal is Hot Jupiters and no earth and unstable stars. The Sun's energy output changes less than 0.1 percent. All other stars start at 3 % and go up. So we are alone. 1)We have found no other Galaxy that can support life. Life needs a barred spiral galaxy with stable arms. 2) In that stable barred spiral galaxy, only stars in the Galactic habitable zone can have life, too close to the center (where most stars are) have too much radiation. Too far from the center and there are no rocky planets, due to the lack of heavy elements. 2) As already stated, half of the stars are in bi-star systems, thus no life. 3) Normal, is solar systems with Hot Jupiters, no life. Why have we not found a stable star like the Sun? The appeal to billions or even a trillion stars does not add any proof of life outside of the solar system. Only a solitary, second generation, G2V star, 4.6 Billion years old with the correct metallicity (0.0122 [high metallicity]) and correct temperature (5,772 K) are stable enough to support complex life. Star must be the correct distance from center of a stable Spiral galaxy (too close too much radiation, too far no rocky planets) and on and on. The planet must be not too large or too small with long lasting magnetic field. Also not too much sulfur or water. Just above and below puts the number of other star-solar systems with life at none. (no other stable Spiral galaxy has been found) The Sun is a G2V star. Only 0.7% of stars are G2V. Only half of the G2V stars are solitary. Age: G2V stars age from 0 to 10 Billion, Sun is 4.6 Billion, must be 4.6. Metallicity: Can range, -4 to +1, need, must be (0.0122 , ± 0.05) G2V Temperature: Can be from 5,860K to 5,720 K, must be 5,772 K And on and on. We are alone.

[@paulrussell1207]

Of course the light from different stars is arriving at us from different time periods. It is true that of each star we have witnessed 100 years of it's life max, so what you've said is true from star to star, but we do have a wider vantage on general conditions of the galaxy at different points in time for up to a million years (the time it takes for starlight from the other side of the galaxy to reach us). Much like we can tell the biology of a Triassic by looking at the right rock layer, if there was a 100,000 year civilization that occurred about 300,000 years ago, we might see it. But, whilst not a mere 100 years of view, 1 million years is very short time compared to 10 billion years lets say. In fact it is only 0.01% of it!

[@markholdon8525]

​@@djsarg7451No we are not, we're just not technically advanced enough to find life like ours. There's life on this planet that can live without oxygen, it may be small but it's here. There's billions, probably trillions of galaxies out there each with maybe a billion stars with multiple planets around them & you don't think at least one of those planets has life on it. That's frankly delusional.

[@djsarg7451]

@@markholdon8525 You are in Si-Fi land not the real world of knowledge. We have ruled out other galaxies. We have not found another galaxy that can support life. In the Milkway, we can not find one star that will support life. We now know that life must be carbon-based. Only carbon has the complexity for life. So no billion stars does not change Facts.

[@Xostrich12X]

Thank you for such great content. I love that you go beyond the typical pop-sci slop and actually get into the math/statistics behind your and others’ work-which I really love learning about. Also, as this video shows, I appreciate your realistic view of the universe-such as the true difficulties of interstellar travel and the likely rareness of other Earths and intelligent life. I can’t wait to become a member of the Cool Worlds Lab when I start my new job after graduating later this summer. Keep up the awesome work.

[@Kroogles]

You are a boon to humanity. Thank you for seeking to ground a conversation widely polluted by people who are happy to say anything that gets them attention.

[@NewMessage]

As a great man once said... "Ack ak. Akk ACK-AKK!"

[@rherbert57]

@@busimagen And release the doves!

[@tunnsie]

Bravo 😂

[@ianhopcraft9894]

Words which are as true today as they were all those years ago.

[@LeonelLimon-nj7tu]

Was He the one that also said "Nuck nuck Nuck."?

[@vlad-pm2zr]

Ack! Ack! Ack-ack-ack!

[@user-blabla-47854]

I'm surprised how we expect E.T.s to be just enormously scaled up version of our tech, when in fact what we already do is shrinking out tech in size, not making it larger. Shrinking dye sizes, quantum computations, increasing power efficiency, DNA engineering. All that means E.T.s probably operate on the scale level of atoms and relying on quantum effects for communication, not at the level of stars, Dyson spheres and communication in radiowaves.

[@Galahad54]

I wrote a scholarly paper on exobiology, reviewing all available pertinent literature, as a college freshman in 1974. The primary conclusion is the same as yours. There is no lower limit to the birth rate. There is no data at all on the death rate, as we ourselves could hit technological death at any time. Sagan realized this in the 1975-1977 range, and proposed nuclear winter as a possible mechanism. As an actuary, there are certain further maths that are relevant to the equations. One relates to ruin theory, and in this case focuses on the high slope part of the curve, as that is the part of the curve that is humanly 'interesting'. The most interesting part of the curve, to me, is how many planetary and stellar systems WE (earth) occupy in humanity's future. This includes augmented humanity. If that number is significantly more than one, next consider death contagion. It's possible that if life on mother Earth goes extinct, that lands a crushing (psychological or economic) blow to the newer worlds.It's also possible that the explorers won't really worry about life on Earth once takeoff point is achieved. Finally, it's possible that one or more greater intelligences exist, either aiding or hindering our potential to expand beyond this solar system. It's also possible that advances in physics/propulsion/life span will make expansion trivial. Or, that some combination of human idiocy kills 90%+ of humanity, returning humanity to the brutish and short phase, temporarily or permanently. None of these have any fine mathematical predictive power, save the the chances for each of the listed outcomes appears to be greater than zero.

[@upupuptheziggurat.liketysplit]

You have found some sort of Legendary Blackboard. Congratulations.

[@premalgorroochurn6431]

This is such a wonderful video, the occupied fraction vs birth-death ratio plot really blew my mind because it showed me how in principle Jayne's distribution can be arrived at, and why its either (almost) all or (almost) nothing. I also love the optimism at the very end, the idea that life could be all around us but we just don't know how to look for it (yet). Keep inspiring us!!

[@earthknight60]

This is actually a good example of why not to oversimplify things, and why some of the factors in the Drake Equation are important. Life, intelligent life, technological life, and detectable technological life are all different things, and not does not necessarily follow the previous one. Another important factor, is that, despite our best efforts so far, we are just barely scratching the barest surface of detection efforts, and at present even a nearby civilization at a technological level comparable to our own would be very difficult to detect. We simply lack the ability to conduct proper surveys so far, and as a result we lack the data to make predictions that fall much out of the philosophy side of things rather than actually standing firmly in the science side of things.

[@flyingeagle3898]

Personally I find this formulation of the problem far more compelling for the existance of "life", than for the prevalence of "technological civilizations". The mere existance of life must indeed be either everywhere or almost nowhere as it is fundamentally a question of the likelihood of chemistry turning into a system of self-replication (similar to the water in the glass flasks analogy and I lean heavily towards "everywhere") However, when it comes to technological civilizations I have always thought the brief "phase transition" to a state where the entire galaxy is covered is flawed. I can imagine several factors that could either slow the expansion or halt it at a value substantially lower than 100%, challenging that assumption and create large regions with minimally visible tech civilizatiions including: Ideology, the usefulness of planets with life for science, Internal and external conflict and disagreements between civilizations, a reasonably high probability of death or decline for civs etc. Additionally, even if the curve does apply, the relative youth of the universe compared to its lifespan increases the liklihood we are in the ascending part of the curve, especially if the rate of civilizational expansion is somewhat slower than some currently beleive.

