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Science's Alternative to an Intelligent Creator: the Multiverse Theory

28 points by rms 18y ago

robg 18y ago
The multiverse is my favorite scientific hypothesis. It just seems right. It's always been cool to think about the boundary conditions of our universe (how big? how long? how much?). But one among many? That's utterly baffling and exciting. Unfortunately, without evidence, it's an argument of faith, like any other.
- thwarted 18y ago
  Baffling and exciting in the same way that the set of reals is larger than the set of integers even though both are infinite. Also, Zeno's Paradox is my favorite.
- trapper 18y ago
  I like the simulation hypothesis. I love how it "explains" some of the constants we see & quantum physics. I don't see how belief in "the multiverse" is any different than belief in a god or the simulation hypothesis. They all have zero evidence and can't be tested. The obvious question in all three is: what was there before? So they all have the same problems.
  - goodness 18y ago
    The simulation hypothesis actually becomes more likely, though still not proven, if we get to the point where we can run our own simulated universe. We might also demonstrate that we were in a simulation if we found an exploit to take over the simulator's webcam (assuming the simulator didn't patch and revert). Universal buffer overflow!
deleted 18y ago
[deleted]
Retric 18y ago
If gravity were slightly more powerful, the consequences would be nearly as grave. A beefed-up gravitational force would compress stars more tightly, making them smaller, hotter, and denser. Rather than surviving for billions of years, stars would burn through their fuel in a few million years, sputtering out long before life had a chance to evolve. This is wrong, with slightly more gravity smaller stars would burn hotter but there is a wide range of stars that can last for 5 billion years. Now if was 100 times as strong they might have a point but there is about an order of magnitude to play around with.
- rsheridan6 18y ago
  But would we still be able to get the elements we need for life? We are partly made of leftovers from supernovas, and so is our sun. It takes more than just a energy source to create life - you have to have something other than hydrogen to work with.
  - Retric 18y ago
    Assuming everything else was the same and gravity was 5x as strong then a star around the size of the sun would go super nova in a short time period. (Granted it would take a lot of time to really model this.) There is some support for Jupitor producing a little fusion with it's current mass. If you increase gravity it becomes smaller until it's heat balances out the force of gravity which increases the amount of fusion taking place. PS: Less massive stars have a higher surface area to volume ratio. This reduces their temerature which reduces their fuel usage. But once they run out of fuel the same type of interesting things are going to happen.
wensing 18y ago
Is the multiverse theory falsifiable? I can't tell.
- rms 18y ago
  >Critics say it doesn’t even qualify as a scientific theory because the existence of other universes cannot be proved or disproved. Advocates argue that, like it or not, the multiverse may well be the only viable nonreligious explanation for what is often called the “fine-tuning problem”—the baffling observation that the laws of the universe seem custom-tailored to favor the emergence of life.
  - jhancock 18y ago
    Its amusing that some are so adamant against the unprovable concept of a creator that they go to such lengths as believing in something else equally unprovable. I like the multiverse concept. Its cool. Maybe a creator created this ;)
- DarkShikari 18y ago
  To some extent, actually, yes. Here's a way of doing it. Let us say that a hyper-advanced civilization has the ability, through simulations or otherwise, of calculating the odds of life arising in a universe with given initial conditions and fundamental constants (to some rough accuracy). They can test billions of possible initial states, including our own, and use that to see whether we lie in a very probable location in phase space or an improbable one. If the location is probable, it strongly supports the multiverse theory. If the location is improbable, the theory is likely false. For example, if the average probability of life arising in a given universe in some chunk of phase space that includes ours is 40%, and ours is in a subsection of that phase space with a 30% probability, the multiverse theory is not falsified. If ours is in a subsection of that phase space with a 0.000001% probability (far lower than average), it suggests that multiverse is unlikely, because our existence seems to be in violation of pure chance. The same method can be used to falsify evolution. Test billions of simulations of the Earth's development of life, and see where our species falls statistically. If we're in a probable area of the phase space (phase space of possible sentient creatures to evolve), our understanding of evolution is likely correct, and if we're in a very improbable area (many many standard deviations away from the most likely), our understanding must be flawed somewhere.
