60 years later, is it time to update the Drake equation?
phys.org
phys.org
What has changed is the assumptions about how we would detect a starfaring civilization. 60 years ago we were assuming radio communications because that seemed to be where our future was and, by extension, what we might expect other civilizations to do.
Obviously the values in the equation are unknown. We use such things to frame problems that involve unknowns like this. A good example: the anthropic principle [1].
Anyway, the more prevalent line of thinking now is that starfaring civilizations are likely to end up building Dyson swarms. This is a long and complex discussion. There are many objections but those objections tend to suffer from the problem that, if that objection is true, there should be more not less starfaring life (eg any form of FTL).
If matter is the ultimate limiter to civilizations then it makes sense that civilizations will try and amass as much of it as possible. It doesn't matter if not every civilization goes this route because even one such galaxy-spanning civilization within a million light years will stand out (based on the IR signature).
Even without that it probably wouldn't take more than about 10M years for humanity to colonize the Milky Way.
For example, if you start building space habitats (even if they are enclosed cylinders such that they hold an atmosphere and provide gravity via rotation) you need to put them somewhere. It makes sense to throw them in orbit around the star at some optimal distance (for example at 1AU +/- some amount), if you continue to put more and more such habitats around a star in similar orbits over time, in sufficient numbers, wouldn't they start to resemble a Dyson swarm?
That's essentially what a full Dyson Swarm looks like.
People have modeled how many orbitals you'd need to achieve this and I believe that if you orbit them at 1 AU (plus or minus) the mean distance between them is still around 150,000km.
What? Civilization runs on cheap, abundant energy. Before the industrial revolution we had to use labor animals, slaves and the occasionally water and wind mill. Providing light was expensive. Global supply chains (transportation), aluminium smelting, fixing nitrogen for fertilizer or calcination for cement consume stupendous amounts of energy.
If energy became cheaper then creating green fuel for airplanes and rockets, electrorefining all metals, desalination or perhaps mining and crushing olivine rocks for carbon sequestration would become more feasible.
Whenever vertical farming is discussed here the main counter-argument boils down to energy not being cheap enough. It's hard to compete with the sun delivering it to plants for free.
Besides, surely it must be simpler to build a fusion reactor on earth than harvesting enough material to cover the sun in solar panels. Would the solar system even have enough resources for that?
That's only true for low values of civilization. Even bronze age tech consumes more than hunter-gatherers which consume more than monkeys.
> Besides, surely it must be simpler to build a fusion reactor on earth than harvesting enough material to cover the sun in solar panels.
Dyson swarms sit higher on the kardashev scale than harvesting whatever you can get on a single planet. At some point waste heat rather than fuel will also become a real problem. Fusion reactors are ultimately thermal power stations, glorified steam engines.
> Would the solar system even have enough resources for that?
You'd start small with asteroids. And then disassemble some moons with shallow gravity wells. Which of course again requires stupendous amounts of energy just to move the material around but the sun still has billions of years left so there will be time to recoup that investment.
I don't lack for aluminium or even transatlantic flights (the most energy intensive think I could think of buying). If I really want to go to X I do. Price doesn't really bother me.
Maybe we can use 10x the current supply so everyone can have my lifestyle. But that's still vastly less than a Dyson sphere would produce.
For a long time energy was a limiting factor on human development. But I don't think that's true for the average westerner anymore. I want time off and less stress and relationships. Those mostly come down to social structures and information, not GJs...
You don't. You only think you do because you are living on borrowed energy, massive amounts of energy stored in carbon over the last billion years. Unleashing this stored energy is going to burn down our planet.
So yes, we need way more energy that is not tied to digging up dead dinosaurs. Even more energy if we want to put them back in the ground. And even more if everyone wants clean water. Everyone else that is not a westerner wants lights and water and food too.
Consider also that in order to grow human population at some point you start to need large amounts of energy to colonize new space, be it planetary, on asteroids or spade stations.
If more energy becomes available, demand for it will scale accordingly because of new possibilities.
