11 ms·

Emergence of Life in an Inflationary Universe (2020)

82 points by rzk 5y ago

nynx 5y ago
I’m curious what the actual estimates of the likelihood of a self-replicating RNA stand coming together randomly are. There’s a lot of volume and time on earth where these random reactions could’ve happened.
- bediger4000 5y ago
  "Random" isn't really a relevant concept when it comes to chemicals. Get out some vinegar and some baking soda. Mix them. Wow! A chemical reaction that shouldn't have happened according to the laws of probability!
  - memling 5y ago
    Can you elaborate on this further? Why don't the laws of probability apply to chemistry?
    - bediger4000 5y ago
      They definitely do apply, but it's like laws of probability apply to gas dynamics: sure there's a very small, but not non-existent chance that all the air in your room will end up confined to the half you're not in. There's a very tiny probability that acetic acid in vinegar and sodium bicarbonate in baking soda won't combine. I suppose some extremely tiny fraction of the acid and baking soda I've mixed together in my life didn't react. But the probability is so tiny, it just doesn't matter: all my cookies and soda bread rose. Same with self replicating organic molecules - if you mix amino acids together, you're going to get some long strands virtually every time you try it because the probability of amino acids not reacting is very tiny. The probability of getting self-replicating strands approaches 1 after only a few trials. That is, your solution of amino acids would end up with some goop in it, some polymerized amino acid strands that had replicated themselves. This "what's the probability!?!?" category of anti-evolutionary arguments is just false. "If you put all the pieces of a car in a box and shook it, the probability of getting a car is zero!" True, but an inapplicable analogy to organic chemistry reactions. Intuition about probability leads you astray. Nuts have an extremely low probability of getting agitated into screwing themselves on a bolt. The chemicals relevant to life have an extremely high probability of reacting to form larger molecules.
      - memling 5y ago
        That's an interesting point, thanks. Please pardon some ignorant questioning. How far down does this apply? E.g., do amino acids come basically for free in the same way? If not, what's the bootstrapping process like, and how random is it? How many steps do you have to take from self replication to functional cells? That chemical reactions are quite deterministic makes sense to me, but I don't quite understand how one gets from chemistry to biology.
        yamrzou 5y ago
        Good question, I wonder the same. If I may add, how far does this apply when getting from biology to consciousness, i.e from functional cells to general intelligence, as seen in living organisms and humans?
        carbonguy 5y ago
        I'm not the parent commenter, but I studied biochemistry and find abiogenesis to be a particularly fascinating topic, so I'll take a crack at answering your questions: > How far down does this apply? E.g., do amino acids come basically for free in the same way? Broadly, I think it is fair to say that many molecules that we associate with biological processes (e.g. amino acids, nucleotides, simple alcohols, etc.) do come "for free" in the sense that there are known pathways for these molecules to be produced in the absence of living organisms. The Miller-Urey experiment is probably the most well-known proof of concept of this idea, though it's debated how well the experimental conditions correspond with "the real world." > ... [W]hat's the bootstrapping process like, and how random is it? If I understand you correctly, here you're asking "what does it take to get from prebiotic organic molecules to living organisms?" And that is a fascinating question that has, to my mind, several possible answers, though ultimately I think the answer is "we don't know." One very suggestive paper I read describes the bootstrapping process as a "surface metabolism" [1] that succeeds through several epochs before eventually producing free-floating lipid-membrane-enclosed micelles containing complex organic molecules and a rudimentary metabolism - i.e. protocells. However, the IIRC paper falls short of explaining how these protocells can then start to independently reproduce. One hypothesis I recall from David Deamer is that hydration/dehydration cycles in shallow pools promote complex organization of simpler protomolecules into structures we typically associate with living organisms [2]; in other words, given the protobiomolecules mentioned above, certain environmental conditions encourage [proto]cell formation. So, to answer your question (I think), there are many good candidates for the "bootstrapping process" and while there is randomness involved, it turns out that certain environmental conditions that were present on the early Earth (as well as currently!) tended to promote complex molecular formation. > How many steps do you have to take from self replication to functional cells? Not many; I would say that if you have something that looks like a cell and reproduces itself, it's a "functional cell." Personally, I think from that point we are at an, if not the, "origin of life," and understand in broad strokes "what happens next" - ever-more-refined single-celled organisms, multi-cell aggregates becoming "true" multi-celled organisms, and so on. Let me know if you're curious about any other aspect of this topic and I'll try to provide more info! [1] https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC373159/ https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC373159/ [2] https://www.liebertpub.com/doi/10.1089/ast.2019.2045 https://www.liebertpub.com/doi/10.1089/ast.2019.2045
