To the point that the Drake equation is arbitrary, take the term fp - the fraction of stars that have planets. It seems to me that a missing term before that would be ft or something - the fraction of stars that could maintain a stable, habitable zone for the time needed for civilization to develop. We might also add a term for the fraction of stars that do not undergo life-sterilizing events such as gamma ray bursts or supernovae nearby, having their planetary system disturbed by close star flybys, existing in an area with too much radiation (galactic core, for example), or being formed from clouds depleted in necessary chemicals for life.
For instance, red dwarfs are the most numerous stars, but they may be completely unsuitable because they tend to throw off flares and because any planet close enough to be in a habitable zone will likely be tidally locked and maybe tidally locked planets never form life.
Hot blue stars don’t live long enough for civilization to develop. Other stars give off powerful flares or are quite variable in brightness.
And I’m willing to bet that as our knowledge grows, we will find all kinds of phenomena problematic for life that we currently don’t even know exist.
Imagine an intelligence that developed outside our universe, put it on a planet that didn’t evolve life (a sterile planet otherwise identical to Earth), give it the same information that we currently have about astrophysics and cosmology. Then ask it to predict the odds of life evolving in this universe (as per our current understanding of what life is). My guess is that it will predict the odds somewhere between zero and virtually zero.
Now put the extra-universal intelligence on Earth as it currently exists with our biosphere and ask it to predict the odds of extra-terrestrial life evolving elsewhere in our universe. My guess is that it will predict the odds much, much higher.
Even though Earth’s biosphere is a single data point, it ups the odds of extra-terrestrial life evolving significantly. If it happened once that we know of, it probably happened many times given ~1025 chances to do so.
The odds of other technological civilizations evolving (given our 1 data point for that too), the odds would just be a magnitude of order lower than basic life.
Did you even read the entire article? Nothing you say here disagrees with their conclusions. They most certainly did increase the space between random distributions-that was the entire point of the study.
They simply realized, after noting that many past studies had, in aggregate, estimates that were both likely too high and too close to each other, that if their Monte Carlo probability distributions have a sufficient spread between the high and low ends of each of the factors, that there is a significant chance that we are It (for the galaxy if not the entire universe). That most certainly can mean that one or more subfactors* may very well be close to zero, in which case the entire result will have a limit very close to zero.
[*Does anyone know if a version of the DE exists with dozens if not hundreds of subfactors?]
Thousands of light years, billions of years old galaxy. Do the math.
There has been sufficient time for a species to spread out across the galaxy. Many times over in fact.
In terms of signals, the fact that we see anything at night shows that signals can propagate over these vast distances. And it doesn’t need to be discrete signals sent to us. I mean, we have been able to infer the existence of planets based on their effect on stellar signals.
But, when it comes to advanced ETs, at this time, we don’t see any deliberate signals, any inadvertant signals and nothing that would allow us to infer their existence either.
I didn’t read every word but I downloaded the PDF and read the abstract, conclusion and skimmed the rest.
And I am explicitly disagreeing with the conclusion, so I think you are the one that didn’t read something – my post. I am disagreeing with the notion that this analysis gives a sound argument for why ETs may be less likely than previously estimated.
Yet you agree with the authors that the odds are less likely, and with their nonmathematical reasoning. If you want to quibble with the use of a very commonly used statistical method to generate probability distributions, knock yourself out.
You claimed that I agreed with their conclusion. I have explicitly stated twice (and this now makes a third time) that I do not, and I gave my reasons why.
Instead of acknowledging your error, you’re now saying that I have agreed with one part of the reasoning behind that argument. Sure. So what?
Right, great & thoughtful post. I have no doubt there is plenty of Life across the universe… even “life as we know it”. And similar but less with Intelligent life of some sort, maybe octopuses. But then we need to drill down to intelligent technological life, and that gets a little chancy- still I think there probably is- somewhere.
But to think there is not just life, but intelligent and technological life within the 100 or so Light years around Earth? I have grave, grave doubts. The fact that there may be such 10 billion light years away is fine. But they ain’t visiting us. Intelligent techo life has developed just once in three billion years.
Mind you- I would not be surprised at all there is life of some sort elsewhere just in our Solar system.
The computation leaves out an important step, or perhaps I missed a definition. I can well imagine a sorta advanced dolphin society that communicates- we have it now, to a limited extent. Or one based upon Cephalopods that communicate via colors, or one that uses scents, or …But then we need one that can communicate off planet, even using radio. If we are talking long distance communication- Humans have used semaphores and telegraph for quite some time before talking over radio. Maybe the advanced civilization never uses anything at all like radio, etc.
I suppose you could, but one term is a property of stars, and the other is a property of planets. Using Ne to encompass characteristics of stars muddies the relationships.
But here’s the big thing I think many miss about the Drake equation: It’s really a tool for organizing your thinking around thr problem, not an equation to be used to find exact numbers of anything. It’s more of a mind map than an equation awaiting numerical solution.
We could probably add many more terms to the Drake equation, and almost any other terms in it could be broken down into unlimited sub-terms. But it might not help us think through the problem any better. I would argue that new terms should be added to the Drake Equation as we find criteria that affect the chance of life at a similarly high level.
For example, let’s say someone did a study which found that over billions of years the majority of star systems came under fire from a gamma ray burst close enough to sterilize them (not true so far as we know, but suitable for a thought exercise.) If it was a major factor in determining the possibility of life, it would make sense to add something like Pgb to the main terms (probability of avoiding a gamma ray burst sterilization). If it’s a small factor, it might be something to be added to one of the terms already there.
I agree with this. Be fruitful and multiply is the sign of a species still filling in their planet. Keep it up once they fill up their planet and they’ll crash, or else not have enough resources to expand.