Maybe we will consume vast resources of energy sending people or machines to explore the universe. Maybe we will need it to reshape our home environs. Maybe we will want to produce more people than can be supported on planet earth and profit in the arts and sciences from their contributions?
Never in human history has any amount of energy been enough so is simple extrapolation that if civilization continues to grow it will consume more energy.
The big differences between us and those merchants (healthcare, communications etc) are matters of technology not energy.
Proper sewers and drinking water has added much more to our lives than cars vs coachs.
And that's what I see going forwards too: I want a longer healthier life. But that will be a matter of medical discovery, not a CAT scanner than uses 1 million times more power...
We are nearly 40x as energy intensive per capita as as were just 2 centuries ago. If we rewind the clock to 1400 it becomes harder yet to compare because we actually captured so very little energy.
“2018, global energy-related CO2 emissions rose 1.7% to a historic high of 33.1 Gt CO2.”
Only thinking of your electricity or transport needs is missing all the other CO2 sources you rely on for your civilisation. For example you eat: “Globally, the fertiliser industry is responsible for about 1.5% of annual carbon emissions, largely because 95 per cent of production relies on natural gas as a feedstock.”.
The easiest proxy for measuring your energy usage is simply the amount you spend annually, which is usually closely related to the amount you earn. Most of our energy usage is hidden throughout our economy, due to our reliance upon our society.
Not quite. You have more than enough energy for what you could imagine using it for. But I guarantee you that a greater abundance of cheap energy will create new uses for that energy. That's how its worked for the entire of human history.
The amount of energy we're talking about here is mind-boggling, almost incomprehensible.
Typically we talk about this in the Kardashev scale (and usually the Sagan normalized variant). The short version of this is that:
- A Kardashev-1 (K1) civilization uses all the energy out planet collects from the Sun, estimated at around 10"16 Watts;
- A K2 civilization uses all the energy output by the Sun, estimated at 10^26W
- A K3 civilization uses all the energy produced by the stars in our galaxy, estimated at 10^36W.
We are roughly a K0.6-0.7 civilization on this scale. Human energy consumption I believe is estimated at 10"11W.
So a K2 civilization has access to 1 million billion times what we have now. It's like if every person on Earth had access to 140 million times the Earth's energy usage.
It looks like we'll move on from that, though the devil is in the details. :-)
Yes, absolutely. The main reason is that building orbitals is largely an engineering problem. You need a material no stronger than stainless steel. If graphite is feasible, it allows you to build bigger orbitals but it's not necessary.
Compare this to a lot of other proposed megastructures like space elevators, which would take a material to build that doesn't currently exist.
Also, to be clear, we're talking about Dyson _Swarms_. This is the original design idea that was called Dyson Spheres but that name is often not used because people mistakenly think we're talking about a rigid shell that encompasses a star. That is not and never was the intent. It's also impossible for many reasons.
A Dyson swarm is simply a collection of orbitals. The great thing about it is you can also build it incrementally.
Note that since these are spinning orbitals they have (spin) gravity and atmospheres.
Energy is absolutely a factor here.
Thank-you for clearing this up for me. I made a post after you, but you addressed the issues that I discarded. I now know more then I did. Thanks!
Also, to remain in a stable orbit, wouldn't the spin force have to match the gravity of the star? So there would be no effective force left to provide gravity would there? (Similar to how people on the ISS are weightless despite still being within earth's gravity well).
If I remember, Isaac Arthur on YouTube[1] explained that space elevators would not need exotic material, they could be built out of steel or stone if you had enough of it - you'd end up with an inverted pyramid of steel chain so wide at the base that the forces were distributed enought that nowhere was stressed past the breaking point of steel.
Not very practical today, but if humans never do develop Ringworld Scrith, not ruled out entirely.
[1] https://www.youtube.com/results?search_query=isaac+arthur+sp...
What Dyson Sphere's excel at is hiding their location* and capturing 100% of a stars output. At those sizes, a civilization MUST have already conquered the energy problem. It'd be impossible to construct without "free energy", because you need to convert that energy into matter to make/engineer enough material to create a sphere the size of the Goldilocks zone.