- marcosdumay 5y ago
  Well, the article is literally doing that math.
- bmitc 5y ago
  > There’s a lot of volume and time on earth where these random reactions could’ve happened. Life began basically as soon as the Earth did. So, in terms of biological or geological time, it took almost no time.
  - AgentME 5y ago
    >Life began basically as soon as the Earth did. Note that this doesn't tell us as much as you might think about the likelihood of abiogenesis happening: we find ourselves relatively near the end of Earth's habitability before the expansion of the Sun will make it uninhabitable in a few hundred million years. If abiogenesis happened much later on Earth, then there would not have been enough time for intelligent life to evolve. Planets where intelligent life manages to evolve within the planet's time of habitability will be the weird rare ones where abiogenesis luckily happened ridiculously fast, no matter how unlikely it is for abiogenesis to happen.
    - amelius 5y ago
      I also wonder why life with a different chirality (if it ever existed) was outcompeted by known life, and could not co-exist with it.
GeorgeKangas 5y ago
I can see two ways around the low probability problem, for RNA abiogenesis: 1) The crystal gene hypothesis of A. G. Cairns-Smith. As a clay crystal grows and splits, the info in the crystal's defect structure is replicating with impressive fidelity, and those defects also interact with the surroundings. So you get the Darwinian game bootstrapped pretty much for free. Later on, the crystals start using organic polymers; later still, the polymer technology is developed well enough to take over from the clay. So this might make abiogenesis reasonably probable on one planet. 2) An observable universe is just any epsilon size patch, on an inflationary universe. The space-time curvature of our whole observable universe is too small to measure, hence the radius of our inflationary universe is a large multiple of the 13 G-lightyear radius we can observe. So abiogenesis could be highly improbable in any observable universe, answering Fermi's paradox, yet be probable within the much greater volume of an inflationary universe (maybe this is what TFA said? TLDR [Edit: yeah, it says that right in the abstract]). And there could even be a large number of inflationary universes, for all we know.
- Enginerrrd 5y ago
  Yeah I think the idea that the first self-replication was RNA-based to be really really dubious.
- benlivengood 5y ago
  Your second point is probably the most critical for this article; all we can conclude (eventually) is an upper bound on the probability of abiogenesis for a certain volume, total mass, age, or number of stars. There is literally no lower bound; there may be uncountably many other inflationary universes without life.
- scarmig 5y ago
  One nice thing about 1) is that it is more falsifiable than 2). 2) basically gives us the ability to explain any almost arbitrarily unlikely event (at least unless we figured out a lower bound on the space time curvature of the observable universe). You might as well say that life is vanishingly unlikely but a series of vanishingly unlikely many-worlds quantum coincidences happened to result in the particular universe we see.
nobrains 5y ago
To my simple mind, unless we find another case of life in this universe, there is no way to determine/estimate/calculate the frequency/probability of origin of life. Unless someone can convince me, in a simple way, that it is possible to determine.
- ShamelessC 5y ago
  > Unless someone can convince me, in a simple way Seems like you're happy with your own theories.
- sandgiant 5y ago
  We might never know with complete certainty, but then what can we know? Exploring the limits of the theories we pose is the only way to gain knowledge. The physical world is after all fairly predictable. Even if we will never know anything with certainty.
- bmitc 5y ago
  I took a course from the Complexity Explorer on the origins of life. It made the point that although understanding life is hard, life is actually seemingly easy when considered in terms of it showing up or starting. It pointed to evidence that life began basically as soon as Earth formed, basically as soon as the oceans arrived. The Solar System itself has plenty of examples of water. For example, Enceladus is surmised to be completely covered in an ocean below its icy crust. As far as I know, there's not much evidence that points to life as being special. Earth is certainly special in the time window that we are experiencing it in given its balances of energy, heat, water, etc. Utilizing models to predict what's out there doesn't seem all that controversial when evidence points to life not being all that hard cosmically. We just don't have strong enough binoculars yet.