elemenohpee 18y ago
I don't think the idea that the universe is finely tuned for life(not necessarily life as we know it) is that unreasonable. I dislike the idea of a creator for the obvious reason that you run into an infinite regression. What created the creator, etc... So how do we get around this? Could it be possible that the universe created itself? In the void, there are infinite possibilities. If there existed a pattern which sustained itself, somehow propagated itself in perpetuity, would it then exist? Then the fact that the universe seems finely tuned for life would be an obvious consequence. Something like us would be needed to tend the light, we would be a necessary component of this pattern. Anyway, I like it better than the idea of a huge number of "dead" universes, although I doubt we'll ever know the Truth of the matter.
sciolizer 18y ago
Anthropic arguments frustrate me to no end. 1.) "Life as we know it" is an extremely important phrase. Ask a biologist what life is, and she will probably say something about cells and DNA. It is possible for other self-replicating combinations of molecules to exist, but not on Earth, because the Cell/DNA model has become so effective at wiping the competition out. It's actually really hard to come to a solid definition of what "life" is, but if you make it sufficiently broad, I suspect you could find life even in some universes where the fundamental constants differ significantly from ours. 2.) We have no idea what determines the fundamental constants. You cannot talk about the "odds" of having a universe like ours until you know the probability distributions for each of the fundamental constants. Look at the H2O on Earth, and you will find that a significant portion of it occurs at 0C and 100C. Of course that is not a coincidence - water often exists at those temperatures because energy is spent on converting state, not on altering temperature. It's an equilibrium point. So likewise, it's POSSIBLE that the fundamental constants (of multiple universes, if they exist) interact in ways that cause them to arrive at equilibrium points. One really fascinating theory promoting this idea (and any theory is as good as the next, since we have very little empirical evidence available to us) is Lee Smolin's argument that the singularities within blackholes are themselves universe phases. Thus, a kind of "natural selection" of black holes occurs, which leads to more and more universes with fundamental constants ideal for producing black holes (and thus close to the constants necessary for life). 3.) The anthropic principle is just way too convenient, and I fear it de-motivates scientists from looking deeper into issues that really need explaining. Roger Penrose argues that there is a surprising lack of parsimony on behalf of whatever forces (spiritual or natural) brought about our universe. While our universe appears to have inflated from an initial region with a phase-space-volume of 10^(10^123), it would have been more than sufficient to create a life-supporting universe (several! in fact) from a region with only a phase-space-volume of 10^(10^117). Additionally, Penrose points out that the odds of creating an exact duplicate of our solar system from the random coming together of gas and radiation (no Darwinian evolution necessary!) is only 1 in 10^(10^60). (Penrose calls it "utter chicken feed" compared to the odds of the Big Bang producing ANY universe of our size). So even when you invoke the anthropic principle, the question still remains - why is our (life-supporting) universe so large and so old, when we could have done with so much less?
- 18y ago
asdflkj 18y ago
The idea that science should even come up with an "alternative" to that bullshit is an insult to science.
- swombat 18y ago
  Not to mention that the multiverse theory can't currently be proven wrong and hence is unscientific.
  - yummyfajitas 18y ago