[@takanara7]

I think the "almost nowhere" for the technological level of intelligent life, because it almost didn't happen on earth. Earth has had life for like 4 billion years, but we only have about 800 million years before the oceans boil off. In fact the earth was much more hospitable to life 100 million years ago with much higher oxygen concentrations, so huge animals could live then that couldn't live today. We also know that longer-lived stars like red dwarfs would likely blow the atmospheres off planets close enough to have life, and huge bright stars don't last very long - so really even with a sunlike star the odds of developing intelligent life would be low. (but, maybe in the future you could have planets around white dwarfs that would last for a very, very long time)

[@kosairox]

In your thinking how much the factors you mentioned (ideology, usefulness, etc.*) would affect the phase transition speed? 10x? 100x? Still not enough I think**. Also, part of your rationale is covered by the birth/death ratio. My intuition is that to make a dent in the fine tuning argument by "widening" the "phase transition" time, we should show that the suggested reasons have a non-linear impact, i.e. they don't just put a coefficient in front of the equation. For example, the larger the perimeter of the empire, the more potentially useful planets are in your reach, so this actually works against your argument. Assume empire radius r. Number of cool planets to explore grows with ~r^2. Even if on average, cool planets are only 10%, this is a constant coefficient in front of a quadratic equation. Internal conflicts would indeed grow with the volume of your empire ~r^3, which might be useful to focus on. Meeting other civs would probably be related to the perimeter of your empire r^2, not its volume. Etc. etc.*** I agree we're in the ascending part of the curve, but that doesn't tell us much. We might be the first, or to be more precise the only one currently spacefaring/doing the expanding. I think this is what the fine tuning argument tells us. * "disagreements with other civs" works against your argument ** remember the simulations were done with current technology in mind, I think we can improve our engines considerably up to a fraction of c. *** another cool idea: I read "Accelerando" lately and there, the constraint on civilization growth was network bandwidth/latency, which caused members of a civilization to prefer being near each other, resulting in matrioshka-brain civilizations. Bandwidth would be subject to inverse square law, so dampens with 1/r^2

[@User-jr7vf]

@@kosairox Your comment is well written and shows that you have a scientific way of thinking.

[@extragoogleaccount6061]

@@kosairox Wouldn't phase transition be slowed depending on the percentage of stars with habitable planets? (Or a planet useable for a self-replicating probe to visit and create more of itself) This is basically an exponential growth curve, right? The closer the useful systems are, the quicker the probe gets there, and the quicker more probes are made, etc, etc. Would this not be able to slow the transition to a more believable level? Like, say the phase transition takes 1 billion years instead of less than 10 million years, and with the universe being 13.6 billion years old, then it wouldnt be too improbable to currently be in that transition - right?

[@kosairox]

@@extragoogleaccount6061 One can come up with many reasons why the phase transition would be slower. If we reduce the number of habitable planets by a factor of 100, would that increase the galactic conquest time from 10 million years 100-fold to 1 billion yeras? I don't think so. For the sake of argument, if you're a self-replacting probe you have less habitable planets to choose as your next "destination", but they're just homogenuously as distant from you. Say, instead of 1000 planets which are 10 ly from you in random directions, you have 10 planets which are 10 ly from you in random directions. I think volume-wise, it doesn't make much difference then. In fact, less planets means less paths to choose from means the expansion (volume-wise) would be faster. It also means you need to produce less probes, though I think the time required to produce probes doesn't matter anyways because it's much shorter (years?) compared to travel time. The "benefit" of having less habitable planets is that a civ is harder to detect, but if we assume that, say, within 10 ly it's practically guaranteed that a detection is successful, it doesn't make much difference. I think we need to consider average distance between habitable planets and distance of detecting a civilization. If distance between habitable planets is smaller than distance of detection, then it is as I said. Otherwise, if distance between habitalbe planets is greater than distance of detection, your argument could work. Though this argument could be applied to bolster the "aliens are everywhere we're just not listening hard enough" scenario just as well, not only to attack the phase transition fine tuning argument. To explore this further one could come up with a maths model, maybe a python simulation, and test for what parameter values would the number of habitable planets benefit or harm the hypothesis? Then compare with real-life detection range estimates and real-life habitability estimates.

[@ScentlessSun]

The Drake equation was a conversation starter. We owe a lot to Frank Drake for getting us started down the path of thinking about this problem in a more cleared-headed way.

[@w0mblemania]

Hmm, I disagree. I think it was a huge diversion. At the end, it had no predictive value. It sounds like math. It sounds like science. But it's actually not.

[@kb9gkc]

@@w0mblemania Bingo

[@christopherdaffron8115]

Well, you could say that Fermi was just starting a conversation with his colleagues by posing a simple question. We can see where that went.

[@ScentlessSun]

@@christopherdaffron8115 He split the atom by accident and didn’t even know it for 5 years until someone else told him. He was just experimenting. That’s what scientists do. Others started the conversation. Should we not have conversations because something bad might happen? I can’t see any purpose to what you wrote.

[@christopherdaffron8115]

@@ScentlessSun Here is the point. Read Carefully! Drake's equation has taken on more purpose than Drake had intended. The Fermi Paradox (I'm sure you have heard of it) has taken on more purpose than Fermi had intended. You see the purpose of what I wrote now?

[@clownearound5751]

I have just discovered your channel via a comment on another video, one of Carl Sagan’s talks and have subscribed and look forward to watching your previous and future content. I have been fascinated by all things to do with space like many people since an early age and it’s great that there are many pushing the boundaries to help others understand more and more. Thank you for sharing this excellent video with everyone. Best wishes to you and your team and your families from England

[@Quintilianator]

My pet theory is that 1) intelligent biological life produces technological life 2) Technological life avoids unbounded self-replication and instead focuses on self-preservation. 3) These life forms would be very hardy and only rarely need interstellar travel. They also likely wouldn't need Dyson Spheres or other mega-architecture. So 4) There may be many such things but we may never detect them.

[@bigjermboktown6976]

Cool worlds always seems to make my day better! Because I'll stop what I'm doing no matter what it is and watch

[@flyingbluelion]

1. Why assume a steady state? 2. Use the Drake equation as follows: think about how our observations influence the bounds on each factor and hence on the product. Then decide to do experiments that improve the accuracy of these bounds. 3. If smartlife is rare we must choose to survive so that the galaxy is not empty. If smartlife is common we should work out how to survive within that more complex context, including choosing a global civilization style that does not attract hostile attention.

[@0ppaiDragon]

If only more teacher has that next level fascination/dedication to the true pursuit of science. The calculations must describe the world/universe as closely as possible to the field data. BRAVO!

[@gwholdom]

But what if we add +1 to the equation? We already know of one, supposedly, intelligent civilisation. The star system we know best brings us off the zero mark. Love your work!

[@dongameleone2489]

I agree. That would be smooth! (computational linguists will understand 😂)

[@bingzhang00]

Thanks for another thoughtful video. But I have some doubt about some of the reasonings here. First of all, you are using a logarithm scale for lambda_bd, which makes the intermediate region appear narrow. In other words, you are assuming that the log of lambda_bd follows more or less a uniform distribution. I don’t see any justification for that. Secondly, it is far from certain our galaxy has reached the equilibrium . It could well be that lambda_bd is quite large but we are still in the early innings of civilization emergence. In other words, both terms are tiny but the ratio is large. We are turning on the lights in the galaxy slowly but steadily. I remember you have a video hypothesize that we might be the early ones. Finally, even if all your assumptions were true, as lambda_bd gets smaller, the occupancy ratio is really close to lambda_bd itself, and not zero. It may be small but given the number of stars in the galaxy the total civilizations can still be large. There is no need to despair.

