8 ms·

"In other words, given what we now know about the number and orbital positions of the galaxy’s planets, the degree of pessimism required to doubt the existence,

"In other words, given what we now know about the number and orbital positions of the galaxy’s planets, the degree of pessimism required to doubt the existence, at some point in time, of an advanced extraterrestrial civilization borders on the irrational." This is terribly silly. It reminds me of the Onion talks: "Step 1: Devise an idea to create a car that runs on compost. Step 2: Create the car. We’ve already completed Step 1. We’re half way there." Increased certainty on three of the seven factors is irrelevant, because 99% of the uncertainty is concentrated in the other four. Specifically, the odds of abiogenesis are ~1/2^n, where n is the complexity in bits of the smallest self-replicator. n is bounded below by ~100 or so (or it would have happened in a lab somewhere), and is bounded above by ~1 million (the smallest existing bacteria), so we know it's somewhere in there. But where? We have only the vaguest guesses. "Specifically, unless the probability for evolving a civilization on a habitable-zone planet is less than one in 10 billion trillion, then we are not the first." "One in 10 billion trillion" sounds like a very large number, and it's put in italics for emphasis, but in information-theoretic terms it's tiny. log2(10^22) is just 73 bits. If all that we know about a number is that it's somewhere between a hundred and a million, saying that X would imply it's higher than 73 (well technically 73 + log2(#incidences of molecular combination), so probably a few hundred) is not a disproof of X, nor really even much evidence against X.

