# If we live in a multiverse, what percentage of universes will be capable of harboring life **URL:** \ **Category:** Factual Questions\ **Created:** [April 17, 2017, 6:41pm UTC](https://boards.straightdope.com/t/if-we-live-in-a-multiverse-what-percentage-of-universes-will-be-capable-of-harboring-life/784651 "2017-04-17T18:41:47Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Tranquilis](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tranquilis/32/3639_2.png) [@Tranquilis](https://boards.straightdope.com/u/Tranquilis)\ **Post date:** [April 17, 2017, 9:20pm UTC](https://boards.straightdope.com/t/if-we-live-in-a-multiverse-what-percentage-of-universes-will-be-capable-of-harboring-life/784651/21 "2017-04-17T21:20:27Z")
> [@Riemann](#): > > I’d suggest that a separate thread is in order. Seems reasonable. Of course, I’ve just about tapped out my science/philosophy of thought and consciouness depths. So if you do it, it’ll be the other brains computing the course of that thread. ---
**Author:** ![boffking](https://avatars.discourse-cdn.com/v4/letter/b/858c86/32.png) [@boffking](https://boards.straightdope.com/u/boffking)\ **Post date:** [April 17, 2017, 9:32pm UTC](https://boards.straightdope.com/t/if-we-live-in-a-multiverse-what-percentage-of-universes-will-be-capable-of-harboring-life/784651/22 "2017-04-17T21:32:42Z")
What percentage of numbers are prime? You can’t take a percent of infinity. ---
**Author:** ![SamuelA](https://avatars.discourse-cdn.com/v4/letter/s/c77e96/32.png) [@SamuelA](https://boards.straightdope.com/u/SamuelA)\ **Post date:** [April 17, 2017, 9:37pm UTC](https://boards.straightdope.com/t/if-we-live-in-a-multiverse-what-percentage-of-universes-will-be-capable-of-harboring-life/784651/23 "2017-04-17T21:37:25Z")
> [@boffking](#): > > What percentage of numbers are prime? > You can’t take a percent of infinity. You can’t? I would swear that you in fact can. Isn’t that what we do in math when we take the limit, for example, the value of an asset over infinite time? (aka an infinite series of a number that is shrinking) Primes are funny because they aren’t smooth mathematically so while we can observe that they get rarer and rarer the bigger the numbers get, we can’t prove exact properties of them over infinity. ---
**Author:** ![OldGuy](https://avatars.discourse-cdn.com/v4/letter/o/3bc359/32.png) [@OldGuy](https://boards.straightdope.com/u/OldGuy)\ **Post date:** [April 17, 2017, 10:30pm UTC](https://boards.straightdope.com/t/if-we-live-in-a-multiverse-what-percentage-of-universes-will-be-capable-of-harboring-life/784651/24 "2017-04-17T22:30:04Z")
> [@boffking](#): > > What percentage of numbers are prime? > You can’t take a percent of infinity. Actually this calculation is the idea behind the Prime Number Theorem. > **[Prime number theorem](https://en.wikipedia.org/wiki/Prime_number_theorem)** > > In mathematics, the prime number theorem (PNT) describes the asymptotic distribution of the prime numbers among the positive integers. It formalizes the intuitive idea that primes become less common as they become larger by precisely quantifying the rate at which this occurs. The theorem was proved independently by Jacques Hadamard and Charles Jean de la Vallée Poussin in 1896 using ideas introduced by Bernhard Riemann (in particular, the Riemann zeta function). > The first such distribution foun... And to a first approximation the number of primes less than x is asymptotically x/ln(x). This means that the fraction of numbers that are prime goes to zero in the limit, but it does so in a well defined way. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 17, 2017, 11:04pm UTC](https://boards.straightdope.com/t/if-we-live-in-a-multiverse-what-percentage-of-universes-will-be-capable-of-harboring-life/784651/25 "2017-04-17T23:04:22Z")
Some probability problems are well-defined when dealing with infinities, and some are not. Some seem well-defined, but turn out not to be once one looks at them with enough rigor. And some problems which lack sufficient rigor can have that rigor applied in multiple different ways, which lead to different answers. Which one applies here depends on just exactly how the multiverse is structured. > [@](#): > > Quoth **Stranger on a Train** : > > As to the concept of other universes, it should be recognized that there are two separate concepts here. One comes from the quantum mechanical notion of simultaneous superposition of possibilities at the quantum level, derived from Hugh Everett’s “relative state” interpretation (note that Everett did not promote the idea that there was a literal “multiverse”; just that we’re experiencing one of a multitude of simultaneous possibilities). In this multiverse, all the laws of physics are the same but the resolutions of individual states fill all possible options, and share the same mass-energy matrix in a state of superposition. There’s a third possibility, also: Bubble universes in the eternal inflation model. In these, you could