And as you said, you'd lose atmosphere & gravity* would be wonky.
But to address the fine article, the equation was a thought experiment. We now have hard data on the number of stars that we've looked at that have planets. And of those we have a hard number that have planets in the habitable zone. The Drake Equation presumes that you guess TINY numbers for those values. Well using known numbers and extrapolating the number of possible worlds with intelligent life jumps from staggering large, to incomprehensible.
As humans, we can barely communicate with others of our own species. Let's frame the problem another way.
Put two Americans in a room. One is deaf, the other is blind. How long does it take for them to agree on what to eat for dinner?
Context depends on language. We may have been bombarded by intelligent alien life for centuries; we just don't know that somebody is talking.
*Everybody forgets about gravity.
There possibly are ever more exotic applications that require more energy. Energy to matter conversion which you mention (and which also conveniently produces antimatter) requires very very large amounts of energy. The mass defect of the Tsar Bomba is merely 2.6kg, which also happens to be roughly equivalent the energy the sun that hits the whole planet each second. And then there are speculative things like the alcubierre drive or anything that involves moving entire stars.
Just FYI, but the Ringworld as Larry Niven envisioned it simply doesn't work because no known or theorized material is remotely strong enough.
To produce gravity a Ringworld needs to orbit the star. This produces centrifugal force that is tearing the ring apart. I believe around our Sun it would need to spin at about 1.2M mph [1].
[1]: https://www.bbc.com/future/article/20150609-will-we-ever-bui....
Because when I looked for an explanation, it wasn’t exponential: https://foothill.edu/psme/daley/tutorials_files/10.%20Error%...
Indeed, and today, the bulk of our communications are via enclosed waveguides -- fiber optics. And our remaining wireless communications are quickly evolving towards both decreasing power use and signal formats that are nearly indistinguishable from noise. Our period of "hot" radio emissions may only span roughly a century.
Radio is really only viable at the moment because pretty much all communications goes to or from Earth (sometimes via relay) and on Earth we can build massive radio dishes to transmit very powerful signals, and enormously amplify reception. In the future a lot of comms will be between points other than Earth, and in many of those locations radio antennas many dozens of metres across won't be viable. I think at that point we'll most likely switch to lasers for communications over interplanetary ranges. Starlink are planning to use lasers for their sat-to-sat relay links.
Specifically the rate of star formation has always been dubious, because there is such an enormous lag between star formation and the emergence of intelligent life (even if we turn out to be an extremely slow outlier), making it unsuitable for estimating the amount of civilizations active at a specific point in time.
My personal drake equation would include only factors that are based on the current state of the galaxy. But that's the Drake equation doing its job: making people think about cosmic odds. It doesn't need an update, because I argue it shouldn't be taken literally in the first place.
A few times a year, authors put out "new" estimations of the number of galactic civilizations, and to do that there is really not much alternative to chaining together these kinds of probabilities. While they sometimes may or more often may not use the actual Drake equation to do it, its value lies in the basic structure, not in its specific implementation.
But, as others have written, it's not really intended to be used that way.
Then at the opposite end of the scale is the long time that it took for life to go multi-cellular, and for a space program to be formed by an instance of that life.
Not really. While suggestive, all it indicates is that it arose on earth easily.
Those two factors may mean that abiogenesis could be an extremely unlikely event that randomly happened to occur very early in the Earth's life span.
Uh, this might be a tad bit hyperbolic. Does anyone even consider it serious science?
Without trying to precisely define scientific methodology, I think it always needs some connection to empirical evidence. This is the problem with the Drake equation, but also with some other speculative fields like string theory.
So I'd say that the Drake equation is scientific in the sense that it's motivated by scientific speculation, but has not yet found a form that can be tested.
If it’s a thought experiment, stop calling it an “equation”. People hear that something is an equation and they think that there’s real math and science involved. Call it the “Drake Conjecture” or something.