reso 10y ago
I had a similar intuition reading the article. I don't think we understand much at all about the probabilities of life forming even under the ideal circumstances. The events that took place on earth could still be one in a billion, or they could be one in an incomprehensibly high number. Nevertheless the progress on the other factors in the Drake equation is very interesting and impressive.
- raverbashing 10y ago
  > . The events that took place on earth could still be one in a billion, or they could be one in an incomprehensibly high number. I disagree with this. It seems that, from what happened to other planets on the solar system, that nothing happened on Earth too much out of the ordinary. Mars had a similar story (except for the whole Moon coming out of a giant collision), and had water. But maybe it was too small to keep warm for enough time Earth had 5 mass-extinctions, that "reset the game" before we got to humans. Doesn't seem too far fetched to me I really don't buy that Earth is one in a billion unless Mars is one in a billion as well. Maybe one in 1000? One in 100000? And that's limiting intelligent life to what we know. Yes, maybe the ideal speed of chemical reactions (for intelligent life) happen around 273K, or maybe there's another way
  - jkeler 10y ago
    It's not about how probable are these conditions but given these conditions how probable is that life will appear.
    - unclebucknasty 10y ago
      It seems that the probability of life appearing (in some form), given the ideal conditions, is higher than that of obtainiing the ideal conditions.
      - unclebucknasty 10y ago
        Phantom downvotes. Awesome. Don't really care about "karma", but thought this was a place for discussion. Anyway, what reason do we have to believe that Earth is special 2X? That we happened to have the right conditions plus some randomness occurred against all odds that gave rise to life? Why is that a rational proposition? We know the chemical elements and processes that give rise to life, and we know why Earth is a suitable place. I suggest that, given the right (e.g. Earth-like) conditions, formation of life is not only more likely than the existence of the conditions, but the formation of life may even be likely overall. Hawking has expressed this possibility. [0] There is fossil evidence suggesting that some forms of life existed on Earth as few as 500 million short years after it was formed. So, what are the odds that one astronomically improbable event (creation of a hospitable environment) was followed in such a short period by another alleged astronomically improbable event (abiogenesis)? [0] http://www.hawking.org.uk/life-in-the-universe.html http://www.hawking.org.uk/life-in-the-universe.html
    - raverbashing 10y ago
      I suspect that given the right conditions, some kind of proto-life appears easily. But it takes a lot of time to get to "life" as we know it. (Now the right conditions are probably not what you have on Earth today except in a couple of places) Life on Earth is at least 4Bi y.o. http://newsroom.ucla.edu/releases/life-on-earth-likely-started-at-least-4-1-billion-years-ago-much-earlier-than-scientists-had-thought http://newsroom.ucla.edu/releases/life-on-earth-likely-start...
ThePhysicist 10y ago
I think what will really help us to get at a better estimate is to answer the question whether there exists life in our solar system that evolved independently of that on Earth. If we should find traces of bacteria on Mars or another planet, that would immediately take the corresponding probability factor in the Drake equation to a number close to 1 (i.e. most solar systems with planets in the habitable zone produce simple organic life), which would then leave us only with the question of how likely it is that such bacterial life evolves into something more complex. That's an incredibly hard question to answer as well of course, but it's also something that we might be able to tackle within the next 50 years given a deeper understanding of how living cells work and how they came to be (and it seems we're making good progress there). So personally I'm quite confident that we will be able to get to a much better estimate of Drake's equation in the next 50 years.
- throwaway_yy2Di 10y ago
  I think what will really help us to get at a better estimate is to answer the question whether there exists life in our solar system that evolved independently of that on Earth. That's definitely the big question. But you left out the elephant in the room: is there life right here on Earth that's evolved independently? Abiogenesis doesn't simply halt after it's achieved its "goal". Perhaps we take the common-origin hypothesis for granted (that the "tree of life" has one root, and is in fact a tree), but it's actually nontrivial, strong evidence about the rate of abiogenesis, right under our noses. If it's true. There's no hard reason why another, orthogonal family of life couldn't coexist with DNA/RNA life. We have 10^7 extant species of DNA/RNA life; that's an existence proof that hostile, competing "types" of life can coexist. Suppose we found terrestrial "XNA life" with a biochemistry totally unrelated to anything else, with no possible common origin or lateral gene transfer. Then we would know life on Earth developed independently N >= 2 times, instead of N >= 1. That would change a lot; we could update P(life | Earth-like planet) from the subjective probability range [10^-Graham's number, 1) to something more like [10^-4, 1). What's really surprising is that this is completely untested! We genuinely don't know if there's "alien" life on Earth, because we don't know how to look for it. There's no black-box tool to approach unknown biochemistry: Some have postulated the existence of a 'shadow biosphere' on Earth, teeming with life that has gone undiscovered because scientists simply don't know where to look. It could contain life that relies on a fundamentally different biochemistry, using different forms of amino acids or even entirely novel ways of storing, replicating and executing inherited information that do not rely on DNA or proteins. [...] The trick is deciding what to look for and how to detect it. The usual way that researchers search for new organisms — by sequencing DNA or RNA — will not pick up life that does not depend on them. http://www.nature.com/news/life-changing-experiments-the-biological-higgs-1.10310 http://www.nature.com/news/life-changing-experiments-the-bio... ...We could even be oblivious to unfamiliar forms of life right under our noses... http://www.sciencemag.org/news/2015/02/shadow-biosphere-might-be-hiding-strange-life-right-under-our-noses http://www.sciencemag.org/news/2015/02/shadow-biosphere-migh...
