25 ms·

A Statistical Estimate of Extraterrestrial Intelligence in the Milky Way Galaxy

66 points by ipnon 6y ago

deleted 6y ago
[deleted]
mellosouls 6y ago
From the introduction: We examine three major parameters: 1) the likelihood rate of abiogenesis ({\lambda}A); 2) evolutionary timescales (Tevo); and 3) probability of self-annihilation of complex life (Pann) To my understanding: 1) Unknown. 2) Unknown outside earth. 3) Unknown. Given the title and the problems above, I didn't read beyond the introduction as time is limited. It sounds like an updating of the Drake equation without addressing the fundamental problems with that as an estimation tool rather than a more modest method for informing interesting speculation.
- lmilcin 6y ago
  Yeah, statistics isn't really good at extrapolation from a single sample. I think statistics is entirely bad approach to resolving this problem at least until we have more data. We need to know more about how planets form (again, we have rather small sample we have studied well), we need to know what exactly is necessary to jumpstart life and how likely it is to happen. Then we have a hard task understanding why exactly intelligent life evolved and whether it is unavoidable or a fluke. And a bunch other questions that statistics is entirely unprepared to answer.
- sampo 6y ago
  > 1) the likelihood rate of abiogenesis > 1) Unknown. Abiogenesis is known on Earth. Life appeared quite soon after Earth had cooled down enough, within the first couple of 100 million years. Of course, we don't know if it took 1 million or 300 million years. And it might be difficult to find out. https://en.wikipedia.org/wiki/Earliest_known_life_forms https://en.wikipedia.org/wiki/Earliest_known_life_forms
  - placebo 6y ago
    Isn't abiogenesis just a fancy way of saying that somehow life began from organic compounds that were created by inorganic means? To my understanding the somehow part is exactly the reason why we don't have enough information to make any intelligent guess on the probability of it happening elsewhere.
  - sanxiyn 6y ago
    We don't know whether Earth went through abiogenesis or was seeded by panspermia.
    - akiselev 6y ago
      It doesn't matter to the Drake equation except to make it far less pessimistic. Abiogenesis had to happen somewhere for panspermia to occur so if it happened so early in the history of our galaxy to then migrate to our planet, the probability of many such colonizers converging on intelligence goes up drastically. Panspermia might even simplify other parts of the equation, like the probability that we'd coexist in the same time period or in range to detect each other's radio waves.
- MauranKilom 6y ago
  I would recommend reading the conclusion before dismissing this as "they picked numbers to throw at the Drake equation". The point of this paper is to provide modeling not only of the scalar output of the drake equation (which is... not used at all) but of the possible spatial and temporal distribution of intelligent life in the galaxy. For example, it turns out that even for wildly different choices of the unknowns, the region (and age) of the Milky Way that contains most life (i.e. that SETI should focus on) is the same. Also, why do you consider "unknown" a problem when they explicitly set out to investigate the influence of these parameters? For example, they explore Pann of 0.0, 0.5 and 0.99 (per Myr). Could you explain what problem you see here?
  - mellosouls 6y ago
    I would recommend reading the conclusion before dismissing this as "they picked numbers to throw at the Drake equation That's a misrepresentation of what I said. I made it clear I had only read as far as I had because the premise of the title was unpromising given the unknowns, and that it sounded like an updating of the Drake equation without its flaws in the calculating of probabilities (as implied by the title) addressed. Feel free to summarise how it fundamentally differs from Drake in that important regard, with the findings and their usefulness in the context of the unknowns and title which promises an estimate of extraterrestrial intelligence.
anonymousiam 6y ago
Without looking up the Drake Equation, here's a rough estimation of the problem. Ignoring all extinct species, there's an estimated 8.7 million unique species of plants and animals currently on Earth. So let's do some dumb estimating and say that there's a one in 10 million chance of "intelligent" life evolving on a planet that supports life. (I will not address the controversial issue of whether or not human life is actually intelligent.) So whatever estimation is used for the number of habitable planets in our galaxy, Only 0.00001% of those planets might have intelligent life. Next, you must factor in how many of the intelligent species develop technology capable of interstellar communication, and when do they do it? Humans have existed for a few million years, but we have only had radio for a hundred years. With the development of technology comes the risk of self