To this day, as WP notes, 'It is typically not possible to solve the Schrödinger equation exactly for situations of physical interest.' Yet he got a Nobel prize for it. Frank used his equation to get us thinking about SETI, and SETI is now decades old.
Yes, just like there are people who consider Crystal Power serious science. A lot of people are deeply impressed by the Drake Equation, presumably because they can't understand it.
In terms of renown, it is probably it the top equations people would be able to recognize by name, and tell you what it is about. The only equations that might be more recognizable by name are the Pythagorean theorem, ideal gas law, and perhaps some Newtons laws of motion.
In terms of scientific relevance, It is a tool for examining what many people consider the single most important questions ever asked.
We have an admittedly very limited knowledge of events outside of our own planet, but so far as we know, abiogenesis has occurred only once, and from that one event, all life on Earth proceeded. (It's possible that abiogenesis occurred independently multiple times during the beginning of life on Earth, but I don't think we yet have a compelling argument that it must have happened more than once.)
My favorite analogy:
Suppose you see a number with this pattern:
0.1001000101001000101001000___
What would you say is the likelihood that a 1 is the next number in the sequence? Not that hard to compute a probability, is it?
But suppose you see a number with this pattern:
0.1000000000000000000000000___
What is the likelihood that a 1 is the next number in the sequence? You could say the odds are 1-in-25, but that doesn't takes into account the clear pattern we see in the sequence. Unless and until we start to see some more ones pop up, it's reasonable to assume that this is a sequence of infinite zeroes, or at the very least that it could perfectly well be a sequence of infinite zeroes. Suppose the sequence goes on for many trillions of numerals. No one's going to say, "Well, if there are trillions of 0s, it's highly unlikely that there won't be some 1s sprinkled in there somewhere."
[0] to the extent that events across vast spans of space can be said to be ordered
None of this is any kind of _hard_ proof of course, it's just attempting to reason through what we expect without having enough data to prove either way.
If we conclude for some reason that we are the first, with enough evidence, sure, like you say someone has to be first.
But with so little data, the priors for "are we first or are we just missing the others" just have to be tilted heavily away from "we're first".
Ultimately, the frequency at which abiogenesis occurs is 1/N.
It may be the case that N is small enough that the universe is positively teaming with life.
Or it may be the case that N is so unfathomably large that the odds are exceedingly small that abiogenesis occurs even once during the lifetime of the universe, and the universe just happened to get lucky.
But until we have some other confirmed, observed instance of abiogenesis, we can say nothing about N other than its lower bound is pretty large.
And I don't think we can pile probabilities on top of probabilities to say, "Well, we have no way of knowing how large N is, so I'm going to just bet that it's medium-sized."
Your perspective reminds me of the anthropic principle: https://en.wikipedia.org/wiki/Anthropic_principle
The popular conception is the "puddle analogy." You can imagine a rain puddle becoming conscious, seeing the intricacies of its perfect fit with the pavement that surrounds it and concluding "wow, this hole fits me SO perfectly, it must have been made for me."
Apart from cells, what are you referring to here? Especially, is there anything that can be considered "somewhat living" that is not a by-product of regular life, which as far as we know has only ever appeared (or thrived) once Earth's history?
We know of no other planet that has waterfalls.
Yet, because we have seen enough waterfalls on Earth we have an evidence-based scientific belief that waterfalls cannot be Earth-specific because all that is required for one: water, erosion, gravity -- exists throughout the cosmos in very large amounts.
Life is the same. We have seen enough of it in enough variety to know that it can take on many forms, including exotic forms that are impossible on Earth but would be possible elsewhere. The abundance of the ingredients and time are all that's required.
As far as we know all life is related and has the same ancestor. Even on earth the emergence of life seems to be a freak accident.
However, for structures where we have no idea of the process by which they are formed (like cells), we can't have any opinion on how likely they are to happen elsewhere, unless we see more examples.
What forms of life that are impossible on earth do we know about?
Furthermore, unlike waterfalls, we actually have no idea how life appeared and, despite trying for many years, have been entirely unable to produce life from non-living things, and we have never observed this process occurring naturally either.