- betwixthewires 5y ago
  Well this article/study talks about the likelihood by looking at the likelihood that an RNA sequence randomly forms long enough enough number of times until a self replicating sequence exists. Such a probabilistic approach indicates that life, while not necessarily rare in the universe, might be rare enough that it is unlikely for it to occur twice in a volume that is observable from one occurrence, or that there is some unknown mechanism that makes it more likely.
titzer 5y ago
None of this probabilistic reasoning matters in the face of the anthropic principle. If there are infinite universes, we could easily be in the mostly stupidly improbable one possible, since we are not observing (and cannot observe) all possible universes, let alone an average one. This why a whole ton of speculation is completely meaningless, because we clearly live in a stupidly improbable universe that is already "fine tuned"--and that's not a problem. It doesn't mean there has to be God or anything. In fact, the settings of our universe imply nothing.
- sandgiant 5y ago
  Indeed we might never be able to measure the global normalization of the likelihood function of life, but that doesn't mean we can't investigate it's local properties. In fact, I think we can learn a lot from doing just that.
- LegitShady 5y ago
  There is no evidence that there are infinite universes and indeed the belief in such a concept absent any evidence beside "nothing says there can't be" by scientific people is a religious belief on the order of there being a god except with less elf honesty. We have never detected an alternate universe and we don't even have math that makes it probable. It's just a concept. The same way "there's no reason entropy can't run backwards according to the physics" doesn't stop us not having any evidence for backwards running entropy or negative mass or a million other things that might conceivably exist but have no real evidence but sound cool.
  - jcims 5y ago
    Having any belief at all, none, one, many, infinite, all falls into the same category. We don't know. To me it seems like the additional universes in this context serve a purpose similar to (my understanding of) additional dimensions in math/physics. It allows you to navigate around singularities.
    - LegitShady 5y ago
kingcharles 5y ago
All our calculations are fucked by having a sample size of one.
- mcswell 5y ago
  The article is an argument against that argument.
fallingfrog 5y ago
Is a single strand of rna with all the right nucleotides to self reproduce the only starting point for life? I feel like there must be alternatives- perhaps a whole network of simpler organisms that each could do a small piece of a complete replication. I’m not a biologist so I can’t say- but notably, neither is the author (he’s an astronomer). I’d like to hear the point of view of a biologist on this.
- GeorgeKangas 5y ago
  One somewhat incremental approach, is called a hypercycle: several simple self replicators "form an alliance" wherein they promote each other's self replication. Not specific to RNA. And I'm not a biologist.
nsonha 5y ago
what if life exists everywhere we are just incapable of detecting it? All we know for sure that there is none on the moon, and soon we will make that claim for Mars, after turning a couple of rocks. If there is life with the same technologies to us sending some beacon signal, what's the odd that we get it?
umvi 5y ago
I'm still skeptical, because even with a statistically improbable RNA forming event, what are the chances actual life will emerge from it? Have we thrown pure RNA into a bucket of water and observed life emerging?
jacknews 5y ago
It seems much more likely to me that life started as an 'autocatalytic set' of molescules, each of which contribute to catalysing reproduction of the whole set, rather than a single strand of active RNA that can reproduce itself. If we look at life now, DNA does not reproduce itself directly, there is an entire ecosystem of chemicals that reproduces itself collectively, using RNA/DNA as a blueprint. The question then is how a set of molecules encoded itself in RNA, but I see that as much more envisionable (eg some RNA, and a host set of catalysts) than a self-reproducing strand of RNA appearing all at once.
Avlin67 5y ago
no, there is not 10^100 stars in universe, only 10^80 atoms. why such a mistake ?
r00tanon 5y ago
Going straight to working RNA is a huge assumption in the analysis, but it's thought provoking to set some sort of lower bound and see how big the cosmos would need to be. Still, somehow we may find a process like natural selection at a cosmic level that makes life way more likely than a purely random starting sequence.
- dandotway 5y ago
  Atheists: "We have faith natural selection at a cosmic level makes life way more likely." Christians: "We have faith supernatural selection at a cosmic level makes afterlife way more likely."
lend000 5y ago
Curious where the estimate of 10^100 stars came from. I've seen the estimate of 10^80 particles in the observable universe thrown around several times. No idea how either is calculated or what assumptions are made.
deleted 5y ago
[deleted]