in principle point with your finger in the direction towards some other universe, but the bubbles are receding from each other at such great speed that causal connection between them is impossible. Such bubbles might or might not show variation in fundamental constants: I don’t think that question is actually resolved. > [@](#): > > The other is from brane cosmology that there are separate, unconnected physical universes formed from an initial singularity of energy and which deconstructed into different balances of dimensions and physical parameters. In this case, each universe has its own separate mass and energy (which may or may not be infinite in extent) and are in no way causally connected with one another. In most braneworld models, the branes are in fact causally connected, just not easily. Electromagnetism, the strong force, and the weak force are confined to the branes, but gravitational effects can still bridge the gap. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 18, 2017, 3:05am UTC](https://boards.straightdope.com/t/if-we-live-in-a-multiverse-what-percentage-of-universes-will-be-capable-of-harboring-life/784651/26 "2017-04-18T03:05:50Z")
> [@](#): > > Quoth me: > > Some probability problems are well-defined when dealing with infinities, and some are not. Some seem well-defined, but turn out not to be once one looks at them with enough rigor. And some problems which lack sufficient rigor can have that rigor applied in multiple different ways, which lead to different answers. Which one applies here depends on just exactly how the multiverse is structured. It occurs to me that I ought to clarify what I mean here. By way of example, here’s an argument that exactly 1/3 of all natural numbers are even. List out all numbers, like so: 1 3 2 5 7 4 9 11 6 13 15 8 17 19 10 21 23 12… That’s a list of all natural numbers, right? And if I look at the first _n_ numbers on that list, and find the proportion that are even, that proportion is definitely approaching a limit of 1/3 as _n_ increases. Now, most people would say that this argument is wrong, because I’m taking the numbers out of order. And this is perhaps a reasonable thing to say, because the natural numbers have an obvious simple order to them. But when I’m looking at the set of all universes, is there a natural order to place them in? I suppose it makes sense to put our own Universe first on the list, but is there one particular universe that ought to be second, or third? Maybe I could list the universes in order of distance from our own… but then, how are we measuring the distance? Some sort of measure of how different they are from our own, perhaps? But then, the first universes I count will always be the ones most like our own, and if there are an infinite number that are enough like our own to have life, then I might never reach any of the non-life-bearing ones on my list. ---
**Author:** ![eburacum45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eburacum45/32/8690_2.png) [@eburacum45](https://boards.straightdope.com/u/eburacum45)\ **Post date:** [April 18, 2017, 9:38am UTC](https://boards.straightdope.com/t/if-we-live-in-a-multiverse-what-percentage-of-universes-will-be-capable-of-harboring-life/784651/27 "2017-04-18T09:38:09Z")
> [@Chronos](#): > > In most braneworld models, the branes are in fact causally connected, just not easily. Electromagnetism, the strong force, and the weak force are confined to the branes, but gravitational effects can still bridge the gap. This opens the possibility of signalling. If we could create gravity waves at will, then we could send messages to nearby branes, and maybe even get messages back. _I can call spirits from the vasty deep. … Why, so can I, or so can any man; But will they come when you do call for them?_ ---
**Author:** ![Mijin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mijin/32/9369_2.png) [@Mijin](https://boards.straightdope.com/u/Mijin)\ **Post date:** [April 18, 2017, 10:09am UTC](https://boards.straightdope.com/t/if-we-live-in-a-multiverse-what-percentage-of-universes-will-be-capable-of-harboring-life/784651/28 "2017-04-18T10:09:28Z")
> [@Riemann](#): > > But an infinite number of things does not imply infinite _variety_. There may be infinitely many universes, but with rather tight constraints on what kind of universe is possible. > > I think that there is often a mistaken conflation of the multiverse with Everett’s many-worlds interpretation of QM. The latter does indeed seem to imply that (in some poorly defined sense) _all_ possible outcomes exist. But most versions of the multiverse are based on completely different ideas. Well I’ve never been clear on that aspect. But if it’s as you say then ISTM the multiverse doesn’t really help with the issue of why all the constants in our universe appear fine-tuned. Because it just kicks it further down the road: considering the infinity of multiverses that could not harbour life, what good fortune this is the one that exists. NB: This isn’t a religious argument. And I’m on the fence of whether I think it’s even a meaningful question ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [April 18, 2017, 11:17am UTC](https://boards.straightdope.com/t/if-we-live-in-a-multiverse-what-percentage-of-universes-will-be-capable-of-harboring-life/784651/29 "2017-04-18T11:17:11Z")