[@GotMyTowel42]

I've come to understand recently just how many events led up to us and how many more are necessary to become a spacefaring civilisation, which alone is quite the feat. No wonder we can't see anyone.

[@JonnoPlays]

The problem with this equation is thinking of humans as one single civilization inhabiting our planet. There are human civilizations that have come and gone and are now extinct. Many of them. All of human kind did not experience the industrial revolution, only certain civilizations made it to industrialization and computerization among the many inhabiting the planet. We still have hunter gatherer people inhabiting the planet with rocket launching people. Calling all of that one human civilization is too simple and can't represent a value of 1 in the equation. If there are aliens, it's safe to assume that not every alien has a space ship or the resources to travel the stars. They may have a shadow government controlling all the best technology too, who knows.

[@FabsHF]

It is safe to say that if not for western/european civilization, most humans would still be living in medieval age (China, Japan, Middle East) and the rest would be living in bronze age or less, like Africans, Oceania and native americans.. So 1 out of 100 humans civilizations made it to the industrial revolution (and took others with them later) If europeans went extinc in 1200 somehow by plague, there would be no tech signals coming from earth

[@silentwilly2983]

You are right, but is it relevant? The way I look at it the answer to the question whether there is a civilization on a planet is a binary one. There is a population that meets the criteria for civilization or there is not. Where you draw the line is of course rather subjective

[@Moochaa]

@@silentwilly2983 Agreed. Throwing in some more discussion, sure there’s some societies more technologically advanced than others, but a neolithic civilisation is not relevant to the search for alien life via current technological means.

[@ravenmad9225]

The civilizations may have failed but the human species is one continuous line of evolution. Survival of the fittest.

[@AmonTheWitch]

we also have many animals that arguably could be considered civilized, whales have incredibly complex language, but clearly are physically incapable of building tech and have no need for a home, Crows can use tools and communicate, even teach their young about individual humans

[@CoughSyrup]

"It is known that there are an infinite number of worlds, simply because there is an infinite amount of space for them to be in. However, not every one of them is inhabited. Therefore, there must be a finite number of inhabited worlds. Any finite number divided by infinity is as near to nothing as makes no odds, so the average population of all the planets in the Universe can be said to be zero. From this it follows that the population of the whole Universe is also zero, and that any people you may meet from time to time are merely the products of a deranged imagination." - Douglas Noel Adams

[@alfaeco15]

Given an infinite number of planets, If only one of two planets is inhabited, there is still a infinite number of inhabited planets. The same if one in a hundred, thousand, million, trillion, etc

[@djsarg7451]

We have studied 20 million stars, and not one can support life as they are ALL too unstable, we are alone. The Sun is the only stable star. Of the 4,100 solar systems studied, not one looks like our solar system, able to support life. Almost all the 4,100 solar systems studied have Hot Jupiters. In normal planetary systems giant planets form beyond snow line and then migrated towards the star. A small percentage of giant planets migrate far from the star. In both types of migrations, any rocky planet like an earth is lost in these planetary migrations. Most stars do not have planets. Many stars are in bi-star systems, thus no earth-type planets. Have not found another galaxy that can support life. Must have stable arms for life. Thus we are alone. The odds are currently at 1 to 20 million. Only a fool would say the odds will be better next year. 10 years ago this was 1 to 1 million and back then people were saying that is only 1 million. Finding more stars will not change the odds, it will be soon, 1 to 30 million and on and on. The normal is Hot Jupiters and no earth and unstable stars. The Sun's energy output changes less than 0.1 percent. All other stars start at 3 % and go up. So we are alone. 1)We have found no other Galaxy that can support life. Life needs a barred spiral galaxy with stable arms. 2) In that stable barred spiral galaxy, only stars in the Galactic habitable zone can have life, too close to the center (where most stars are) have too much radiation. Too far from the center and there are no rocky planets, due to the lack of heavy elements. 2) As already stated, half of the stars are in bi-star systems, thus no life. 3) Normal, is solar systems with Hot Jupiters, no life. Why have we not found a stable star like the Sun? The appeal to billions or even a trillion stars does not add any proof of life outside of the solar system. Only a solitary, second generation, G2V star, 4.6 Billion years old with the correct metallicity (0.0122 [high metallicity]) and correct temperature (5,772 K) are stable enough to support complex life. Star must be the correct distance from center of a stable Spiral galaxy (too close too much radiation, too far no rocky planets) and on and on. The planet must be not too large or too small with long lasting magnetic field. Also not too much sulfur or water. Just above and below puts the number of other star-solar systems with life at none. (no other stable Spiral galaxy has been found) The Sun is a G2V star. Only 0.7% of stars are G2V. Only half of the G2V stars are solitary. Age: G2V stars age from 0 to 10 Billion, Sun is 4.6 Billion, must be 4.6. Metallicity: Can range, -4 to +1, need, must be (0.0122 , ± 0.05) G2V Temperature: Can be from 5,860K to 5,720 K, must be 5,772 K And on and on. We are alone.

[@bofa722]

​@@alfaeco15 yeah this guy sounds like he doesn't know much math lol If there are an infinite number of planets, it would then follow that there are also an infinite number of inhabited planets, regardless of how unlikely it may be. They would simply be "different" infinities in that inhabited planets are less common My calculus professor explained this exact idea to me but with decimals and rational numbers. No wonder the guy that said this was an author and not a mathematician lol

[@paulrussell1207]

That was a long way to write "I can't grasp infinity".

[@albertvanderheiden7419]

​@@djsarg7451that is a bold statement. There are 2000 trilion galaxys with each 100 bilion stars. If we are alone then someone God ? wasted a lot of space

[@ronaldgarrison8478]

0:12 I see Michio in the thumbnail, I click away. This goes back. Way back. About 35 years. A steady drip, drip, drip.

[@Sparxcwg54]

Something that this does for me, as a SETI optimist, is that, even if we are on the bottom plateau of your equation, it implies that eventually, humanity may be able to "watch" the galaxy/universe populate. To me, this doesn't prove than aliens *can't* exist, so much as it proves that they don't exist *yet*. And to me, that is incredibly promising.

[@Philomats]

A bodhisattva of science. You teach us how to think. And you accomplish this in the format of playfully expanding our imagination. The most pleasant of arts.

[@yooperish6985]

Taking the beaker analogy, what if a random, unknown number of the beakers are empty. Then, no, compound x won't dissolve. If you don't know how many beakers are empty, then instead of close to 0 or 100%, we should expect either close to 0 or 50%. Anything that would make a planet permanently uninhabitable would be like an empty beaker. And that brings some of the vagaries and problems with the Drake equation back into the mix.

[@ScientiaHistoria]

Exactly. The Kipping formulation is useful but assumes homogeneity of the population. The answer could be that we are at the “near 100 percent” end of the set of X-type stars with Y-type planets in the Z-band of their lifetimes…a number as mysterious as it ever was.

[@ScientiaHistoria]

@@HonorableBoor I still think their model assumes homogeneity *at every scale* of unit choice or size (LY^3 or planets or whatever). At smaller scales homogeneity shrinks and the model’s power decreases. The beakers are not comparable. At larger scales homogeneity among cells increases, which does make this model interesting but begins to limit its application to a galaxy rife with regional features. This homogeneity/scalability problem is not unique to what they’re trying to do - it’s inherent in any survey sample estimate and I suspect trying to apply this model to a heterogeneous galaxy (uninhabitable center, spiral arms, interstellar dense cloud regions) would be informative but challenged as you run out of degrees of freedom…in other words, there would so many 0-100 spectra to multiple against each other you’d be drifting back to Fermi. [I say all this having not read the paper. Mea culpa.]