annihilation. We humans have had the ability to destroy ourselves for roughly 60 years. How much longer we go is anybody's guess, but given that life on our planet has existed for roughly 3.5 billion years, and the planet will become uninhabitable in another 5 billion (when the sun changes modes), the time window is pretty small. It's likely that life needs some elements that were less available in the early universe, so let's assume that it's only possible on planets of third-generation stars like ours. Also consider the speed-limit of EM propagation (C). There are only 76 stars within 100 light years of us. It's unlikely that intelligent life exists in any of those systems, but if it did, the inhabitants (if they were listening) would just now be able to hear us. Assuming we survive our technological revolution/evolution for another 100 years, we might get a message from a nearby system. Before then, we might receive some communications from systems farther away, but how long does a technological civilization use radio with simple modulation schemes that we would recognize as something other than noise? Maybe in less than a hundred years, we will have gone through radio, optical, and then quantum communications technology. It's likely that other technological civilizations (if they exist) are using communication technology that is incompatible with ours. I'm not sure if Drake considered all of these things, but it looks pretty bad for us with regard to our ability to confirm the existence of extraterrestrial intelligence any time soon.
- Gupie 6y ago
  > there's an estimated 8.7 million unique species of plants and animals currently on Earth. So [...] there's a one in 10 million chance of "intelligent" life evolving on a planet that supports life Isn't that the probability that a species is intelligent. The probability that intelligence will eventually evolve on a planet with life is 1.0, from the evidence that we have so far.
Blammar 6y ago
Another thing that may affect the probability of life in a solar system is the number of planets. More planets seem to make the planetary orbits much more circular and stable, allowing more time for life to occur and develop. This matters because, as far as we can see, our solar system has more planets than any other system we have been able to observe (so far.) See https://www.sciencenewsdigital.org/sciencenews/december_19__2020___january_2__2021/ https://www.sciencenewsdigital.org/sciencenews/december_19__..., article #9 (subscription required.)
- ben_w 6y ago
  > as far as we can see, our solar system has more planets than any other system we have been able to observe I may be out of date, but I thought that was an artefact of our methods and equipment rather than anything else — we can only see big things close to their stars, so if we were looking at our own system we’d miss (I forget, so e.g.) Mars, Uranus and Neptune?
biggestlou 6y ago
I'm still looking for intelligent life on this planet!
- w_t_payne 6y ago
  Good luck!!!!
MauranKilom 6y ago
A (terrible) article based on this (reasonable, in my layperson eyes) paper was recently discussed: https://news.ycombinator.com/item?id=25537049 https://news.ycombinator.com/item?id=25537049
- caesar27 6y ago
  This was already written by many western researches. Copy and past, chinese immigrants style.
11thEarlOfMar 6y ago
Whenever I contemplate this, I always return to the notion of concurrence. Any sentient alien life we'd hope to encounter alive will need to exist at the same (relative) time that we do. The Earth is 4.5 Billion years old. Man has existed as 'man' for about 5 million years. That's 0.1% of the age of Earth. If alien species evolved in a similar manner, but 0.1% faster or slower, we'd miss them by millions of years.
- grishka 6y ago
  And their perception of time itself might be different too.
  - awwaiid 6y ago
    Maybe creatures from planets with higher gravity think faster to deal with the accelerated thrown-object calculations.
- cortesoft 6y ago
  As long as the older species survives, they would eventually coexist.
- kumarvvr 6y ago
  Proof of aliens need not be actual living specimens. Left over artifacts from their civilizations are just as exciting a find. Personally, I feel the thought that we are alone in this universe is a wee bit arrogant. The universe is so big and existed for so long, we have to assume that sentient life existed in the past, perhaps exists now and will definitely exist in the future. Hopefully, we find at least artifacts that prove alien life, just because the minds of humans expand a bit more, because imagine how shocking it is to religions around the world if existence of aliens is confirmed.
  - Causality1 6y ago
    Universe no, our galaxy, probably. A species that doesn't colonize beyond their homeworld will sooner or later be wiped out by natural phenomena if not their own mistakes. A species that colonizes will fill the galaxy in a few million years unless it just decides to stop. If anything like us existed in the milky way it's almost certainly dead now. If there's something alive it will be almost incomprehensibly different than us.