In other words you can create a condition of scarcity and poverty as you expand, or you can use birth control. Not a hard choice.
As for consciousness, I kind of agree, which is why I said “as far as we can tell.” There is some evidence other apes are conscious. Who knows about dolphins?
Yeah, but it’s never going to be practical. To expect a civilization to travel the stars (and presuming that light speed is indeed a limit, and one that is not remotely approachable for beings with significant mass), you’re talking about it traveling away from its home planet for thousands of years, at minimum.
I think that it’s entirely possible that it’s beyond the scope of physics for any advanced society, no matter how complex they get, to be able to colonize outside their own solar system. All of our sci fi where this happens is predicated on the ability to easily travel between the stars, at speeds significantly faster than light - what if that is simply not feasible, and never will be, no matter how much we learn or develop.
If that be the case, and if the typical civilization is a few thousand light years from any other civilization, then there might never be contact.
What’s that old mantra? Absence of evidence is not evidence of absence. Our exploration is in its infancy, counted in mere decades. (Voyager is something like 19 light hours from Earth)
I wonder, though, to what degree we may misinterpret signals, or if we may be yet again limited by distance, such that signals dissipate or fade into obscurity. Again: the vastness of space may simply be prohibitive.
(You’re also comparing the signaling power of stars - the most imposing force in the solar system - with something a sentient life on a planet can create. I don’t care how advanced we get, humans may never be able to create an alien communication device with the luminescence of the sun).
You said you disagreed with their methods, not their conclusion, which perfectly and simply dovetails with your upthread statement, which explicitly said that it is likely that some of the DE terms were close to zero because some of the subfactors would be close to zero. They merely came up with a statistical method to quantify that (vs. doing what most others have done over the decades, which is to make single guesses then just multiply them together), that you said you didn’t give much credence to. Their conclusion (tech civs = 0 is pretty likely) would likely be strengthened by adding extra subfactors into their proceedings.
No longer interested in this silly nitpicky nondebate with you, btw. My googling of discussions of the paper has revealed no criticism of their statistical methods per se. If you want to try to dig some up, knock yourself out.
Correct. To often I have seen the following bad logic- 1. There are thousands of billions of stars, with thousands of billions of stars (true). There must be life and intelligent life on maybe billions of planets (Logical) 3. Thus- UFOs are real!!! (Bad logic)
There certainly could be intelligent life out there far advanced from our civilization, I am willing to accept that as a solid maybe. But- we will never see them, meet them or even know they exist.
“Eukaryotic” is not synonymous with multicellular. But I think the evolution of multicellular life is your point here? Although it took a long time for it to happen for the first time, multicellular life has evolved on many independent occasions just on Earth.
A reasonable model might be that a certain amount of complexity is required in the single-celled precursor, but that the evolution of multicellularity is then not too improbable. This is unlikely to be the Great Filter.
An alternative to the Great Filter is the possibility that the Fermi Paradox implies a higher probability that the universe is a simulation. I hope not, because this would be deeply unsatisfying. It amounts to “god did it”.
Biology is my weak suit. I thought Eukarotes were the unlikely development as they had mitochondria and complex cellular machinex for doing things like transcribing DNA. But naybe I got it wrong, and that wasn’t the highly unlikely development?
I think another explanation for the Fermi paradox is that complex living systems do not expand exponentially in perpetuity, and ghere is some as-yet not understood mechanism that limits ghe expansion of creatures so that they do not colonize entire galaxies.
Complex living systems can go through exponential growth phases, but in our experience on Earth something always stops the exponential growth: lack of resources, the rise of predators, or just a change in the behaviour of the species. Comolex systems thrive on diversity, because they behave in a directed but random way and any individual system can be wiped out. So ants never ‘took over’ and created a global ant hill, wolves and coyotes don’t form super-packs of thousands of individuals, aggressive fish species eventually either stop being aggressive or hit some limit to their expansion, etc.
Maybe by the time civilizations get to the point where they can move through space to other star systems, they attract attention from other civilizations who fight their expansion, and none of them ever get to the point where they can do big enough things to the universe that we can detect their works. Maybe if we ever discover extra-terrestrial civilizations, first contact will carry a warning not to step out too far or too big, or face extermination.
I agree that it’s likely that “expansion” might not mean colonization in the way that we conceive it, it might not mean exponential growth and spread of independent organisms. But I find it harder to imagine why an advancing civilization would not entail an exponentially growing energy budget. Even if we are all part of some uploaded unified consciousness living in virtual reality and simulating new universes, unless we lose all ambition to do new and better things our computronium requirements will increase. Is this possible without physical expansion?
Alternatively, perhaps a vast number of advanced civilzations do exist, but they lack the diversity that we might expect. Perhaps all advanced civilizations tend spontaneously (without interaction) to converge in certain important characteristics. That would allow scenarios related to the Dark Forest hypothesis but less unpleasant. It might be that all advanced civilizations avoid contact and conceal themselves for more benign reasons. Perhaps for the benefit of less advanced civilizations (a less incompetent version of the Star Trek “Prime Directive”), but I think more likely just because their own priorities change. We probably have no more insight into the likely motivations of a Type II civilization than nematode worms have about us. Perhaps exploring the external physical universe and interacting with other civilizations just becomes far less interesting than virtual reality. Maybe simulating trillions of new universes is more interesting than exploring this one.
If you want to quibble with the use of a very commonly used statistical method to generate probability distributions, knock yourself out.
And similar but less with Intelligent life of some sort, maybe octopuses. But then we need to drill down to intelligent technological life, and that gets a little chancy- still I think there probably is- somewhere.