    True, neither multiverse theory nor a singleverse theory can be proven. But both are scientific in the sense that they (sort of) predict the structure of our universe. The question then becomes how to select one of the theories. Occams razor provides little help, since both theories are similarly complex, so one possible way to select a theory is to use Bayes rule. I'll sketch this reasoning: The laws of physics are governed by equations which output only a probability distribution P(x) for various quantities (positions of particles, the values of certain fundamental constants). (Note: I really don't understand any of this stuff well, so if someone (Dani?) with better knowledge can correct me or clarify, I'd love to see it.) In a single-universe theory (SUT), one postulates that a particular x is selected, at random, relative to P(x) dx. In this theory, it is highly unlikely that the universe can support life (or at least life like us). In a multiverse theory (MUT), one postulates that all x are selected in parallel. In this case, our particular x will be chosen; the fact that we live in a good universe is not luck, merely natural selection. So the probability we exist is close to 1. Both these theories are more or less equally "simple" (think Kolmogorov complexity), so let us assume they each "occur" with the same or similar "probability" (i.e., p(SUT)=p(MUT)=1/2). Then we use Bayes rule: p(SUT | we exist) = p(we exist | SUT) p(SUT) / p(we exist) = (really freakin low) (1/2) / (1/2+really freakin low) = (unlikely) p(MUT | we exist) = p(we exist | MUT) p(MUT) / p(we exist) = (almost 1) (1/2) / (1/2 + really freakin low) = (highly likely) So multiverse theory is more "probable" than single universe theory. This remains true even if you wildly alter the complexity of competing theories, e.g. p(SUT)/p(MUT) = 1e6. It's true, we can never falsify SUT or MUT relative to each other. But we can make educated guesses as to which one is more "probable". And yes, this is pretty sketchy, hence my use of scare quotes everywhere. But it's the best we can do right now. Note: I computed p(we exist) = p(MUT)p(we exist | MUT) + p(SUT)p(we exist) = (1/2) 1 + (1/2)(really freakin low). [edit: just curious why I'm being downmodded. Not begging for upmods, I'm honestly curious. Did I make a mistake here?]
trapper 18y ago
They should get blossom goodchild to ask the galatic federation of light, perhaps they know :P
markessien 18y ago
The solution is too complex. Complex things don't survive, because complexity tends to decay. The universe has to be based of a very simple concept - but our minds, which are developed for earth-style biology has not yet landed on that concept. I'll consider any theory seriously that is: 1. Very simple 2. Very stable
- crabapple 18y ago
  The universe has to be based of a very simple concept why?
  - markessien 18y ago
    Because everything we have ever observed in nature follows the exact same pattern: 1. Single instable thing exists that tends to combine with other items to form a somewhat stable object 2. The results combine with other more complex things in the same manner to create something else It's like a recursion. Something simple gets executed over and over again, each time gaining in parameters and complexity.
speek 18y ago
Isn't this a major part of string theory?
river_styx 18y ago
If I recall correctly, the "universe" is a concept meant to encompass all that exists. How then can there be multiple universes? Wouldn't the set of all universes itself exist within the universe? It seems more likely to me that "universe" here is being defined as "what we can observe", in which case these multiverses are simply the unobservable part of our universe.
- r7000 18y ago
  "Universes" in this context means discrete space-times with potentially different physical constants where the laws of physics would be different. http://en.wikipedia.org/wiki/Multiverse#Bubble_theory http://en.wikipedia.org/wiki/Multiverse#Bubble_theory The Many-Worlds hypothesis also implies separate "realities" ("universes"?) diverge with every quantum measurement. The word is used for convenience.
  - river_styx 18y ago
    I guess that's part of my objection, really. The use of the word "universe" implies that there is only one of them, as the prefix "uni-" in Latin means "one".
- lehmannro 18y ago
  Back in the day "atoms" were meant to be indivisible as well. It's just relics of our language not keeping up with science.
crabapple 18y ago
there's a lot of talk of probabilities in the article but it seems hackneyed the universe has almost countless variables that can result in near-infinite states, but there is a 100% chance that one state must emerge (i.e. a 100% chance that reality exists), and it isn't clear if the alternative scenarios they describe (particles of different masses, stronger gravitational impact on stellar mass) are more probable than our own. the scientists see our state as optimal because we live in it, but why couldn't our state be suboptimal? maybe there was a potential state (never realized) that resulted in us all being omnipotent. there seems to be a bias from the researchers regarding our own state, but they haven't demonstrated that its any more or less likely than any other outcome

