Crowded or Lonely? The Statistics of Alien Life

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 https://youtu.be/iLbbpRYRW5Y 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)

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!

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.

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.

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

YouTube is either teeming with intelligent scientific channels or there are barely any. Cool Words is the shining beacon on an otherwise desolate video sharing platform!

very rare to see a video mentioning aliens, while still grounded in reality

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

"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 😅

E.T. Jaynes thought experiment is the perfect embodiment of the quote "Once is never, twice is always." Unfortunately, we are stuck on the once is never part of it, both for stars with life in the universe, and in regard to civilization developing on a world filled with life.

I do think there is one major problem with this though is that while you have a 'death' term a more accurate term would be 'invisible' - in other words when we would no longer be able to detect a civilization with our existing telescope technology. One reason for that could be death, another reason would just be a switch to wideband radio communication, as well as more use of cables, etc. Like, even though we use way more communication tech today then in the 1960s the amount of 'radio light' we give off from more modern technology is probably a lot lower. And TBH I don't really think that if there was another planet with earth-like technology, we wouldn't see it. All the techno signature stuff is based on the idea of civilizations way more advanced then ours (i.e. dyson spheres, etc) But we don't actually know if there will ever be a dyson sphere around the sun, for example. Honestly at this point, it doesn't seem like we would be able to detect a planet with earth level technology with our current "observation power" (other then, ironically, chlorofluorocarbons in the atmosphere - which we are phasing out anyway!)

"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

Been waiting for this update from Cool Worlds for several years. Probes the limits of academic literature relevant to the Fermi paradox and the question of aliens all the while steeping in the ever deeper wonders and mysteries of the universe - Cool Worlds doing what Cool Worlds does best.

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.

CIVILIZATION BLINK RATE Q: Hypothetically, if Moore's Law continues indefinitely, then how many years before a silicon computer must become an optical computer, then subatomic computer, and then for superintelligence to operate most efficiently the computer must be made of neutron star or quark star material? How many years for the shrinking CPU to become so miniaturized that it becomes identical to a primordial black hole? How many years does the math dictate when that would be necessary? Just as a mathematical exercise. Now, if all superintelligent alien civilizations followed Moore's Law in this way, and entire planets and solar systems were converted into pure CPU's, would that 500?-year progression be detectable from Earth, merely a quick blink at galactic time scales? Exponential growth has a way of growing exponentially. Until the limits of the physical substrates of intelligence, the Planck-scale circuitry. Would trillions of such quark-plasma CPU's all over the galaxy behave like dark matter?

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.

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.

While our observations can clearly rule out every planet having a technological civilization, it's still entirely possible that every suitable planet has life. The Earth could very well be representative of this; it has had life for almost its entire history, while only having a civilization for a very brief moment. In other words, maybe life is extremely common, and civilizations do try to emerge very frequently, but they are so short-lived that no one ever lives long enough on astronomical timescales.

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.

Amazing research and great video as always. A couple thoughts; If Galileo could glimpse the International Space Station with his telescope—a revolutionary technology in his own time—he wouldn’t have the resolution to even guess at what he saw. He would only see a bright moving point in the sky. The difference in our level of technology from Galileo’s time is impressive, but it might pale in comparison to the difference in technology between a Kardashev 0.7 civilization and a Level 3 civilization. An alien civilization capable of colonizing the galaxy would possess exotic technology that we may not have even dreamed of yet. I’ve always thought it presumptive to assume that we would be able to identify their presence at this point in our development. If we assume there’s some merit to this argument, this makes it difficult to dismiss the high-occupation scenario. We still wouldn’t have a clue where we were on the curve unless we improbably spot another sub 1 civilization. And then we would have an n of 2.