throwaway_yy2Di 10y ago
"One in 10 billion trillion" sounds like a very large number, and it's put in italics for emphasis," And the author even asserts it's "irrational" to think real-world probabilities are this small! It's easy to construct "unreasonably" small probabilities: take a few small ones and multiply them. If you path-sum all the evolutionary state transitions summing to P(intelligent life|planet), is it a shallow graph with many alternatives (additive probabilities), or a deep graph dominated by long, conjunctive sequences (probabilities multiply)?
wtbob 10y ago
> Specifically, the odds of abiogenesis are ~1/2^n, where n is the complexity in bits of the smallest self-replicator. n is bounded below by ~100 or so (or it would have happened in a lab somewhere), and is bounded above by ~1 million (the smallest existing bacteria), so we know it's somewhere in there. If the odds of abiogenesis are 1/2^128, and if that is the source of life, then we're the only life in the Universe. As the article indicates, there are only 2^73 stars.
- ThePhysicist 10y ago
  OP's argument here is slightly wrong I think, as it does not take into account the amount of time: Abiogenesis probably hasn't happened in a lab yet because the corresponding experiments have been running for a couple of years or decades at most, whereas nature's "experiments" have been continuously running at planetary scale for billions of years. If we count the number of attempts to invent life in the sense of putting together some anorganic and organic chemicals, supplying some energy and waiting for e.g. one year, then Nature has probably run 10^18 times more experiments than we have (10^9 years of experiments, each one running on a 1 m² surface [not taking into account depth]). And, fossil evidence points to life having started 4.1 billion years ago, or roughly 500 million years after the formation of the planet, which is a rather short amount of time (it's very likely that first lifeforms existed even earlier than that). So my naive guess would be that n < 100, though without further evidence (e.g. finding life on other planets) this is hardly more than a belief.
- Guillaume86 10y ago
  In the Observable Universe
dave_sullivan 10y ago
One of my favorite explanations and counterpoints come from Neil deGrasse Tyson: It took modern astrophysics to determine the origin of the chemical elements. We observe stars (and) we know what goes on in their center. They explode, laying bare their contents. And what we have discovered is that the elements of the periodic table -that which we are made of- derive from the actions of stars that have manufactured the elements, exploded (and) scattered their rich guts across the galaxy, contaminating or enriching gas clouds that then form a next generation of stars populated by planets and possibly life. And so, when you look at the ingredients of the universe, the number one ingredient is hydrogen, next is helium, next is carbon- sorry- hydrogen, helium, oxygen, carbon, nitrogen. Those are the top ingredients in the universe. And you say well, okay, that’s kind of cool. Well, and you look at Earth- cause we like thinking of ourselves as special- we say Oh! we’re special! What are we made of? Well what’s the number one molecule in the body? It’s water. But what’s water made of? H-2-O. Hydrogen and oxygen. Hm. Hydrogen and oxygen. In fact, if you rank the elements in the human body, with the exception of helium, which is chemically inert- useless to you for any reason other than just to inhale it and sound like Mickey Mouse. You can’t die from helium unless that’s all you breathe. So, number one in the human body is hydrogen. Matches the universe. Number two? Is oxygen. Matches the universe. Number 3? Carbon. Matches the universe. Number 4? Nitrogen. Matches the universe. And for each of us the fifth element- other- is the same in both places. Ok? Other. So, we learned in the last 50 years that, of course, not only do we exist in this universe. It is the universe itself that exists within us. And had we been made of some rare isotope of bismuth, you’d argue and say hey, we’re something special. From https://tiainkorea.wordpress.com/2012/04/22/a-fascinatingly-disturbing-thought-by-dr-neil-degrasse-tyson-transcript/ https://tiainkorea.wordpress.com/2012/04/22/a-fascinatingly-... Also, this is the most interesting explanation to the Fermi paradox that I've seen: http://accelerating.org/articles/transcensionhypothesis.html http://accelerating.org/articles/transcensionhypothesis.html
- chmike 10y ago
  The only paradox in Fermi's paradox is the discarding of UFOs as possible ET manifestation
- yoha 10y ago
  Most common elements in the universe [1]: Hydrogen, Helium, Oxygen, Carbon, Neon, Iron, Nitrogen Most common elements in the human body [2]: Hydrogen, Oxygen, Carbon, Nitrogen I agree that we can skip helium and neon since those are noble gases, but I do find the lack of iron interesting. [1] https://en.wikipedia.org/wiki/Abundance_of_the_chemical_elements https://en.wikipedia.org/wiki/Abundance_of_the_chemical_elem... [2] https://en.wikipedia.org/wiki/Composition_of_the_human_body#Elemental_composition_list https://en.wikipedia.org/wiki/Composition_of_the_human_body#... (look for table, sort per atomic percent)
andbberger 10y ago