[@auroraglacialis]

"Only a Sith deals in Absolutes" - or more seriously - I am doubtful of that "all or nothing" idea. It would have to be expanded really - it would also imply that basically if you have life on a planet at all, it either almost never develops into multicellular life or it almost always does. It either almost always develops a civilization or it almost never does. And then you end up with a galaxy that either has civilizations and life on almost all planets or on almost none - and at the same time it means that it would be improbable to have life without civilization on any other planet. And I think that makes it more likely that we dont deal in absolutes but that basically something similar to the Drake equation makes sense - to describe each of the features of technological life separately because it could be something in between.

[@justaname999]

So, you do touch on this towards the end, so I am not saying you (and others) completely ignore this point, but I'd like to add perspective to the "simpler" civilizations bit. It *really* depends on what we classify as "simple" and what we expect as the "norm" of expected progress and it would be great if more people could consider that. For context and to show that it can take a while to maybe have a more varied view: I did my undergrad in physics, then did complex dynamic systems modeling in grad school and gradually drifted towards computational neuroscience. During my postdoc and later faculty position I got to work with a more diverse group of researchers for the first time. I came into my postdoc research thinking I have a decent grasp on how much we know or don't know about human cognition but then had to learn that basing our wealth of knowledge on a population of 90% college students from a very particular life style background might possibly be a tad too simplistic. Not all cultures are like the European-influenced subjects we had data from, not all languages work the way English does, not all cognitive tasks are mastered equally by people from different backgrounds. Yet, we know that on a structural level a person is the same no matter if they are from a community that has no concept of ownership or one that has no concept of counting in numbers higher than a handful or whether they are a NASA scientist. So... are we classifying one community as "higher" civilization and the others as not, simply because only one of these would be able to send communicative messages to other worlds? You are obviously not saying that humans who do not live in the same culture as you or me, or humans 5000 or 10,000 years, or even 500k years, ago were simpler than we are now. But at the same time, there seems to be an implication that out of the cognitive complexity of the kind that our particular species of ape has to work with, technological progress of a very specific kind necessarily should emerge. It also somewhat necessarily implies that any species with this sort of cognitive complexity would have similar goals and means to reach them. And those are conceptual hurdles I somewhat struggle with. I really wonder how much the historical fact of the particular type of historical developments that happened to influence our species' progress influences our notions about "typicality". If you ever did a video on why these assumptions should hold, I'd be happy if anyone could share a link. If not, maybe that's a video idea to consider ;)

[@jimmyzhao2673]

I hate those misleading thumbnails featuring Michio Kaki on other channels

[@twonumber22]

Michio doesn't help with all his sensationalism and religious language.

[@kinguq4510791]

Have to say I don't follow this argument. As a biologist, I will use animal populations as an example. Simply put, there are more chipmunks than bears in the forest, because the forest has a higher carrying capacity for chipmunks. Both populations may be stable, but the number of bears will never approach that of chipmunks. So, why can't technological civilizations be more like bears than chipmunks, in that there is simply a very low carrying capacity in the galaxy for them? By that I mean that such civilizations may require specific conditions that are relatively infrequent. So the galaxy could already be "full" of such civilizations, but "full" in this case could be a very low number. I know I must be missing something here, so I would be happy if someone could correct my thinking on this. Thanks for another thought provoking video.

[@CoolWorldsLab]

There’s an interesting comparison. I’d say that humanity as the sole example of a technological species is unlikely to be near the carrying capacity of the galaxy though. That would require Earth to be the only habitable planet both now and at all times. But if this was so, it actually falls nicely into Jayne’s perspective. Either Earth-like planets are common around Sun-like stars, or they’re very rare.

[@kinguq4510791]

@@CoolWorldsLab Thanks. But surely we are nowhere close to demonstrating that we are the only example. There could be hundreds and the probability of detection would be rather low.

[@christophernewcombe9524]

Aren't you forgetting something? Detection of intelligent life does not only depend on its presence, but on our ability to detect it. We've only had the technology to do so for a few decades, and that technology is still rudimentary. Go back 150 years and electromagnetic waves were still just a theoretical prediction.

[@ColbyAzimuth]

The hills are alive.

[@scottcohen1776]

With the sound of music.

[@CoughSyrup]

Yes, based on all the available information and after crunching some numbers I conclude that our existence is statistically improbably, so much so that I tend to regard all the actual people I regularly encounter day to day as little more than a curious and highly eccentric artifact of floating point arithmetic imprecision; a continuously growing cumulative error.

[@bunzinthesun]

That was my takeaway, that we can't possibly exist.

[@Abacae7]

3 observations: 1. Compared to its lifespan, the universe is young as is the galaxy. 2. Cognitive science suggest that life and self-awareness are not too uncommon in the galaxy, but that intelligence and the evolutionary means to implement it may be very rare. 3. The speed of light is very slow and there are many puzzles about the nature of the universe and galaxy that we have yet to understand. I am in the camp of those who believe that intelligent life on earth may be a one off in the galaxy, if not the universe, and that we should do everything we can to preserve it and propagate it through the universe

[@jeredjamesaz]

I've been a fan of this channel for a long time, and this is one of my favorites. While listening to the birth/death theory, I couldn't help thinking about the simulation hypothesis. The absence of detectable civilizations always takes me to the simulation hypothesis. My mind then immediately takes me to the double slit experiments where light wave functions suddenly collapse and change from a wave to a particle when being observed. I'm not a PHD experimental physicist, but this phenomenon scares the hell out of me.

[@EstudioVoitheia]

This increases even further the Copernicus Paradox. Why we are in a planet where technology can be develop when practically all habitable planets technology development is impossible?

[@rogerschus7934]

Great take!

[@TicTac2]

selection bias? why am I talking to you when existing as exactly who we are is even less likely than 1 divided by the number of stars

[@filonin2]

You could not ask that question if it were not so. It's like being a puddle and asking why this pothole fits you so well.

[@User-jr7vf]

Answer: because we couldn't live on a planet where live can't exist as we know it.

[@EstudioVoitheia]

@@filonin2 I think that you are missing the point. You should be able to ask the question If intelligent life can came into existence in planets where technology cannot develop (a ocean planet or in a planet with instabilities as in M-Star systems or many others).

[@mrcoolguy819]

This is one of the few channels, if not the only one, where the presenter has not been afraid to disagree with the optimistic search for life. He's expressed his skepticism in other videos and I think it's refreshing. I think some anti science logic has become so ingrained that people cannot fathom the opposite being true. We've all heard that "Is arrogant and self centered to think we are the only ones in the galaxy" but like... Even scientist think there's a strong, rational, chance that's the case.

[@No_OneV]

Greats analysis, great video. Well done.

[@CoolWorldsLab]

👊

[@erikfinnegan]

I just watched Avi Loeb's TED talk and was reminded of this video. I love the science I see here. Fair enough, all that Loeb suggests in his talk is that we keep looking and spend money on that endeavour rather than shooting at each other. And that's alright with me.

[@blanwhit]

The hypothesis of us living during a period of expansion actually implies an even lower number of occupied planets, since instead of equating N_o and (N_t - N_o) we now have the former being strictly less than the latter. Thus, after rearranging we get that F (the occupancy fraction) is strictly less than lambda_BD/(1+lambda_BD), and the difference between lambda_BD/(1+lambda_BD). And, F is in direct correlation with the rate of expansion, meaning that the more rapidly aliens are expanding the less chance we have of meeting them at this time.