82 points by rzk 5y ago

nynx 5y ago

I’m curious what the actual estimates of the likelihood of a self-replicating RNA stand coming together randomly are. There’s a lot of volume and time on earth where these random reactions could’ve happened.

bediger4000 5y ago
"Random" isn't really a relevant concept when it comes to chemicals. Get out some vinegar and some baking soda. Mix them. Wow! A chemical reaction that shouldn't have happened according to the laws of probability!
- memling 5y ago
  Can you elaborate on this further? Why don't the laws of probability apply to chemistry?
  - bediger4000 5y ago
    They definitely do apply, but it's like laws of probability apply to gas dynamics: sure there's a very small, but not non-existent chance that all the air in your room will end up confined to the half you're not in. There's a very tiny probability that acetic acid in vinegar and sodium bicarbonate in baking soda won't combine. I suppose some extremely tiny fraction of the acid and baking soda I've mixed together in my life didn't react. But the probability is so tiny, it just doesn't matter: all my cookies and soda bread rose. Same with self replicating organic molecules - if you mix amino acids together, you're going to get some long strands virtually every time you try it because the probability of amino acids not reacting is very tiny. The probability of getting self-replicating strands approaches 1 after only a few trials. That is, your solution of amino acids would end up with some goop in it, some polymerized amino acid strands that had replicated themselves. This "what's the probability!?!?" category of anti-evolutionary arguments is just false. "If you put all the pieces of a car in a box and shook it, the probability of getting a car is zero!" True, but an inapplicable analogy to organic chemistry reactions. Intuition about probability leads you astray. Nuts have an extremely low probability of getting agitated into screwing themselves on a bolt. The chemicals relevant to life have an extremely high probability of reacting to form larger molecules.
    - memling 5y ago
      That's an interesting point, thanks. Please pardon some ignorant questioning. How far down does this apply? E.g., do amino acids come basically for free in the same way? If not, what's the bootstrapping process like, and how random is it? How many steps do you have to take from self replication to functional cells? That chemical reactions are quite deterministic makes sense to me, but I don't quite understand how one gets from chemistry to biology.
      - yamrzou 5y ago
        Good question, I wonder the same. If I may add, how far does this apply when getting from biology to consciousness, i.e from functional cells to general intelligence, as seen in living organisms and humans?
      - carbonguy 5y ago
        I'm not the parent commenter, but I studied biochemistry and find abiogenesis to be a particularly fascinating topic, so I'll take a crack at answering your questions: > How far down does this apply? E.g., do amino acids come basically for free in the same way? Broadly, I think it is fair to say that many molecules that we associate with biological processes (e.g. amino acids, nucleotides, simple alcohols, etc.) do come "for free" in the sense that there are known pathways for these molecules to be produced in the absence of living organisms. The Miller-Urey experiment is probably the most well-known proof of concept of this idea, though it's debated how well the experimental conditions correspond with "the real world." > ... [W]hat's the bootstrapping process like, and how random is it? If I understand you correctly, here you're asking "what does it take to get from prebiotic organic molecules to living organisms?" And that is a fascinating question that has, to my mind, several possible answers, though ultimately I think the answer is "we don't know." One very suggestive paper I read describes the bootstrapping process as a "surface metabolism" [1] that succeeds through several epochs before eventually producing free-floating lipid-membrane-enclosed micelles containing complex organic molecules and a rudimentary metabolism - i.e. protocells. However, the IIRC paper falls short of explaining how these protocells can then start to independently reproduce. One hypothesis I recall from David Deamer is that hydration/dehydration cycles in shallow pools promote complex organization of simpler protomolecules into structures we typically associate with living organisms [2]; in other words, given the protobiomolecules mentioned above, certain environmental conditions encourage [proto]cell formation. So, to answer your question (I think), there are many good candidates for the "bootstrapping process" and while there is randomness involved, it turns out that certain environmental conditions that were present on the early Earth (as well as currently!) tended to promote complex molecular formation. > How many steps do you have to take from self replication to functional cells? Not many; I would say that if you have something that looks like a cell and reproduces itself, it's a "functional cell." Personally, I think from that point we are at an, if not the, "origin of life," and understand in broad strokes "what happens next" - ever-more-refined single-celled organisms, multi-cell aggregates becoming "true" multi-celled organisms, and so on. Let me know if you're curious about any other aspect of this topic and I'll try to provide more info! [1] https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC373159/ https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC373159/ [2] https://www.liebertpub.com/doi/10.1089/ast.2019.2045 https://www.liebertpub.com/doi/10.1089/ast.2019.2045
marcosdumay 5y ago
Well, the article is literally doing that math.
bmitc 5y ago
> There’s a lot of volume and time on earth where these random reactions could’ve happened. Life began basically as soon as the Earth did. So, in terms of biological or geological time, it took almost no time.
- AgentME 5y ago
  >Life began basically as soon as the Earth did. Note that this doesn't tell us as much as you might think about the likelihood of abiogenesis happening: we find ourselves relatively near the end of Earth's habitability before the expansion of the Sun will make it uninhabitable in a few hundred million years. If abiogenesis happened much later on Earth, then there would not have been enough time for intelligent life to evolve. Planets where intelligent life manages to evolve within the planet's time of habitability will be the weird rare ones where abiogenesis luckily happened ridiculously fast, no matter how unlikely it is for abiogenesis to happen.
  - amelius 5y ago
    I also wonder why life with a different chirality (if it ever existed) was outcompeted by known life, and could not co-exist with it.