> [@Mijin](#): > > Well I’ve never been clear on that aspect. But if it’s as you say then ISTM the multiverse doesn’t really help with the issue of why all the constants in our universe appear fine-tuned. Because it just kicks it further down the road: considering the infinity of multiverses that could not harbour life, what good fortune this is the one that exists. The “fine tuning” argument is really solipsistic nonsense. If the universe were not configured as it is, we would not be here to ask the question and the issue would be resolved. The need for the universe to be finely tuned to permit our existence is predicated on some essential necessity of that existence, rather than that we just happened to emerge from the existing mechanics of physics and chemisty of a convenient universe. Could those mechanics be altered by an arbitrary change in universal constants making any order impossible? Sure, that is concievable, but there would be no one in that universe to ask questions. The question of multiple universes is purely speculative and not possible of being frames as even a hypothesis without some fundamental breakthoughs in the physics of cosmology, e.g. some ability to finely measure and control gravity (which, as **Chronos** adroitly corrected me, may allow causal connections between seperate branes), so any question predicated on their existence is also speculative. Speculation can be quite fun, of course, and lead to enjoyable fiction, but we cannot draw any useful conclusions without observable phenomena and measureable data. Stranger ---
**Author:** ![Hari\_Seldon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hari_seldon/32/5173_2.png) [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)\ **Post date:** [April 18, 2017, 11:33am UTC](https://boards.straightdope.com/t/if-we-live-in-a-multiverse-what-percentage-of-universes-will-be-capable-of-harboring-life/784651/30 "2017-04-18T11:33:49Z")
> [@Riemann](#): > > There are infinitely many positive integers. Yet we know what proportion are divisible by 2. This is true only if you look at the integers as an ordered set and then only in the usual order. What proportion is even if you put them in the order: 1,2,3,5,4,7,9,11,6,13,15,17,19,8,… putting n odd numbers between 2n-2 and 2n? As far as anyone knows, there is no way of ordering the universes and Stranger’s point is well taken. Anyway, I’ll take a flier and say the odds are 0. Suppose there is a universe out there just like ours except the gravitational constant differs in the 10th decimal. Maybe life would still be possible, maybe not. How could we know? I think the question is essentially meaningless. ---
**Author:** ![Mijin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mijin/32/9369_2.png) [@Mijin](https://boards.straightdope.com/u/Mijin)\ **Post date:** [April 18, 2017, 1:00pm UTC](https://boards.straightdope.com/t/if-we-live-in-a-multiverse-what-percentage-of-universes-will-be-capable-of-harboring-life/784651/31 "2017-04-18T13:00:48Z")
> [@Stranger\_On\_A\_Train](#): > > The “fine tuning” argument is really solipsistic nonsense. If the universe were not configured as it is, we would not be here to ask the question and the issue would be resolved. The need for the universe to be finely tuned to permit our existence is predicated on some essential necessity of that existence, rather than that we just happened to emerge from the existing mechanics of physics and chemisty of a convenient universe. Could those mechanics be altered by an arbitrary change in universal constants making any order impossible? Sure, that is concievable, but there would be no one in that universe to ask questions. As I mentioned in my previous post, I’m not sure that the fine-tuning “problem” is really a problem that needs or could be solved. However, I also don’t find the anthropic principle compelling either. A pretty sizeable chunk of science is investigating and understanding phenomena that human life depends on. Now it’s true that why this constant is 4.3 instead of 4.2 is a different kind of question to “How does water dissolve so many things?”, say. It’s a Why question vs a How question, for a start. But for me, I don’t see why that makes the anthropic principle “work” or be a satisfying answer. ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [April 18, 2017, 1:02pm UTC](https://boards.straightdope.com/t/if-we-live-in-a-multiverse-what-percentage-of-universes-will-be-capable-of-harboring-life/784651/32 "2017-04-18T13:02:34Z")