[@jamesbond_007]

I'm glad you made the point at the end about not looking in the right way. We've made assumptions that alien civilizations will communicate with technology we know about, and/or that they're "leaking" communications. Imagine, for a minute, that there is some FTL communications mechanism, a la Star Trek's subspace. We would not detect it at all. Assume further that if there is such a mechanism, that the time from a civilization that's radio-leaking to a civilization that's "subspace" using is only about 200 years or so. We might pick up one or two signals (assuming they are radiating with sufficient power to be detected) over a substantial realm of time. That inverse square law renders the signal strength that leaking civilizations emit very very small with intra-galactic distances...so our chance of detecting them seem incredibly slim.

[@johnbennett1465]

Jumping from flasks that are almost identical to planets that have been shown to be extremely varied is a huge leap! Consider a more relevant flask example. Take a bunch of flasks with random mixtures of 20 different chemicals and ask how many will dissolve your additive. Even if you know what the 20 chemicals are, you are still going to be hard pressed to make an accurate guess. I am going to try to watch more of this. But it really puts me off seeing such a wild non-sequitor.

[@colixo5731]

I love the approach, and it informs us of a likely outcome in a way which the drake equation cannot (my issue with it has always been its arbitrary unbounded nature) There are still many many variables which are unknown and unaccounted for however, so while i understand the pessimism, I wouldn't wallow in it too much.

[@lorenzo.bernacchioni]

Hello David, I landed here after watching your interview with Lex Fridman, I was really caught by the accuracy with which you present your thoughts 👏 About this video, really appreciate how you (and others) were able to build a reasonig and get conclusions on such precarious grounds (the little we know) 👏 Now my question: when you say "if lambda BD was really high we should see technological signature everywhere around us"... perhaps it's me but I'm missing the consideration of how the technological age could be incredibly ephemeral, meaning life could be everywhere and lasts millions/billions of years but when the phase transition to technology happens.. it's an instant in cosmological scale. I like to think to civilizations as lighting bolts, even in a stormy night full of bolts and thinders each one lasts few milliseconds and if you were a lighting and you looked around during those milliseconds...you probably wouldn't see any other lighting, and you would ask yourself "Really?! am I alone?!" Thank you very much for all your top quality contents 💙

[@annebevan5047]

Have you considered that the birth to death ratio may oscillate rather than be continuously rising or falling or remaining steady. Eg, in earths history boom and bust population cycles are common, viz the 5 mass extinctions that were followed by biodiversity explosions eg the Cambrian explosion. Also chaos effects allowing possibility of random oscillations around a mean may be relevant. If the Galaxy could be in one of the oscillations with a low Birth to death ratio, but way in future it may be way a higher, ratio. Food for Thought! Thanks

[@pa3efu]

Another great video David! There is possibly an issue with that what we are looking for: We have modeled our searches on where we currently are, but that is at best a short period stage in development. Our energy use has gone from practically zero 180 years ago, to a level that most of us agree is now unsustainable. It is this unsustainable energy use that results in this ‚techno‘ signature. If we were to completely resolve our unsustainable energy use in the next 100 years or so, then our signature may disappear too. That would leave us only visible for 250 years or so, which is nothing on the cosmic time scale. Jan

[@CoolWorldsLab]

Ye this is sometimes called the sustainability paradox (but I don’t see why folks call it a paradox)

[@Alexanders-Type-I-Civilization]

I'm sorry I have to say this but mainstream science needs a reality check. When goverments all over the world are worried about what flying in the skies that no one can explain scientist should pay more attention. An alien civilization could be 100% different from all the scientific methods we apply to comunicate or discover them. The science may be absolete here and we need to change our way of understanding other worlds. We may exceeded in math but our theories are as best as our primitive thinking.

[@adscomics]

It’s also worth mentioning that the Drake Equation was never meant to be taken seriously. It was always more a thought experiment than anything else.

[@MikeViker]

This is true science, no wishful thinking nor green men or story tales.

[@tonybarry5101]

Very good exposition of the paper ! I only wish more papers came with such a clear explanation. Well done.

[@johancos8532]

Thank you, Dr. Kipping, and the Cool Worlds team for this video. One of the things I appreciate most about your channel is your willingness to share perspectives that challenge the prevailing cultural narratives. While science must evolve with new information and synthesize data into new hypotheses, cultural shifts aren't typically grounded in evidence. Because of this, I believe it's a mistake for science to be swayed by cultural trends.

[@yahccs1]

What was the formula for that S shaped curve? and that probability curve with the valley? It would be nice to see those on the screen when you show graphs like that.

[@carrickrichards2457]

The big factor I'd like to see included in any reformulation of Drake is an 'endurance' factor for solar ecosystems. How many asteroid/ solar flare/ orbital instability (or other) 'interuptions' will there be in a ~3 billion year process? Our own system is very well protected by the very unusual planetary layout.

[@dvanremortel]

Thank you for this video. It captivated me and moved me to revisit this premise.

[@MagicalHackerMTG]

The answer may be this: 1. Take the image from @10:21, and keep that in mind as the rate of existence. 2. Multiply each value by X, where X is the probability that we can detect that civilization. 3. If X is low, then the entire right side of the graph becomes more likely. Is it possible that X is low? Yes for a few reasons: A. As civilizations become more advanced, aren't they progressing towards producing less impact on their environment? Maybe advanced civilizations are difficult to detect because those civilizations intentionally hide themselves. Maybe they are inadvertently hiding themselves out of a desire to preserve their environment. B. As civilizations become more advanced, they may fear being detected due to detection leading to possible immediate annihilation out of another civilization becoming afraid. The only way to prevent that is a single civilizations being so much more advanced that they become the "parent" to the fighting kids. This system could mean that it's galactically illegal to intentionally contact civilizations that meet some particular criteria. C. As civilizations become more advanced, they have further reach and expansion, but why do we claim to know all the possibilities for where they advance towards? Who can reasonably say that expansion occurs outward in the x, y, and z coordinates and not to coordinates we currently cannot travel towards? D. A serious application needs to be applied towards the simulation theory, which uses a similar argument: If simulations exist such that recognizing them as simulations are impossible from within the simulation, then it's more likely that we are in one than not. Just because something is more or less likely does not mean that it's more or less correct. A person with a rare disease still has that disease, regardless of how rare it is. Basically, we cannot apply probability to the process of discovering truth.

[@prototropo]

What a fabulous new approach to considering the Drake Equation--and, of course, the Fermi Paradox. Dr. Kipping breaks new ground--again. I'm so proud to support this channel. My problem with the Drake and Fermi challenges has been that few assessments so far have integrated an astrophysical conclusion with the input of abiogenesis, biology, evolution, paleontology, anthropology, history and the philosophy of civilizations and technology. If we continue spending a lot of time and money on the search for alien life forms in the universe, let alone intelligent life, a confident assessment should absolutely recruit the regard of those other disciplines. No? I say that as someone who maintains a personal list of all the implausible turns of fortune that permitted life on Earth to get this far. It's a long and daunting list. If ever such a grand, integrated effort to answer the alien life dilemma gathers together multiple fields of study, I sure hope David Kipping is in that room.

[@25usd94]

Birth death formalism seems pretty useful. I like to wonder if it it is possible , in the high occupation case, for a given civ to passively emit enough techno signature to be seen across cosmic distances WITHOUT megastructures. Those distances are huge!