option 6y ago
Read the conclusion, imho, this is very interesting: “ We also concluded that at the current time of the study, most intelligent life in the Galaxy is younger than 0.5 Gyr, with values of probability parameter for self-annihilation between 0 - 0.01; with a relatively higher value of the annihilation parameter (≥ 0.1), most intelligent life is younger than 0.01 Gyr.” If other intelligent life is very young (just like us) could there be more room for understanding if we ever communicate?
- rendall 6y ago
  I think what most people mean by intelligent alien civilization is basically illustrated by Star Trek, and I suspect in the entire perceivable universe we will never find anything remotely like that. Even the aliens in Arrival, as well done as they are, are magic humans in disguise I suspect we will barely recognize even alien sentience, since it will literally be alien to our understanding
  - option 6y ago
    that depends on how fast intelligence evolves. If most intelligences are still young (claim in this paper) then we are more likely to understand them. If we ever encounter something which had a billion years head start, then yeah, no way we would comprehend anything
    - rendall 6y ago
      > "If most intelligences are still young (claim in this paper) then we are more likely to understand them" Would you mind expanding on that? Why would intelligences being young mean we are more likely to understand them?
      - option 6y ago
        because we are super young ourselves, hence cognition gap between us and them are likely smaller.
caesar27 6y ago
This was already written by many western researches. Copy and past, chinese immigrants style.
ipnon 6y ago
Really incredible that the first author appears to be a high school student
- dasudasu 6y ago
  In many sub-fields of physics, authorship is alphabetical.
zaphirplane 6y ago
The earth is a life bearing planet with only 1 technological advanced life form. I would think this has a large impact on the possibility of detecting alien life (its rare for life bearing planets, rarer to evolve sentient, even rarer to create a civilization)
- AnIdiotOnTheNet 6y ago
  It's actually quite possible that earth has had one or more technologically advanced, for certain definitions of the term, lifeforms in its 4 billion year history but these have all been wiped out in one way or another before being able to leave any significant trace in the geological record. The best evidence against this is the lack of evidence of plastics and isotopes indicative of atomic energy use.
  - grishka 6y ago
    There are those Egyptian artifacts that we would've struggled to replicate even with our current technology.
    - enchiridion 6y ago
      I haven't heard of this.
    - todd8 6y ago
      Could you describe an example of such?
      - grishka 6y ago
        https://www.youtube.com/watch?v=BNSb5gPdqsA https://www.youtube.com/watch?v=BNSb5gPdqsA
        todd8 6y ago
        Nice, I've seen large Egyptian exhibits at the Louvre and the King Tut traveling exhibit in San Fransisco. Very impressive indeed. The same day I saw the King Tut exhibit I also saw an exhibit from feudal Japan. The workmanship of the Japanese items was absolutely stunning, much more impressive than the King Tut items as one would expect from a period many centuries later. All of these examples were still done by hand. It's hard to imagine a person in the modern era devoting a lifetime to make only a handful of swords. What makes these items interesting is that they were made without modern tools or technology. Today our manufacturing technology could replicate these achievements easily. Even common items like grave tombstones can be produced in short order with highly polished stone and precise engraving. See [1]. [1] https://legacyheadstones.com/gallery/photo-gallery.html https://legacyheadstones.com/gallery/photo-gallery.html
johndoe42377 6y ago
This is exactly how are why statistical estimation is bullshit. Correlation, if any, does not imply causation, and the causality principle has nothing to do with statistics. Observations (counting), however many, will never reveal causality, because they are orthogonal.
esarbe 6y ago
It's not even that space is too big. Time's too big. There's no reason to assume that the lifetime of technological civilization is more than a few hundred years. By then they will have destroyed their own habitat and - despite some half-hearted (or even serious) attempts on colonizing different planets/planetoids - will have come to an inglorious end. Let's be generous and say that the lifetime of a technological civilization is a thousand years. That's the time that it can both send and receive signals from another technological civilization. The chance that one technological civilization is able to receive the signals of another is so vanishingly small as to be zero for all practical purposes.
valuearb 6y ago
GIGO.