> [@Hari\_Seldon](#): > > This is true only if you look at the integers as an ordered set and then only in the usual order. What proportion is even if you put them in the order: > 1,2,3,5,4,7,9,11,6,13,15,17,19,8,… > putting n odd numbers between 2n-2 and 2n? As far as anyone knows, there is no way of ordering the universes and Stranger’s point is well taken. Anyway, I’ll take a flier and say the odds are 0. Suppose there is a universe out there just like ours except the gravitational constant differs in the 10th decimal. Maybe life would still be possible, maybe not. How could we know? I think the question is essentially meaningless. Yes, but please take my point in the context of what it was replying to. I was not claiming that we actually _do_ know anything about the properties of the multiverse, if it exists. Of course we do not. I was countering the false assertion that it is impossible, in principle, to determine _any_ properties of something that is infinite. ---
**Author:** ![Lemur866](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lemur866/32/434_2.png) [@Lemur866](https://boards.straightdope.com/u/Lemur866)\ **Post date:** [April 18, 2017, 3:47pm UTC](https://boards.straightdope.com/t/if-we-live-in-a-multiverse-what-percentage-of-universes-will-be-capable-of-harboring-life/784651/33 "2017-04-18T15:47:47Z")
> [@Mijin](#): > > As I mentioned in my previous post, I’m not sure that the fine-tuning “problem” is really a problem that needs or could be solved. However, I also don’t find the anthropic principle compelling either. > > A pretty sizeable chunk of science is investigating and understanding phenomena that human life depends on. > Now it’s true that why this constant is 4.3 instead of 4.2 is a different kind of question to “How does water dissolve so many things?”, say. It’s a Why question vs a How question, for a start. > But for me, I don’t see why that makes the anthropic principle “work” or be a satisfying answer. Isn’t it amazing that human beings just happen to live on Earth, where there is liquid water, an oxygen atmosphere and photosynthesis, which can support us, instead of Mars, where we’d freeze, suffocate, and starve to death? Of course there aren’t any human beings on Mars, and it’s not just random chance that humans evolved on Earth, a planet fine-tuned to support human life, rather than on Mars, a planet without any of the things required to support human life. Our lungs aren’t perfectly adapted to breathe Earth’s air by chance, rather, the Earth’s atmosphere existed and our ancestors evolved to breathe it. So since we exist, we must exist in a universe and planet where human life could exist. Of course, our universe isn’t exactly finely tuned to support the presence of life, since even here in our solar system life apparently only exists on one small planet. The other bodies in the solar system are implacably hostile to life. Most of the matter in the universe is collected into starts, which can’t support life, or frozen iceballs that can’t support life, or finely dispersed gas and dust, which can’t support life. If I were going to design a universe capable of supporting life as we know it, Jim, I could do a much better job. Like that giant sun and tiny Earth, that’s ridiculous, it should be the other way around. And those other big planets are just a waste of space, so replace them with tiny moving lights. And other stars? Silly. And let’s put a dome over the Earth to hold in the atmosphere rather than use gravity. So something more like this: [http://i.onionstatic.com/avclub/6235/81/16x9/1200.jpg](http://i.onionstatic.com/avclub/6235/81/16x9/1200.jpg) ---
**Author:** ![SamuelA](https://avatars.discourse-cdn.com/v4/letter/s/c77e96/32.png) [@SamuelA](https://boards.straightdope.com/u/SamuelA)\ **Post date:** [April 18, 2017, 4:19pm UTC](https://boards.straightdope.com/t/if-we-live-in-a-multiverse-what-percentage-of-universes-will-be-capable-of-harboring-life/784651/34 "2017-04-18T16:19:12Z")
> [@Stranger\_On\_A\_Train](#): > > The “fine tuning” argument is really solipsistic nonsense. If the universe were not configured as it is, we would not be here to ask the question and the issue would be resolved. The need for the universe to be finely tuned to permit our existence is predicated on some essential necessity of that existence, rather than that we just happened to emerge from the existing mechanics of physics and chemisty of a convenient universe. Could those mechanics be altered by an arbitrary change in universal constants making any order impossible? Sure, that is concievable, but there would be no one in that universe to ask questions. > Stranger Stranger, it isn’t, and it in fact supports the multiple universe hypothesis. Observation : the various parameters of this universe must be set an exact way or we would not be here. Observation : no coherent model of time and cause and effect as observed by the nature of this universe allows an event to spontaneously, from nothing, create just this universe and no other. Resulting Hypothesis : some type of eternal mechanism has created this universe and others with different parameters and will do so forever. If this hypothesized mechanism didn’t create all possible parameters somehow (whether those extra universes will exist before/after this one, or they all exist right now simultaneously), it would be extraordinarily unlikely for us to be here. I know this hypothesis is thin. There are many other explanations for our existence, but this one has the benefit of being as simple as possible. The simplest possible explanation that explains all observations is the model you should use. ---