[@petrosros]

Applying what we think is happening here, extended through speculative mathematics (as implied by the use of the word 'Relative'). The upshot being that we have no table, jars or civilisations. Our starting point is a philosophical conundrum that must first be undone, and it is no Gordian knot, as we have no sword to begin with. Said sword being our collective epistemological undoing.

[@ericlondon2663]

Besides, we would recognize ancient Rome as a civilization of sentient beings. BUT we would not get a technological signature from an alien version of ancient Rome. We could be living in a galaxy teeming with life and civilizations but none of us meet or make contact due to technology and the mere factor of time.

[@Henriiyy]

I have some questions about this: As far as I've understood from watching the video and reading the paper, you assume that lambda is distributed log-uniformly between some lambda_min and lambda_max. You then calculate the probability distribution for the occupation fraction F using that assumed prior. My remarks are: 1. You can pretty much choose arbitrarily low values for lambda_min. Doesn't this choice already presuppose the conclusion when choosing very small values of lambda_min, like 10^(-10^10)? I can't really see what prior distribution the choice of that lambda_min itself should follow. 2. In your paper i haven't found any calculation for the expected value of F using this prior. I find it hard to come to any conclusions about the observations (like you do) without seeing directly which impact assumptions about lambda_min/max have to . So I (tried to) did it myself: I took your prior function Pr(F) dF and integrated \int_{F_min}^{F_max} F Pr(F) dF. I conservatively chose F_max = 10^-3, because values much higher are ruled out by observations. Note, that this also rules out even the "Zone 1" in your diagram. This gives: For lambda_min = 10^-10: F = 6e-5 For lambda_min = 10^-30: F = 1e-5 For lambda_min = 10^-100: F = 5e-6 For lambda_min = 10^-1000: F = 4e-7 Considering that there are surveys like GAIA looking at about 10^9 objects, I think your calculations are not neccesarily a cause for despair, even for very small values of lambda_min. I would be very interested in what you think about this. PS: The expactation value for F is ( ln(lambda_max+1) - ln(lambda_min+1) ) / ( ln(lambda_max) - ln(lambda_min) ), approximately lambda_max / ( ln(lambda_max) - ln(lambda_min) ) for small values of lambda_max.

[@jamespalmer6278]

17:27 - You just made a case for buying lottery tickets.

[@shawnraborn6637]

It’s absolutely incredible that we can use sheer logic and reasoning to draw conclusions for things which we have so little data. If hypothetically we were to establish contact with someone out there, could the same skills be used to decipher their language? I realize this might be a little too speculative for your taste, but I would love to see a video on something like that! Anyway, much love! I look forward to every new video from this channel ❤

[@bunzinthesun]

It’s absolutely silly to think that we can use sheer logic and reasoning to draw conclusions for things which we have so little data.

[@DonNoddingPolitely]

Great work man. I always find myself oscillating between 2 positions when faced with the apparent lack of other technologically advanced life. 1. We are too early - 5Ba year old planet in a 14Ba universe. Basically just a kiddy-wink. 2. We are too late - There was a 0.5 billion year window when the universe background temperature was 0-100 degrees Celsius. Liquid water everywhere. The universe would have been teeming with life. Now we are in universe a few degrees above absolute zero. We are at the tail-end of things. Sigh.

[@DivineEternalOne]

Nice, you used the end scene of Star Trek:TNG's episode 'Family', where Picard's nephew is watching the stars.

[@Jedbullet29]

Ahh, I'd forgotten about the J.ET bathtub equation. Great work in linking it to...errm, we are very rare or alone. I'm terrified and disconcerted but that's what the data says for now.

[@riroo8275]

While I am somewhat critical of your criticisms of the Drake equation (among other things, it was deliberately open-ended to account for, as Donald Rumsfeld once put it, "unknown unknowns") I greatly appreciated how your "birth-death formalism" naturally yields a logistic curve & its attendant implications. As I'm writing this comment before finishing the video, something I find myself wondering about is whether you've explored how this model squares with various astrobiological scenarios--I am struck by how well it models the grabby aliens hypothesis, for example. In addition w/r/t your comment about not seeing any result yet, my comment is this: We've only had technology capable of communicating with aliens for, what, a hundred years? If an alien civilization at the edge of our radiosphere (so to speak) heard it TODAY and sent a message back, it wouldn't be heard for *another* hundred years, so the effective limit of space where our radiosphere has exhausted the option of communicative intelligence (i.e. they could've sent a message *and* we heard it by now) is really only 50 ly, and a sphere with that radius is such a tiny tiny tiny fraction of the Milky Way that I think it's frankly naive to give up by this point, and doesn't really have any bearing on the results your model provides.

[@johnbennett1465]

Why do people assume colonization is inevitable? Small self replicating probes are impossible without major changes to our understanding of physics. It will be very complex and expensive to set up a colony. So even if a few planets setup a colony, it is unlikely that the colonies will do it. Thus it is unlikely to expand to the whole galaxy.

[@ericastross4177]

Really clear with supportable conclusions. Dreamt last week that aliens applied perception filters and although all about us, like Dr Who battling the Silent, we have no capacity to conceive the other. So thumbs up to rethinking sensors. Btw, as total speculation: if non-local comms were a thing, do you think anyone would bother with those operating with radio signals?

[@qpwodkgh2010]

Fundamentally, there are not true steady states in our universe until we reach maximum entropy.

[@AndoLarousse]

What if it is not physically possible for a galactic colonization to exist in the first place? that's the one thing I never see questioned in these theories. What I mean is, what if the maximum speed available to a mortal being is so slow that it makes interstellar travel both futile and pointless? Maybe you can get to other stars, but by the time you get the technology to do so, you already got the technology to create the resources that you initially would think you would only get from colonizing other stars. Another thing is, why do we assume that entire galactic colonization is the natural course of the average civilization? Don't dyson spheres theorize against this? If a civilization can manipulate the power of their own sun and system and regenerate it at will then there is basically no need to go out but rather to go in. Maybe the natural course isn't to expand outwards but inwards into a simulated universe. Maybe the average height of civilization takes place in a type 2 civilization with all of its inhabitants gathering infinite energy from their regenerative star and sleeping living in a sort of matrix where everything is just better or more psychologically convenient, with no reason to expand onto other stars, idk.

[@BMXaster]

Wouldn't another option out of your paper be that the flask analogy from the beginning is wrong? Yes you could say on all those earth-like planets, either life should be possible or impossible to emerge. But what if the parameters for life to start are really just that incredibly tight? Maybe one day we find an exact earth replica, except that there doesn't exist any carbon and there is in fact no alternative for lifes base material, like silicon. In that case, we would find that according to that flask analogy, even though the earth planet is 99% the same as our earth, there is no life and we then conclude that life is really rare among all those almost identical flask, when in fact a very very key parameter just was of. Like the water in the flasks, but sometimes it's regular water, and sometimes it's tritium. We then try to conclude if water is radioactive and see that in 50% it is, and in 50% of cases it is not. On the surface, the circumstances are perfectly the same but in reality, we missed a key aspect of the whole experiment. Maybe my thinking is off but to me, this seems like a possibility. Also, I triee my best to explain my thoughts but english is not my native tongue. Very cool paper and video still!! Thank you

[@kylekingsberry5680]

It seems to me that the most likely explanation is indeed just that we are at the forefront of the "state change" in our galaxy of it becoming colonized with life. Even just looking back over the last 100 years of human civilization, it is incredibly apparent. We are growing and expanding at an ever increasing rate, and really if anything we are now able to peer into the future through the lens provided by your paper. Very very intriguing :)

[@metroidragon]