Your assumption that the odds of abiogenesis is given by `~1/2^n, where n is the complexity in bits' is utterly, completely false. Statistical mechanical entropy and information theoretical entropy ('complexity in bits') are not the same quantities! But even if they were, your expression would still be incorrect because living system are definitionally not at equilibrium - so equilibrium statistical mechanics (whose predictions you are using to get that expression) does not apply. No one is surprised when convection rolls spontaneously form as they boil a pot of water. But equilibrium statistical mechanics predicts that this should be extremely unlikely as convection roll states have very low entropy. That is, of all of the ways that the molecules in that pot of water could be oriented, vanishingly few of them correspond to convection roll states, where several Avogrado's numbers worth of particles conspire to all swirl around in a coordinated fashion to dissipate the heat of the burner faster than would occur just by diffusion. The origin of life is very much analogous to the formation of convection rolls in the pot. And I believe is far more common than classical predictions imagine it to be - nearly everywhere there is an energy gradient in the universe, you will probably find life. Citation: I have a degree in physics
- cgio 10y ago
  How do you substantiate the analogy between origin of life and convection rolls formation?
  - gilleain 10y ago
    I presume the idea is that of 'the other half' of evolution - that is, the spontaneous formation of order through simple physical processes coupled to symmetry breaking. Of course it can be easy to over-do the analogies between things like convection rolls and the emergence of lipid bilayers (or whatever). However, the origin of life necessarily came about through purely physical processes and only once that bootstrap phase was over did evolution come into play as biological systems took over acting upon themselves. As I understand it the idea is that a closed system that is driven far from equilibrium by a constant influx of energy can undergo 'symmetry breaking' where the symmetries of the system are changed. So the symmetric situation of the boiling pot is broken such that convection rolls are formed - which is new structure. Similarly, a uniform soup of primitive chemical compounds could have been broken into less-uniform patches by some energy gradient (black or white smokers, for example). This diversity of chemical conditions then helped to form the initial replicators that could then further exploit various temperature, chemical, or proton gradients to create primitive life.
deleted 10y ago
[deleted]
tim333 10y ago
An alternative is if you believe in the principle of terrestrial mediocrity, that we are on a fairly average planet in a fairly average bit of the universe where fairly average things happen, the fact that life popped up on our planet in less than a billion years implies it probably has done so in loads of other places. Quote Martin Amis's The Information: “The history of astronomy is the history of increasing humiliation. First the geocentric universe, then the heliocentric universe. Then the eccentric universe – the one we’re living in. Every century we get smaller. Kant figured it all out, sitting in his armchair. What’s the phrase? The principle of terrestrial mediocrity.”
- jessriedel 10y ago
  The actual time taken to randomly clear a hurdle actually tells you very little about how unlikely it was to clear, so long as there are several hurdles and you condition on them all occurring (i.e., that you exist). In particular, the expected time to clear a hurdle asymptotes at a constant value even as the difficulty becomes arbitrarily hard. This is a very unintuitive but very important result for thinking about this topic. http://mason.gmu.edu/~rhanson/greatfilter.html http://mason.gmu.edu/~rhanson/greatfilter.html
gpsx 10y ago
I don't know enough to know if the range you specify is right, but I agree that it is silly to say 10^-22 is a ridiculously small number. For one thing, when talking about the size of probabilities, we should talk about the size of the exponent. -22 is not a ridiculously small number. People base the idea that there should be other life in the universe on the fact that life developed at least once, which is here on earth. The odds are it would happen either 0 times or many times, but not exactly once. This argument is reasonable if there is one universe. Another scenario is that there is some god awful large number of universes (for round numbers let's say 10^1000 raised to the 10^10000 power, which would be a huge underestimate), and that most of these universes contain no life, because the odds of life developing are also very, very small. We ARE special in that we are viewing one of the small fraction of universes that has life, because if it didn't we wouldn't be viewing it. This allows for life to exist exactly once in our universe. There could also be universe where life developed independently more than once, but the odds of us being in that universe are very small relative to the odds of being in a universe with one life. But how would there be many universes? Here is one possibility that is surely controversial. In quantum mechanics, things happen in parallel. Is that electron spin up or spin down? It is both, but the electron in one state is not influenced by the electron in the other state. Each exists wholly on its own. This is true whether you believe the Stockholm or the Many Worlds interpretation of quantum mechanics. These two cases only differ when some special life form makes an observation, in which cases something very dramatic happens in the Stockholm interpretation (which is observationally indistinguishable from the "nothing different" that happens in the Many Worlds interpretation). If we think about the simplest form of life that can not make observations rather than looking for human-like life, the distinction between Stockholm and Many Worlds is mute. These parallel states of the system form our many universes, some that contain life and some that do not.
- nitrogen 10y ago
  AIUI the term "observation" in quantum physics has absolutely nothing to do with life.
  - sampo 10y ago
    In some interpretations of quantum mechanics, it actually has: https://en.wikipedia.org/wiki/Von_Neumann%E2%80%93Wigner_interpretation https://en.wikipedia.org/wiki/Von_Neumann%E2%80%93Wigner_int... https://en.wikipedia.org/wiki/Many-minds_interpretation https://en.wikipedia.org/wiki/Many-minds_interpretation More precisely, these interpretations require consciousness, but we can take that consciousness requires life.
PepeGomez 10y ago
73 bits is massive. Considering the variability of conditions on each planet, you will get into ridiculously contrieved scenarios of what could be needed to start life way before you come even close to that number.