28 points by rms 18y ago

robg 18y ago

The multiverse is my favorite scientific hypothesis. It just seems right. It's always been cool to think about the boundary conditions of our universe (how big? how long? how much?). But one among many? That's utterly baffling and exciting. Unfortunately, without evidence, it's an argument of faith, like any other.

thwarted 18y ago
Baffling and exciting in the same way that the set of reals is larger than the set of integers even though both are infinite. Also, Zeno's Paradox is my favorite.
trapper 18y ago
I like the simulation hypothesis. I love how it "explains" some of the constants we see & quantum physics. I don't see how belief in "the multiverse" is any different than belief in a god or the simulation hypothesis. They all have zero evidence and can't be tested. The obvious question in all three is: what was there before? So they all have the same problems.
- goodness 18y ago
  The simulation hypothesis actually becomes more likely, though still not proven, if we get to the point where we can run our own simulated universe. We might also demonstrate that we were in a simulation if we found an exploit to take over the simulator's webcam (assuming the simulator didn't patch and revert). Universal buffer overflow!

deleted 18y ago

[deleted]

Retric 18y ago

If gravity were slightly more powerful, the consequences would be nearly as grave. A beefed-up gravitational force would compress stars more tightly, making them smaller, hotter, and denser. Rather than surviving for billions of years, stars would burn through their fuel in a few million years, sputtering out long before life had a chance to evolve. This is wrong, with slightly more gravity smaller stars would burn hotter but there is a wide range of stars that can last for 5 billion years. Now if was 100 times as strong they might have a point but there is about an order of magnitude to play around with.

rsheridan6 18y ago
But would we still be able to get the elements we need for life? We are partly made of leftovers from supernovas, and so is our sun. It takes more than just a energy source to create life - you have to have something other than hydrogen to work with.
- Retric 18y ago
  Assuming everything else was the same and gravity was 5x as strong then a star around the size of the sun would go super nova in a short time period. (Granted it would take a lot of time to really model this.) There is some support for Jupitor producing a little fusion with it's current mass. If you increase gravity it becomes smaller until it's heat balances out the force of gravity which increases the amount of fusion taking place. PS: Less massive stars have a higher surface area to volume ratio. This reduces their temerature which reduces their fuel usage. But once they run out of fuel the same type of interesting things are going to happen.

wensing 18y ago

Is the multiverse theory falsifiable? I can't tell.

rms 18y ago
>Critics say it doesn’t even qualify as a scientific theory because the existence of other universes cannot be proved or disproved. Advocates argue that, like it or not, the multiverse may well be the only viable nonreligious explanation for what is often called the “fine-tuning problem”—the baffling observation that the laws of the universe seem custom-tailored to favor the emergence of life.
- jhancock 18y ago
  Its amusing that some are so adamant against the unprovable concept of a creator that they go to such lengths as believing in something else equally unprovable. I like the multiverse concept. Its cool. Maybe a creator created this ;)
DarkShikari 18y ago
To some extent, actually, yes. Here's a way of doing it. Let us say that a hyper-advanced civilization has the ability, through simulations or otherwise, of calculating the odds of life arising in a universe with given initial conditions and fundamental constants (to some rough accuracy). They can test billions of possible initial states, including our own, and use that to see whether we lie in a very probable location in phase space or an improbable one. If the location is probable, it strongly supports the multiverse theory. If the location is improbable, the theory is likely false. For example, if the average probability of life arising in a given universe in some chunk of phase space that includes ours is 40%, and ours is in a subsection of that phase space with a 30% probability, the multiverse theory is not falsified. If ours is in a subsection of that phase space with a 0.000001% probability (far lower than average), it suggests that multiverse is unlikely, because our existence seems to be in violation of pure chance. The same method can be used to falsify evolution. Test billions of simulations of the Earth's development of life, and see where our species falls statistically. If we're in a probable area of the phase space (phase space of possible sentient creatures to evolve), our understanding of evolution is likely correct, and if we're in a very improbable area (many many standard deviations away from the most likely), our understanding must be flawed somewhere.