Furthermore, every living thing we've ever looked at has been a relative of other living things - as far as we've been able to determine, all of the life on Earth has a single origin, a single original RNA/DNA code which must have been present in a single population of organisms, at a single location. This is a strong suggestion that the conditions that allowed life to appear on Earth may have been extraordinarily specific - otherwise, we would expect many unrelated beings sharing the planet (or at least it means that a particular for of life was overwhelmingly more adaptive and entirely wiped out all of the others).
Even worse, there is another phenomenon for which we only have evidence of one instance happening in the history of the Earth: all eukaryotic life has a single common ancestor, and there are no complex multicellular organisms which are not eukaryotes.
So, not only did life arise only once on the one planet we know it can thrive in, but complex life only arose once from simpler life.
So, while we can't say that it's plausible life will never again arise in the universe, we can say that for any particular moment of time, it is plausible that no new life is being formed anywhere else in the universe.
Which is to say, two things are certainly true:
The universe is incredibly fantastically basically unimaginably vast. Practically countless (~10 million estimated) super-clusters of galaxies dot the heavens. There's just so many chances, so many opportunities, so much probability that, if you believe in life arising from a primordial soup, seem almost certain to be replicated.
Sometimes chaos, in it's fumbling teaming randomness, happens upon patterns. Patterns which sometimes stick, which sometimes reproduce, which sometimes grow. Entropy amid complex systems sometimes produces it's own enclaves of stability, sometimes.
The other true fact is that time is long and deep. Life on earth is not a flash in the pan, not an instant thing; it emerged slowly, over time, in differing waves, across time. The promise that life, once began, has a chance to ride these waves of time & to become significant, that it grows to fill rich biodiverse roles, grows to complete, that it thrives: if we believe in the soup of life, believe in the complex chemistries that powers cells, and believe in time, then a belief in other life seems not certain, but to me, highly highly probable.
But life capable of communicating across space didn't arrive until 4.5 billions years and after several mass extinctions. Even on a cosmic scale that's a very long time.
Oh, my goodness. Hyperbole much?
Detecting signs of life is all very well; but most (all?) such signals will have come from so far away that either we'll have evolved, or they'll have evolved. The chances that we'll ever meet such beings is minute.
I would expect the greatest discovery ever to actually make practical difference to something.
The tiny bandwidth and enormous turnaround time for any electromagnetic signal over (say) 20LY will stymie any attempt to transfer useful amounts of information. Probes are more promising; but note that Voyager 1 has travelled just over 1/1,000 of a light-year so far. To travel 20LY, it would need to survive in deep space for 40,000 years. Humans have never built a machine that could survive in working order for more than about 200 years.
For such a probe to tell us anything interesting, we'd be faced again with the bandwidth problem; or the probe would have to come back. By the time we got information back, it would be 40,000 years in the future. We know barely anything about human culture 40,000 years ago; if we had launched an interstellar probe 40,000 years ago, we'd have zero cultural memory of that fact by now.
So this "greatest discovery" is most likely to fall into the "gosh, that's quite interesting" category, rather than the "most important ever" category.
The greater the distance, the more the signal is attenuated, so the harder it becomes to distinguish signal from background-noise, so the slower you have to send.
'Modulate the light from our star':
Not sure how one might set about that. As things stand, we need extremely sensitive instruments to detect the starlight-modulation caused by orbiting exoplanets. A planetary-scale modulator would give you a bandwidth in the order of one bit per orbit.
Supposing we could construct a device that could modulate sunlight, it would need to be big - orders of magnitude bigger than anything humans have ever made. Our interstallar probe would have to deploy such a device on arrival, in order to 'call home'.
I suppose it's conceivable, as an idea; but the cost of such a project would be unimaginable, and the benefit would be useless information: e.g. "There is life on this planet; but you have no chance of getting here, and they have no chance of getting to you". That's not actionable information.