66 points by ipnon 6y ago

deleted 6y ago

[deleted]

From the introduction: We examine three major parameters: 1) the likelihood rate of abiogenesis ({\lambda}A); 2) evolutionary timescales (Tevo); and 3) probability of self-annihilation of complex life (Pann) To my understanding: 1) Unknown. 2) Unknown outside earth. 3) Unknown. Given the title and the problems above, I didn't read beyond the introduction as time is limited. It sounds like an updating of the Drake equation without addressing the fundamental problems with that as an estimation tool rather than a more modest method for informing interesting speculation.

lmilcin 6y ago
Yeah, statistics isn't really good at extrapolation from a single sample. I think statistics is entirely bad approach to resolving this problem at least until we have more data. We need to know more about how planets form (again, we have rather small sample we have studied well), we need to know what exactly is necessary to jumpstart life and how likely it is to happen. Then we have a hard task understanding why exactly intelligent life evolved and whether it is unavoidable or a fluke. And a bunch other questions that statistics is entirely unprepared to answer.
sampo 6y ago
> 1) the likelihood rate of abiogenesis > 1) Unknown. Abiogenesis is known on Earth. Life appeared quite soon after Earth had cooled down enough, within the first couple of 100 million years. Of course, we don't know if it took 1 million or 300 million years. And it might be difficult to find out. https://en.wikipedia.org/wiki/Earliest_known_life_forms https://en.wikipedia.org/wiki/Earliest_known_life_forms
- placebo 6y ago
  Isn't abiogenesis just a fancy way of saying that somehow life began from organic compounds that were created by inorganic means? To my understanding the somehow part is exactly the reason why we don't have enough information to make any intelligent guess on the probability of it happening elsewhere.
- sanxiyn 6y ago
  We don't know whether Earth went through abiogenesis or was seeded by panspermia.
  - akiselev 6y ago
    It doesn't matter to the Drake equation except to make it far less pessimistic. Abiogenesis had to happen somewhere for panspermia to occur so if it happened so early in the history of our galaxy to then migrate to our planet, the probability of many such colonizers converging on intelligence goes up drastically. Panspermia might even simplify other parts of the equation, like the probability that we'd coexist in the same time period or in range to detect each other's radio waves.
MauranKilom 6y ago
I would recommend reading the conclusion before dismissing this as "they picked numbers to throw at the Drake equation". The point of this paper is to provide modeling not only of the scalar output of the drake equation (which is... not used at all) but of the possible spatial and temporal distribution of intelligent life in the galaxy. For example, it turns out that even for wildly different choices of the unknowns, the region (and age) of the Milky Way that contains most life (i.e. that SETI should focus on) is the same. Also, why do you consider "unknown" a problem when they explicitly set out to investigate the influence of these parameters? For example, they explore Pann of 0.0, 0.5 and 0.99 (per Myr). Could you explain what problem you see here?
- mellosouls 6y ago
  I would recommend reading the conclusion before dismissing this as "they picked numbers to throw at the Drake equation That's a misrepresentation of what I said. I made it clear I had only read as far as I had because the premise of the title was unpromising given the unknowns, and that it sounded like an updating of the Drake equation without its flaws in the calculating of probabilities (as implied by the title) addressed. Feel free to summarise how it fundamentally differs from Drake in that important regard, with the findings and their usefulness in the context of the unknowns and title which promises an estimate of extraterrestrial intelligence.