GeorgeKangas 5y ago

I can see two ways around the low probability problem, for RNA abiogenesis: 1) The crystal gene hypothesis of A. G. Cairns-Smith. As a clay crystal grows and splits, the info in the crystal's defect structure is replicating with impressive fidelity, and those defects also interact with the surroundings. So you get the Darwinian game bootstrapped pretty much for free. Later on, the crystals start using organic polymers; later still, the polymer technology is developed well enough to take over from the clay. So this might make abiogenesis reasonably probable on one planet. 2) An observable universe is just any epsilon size patch, on an inflationary universe. The space-time curvature of our whole observable universe is too small to measure, hence the radius of our inflationary universe is a large multiple of the 13 G-lightyear radius we can observe. So abiogenesis could be highly improbable in any observable universe, answering Fermi's paradox, yet be probable within the much greater volume of an inflationary universe (maybe this is what TFA said? TLDR [Edit: yeah, it says that right in the abstract]). And there could even be a large number of inflationary universes, for all we know.

Enginerrrd 5y ago
Yeah I think the idea that the first self-replication was RNA-based to be really really dubious.
benlivengood 5y ago
Your second point is probably the most critical for this article; all we can conclude (eventually) is an upper bound on the probability of abiogenesis for a certain volume, total mass, age, or number of stars. There is literally no lower bound; there may be uncountably many other inflationary universes without life.
scarmig 5y ago
One nice thing about 1) is that it is more falsifiable than 2). 2) basically gives us the ability to explain any almost arbitrarily unlikely event (at least unless we figured out a lower bound on the space time curvature of the observable universe). You might as well say that life is vanishingly unlikely but a series of vanishingly unlikely many-worlds quantum coincidences happened to result in the particular universe we see.

nobrains 5y ago

To my simple mind, unless we find another case of life in this universe, there is no way to determine/estimate/calculate the frequency/probability of origin of life. Unless someone can convince me, in a simple way, that it is possible to determine.

ShamelessC 5y ago
> Unless someone can convince me, in a simple way Seems like you're happy with your own theories.
sandgiant 5y ago
We might never know with complete certainty, but then what can we know? Exploring the limits of the theories we pose is the only way to gain knowledge. The physical world is after all fairly predictable. Even if we will never know anything with certainty.
bmitc 5y ago
I took a course from the Complexity Explorer on the origins of life. It made the point that although understanding life is hard, life is actually seemingly easy when considered in terms of it showing up or starting. It pointed to evidence that life began basically as soon as Earth formed, basically as soon as the oceans arrived. The Solar System itself has plenty of examples of water. For example, Enceladus is surmised to be completely covered in an ocean below its icy crust. As far as I know, there's not much evidence that points to life as being special. Earth is certainly special in the time window that we are experiencing it in given its balances of energy, heat, water, etc. Utilizing models to predict what's out there doesn't seem all that controversial when evidence points to life not being all that hard cosmically. We just don't have strong enough binoculars yet.
betwixthewires 5y ago
Well this article/study talks about the likelihood by looking at the likelihood that an RNA sequence randomly forms long enough enough number of times until a self replicating sequence exists. Such a probabilistic approach indicates that life, while not necessarily rare in the universe, might be rare enough that it is unlikely for it to occur twice in a volume that is observable from one occurrence, or that there is some unknown mechanism that makes it more likely.