The best video on the drake equation and probability of alien life I've ever seen, and I've seen at least a half dozen. One aspect I've always considered undertalked about is how if there is a 'galactic habitable zone' then stars that are similar in composition and location to ours would be 'good' candidates for finding life, since we know that they have approximately the correct mix of elements and history. Intelligent life might evolve in condensed pockets, likely with titanic swaths of lifeless universe between these. Anyways, assuming we aren't the local firstborn, I say we will have better luck finding ET if we hyperfocus SETI on similar G-type main-sequence stars born from the same parent nebula as us. (also any local aliens are much more dangerous from a grabby aliens perspective)

[@erickhedberg6564]

I would recommend Joes Arguelles' "Surfers of the Zuvuya." He tells of the Arcturus-Antares midway station. It's about 300 light years away. The Pleiadeans have an empire, we exist on their outskirts. I try to get hard data from the alien at the midway station, or read the screens, but it is hard to focus and I imagine such data would be privy, I'd have to perform some service to earn the curiosity, and what can I do but bounce around, but I was there for a fraction of a second, out of body, which I don't do anymore, but the bliss was too much, although I readied my notepad. I know of four aliens, the Pleiadeans, the Midway Station, a megastructure and a reptilian Emperor some Causal layers away.

[@vlad-pm2zr]

OP I've actually clicked on your video exactly because it was not a clickbait thinking this must be legit good. I wasn't disappointed!

[@dcasteaux9181]

All I know is that Mother Nature always has multiple variants of life. Diversity really is her strength.

[@imtrex521]

I'm just glad to live in a time when we consider such possibilities, depressing as they might be.

[@koozdorah]

Subscribed. Initially because it’s not AI and I can see the actual person. Yes, it’s come to this. Who would’ve thought. But also well done, how have I not come across this channel before.

[@justsomedudeontheinternet]

what is your reasoning behind saying that the births/deaths will reach an equilibrium?

[@justsomedudeontheinternet]

other than the mold thing, that would mean your equilibrium would take place at a universe completely filled with life

[@crush_ed_it]

I really appreciate what you and the team create. Thank you so much!

[@jeroenvancraenenbroeck1071]

First of all: this is a great approach to nail things down via some basic mathematics. However, at first the S-shaped curve of F versus lambda-BD seems to make sense to me but in fact, upon further reflection, it makes it rather confusing and things get blurry. Basically the correlation F versus lambda-BD (simplified as equation y=(x/1+x)) is logarithmic and not S-shaped, isn't it? What you get is a correlation that readily jumps sky high and then goes (asymptotically) to a maximum. The S-shape arises when plotting the function on a logarithmic X-axis. But that's obvious: for very small values of lambda-BD, F is equal to (+/-)....lambda-BD (yes, for small lambda-BD, the correlation can be considered to be linear). And for high values of lambda-BD, F gets close to its maximum, being value 1. What is done here, by converting it on a logarithmic X-axis, is kind of stretch the graph out of perspective. The S-curve indicates there should be an inflection point (middle of the S-curve) but for the function x/(1+x) there is no such inflection point at which the slope is the highest; it is a basic logarithmic curve. This also means there is no induction period followed by a steep rise and then, after inflection a rapid flattening of the curve; there is no "all or nothing but nothing in between" in this relation at all. Moreover: for the logarithmic relation the steepest slope is at the very beginning, (d(F)/d(lambda)) = lambda), this is in the limit lambda-BD = 0), not somewhere halfway the curve like in the S-shaped version. From this point on, at the very beginning, the slope only gets less steep. So when comparing to things like mold growth or Iphone sales, the amount of mold or number of Iphones sold indeed renders a S-shaped curve when plotted on an absolute time axis, not on a logarithmic time-scale. I'm confused....What did I overlook? But apart from that kink in my reasoning, this is a great video. Cool Worlds rock!

[@davecorry7723]

The question is: is life thermodynamically favourable? If it is, it'll be unstoppable and everywhere. If it's not, we're probably alone. I remember reading a paper years ago that said the photons bouncing-off a sterile moon have lower entropy than those bouncing-off a planet with a biosphere. Thus life degrades energy more than non-life. And as the universe wants all energy maximally degraded, then life's the party it wants to spread everywhere. Is this true? Is this measurable? Surely this is the key question.

[@jolez_4869]

I disagree with the conclusion that F has to be very small or large with a high probability in the steady state model that was presented. The reason it seems that way is because the plot shown in 10:30 is logaritmic, not linear. Nothing wrong with log-plots, but they don't really reveal how "many" numbers lie in a certain interval. What I mean by this is that the "size" of the set A = [ 0 = 10^-∞, 10^-6] is 10^-6 but the "size" of the set B = [0.2 ≈ 10^0, 0.8 ≈ 10^0] is about 1, about a million times larger than B. So, the case that λ_(bd) has a really high negative exponent is not more likely than it having an exponent that is close to 0. If the explanation above seems difficult to understand, just take the function x / (1 + x) and make a linear i.e. a normal plot of it in the range of [0, ∞]. You will see that it covers all ranges of F from 0 to 1 pretty uniformly in x and then asymptotically approaching 1. There is no spike, i.e. it does not look like a step function, which it would need to look like if you wanted to reach the same conclusion as was presented in the video. I can agree with the fact that λ_(bd) is probably not large since F is probably not close to 1. However, that does not really tell anything how small F is as was reasoned above. It could be 0.5 for all we know. DISCLAIMER: I do actually agree with the conclusion if it can be shown that λ_(bd) is uniformly distributed in the log interval, shown in 10:30. However, the reasoning of why that would be the case was not shown in the video. This would be a fact that would really warrant an explanation since the whole argument of this video is based on that premise. I don't really understand why λ_(bd) should be log-distributed and I think normal uniform distribution would be more reasonable. However, someone that has read this subject more thorougly than me can explain why this is the case.

[@CoolWorldsLab]

It’s a subtle point and one I didn’t justify in detail in the video for the sake of brevity. If you have a scale parameter (such as this one) that is bound between two positive real numbers, then the reference prior (also known as the Jeffreys prior) is a lot-uniform distribution. This is essentially the prior that is most agnostic, least informative - imposes the minimal possible bias or preference into the analysis. It’s rigorously found by computing the Fisher information matrix and then evaluating the determinant of said matrix. A normal distribution would be much more informative, since it has a defined mean value. That’s appropriate for a measurement of something, but not for a positive real scalar like this.

[@jolez_4869]

@@CoolWorldsLab Wow, I did not expect a reply straight from you! I am honored! The subject I wrote in the question above actually started to intrique me somewhat and I took some time to read your paper and about prior distributions. It has been a while since I studied bayesian statistics and hence I have been looking for some good reference material for this subject. Do you have some in mind, if I may ask? Again, thanks for replying!

[@wabbit4936]

One thing i always thought about the question of technological civilisations is that their technology may be undetectable to us, if you're a squirrel your understanding of squirrel made inventions is to the extent of twig nests, you don't look at skyscrapers, cars and airplanes and think they are made by others like you, you just imagine they were always there, same as the trees and the grass and the sky. Maybe the technology we're looking for is actually so advanced that it takes the place of the universe, perhaps when we look at the universe itself with star systems and black holes and dark matter, most of it isn't natural at all, it's just so far beyond our narrow minded grasp that we don't see it for what it truly is.