**Author:** ![SamuelA](https://avatars.discourse-cdn.com/v4/letter/s/c77e96/32.png) [@SamuelA](https://boards.straightdope.com/u/SamuelA)\ **Post date:** [April 18, 2017, 4:23pm UTC](https://boards.straightdope.com/t/if-we-live-in-a-multiverse-what-percentage-of-universes-will-be-capable-of-harboring-life/784651/35 "2017-04-18T16:23:14Z")
> [@Lemur866](#): > > Of course, our universe isn’t exactly finely tuned to support the presence of life, since even here in our solar system life apparently only exists on one small planet. No, but it is thought that slight changes in the parameters and the universe would just be an ever expanding ball of dark gas, or just light expanding forever and no matter, or other such possibilities where no life at all can be possible. The possibility of self replicating complex matter spontaneously evolving requires an awful lot of characteristics specific to this universe. That specificity is information, and the simplest model of universe formation posits a simple, eternal mechanism that creates them. Therefore, that mechanism could not have the information to create this specific universe alone, and thus, there must be other universes - or this one must repeat with different parameters. Everything beyond that is mostly speculation, but the edge possibility that the other universes are visible from telescopes here allows at least a possibility of gathering the evidence to investigate it one way or another. ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [April 18, 2017, 4:38pm UTC](https://boards.straightdope.com/t/if-we-live-in-a-multiverse-what-percentage-of-universes-will-be-capable-of-harboring-life/784651/36 "2017-04-18T16:38:56Z")
> [@SamuelA](#): > > …the simplest model of universe formation… I don’t think I accept your invocation of Occam’s Razor here. First, here’s Andre Linde with a good account of the fine-tuning problem, the anthropic principle and the multiverse: [https://www.edge.org/response-detail/25535](https://www.edge.org/response-detail/25535) > [@](#): > > From the early days of string theory, physicists knew that there are exponentially many different ways to compactly the extra 6 dimensions, but we did not know what can prevent the compactified dimensions from blowing up. This problem was solved about 10 years ago, and the solution validated the earlier expectations of the exponentially large number of possibilities. Some estimates of the number of different options are as large as 10^500. And each of these options describes a part of the universe with a different vacuum energy and different types of matter. > > In the context of the inflationary theory, this means that our world may consist of incredibly large number of exponentially large “universes” with 10^500 different types of matter inside them. > > A pessimist would argue that since we do not see other parts of the universe, we cannot prove that this picture is correct. An optimist, on the other hand, may counter that we can never disprove this picture either, because its main assumption is that other “universes” are far away from us. And since we know that the best of the theories developed so far allow about 10^500 different universes, anybody who argues that the universe must have same properties everywhere would have to prove that only one of these 10^500 universes is possible. > > And then there is something else. There are many strange coincidences in our world. The mass of the electron is 2000 times smaller than the mass of the proton. Why? The only known reason is that if it would change few times, life as we know it would be impossible. The masses of the proton and neutron almost coincide. Why? If one of their masses would change just a little, life as we know it would be impossible. The energy of empty space in our part of the universe is not zero, but a tiny number, more than a hundred orders of magnitude below the naive theoretical expectations. Why? The only known explanation is that we would be unable to live in the world with a much larger energy of vacuum. > > The relation between our properties and the properties of the world is called the anthropic principle. But if the universe were given to us in one copy, this relation would not help… But it seems to me that there are _three_ possible resolutions to the apparent fine-tuning problem, and (given the lack of evidence to support string theory) it would be extremely difficult to defend the position that any one of