And you'll be getting the signal 20,000 years after launching the probe; that's the span of all of human civilisation. There's every chance that humans 20,000 years in the future would not be very interested in a signal from a probe launched by their 'primitive' ancestors. That's if they had any cultural memory from their ancestors that there ever was such a probe; but how much do we know about the culture of humans 20,000 years ago? If they had launched a probe, we would have to learn that from fossilised bones, which seems far-fetched.
The problem isn't with the Drake equation, it's with the pop science articles that extrapolated things from it way beyond the original intent or scope.
However thanks to speed of light the data set is not infinite, just absurd.
So we know almost nothing.
Given time the expansion of the universe will push all galaxies and stars away from us. The data set will be 1.
We now know everything.
As expansion continues all hydrogen items will eventually break apart. All life has ended.
Nothing now knows us.
"Rather than being an actual means for quantifying the number of intelligent species in our galaxy, the purpose of the equation was meant to frame the discussion on SETI. In addition to encapsulating the challenges facing scientists, it was intended to stimulate scientific dialog among those attending the meeting. As Drake would later remark:..."
Then follows a video of Drake speaking.
For some combinations of parameters, we should expect to see life on most other bodies within the solar system. The search for life on the moon and mars are simple empirical tests of these predictions.
What do you mean here?
SETI is incredibly poorly funded compared to other science. For a long time it was barely funded at all. There's been an uptick recently, but a project like Breakthrough Listen runs on $10m/yr and gets ridiculously constrained access to telescope time.
The remaining SETI projects get by on less than $5m/yr. So SETI as a whole gets about as much funding as one episode of The Mandalorian.
No wonder we haven't found anything. We're barely even looking.
Suppose we detected a radio signal from a location outside the solar system, that seemed to bespeak intelligence. That means it must be at least 1.5 LY away. But we haven't yet detected an exoplanet around Alpha Centauri, let alone one with goldilocks properties.
But for the sake of argument, let's suppose that we detect a radio signal from Alpha Centauri, and a matching exoplanet.
I suppose that would make it reasonable to conclude that (a) we have neighbours, and (b) that they're probably common. But we have only highly-speculative and fantastically expensive ideas about how we might get a human to Alpha Centauri. It would, for example, require a Generation spaceship.
I suppose we could imagine exchanging scientific knowledge with the beings of Alpha Centauri, over a radio link - with a ping time of 3 years. And the bandwidth isn't going to be that impressive, either.
I totally believe that there is other intelligent life in the Universe; but I simply don't believe that, if they are really intelligent, they would burn their resources on a project that might not be complete before they become extinct. I doubt they're anything like as close as Alpha Centauri, and therefore I doubt that we'll ever encounter them physically. From that point of view, it doesn't make much difference to anything whether they exist or not.
No it doesn't. It grows geometrically.
"the number of confirmed exoplanets has grown exponentially"
That implies that the rate of discovery of exoplanets is proportional to the number already discovered. I've no reason to think that's the case; and it seems really improbable.
When a science journalist uses the word "exponential" to mean "very fast", I conclude that I'm reading some kind of low-grade popsci from a lazy writer who thinks fancy words make them look clever. Well, it might to some people; to me, it just makes them look ignorant.
I'll try to explain my reasoning. First, a few assumptions:
- Life and intelligence are physical processes. Given the starting conditions of the universe, they'll eventually pop up somewhere.
- Where it pops up, is random and relatively uniformly distributed in space (as for the density, I don't know)
- Humans are an average civilization
- For most civilizations it takes about the same time than us from the start of the universe to reach our current level of advancement (given that we presume that we're average).
Under these assumptions, we have been detectable for roughly the last 100 years. So we can assume, that it's about the same for an average civilization out there.
Even if they're plentiful, it's unlikely that the signals from the close ones would have reached us yet. So everything looks dark.
It wouldn't surprise me if in a few thousand years, the sky starts lighting up with signals from other worlds, as the signals from the ones that are reaching detectability start getting to us.
"Two possibilities exist: we are either the only things in the Universe that regularly speak Swedish or we are not. Both are equally terrifying".
My dog is looking for signs of extraterrestrial super-olfaction.