anonymousiam 6y ago

Without looking up the Drake Equation, here's a rough estimation of the problem. Ignoring all extinct species, there's an estimated 8.7 million unique species of plants and animals currently on Earth. So let's do some dumb estimating and say that there's a one in 10 million chance of "intelligent" life evolving on a planet that supports life. (I will not address the controversial issue of whether or not human life is actually intelligent.) So whatever estimation is used for the number of habitable planets in our galaxy, Only 0.00001% of those planets might have intelligent life. Next, you must factor in how many of the intelligent species develop technology capable of interstellar communication, and when do they do it? Humans have existed for a few million years, but we have only had radio for a hundred years. With the development of technology comes the risk of self annihilation. We humans have had the ability to destroy ourselves for roughly 60 years. How much longer we go is anybody's guess, but given that life on our planet has existed for roughly 3.5 billion years, and the planet will become uninhabitable in another 5 billion (when the sun changes modes), the time window is pretty small. It's likely that life needs some elements that were less available in the early universe, so let's assume that it's only possible on planets of third-generation stars like ours. Also consider the speed-limit of EM propagation (C). There are only 76 stars within 100 light years of us. It's unlikely that intelligent life exists in any of those systems, but if it did, the inhabitants (if they were listening) would just now be able to hear us. Assuming we survive our technological revolution/evolution for another 100 years, we might get a message from a nearby system. Before then, we might receive some communications from systems farther away, but how long does a technological civilization use radio with simple modulation schemes that we would recognize as something other than noise? Maybe in less than a hundred years, we will have gone through radio, optical, and then quantum communications technology. It's likely that other technological civilizations (if they exist) are using communication technology that is incompatible with ours. I'm not sure if Drake considered all of these things, but it looks pretty bad for us with regard to our ability to confirm the existence of extraterrestrial intelligence any time soon.

Gupie 6y ago
> there's an estimated 8.7 million unique species of plants and animals currently on Earth. So [...] there's a one in 10 million chance of "intelligent" life evolving on a planet that supports life Isn't that the probability that a species is intelligent. The probability that intelligence will eventually evolve on a planet with life is 1.0, from the evidence that we have so far.

Blammar 6y ago

Another thing that may affect the probability of life in a solar system is the number of planets. More planets seem to make the planetary orbits much more circular and stable, allowing more time for life to occur and develop. This matters because, as far as we can see, our solar system has more planets than any other system we have been able to observe (so far.) See https://www.sciencenewsdigital.org/sciencenews/december_19__2020___january_2__2021/ https://www.sciencenewsdigital.org/sciencenews/december_19__..., article #9 (subscription required.)

ben_w 6y ago
> as far as we can see, our solar system has more planets than any other system we have been able to observe I may be out of date, but I thought that was an artefact of our methods and equipment rather than anything else — we can only see big things close to their stars, so if we were looking at our own system we’d miss (I forget, so e.g.) Mars, Uranus and Neptune?

biggestlou 6y ago

I'm still looking for intelligent life on this planet!

w_t_payne 6y ago
Good luck!!!!

MauranKilom 6y ago

A (terrible) article based on this (reasonable, in my layperson eyes) paper was recently discussed: https://news.ycombinator.com/item?id=25537049 https://news.ycombinator.com/item?id=25537049

caesar27 6y ago
This was already written by many western researches. Copy and past, chinese immigrants style.

11thEarlOfMar 6y ago

Whenever I contemplate this, I always return to the notion of concurrence. Any sentient alien life we'd hope to encounter alive will need to exist at the same (relative) time that we do. The Earth is 4.5 Billion years old. Man has existed as 'man' for about 5 million years. That's 0.1% of the age of Earth. If alien species evolved in a similar manner, but 0.1% faster or slower, we'd miss them by millions of years.

grishka 6y ago
And their perception of time itself might be different too.
- awwaiid 6y ago
  Maybe creatures from planets with higher gravity think faster to deal with the accelerated thrown-object calculations.
cortesoft 6y ago
As long as the older species survives, they would eventually coexist.
kumarvvr 6y ago
Proof of aliens need not be actual living specimens. Left over artifacts from their civilizations are just as exciting a find. Personally, I feel the thought that we are alone in this universe is a wee bit arrogant. The universe is so big and existed for so long, we have to assume that sentient life existed in the past, perhaps exists now and will definitely exist in the future. Hopefully, we find at least artifacts that prove alien life, just because the minds of humans expand a bit more, because imagine how shocking it is to religions around the world if existence of aliens is confirmed.
- Causality1 6y ago
  Universe no, our galaxy, probably. A species that doesn't colonize beyond their homeworld will sooner or later be wiped out by natural phenomena if not their own mistakes. A species that colonizes will fill the galaxy in a few million years unless it just decides to stop. If anything like us existed in the milky way it's almost certainly dead now. If there's something alive it will be almost incomprehensibly different than us.