titzer 5y ago

None of this probabilistic reasoning matters in the face of the anthropic principle. If there are infinite universes, we could easily be in the mostly stupidly improbable one possible, since we are not observing (and cannot observe) all possible universes, let alone an average one. This why a whole ton of speculation is completely meaningless, because we clearly live in a stupidly improbable universe that is already "fine tuned"--and that's not a problem. It doesn't mean there has to be God or anything. In fact, the settings of our universe imply nothing.

sandgiant 5y ago
Indeed we might never be able to measure the global normalization of the likelihood function of life, but that doesn't mean we can't investigate it's local properties. In fact, I think we can learn a lot from doing just that.
LegitShady 5y ago
There is no evidence that there are infinite universes and indeed the belief in such a concept absent any evidence beside "nothing says there can't be" by scientific people is a religious belief on the order of there being a god except with less elf honesty. We have never detected an alternate universe and we don't even have math that makes it probable. It's just a concept. The same way "there's no reason entropy can't run backwards according to the physics" doesn't stop us not having any evidence for backwards running entropy or negative mass or a million other things that might conceivably exist but have no real evidence but sound cool.
- jcims 5y ago
  Having any belief at all, none, one, many, infinite, all falls into the same category. We don't know. To me it seems like the additional universes in this context serve a purpose similar to (my understanding of) additional dimensions in math/physics. It allows you to navigate around singularities.
  - LegitShady 5y ago

kingcharles 5y ago

All our calculations are fucked by having a sample size of one.

mcswell 5y ago
The article is an argument against that argument.

fallingfrog 5y ago

Is a single strand of rna with all the right nucleotides to self reproduce the only starting point for life? I feel like there must be alternatives- perhaps a whole network of simpler organisms that each could do a small piece of a complete replication. I’m not a biologist so I can’t say- but notably, neither is the author (he’s an astronomer). I’d like to hear the point of view of a biologist on this.

GeorgeKangas 5y ago
One somewhat incremental approach, is called a hypercycle: several simple self replicators "form an alliance" wherein they promote each other's self replication. Not specific to RNA. And I'm not a biologist.

nsonha 5y ago

what if life exists everywhere we are just incapable of detecting it? All we know for sure that there is none on the moon, and soon we will make that claim for Mars, after turning a couple of rocks. If there is life with the same technologies to us sending some beacon signal, what's the odd that we get it?

umvi 5y ago

I'm still skeptical, because even with a statistically improbable RNA forming event, what are the chances actual life will emerge from it? Have we thrown pure RNA into a bucket of water and observed life emerging?

jacknews 5y ago

It seems much more likely to me that life started as an 'autocatalytic set' of molescules, each of which contribute to catalysing reproduction of the whole set, rather than a single strand of active RNA that can reproduce itself. If we look at life now, DNA does not reproduce itself directly, there is an entire ecosystem of chemicals that reproduces itself collectively, using RNA/DNA as a blueprint. The question then is how a set of molecules encoded itself in RNA, but I see that as much more envisionable (eg some RNA, and a host set of catalysts) than a self-reproducing strand of RNA appearing all at once.

Avlin67 5y ago

no, there is not 10^100 stars in universe, only 10^80 atoms. why such a mistake ?

r00tanon 5y ago

Going straight to working RNA is a huge assumption in the analysis, but it's thought provoking to set some sort of lower bound and see how big the cosmos would need to be. Still, somehow we may find a process like natural selection at a cosmic level that makes life way more likely than a purely random starting sequence.

dandotway 5y ago
Atheists: "We have faith natural selection at a cosmic level makes life way more likely." Christians: "We have faith supernatural selection at a cosmic level makes afterlife way more likely."

lend000 5y ago

Curious where the estimate of 10^100 stars came from. I've seen the estimate of 10^80 particles in the observable universe thrown around several times. No idea how either is calculated or what assumptions are made.

deleted 5y ago

[deleted]