reso 10y ago

I had a similar intuition reading the article. I don't think we understand much at all about the probabilities of life forming even under the ideal circumstances. The events that took place on earth could still be one in a billion, or they could be one in an incomprehensibly high number. Nevertheless the progress on the other factors in the Drake equation is very interesting and impressive.

raverbashing 10y ago
> . The events that took place on earth could still be one in a billion, or they could be one in an incomprehensibly high number. I disagree with this. It seems that, from what happened to other planets on the solar system, that nothing happened on Earth too much out of the ordinary. Mars had a similar story (except for the whole Moon coming out of a giant collision), and had water. But maybe it was too small to keep warm for enough time Earth had 5 mass-extinctions, that "reset the game" before we got to humans. Doesn't seem too far fetched to me I really don't buy that Earth is one in a billion unless Mars is one in a billion as well. Maybe one in 1000? One in 100000? And that's limiting intelligent life to what we know. Yes, maybe the ideal speed of chemical reactions (for intelligent life) happen around 273K, or maybe there's another way
- jkeler 10y ago
  It's not about how probable are these conditions but given these conditions how probable is that life will appear.
  - unclebucknasty 10y ago
    It seems that the probability of life appearing (in some form), given the ideal conditions, is higher than that of obtainiing the ideal conditions.
    - unclebucknasty 10y ago
      Phantom downvotes. Awesome. Don't really care about "karma", but thought this was a place for discussion. Anyway, what reason do we have to believe that Earth is special 2X? That we happened to have the right conditions plus some randomness occurred against all odds that gave rise to life? Why is that a rational proposition? We know the chemical elements and processes that give rise to life, and we know why Earth is a suitable place. I suggest that, given the right (e.g. Earth-like) conditions, formation of life is not only more likely than the existence of the conditions, but the formation of life may even be likely overall. Hawking has expressed this possibility. [0] There is fossil evidence suggesting that some forms of life existed on Earth as few as 500 million short years after it was formed. So, what are the odds that one astronomically improbable event (creation of a hospitable environment) was followed in such a short period by another alleged astronomically improbable event (abiogenesis)? [0] http://www.hawking.org.uk/life-in-the-universe.html http://www.hawking.org.uk/life-in-the-universe.html
  - raverbashing 10y ago
    I suspect that given the right conditions, some kind of proto-life appears easily. But it takes a lot of time to get to "life" as we know it. (Now the right conditions are probably not what you have on Earth today except in a couple of places) Life on Earth is at least 4Bi y.o. http://newsroom.ucla.edu/releases/life-on-earth-likely-started-at-least-4-1-billion-years-ago-much-earlier-than-scientists-had-thought http://newsroom.ucla.edu/releases/life-on-earth-likely-start...

ThePhysicist 10y ago

I think what will really help us to get at a better estimate is to answer the question whether there exists life in our solar system that evolved independently of that on Earth. If we should find traces of bacteria on Mars or another planet, that would immediately take the corresponding probability factor in the Drake equation to a number close to 1 (i.e. most solar systems with planets in the habitable zone produce simple organic life), which would then leave us only with the question of how likely it is that such bacterial life evolves into something more complex. That's an incredibly hard question to answer as well of course, but it's also something that we might be able to tackle within the next 50 years given a deeper understanding of how living cells work and how they came to be (and it seems we're making good progress there). So personally I'm quite confident that we will be able to get to a much better estimate of Drake's equation in the next 50 years.