I do, however, like the "solution" posited in the short story "The Crystal Spheres": https://en.wikipedia.org/wiki/The_Crystal_Spheres
Are we sure now that DNA-based life and only of those four bases is the only form of life that was born here?
If "yes" then it means that it is highly probable that other forms of life are also DNA based, no?
Eg, no signal sent from any probe will ever get as far as our first radio signals sent into the universe, unless we find a faster than light solution.
This is what Einstein discovered for us, which is called the theory of relativity.
That said, the signal would be much stronger if you tuned it for specific regions of space.
The fact that some of the factors may be close to 1.0 or may be unknowable directly is not a bug.
Maybe we should figure out what all these UFOs are here first.
https://www.washingtonpost.com/nation/2021/05/17/ufo-sightin...
https://www.cbsnews.com/news/ufo-military-intelligence-60-mi...
[edited for grammar]
It also doesn't address first-person sightings by military observers, as interviewed in the video I linked to.
Stars have lifecycles, and they can only support life in a stable manner in some stages of that lifecycle.
I guess Drake just assumed that stars lifecycles have such a slow progression that for the purposes of determining alien life we can just assume it is constant.
That is what the 'L' is in the formula
"As I planned the meeting, I realized a few day[s] ahead of time we needed an agenda. And so I wrote down all the things you needed to know to predict how hard it's going to be to detect extraterrestrial life. And looking at them, it became pretty evident that if you multiplied all these together, you got a number, N, which is the number of detectable civilizations in our galaxy. This was aimed at the radio search, and not to search for primordial or primitive life forms."
So the sample size isn't 1 and there are known ways to detect all but 2 or 3 parameters of the drake equation.
Actually, only 2 or 3 parameters of the Drake equation are estimable. (It depends on how you want to define "planets that can potentially support life"--you can argue that the answer is anywhere between 1 and 5 in our own solar system). Everything that talks about the possibility of life evolving, let alone speculating about how it will evolve or the xenosociology of what that life will try to do, is pure conjecture: that's the last 4 values of the equation, more than half of it.
EDIT:
If you go through the factors, only the first three even make sense to talk about. And the third, about "number of planets per star that can potentially support life" can only be discussed in terms of our particular form of life. We have no idea at all what other types of life there could be, much less under what conditions that might happen.
The others are completely unknowable. For example:
f_i: The fraction of planets with life that actually go on to develop intelligent life (civilizations)"
I'm embarrassed even writing it out. How can anyone even start to think that they could come even with 10 orders of magnitude of the right answer, if it's even a well defined probability, which I doubt.
We know of exactly one planet with life, and it has intelligent life that emits radio waves. Is that an inevitability, or a one in a trillion fluke?
But what bother me the most is how you even think you can talk about probabilities when there's only one trial, and for the later factors, the sample size is most definitely 1. It's just inane.
The Drake equation is treated as fodder for late-night Cheetos-driven college sophomore discussions. But we use it, and siblings, to estimate the inestimable: how much value do we get out of a dollar put towards actually investigating this?
No matter what the field, it's always all over the map. Do we want to spend gigabucks on an LHC successor in the hopes of a vast payoff? Do we want to spend megabucks on this specific line of cancer research? Or should we spend the same money on thousands of kilobuck experiments in everything from economics to psychology to polymer chemistry?
It's even harder when there isn't actually a dollar value attached. Even if we discover alien life, what's the merit of that? Economically, perhaps nothing, other than sales of "I wanted to believe/and I was right" tee shirts. But in terms of satisfaction, perhaps more than all of the movies and video games ever made put together.
That's why we spend so much effort trying to estimate priors that we know are too wild to be of actual value in that calculation. Playing with the Drake equation is fun. That's all. But it does also ultimately inform the expenditure of some resources, even if we don't actually do the math.
Any questions of resource allocation ultimately come down to a question individual and social values, or merit, as you phrased it.
Merit is inherently arbitrary. Some people can and do think answering the question of the existence of extraterrestrial life has intrinsic merit and is the single most important society could do. More important than improving global prosperity or even continuation of the species.