these is a more economical explanation than the others. (1) Multiverse + anthropic principle. No constraint on parameter space, a vast variety of universes DO all exist, the vast majority inconsistent with life. The anthropic principle explains why we see ours. (2) There is a better model for how universes are built, that does not have all the free parameters of current string theory. In other words, the parameter values found in our universe arise from the model somehow as the only valid solution. The only real basis to claim that this is _unlikely_ is that we have been looking for such a model for decades and have failed. But that seems a weak argument to me. (3) We are wrong about our interpretation of the parameter space and “life” is not as unlikely as it appears. This would probably need to be combined with a weaker form of (2) above, where a better model that current string theory might constrain parameter space allowing a much narrower variety of possible universes. ---
**Author:** ![Mijin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mijin/32/9369_2.png) [@Mijin](https://boards.straightdope.com/u/Mijin)\ **Post date:** [April 18, 2017, 4:50pm UTC](https://boards.straightdope.com/t/if-we-live-in-a-multiverse-what-percentage-of-universes-will-be-capable-of-harboring-life/784651/37 "2017-04-18T16:50:44Z")
> [@Lemur866](#): > > Of course, our universe isn’t exactly finely tuned to support the presence of life, since even here in our solar system life apparently only exists on one small planet. The other bodies in the solar system are implacably hostile to life. Most of the matter in the universe is collected into starts, which can’t support life, or frozen iceballs that can’t support life, or finely dispersed gas and dust, which can’t support life. Of course, but the issue with the fine-tuning argument is that even our universe, even if earth is the only planet with life, would look lush compared to one where the strong force was a smidge stronger, say. I’m no proponent of the fine-tuning argument, I am just saying I don’t think these standard handwaves quite work. (although, as I say, I’m not sure it’s an issue that _needs_ addressing anyway) ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [April 18, 2017, 4:58pm UTC](https://boards.straightdope.com/t/if-we-live-in-a-multiverse-what-percentage-of-universes-will-be-capable-of-harboring-life/784651/38 "2017-04-18T16:58:19Z")
> [@Mijin](#): > > Of course, but the issue with the fine-tuning argument is that even our universe, even if earth is the only planet with life, would look lush compared to one where the strong force was a smidge stronger, say… Yes. If the current model of string theory is correct, it appears the vast majority of allowable parameter values are inconsistent with the existence of any form of stable _matter_, let alone “life” under even the broadest of definitions. This _may_ be wrong, but that’s what the only viable current models seem to say. And we need a little better than a hand-wavey “maybe life is less unlikely than we think” to resolve it. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 18, 2017, 5:07pm UTC](https://boards.straightdope.com/t/if-we-live-in-a-multiverse-what-percentage-of-universes-will-be-capable-of-harboring-life/784651/39 "2017-04-18T17:07:08Z")
Keep in mind, we’re all talking about “life as we know it”, here. I can envision, for instance, a form of life not dependent on any form of matter at all, and composed entirely of gravitational waves. Such life would exist far more slowly than the sort we’re familiar with, but that only matters if you’re measuring using life-as-we-know-it time units. By the same token, I can also envision a form of life based on strong-force “chemistry” instead of electromagnetic, which could only have existed in the first few minutes of our Universe’s history, and which would consider absurd the notion that anything could live 10^28 picoseconds past the heat death of the Universe. ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [April 18, 2017, 5:19pm UTC](https://boards.straightdope.com/t/if-we-live-in-a-multiverse-what-percentage-of-universes-will-be-capable-of-harboring-life/784651/40 "2017-04-18T17:19:33Z")
> [@Chronos](#): > > Keep in mind, we’re all talking about “life as we know it”, here. I can envision, for instance… But I think the argument is that even forms of “life” that are beyond our wildest imagination surely have a requirement for some degree of stability, and that under the current unconstrained models the vast majority of the parameter space is unstable. (I’m not quite sure if stable/unstable is the best terminology here, but something like that.) [Previous page](https://boards.straightdope.com/t/if-we-live-in-a-multiverse-what-percentage-of-universes-will-be-capable-of-harboring-life/784651.md?page=1) [Next page](https://boards.straightdope.com/t/if-we-live-in-a-multiverse-what-percentage-of-universes-will-be-capable-of-harboring-life/784651.md?page=3)