throwaway_yy2Di 10y ago
I think what will really help us to get at a better estimate is to answer the question whether there exists life in our solar system that evolved independently of that on Earth. That's definitely the big question. But you left out the elephant in the room: is there life right here on Earth that's evolved independently? Abiogenesis doesn't simply halt after it's achieved its "goal". Perhaps we take the common-origin hypothesis for granted (that the "tree of life" has one root, and is in fact a tree), but it's actually nontrivial, strong evidence about the rate of abiogenesis, right under our noses. If it's true. There's no hard reason why another, orthogonal family of life couldn't coexist with DNA/RNA life. We have 10^7 extant species of DNA/RNA life; that's an existence proof that hostile, competing "types" of life can coexist. Suppose we found terrestrial "XNA life" with a biochemistry totally unrelated to anything else, with no possible common origin or lateral gene transfer. Then we would know life on Earth developed independently N >= 2 times, instead of N >= 1. That would change a lot; we could update P(life | Earth-like planet) from the subjective probability range [10^-Graham's number, 1) to something more like [10^-4, 1). What's really surprising is that this is completely untested! We genuinely don't know if there's "alien" life on Earth, because we don't know how to look for it. There's no black-box tool to approach unknown biochemistry: Some have postulated the existence of a 'shadow biosphere' on Earth, teeming with life that has gone undiscovered because scientists simply don't know where to look. It could contain life that relies on a fundamentally different biochemistry, using different forms of amino acids or even entirely novel ways of storing, replicating and executing inherited information that do not rely on DNA or proteins. [...] The trick is deciding what to look for and how to detect it. The usual way that researchers search for new organisms — by sequencing DNA or RNA — will not pick up life that does not depend on them. http://www.nature.com/news/life-changing-experiments-the-biological-higgs-1.10310 http://www.nature.com/news/life-changing-experiments-the-bio... ...We could even be oblivious to unfamiliar forms of life right under our noses... http://www.sciencemag.org/news/2015/02/shadow-biosphere-might-be-hiding-strange-life-right-under-our-noses http://www.sciencemag.org/news/2015/02/shadow-biosphere-migh...

throwaway_yy2Di 10y ago

"One in 10 billion trillion" sounds like a very large number, and it's put in italics for emphasis," And the author even asserts it's "irrational" to think real-world probabilities are this small! It's easy to construct "unreasonably" small probabilities: take a few small ones and multiply them. If you path-sum all the evolutionary state transitions summing to P(intelligent life|planet), is it a shallow graph with many alternatives (additive probabilities), or a deep graph dominated by long, conjunctive sequences (probabilities multiply)?

wtbob 10y ago

> Specifically, the odds of abiogenesis are ~1/2^n, where n is the complexity in bits of the smallest self-replicator. n is bounded below by ~100 or so (or it would have happened in a lab somewhere), and is bounded above by ~1 million (the smallest existing bacteria), so we know it's somewhere in there. If the odds of abiogenesis are 1/2^128, and if that is the source of life, then we're the only life in the Universe. As the article indicates, there are only 2^73 stars.

ThePhysicist 10y ago
OP's argument here is slightly wrong I think, as it does not take into account the amount of time: Abiogenesis probably hasn't happened in a lab yet because the corresponding experiments have been running for a couple of years or decades at most, whereas nature's "experiments" have been continuously running at planetary scale for billions of years. If we count the number of attempts to invent life in the sense of putting together some anorganic and organic chemicals, supplying some energy and waiting for e.g. one year, then Nature has probably run 10^18 times more experiments than we have (10^9 years of experiments, each one running on a 1 m² surface [not taking into account depth]). And, fossil evidence points to life having started 4.1 billion years ago, or roughly 500 million years after the formation of the planet, which is a rather short amount of time (it's very likely that first lifeforms existed even earlier than that). So my naive guess would be that n < 100, though without further evidence (e.g. finding life on other planets) this is hardly more than a belief.
Guillaume86 10y ago
In the Observable Universe