[@aasishwarsaravana5748]

This video was amazing and thought provoking, and although unrelated to the video, I would like to share few of my thoughts. I think the phase transition in which civilisation becomes widespread across the universe depends on two fundamental factors :- Energy and Will The more energy a civilisation can produce, control and harness, the faster it can use the energy to expand its civilisation to other celestial bodies which might be uninhabitable, and use the energy to harness and convert resources to build structures for habitation such as cities and space stations. But for all of these to happen, any technologically progressive civilisation must have the Will, Curiosity and Stubbornness to explore and colonise celestial bodies, harvest resources, harness more energy in different forms and use that extra energy to further colonise systems. Without this Will, even if any civilisation may even be more technologically advanced than ours and harvest lots of energy, if they are contempt in living in their own planet and living the good life, they can never expand to space. We as humans have come this far because of our innate Curiousity, and as an expansionist species and our stubborness, and the will to do more crazy experiments, we have come far, and our deep desire to set foot on the Moon, we essentially have the technology to become a space faring civilisation. However, current trends of people looking upto tiktokers and celebrity influencers have muddled our brains to seek instant gratification rather than pursue our innate curiousity, not to mention progress is also held back by bureaucracy and corporate financial performance, therefore extinguishing humanity’s ability to take great risks just to find answers, and use the technology to create a better future for children and hope they carry on the decades of work done to further develop the technology and answer more questions. And this is all if we don’t destroy each other in the process. In fact, I would say excessive mindless regulation, corporate pursuit for numbers and the over-looming threat of competitive humans wanting to destroy each other and harvest all resources without consideration is what will be our GREAT FILTER to colonise the solar system. Although the future of many people seems bleak, I still have optimism that humans will further advance civilisation. With companies such as SpaceX and newly formed rocket companies wanting to launch tons of mass to orbit enabling more space habitats and the infrastructure to colonise other planets. And the valuable research done by ITER and LHC will help us harness the megawatt energies from powerful star powering fusion reactions will enable humanity to enter a new age, with abundant energy production and mass tonnage to orbit. And if the great filter doesn’t hinder our ability to visit space, we will eventually become a space faring civilisation. What is even more wonderful is that even if the majority pf population wont understand the challenges of space, they still root for it, which gives me hope that one day, all of humanity regardless of religion and race will come together in favour of making humanity space faring, as every human still has the innate curiousity which defines the human species. If you read my comment, thank you for reading this far! Have a great day!

[@Malhorne]

There was never any "glass ceiling" into the Drake equation, which could be very interesting to introduce : Considering the ""minimum" size of the universe, and the fact it is expending so fast, if there is no proper way to consider that travelling faster than speed of light is in any way possible, it looks like totally impossible that we meet one day any alien intelligence, if there was any, it would be no tiny chance that we cross any one by the time our own civilisation or any other should leave any proof of existence on a very long time scale... so being alone or many, would not change anything, as we will be all the way long not be able to prove it.

[@Pabz2030]

Personally I think these facts are true: 1) The likelihood of many alien lifeforms across the multiverses is very high 2) But the speed of light really is a hard cap on travel times for any lifeform 3) So the scales involved mean the chances of any ever being close enough to meet before they go extinct are very infinitesimally small Even the closest galaxy is nearly our entire existence away from us (179,000 years) if you travelled AT the speed of light the whole way. And Andromeda Galaxy is 10x our entire Human existence away (2.5Mn years) at the speed of light. Most galaxies we'd never reach before our sun went nova back here. And that's just this universe. Imagine ant colonies in the Australian outback... There's many of them, but they are so far apart they never meet within their lifespans. All we've managed to do is look at a few rocks within a few meters of our nest and conclude that the entire continent is empty

[@Inug4mi]

I appreciate you still wanting to believe even though the math increasingly seems to suggest that we might be alone. My own feeling (and yes I’m aware it’s a feeling) is that we are alone. I hope I’m wrong, and I still think we should keep looking despite my feeling, but, yeah.

[@marqod1437]

Thank you for mentioning that a good practice before publishing a scientific paper is to try to tear your own findings apart. Sure the peer review process will do that as well, but it could save you some embarrassment if they find an elementary flaw. After all, that is the bedrock of Science, skepticism and doubt, questioning EVERYTHING, including your own assumptions.

[@TheMightyCookieShow]

My ultimate and for real sense is that we are surrounded. I think when we finally have the technology and I'm talking Star Trek scanners level technology to detect life we will probably detect it about any and everywhere we look in some form or fashion.

[@ElephantWhisperer222]

I think there are a lot of people, especially mainstream scientists, who are afraid to think that there may be species out there that are much more intelligent than we are. Our egos never fail to make us look frail.

[@CoolWorldsLab]

I’ve never met a scientist who felt that way personally, I think we mostly think it would be super cool

[@rosaeruber225]

There's no such thing a mainstream scientists. There are only scientists.

[@TicTac2]

personally I see more mainstream scientists doing the opposite (implying life is a very common/normal property of the universe on no evidence)

[@djsarg7451]

We have studied 20 million stars, and not one can support life as they are ALL too unstable, we are alone. The Sun is the only stable star. Of the 4,100 solar systems studied, not one looks like our solar system, able to support life. Almost all the 4,100 solar systems studied have Hot Jupiters. In normal planetary systems giant planets form beyond snow line and then migrated towards the star. A small percentage of giant planets migrate far from the star. In both types of migrations, any rocky planet like an earth is lost in these planetary migrations. Most stars do not have planets. Many stars are in bi-star systems, thus no earth-type planets. Have not found another galaxy that can support life. Must have stable arms for life. Thus we are alone. The odds are currently at 1 to 20 million. Only a fool would say the odds will be better next year. 10 years ago this was 1 to 1 million and back then people were saying that is only 1 million. Finding more stars will not change the odds, it will be soon, 1 to 30 million and on and on. The normal is Hot Jupiters and no earth and unstable stars. The Sun's energy output changes less than 0.1 percent. All other stars start at 3 % and go up. So we are alone. 1)We have found no other Galaxy that can support life. Life needs a barred spiral galaxy with stable arms. 2) In that stable barred spiral galaxy, only stars in the Galactic habitable zone can have life, too close to the center (where most stars are) have too much radiation. Too far from the center and there are no rocky planets, due to the lack of heavy elements. 2) As already stated, half of the stars are in bi-star systems, thus no life. 3) Normal, is solar systems with Hot Jupiters, no life. Why have we not found a stable star like the Sun? The appeal to billions or even a trillion stars does not add any proof of life outside of the solar system. Only a solitary, second generation, G2V star, 4.6 Billion years old with the correct metallicity (0.0122 [high metallicity]) and correct temperature (5,772 K) are stable enough to support complex life. Star must be the correct distance from center of a stable Spiral galaxy (too close too much radiation, too far no rocky planets) and on and on. The planet must be not too large or too small with long lasting magnetic field. Also not too much sulfur or water. Just above and below puts the number of other star-solar systems with life at none. (no other stable Spiral galaxy has been found) The Sun is a G2V star. Only 0.7% of stars are G2V. Only half of the G2V stars are solitary. Age: G2V stars age from 0 to 10 Billion, Sun is 4.6 Billion, must be 4.6. Metallicity: Can range, -4 to +1, need, must be (0.0122 , ± 0.05) G2V Temperature: Can be from 5,860K to 5,720 K, must be 5,772 K And on and on. We are alone.

[@frankkolmann4801]

As always I am in awe. Just a teeny tiny point. The colonisation of the Milky Way at speeds we can presently attain means use of Generation Ships. Many have tried but no one has succeeded in building a self sustaining bio-dome here in the most hospitable place we have. What chance Generation Ships?

[@TicTac2]

what is a self sustaining bio dome exactly