option 6y ago

Read the conclusion, imho, this is very interesting: “ We also concluded that at the current time of the study, most intelligent life in the Galaxy is younger than 0.5 Gyr, with values of probability parameter for self-annihilation between 0 - 0.01; with a relatively higher value of the annihilation parameter (≥ 0.1), most intelligent life is younger than 0.01 Gyr.” If other intelligent life is very young (just like us) could there be more room for understanding if we ever communicate?

rendall 6y ago
I think what most people mean by intelligent alien civilization is basically illustrated by Star Trek, and I suspect in the entire perceivable universe we will never find anything remotely like that. Even the aliens in Arrival, as well done as they are, are magic humans in disguise I suspect we will barely recognize even alien sentience, since it will literally be alien to our understanding
- option 6y ago
  that depends on how fast intelligence evolves. If most intelligences are still young (claim in this paper) then we are more likely to understand them. If we ever encounter something which had a billion years head start, then yeah, no way we would comprehend anything
  - rendall 6y ago
    > "If most intelligences are still young (claim in this paper) then we are more likely to understand them" Would you mind expanding on that? Why would intelligences being young mean we are more likely to understand them?
    - option 6y ago
      because we are super young ourselves, hence cognition gap between us and them are likely smaller.

caesar27 6y ago

This was already written by many western researches. Copy and past, chinese immigrants style.

ipnon 6y ago

Really incredible that the first author appears to be a high school student

dasudasu 6y ago
In many sub-fields of physics, authorship is alphabetical.

zaphirplane 6y ago

The earth is a life bearing planet with only 1 technological advanced life form. I would think this has a large impact on the possibility of detecting alien life (its rare for life bearing planets, rarer to evolve sentient, even rarer to create a civilization)

AnIdiotOnTheNet 6y ago
It's actually quite possible that earth has had one or more technologically advanced, for certain definitions of the term, lifeforms in its 4 billion year history but these have all been wiped out in one way or another before being able to leave any significant trace in the geological record. The best evidence against this is the lack of evidence of plastics and isotopes indicative of atomic energy use.
- grishka 6y ago
  There are those Egyptian artifacts that we would've struggled to replicate even with our current technology.
  - enchiridion 6y ago
    I haven't heard of this.
  - todd8 6y ago
    Could you describe an example of such?
    - grishka 6y ago
      https://www.youtube.com/watch?v=BNSb5gPdqsA https://www.youtube.com/watch?v=BNSb5gPdqsA
      - todd8 6y ago
        Nice, I've seen large Egyptian exhibits at the Louvre and the King Tut traveling exhibit in San Fransisco. Very impressive indeed. The same day I saw the King Tut exhibit I also saw an exhibit from feudal Japan. The workmanship of the Japanese items was absolutely stunning, much more impressive than the King Tut items as one would expect from a period many centuries later. All of these examples were still done by hand. It's hard to imagine a person in the modern era devoting a lifetime to make only a handful of swords. What makes these items interesting is that they were made without modern tools or technology. Today our manufacturing technology could replicate these achievements easily. Even common items like grave tombstones can be produced in short order with highly polished stone and precise engraving. See [1]. [1] https://legacyheadstones.com/gallery/photo-gallery.html https://legacyheadstones.com/gallery/photo-gallery.html

johndoe42377 6y ago

This is exactly how are why statistical estimation is bullshit. Correlation, if any, does not imply causation, and the causality principle has nothing to do with statistics. Observations (counting), however many, will never reveal causality, because they are orthogonal.

esarbe 6y ago

It's not even that space is too big. Time's too big. There's no reason to assume that the lifetime of technological civilization is more than a few hundred years. By then they will have destroyed their own habitat and - despite some half-hearted (or even serious) attempts on colonizing different planets/planetoids - will have come to an inglorious end. Let's be generous and say that the lifetime of a technological civilization is a thousand years. That's the time that it can both send and receive signals from another technological civilization. The chance that one technological civilization is able to receive the signals of another is so vanishingly small as to be zero for all practical purposes.

valuearb 6y ago

GIGO.