dave_sullivan 10y ago

One of my favorite explanations and counterpoints come from Neil deGrasse Tyson: It took modern astrophysics to determine the origin of the chemical elements. We observe stars (and) we know what goes on in their center. They explode, laying bare their contents. And what we have discovered is that the elements of the periodic table -that which we are made of- derive from the actions of stars that have manufactured the elements, exploded (and) scattered their rich guts across the galaxy, contaminating or enriching gas clouds that then form a next generation of stars populated by planets and possibly life. And so, when you look at the ingredients of the universe, the number one ingredient is hydrogen, next is helium, next is carbon- sorry- hydrogen, helium, oxygen, carbon, nitrogen. Those are the top ingredients in the universe. And you say well, okay, that’s kind of cool. Well, and you look at Earth- cause we like thinking of ourselves as special- we say Oh! we’re special! What are we made of? Well what’s the number one molecule in the body? It’s water. But what’s water made of? H-2-O. Hydrogen and oxygen. Hm. Hydrogen and oxygen. In fact, if you rank the elements in the human body, with the exception of helium, which is chemically inert- useless to you for any reason other than just to inhale it and sound like Mickey Mouse. You can’t die from helium unless that’s all you breathe. So, number one in the human body is hydrogen. Matches the universe. Number two? Is oxygen. Matches the universe. Number 3? Carbon. Matches the universe. Number 4? Nitrogen. Matches the universe. And for each of us the fifth element- other- is the same in both places. Ok? Other. So, we learned in the last 50 years that, of course, not only do we exist in this universe. It is the universe itself that exists within us. And had we been made of some rare isotope of bismuth, you’d argue and say hey, we’re something special. From https://tiainkorea.wordpress.com/2012/04/22/a-fascinatingly-disturbing-thought-by-dr-neil-degrasse-tyson-transcript/ https://tiainkorea.wordpress.com/2012/04/22/a-fascinatingly-... Also, this is the most interesting explanation to the Fermi paradox that I've seen: http://accelerating.org/articles/transcensionhypothesis.html http://accelerating.org/articles/transcensionhypothesis.html

chmike 10y ago
The only paradox in Fermi's paradox is the discarding of UFOs as possible ET manifestation
yoha 10y ago
Most common elements in the universe [1]: Hydrogen, Helium, Oxygen, Carbon, Neon, Iron, Nitrogen Most common elements in the human body [2]: Hydrogen, Oxygen, Carbon, Nitrogen I agree that we can skip helium and neon since those are noble gases, but I do find the lack of iron interesting. [1] https://en.wikipedia.org/wiki/Abundance_of_the_chemical_elements https://en.wikipedia.org/wiki/Abundance_of_the_chemical_elem... [2] https://en.wikipedia.org/wiki/Composition_of_the_human_body#Elemental_composition_list https://en.wikipedia.org/wiki/Composition_of_the_human_body#... (look for table, sort per atomic percent)

andbberger 10y ago

Your assumption that the odds of abiogenesis is given by `~1/2^n, where n is the complexity in bits' is utterly, completely false. Statistical mechanical entropy and information theoretical entropy ('complexity in bits') are not the same quantities! But even if they were, your expression would still be incorrect because living system are definitionally not at equilibrium - so equilibrium statistical mechanics (whose predictions you are using to get that expression) does not apply. No one is surprised when convection rolls spontaneously form as they boil a pot of water. But equilibrium statistical mechanics predicts that this should be extremely unlikely as convection roll states have very low entropy. That is, of all of the ways that the molecules in that pot of water could be oriented, vanishingly few of them correspond to convection roll states, where several Avogrado's numbers worth of particles conspire to all swirl around in a coordinated fashion to dissipate the heat of the burner faster than would occur just by diffusion. The origin of life is very much analogous to the formation of convection rolls in the pot. And I believe is far more common than classical predictions imagine it to be - nearly everywhere there is an energy gradient in the universe, you will probably find life. Citation: I have a degree in physics

cgio 10y ago
How do you substantiate the analogy between origin of life and convection rolls formation?
- gilleain 10y ago
  I presume the idea is that of 'the other half' of evolution - that is, the spontaneous formation of order through simple physical processes coupled to symmetry breaking. Of course it can be easy to over-do the analogies between things like convection rolls and the emergence of lipid bilayers (or whatever). However, the origin of life necessarily came about through purely physical processes and only once that bootstrap phase was over did evolution come into play as biological systems took over acting upon themselves. As I understand it the idea is that a closed system that is driven far from equilibrium by a constant influx of energy can undergo 'symmetry breaking' where the symmetries of the system are changed. So the symmetric situation of the boiling pot is broken such that convection rolls are formed - which is new structure. Similarly, a uniform soup of primitive chemical compounds could have been broken into less-uniform patches by some energy gradient (black or white smokers, for example). This diversity of chemical conditions then helped to form the initial replicators that could then further exploit various temperature, chemical, or proton gradients to create primitive life.

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tim333 10y ago

An alternative is if you believe in the principle of terrestrial mediocrity, that we are on a fairly average planet in a fairly average bit of the universe where fairly average things happen, the fact that life popped up on our planet in less than a billion years implies it probably has done so in loads of other places. Quote Martin Amis's The Information: “The history of astronomy is the history of increasing humiliation. First the geocentric universe, then the heliocentric universe. Then the eccentric universe – the one we’re living in. Every century we get smaller. Kant figured it all out, sitting in his armchair. What’s the phrase? The principle of terrestrial mediocrity.”

jessriedel 10y ago
The actual time taken to randomly clear a hurdle actually tells you very little about how unlikely it was to clear, so long as there are several hurdles and you condition on them all occurring (i.e., that you exist). In particular, the expected time to clear a hurdle asymptotes at a constant value even as the difficulty becomes arbitrarily hard. This is a very unintuitive but very important result for thinking about this topic. http://mason.gmu.edu/~rhanson/greatfilter.html http://mason.gmu.edu/~rhanson/greatfilter.html

gpsx 10y ago

I don't know enough to know if the range you specify is right, but I agree that it is silly to say 10^-22 is a ridiculously small number. For one thing, when talking about the size of probabilities, we should talk about the size of the exponent. -22 is not a ridiculously small number. People base the idea that there should be other life in the universe on the fact that life developed at least once, which is here on earth. The odds are it would happen either 0 times or many times, but not exactly once. This argument is reasonable if there is one universe. Another scenario is that there is some god awful large number of universes (for round numbers let's say 10^1000 raised to the 10^10000 power, which would be a huge underestimate), and that most of these universes contain no life, because the odds of life developing are also very, very small. We ARE special in that we are viewing one of the small fraction of universes that has life, because if it didn't we wouldn't be viewing it. This allows for life to exist exactly once in our universe. There could also be universe where life developed independently more than once, but the odds of us being in that universe are very small relative to the odds of being in a universe with one life. But how would there be many universes? Here is one possibility that is surely controversial. In quantum mechanics, things happen in parallel. Is that electron spin up or spin down? It is both, but the electron in one state is not influenced by the electron in the other state. Each exists wholly on its own. This is true whether you believe the Stockholm or the Many Worlds interpretation of quantum mechanics. These two cases only differ when some special life form makes an observation, in which cases something very dramatic happens in the Stockholm interpretation (which is observationally indistinguishable from the "nothing different" that happens in the Many Worlds interpretation). If we think about the simplest form of life that can not make observations rather than looking for human-like life, the distinction between Stockholm and Many Worlds is mute. These parallel states of the system form our many universes, some that contain life and some that do not.

nitrogen 10y ago
AIUI the term "observation" in quantum physics has absolutely nothing to do with life.
- sampo 10y ago
  In some interpretations of quantum mechanics, it actually has: https://en.wikipedia.org/wiki/Von_Neumann%E2%80%93Wigner_interpretation https://en.wikipedia.org/wiki/Von_Neumann%E2%80%93Wigner_int... https://en.wikipedia.org/wiki/Many-minds_interpretation https://en.wikipedia.org/wiki/Many-minds_interpretation More precisely, these interpretations require consciousness, but we can take that consciousness requires life.

PepeGomez 10y ago

73 bits is massive. Considering the variability of conditions on each planet, you will get into ridiculously contrieved scenarios of what could be needed to start life way before you come even close to that number.