elemenohpee 18y ago

I don't think the idea that the universe is finely tuned for life(not necessarily life as we know it) is that unreasonable. I dislike the idea of a creator for the obvious reason that you run into an infinite regression. What created the creator, etc... So how do we get around this? Could it be possible that the universe created itself? In the void, there are infinite possibilities. If there existed a pattern which sustained itself, somehow propagated itself in perpetuity, would it then exist? Then the fact that the universe seems finely tuned for life would be an obvious consequence. Something like us would be needed to tend the light, we would be a necessary component of this pattern. Anyway, I like it better than the idea of a huge number of "dead" universes, although I doubt we'll ever know the Truth of the matter.

sciolizer 18y ago

Anthropic arguments frustrate me to no end. 1.) "Life as we know it" is an extremely important phrase. Ask a biologist what life is, and she will probably say something about cells and DNA. It is possible for other self-replicating combinations of molecules to exist, but not on Earth, because the Cell/DNA model has become so effective at wiping the competition out. It's actually really hard to come to a solid definition of what "life" is, but if you make it sufficiently broad, I suspect you could find life even in some universes where the fundamental constants differ significantly from ours. 2.) We have no idea what determines the fundamental constants. You cannot talk about the "odds" of having a universe like ours until you know the probability distributions for each of the fundamental constants. Look at the H2O on Earth, and you will find that a significant portion of it occurs at 0C and 100C. Of course that is not a coincidence - water often exists at those temperatures because energy is spent on converting state, not on altering temperature. It's an equilibrium point. So likewise, it's POSSIBLE that the fundamental constants (of multiple universes, if they exist) interact in ways that cause them to arrive at equilibrium points. One really fascinating theory promoting this idea (and any theory is as good as the next, since we have very little empirical evidence available to us) is Lee Smolin's argument that the singularities within blackholes are themselves universe phases. Thus, a kind of "natural selection" of black holes occurs, which leads to more and more universes with fundamental constants ideal for producing black holes (and thus close to the constants necessary for life). 3.) The anthropic principle is just way too convenient, and I fear it de-motivates scientists from looking deeper into issues that really need explaining. Roger Penrose argues that there is a surprising lack of parsimony on behalf of whatever forces (spiritual or natural) brought about our universe. While our universe appears to have inflated from an initial region with a phase-space-volume of 10^(10^123), it would have been more than sufficient to create a life-supporting universe (several! in fact) from a region with only a phase-space-volume of 10^(10^117). Additionally, Penrose points out that the odds of creating an exact duplicate of our solar system from the random coming together of gas and radiation (no Darwinian evolution necessary!) is only 1 in 10^(10^60). (Penrose calls it "utter chicken feed" compared to the odds of the Big Bang producing ANY universe of our size). So even when you invoke the anthropic principle, the question still remains - why is our (life-supporting) universe so large and so old, when we could have done with so much less?

18y ago

asdflkj 18y ago

The idea that science should even come up with an "alternative" to that bullshit is an insult to science.

swombat 18y ago
Not to mention that the multiverse theory can't currently be proven wrong and hence is unscientific.
- yummyfajitas 18y ago
  True, neither multiverse theory nor a singleverse theory can be proven. But both are scientific in the sense that they (sort of) predict the structure of our universe. The question then becomes how to select one of the theories. Occams razor provides little help, since both theories are similarly complex, so one possible way to select a theory is to use Bayes rule. I'll sketch this reasoning: The laws of physics are governed by equations which output only a probability distribution P(x) for various quantities (positions of particles, the values of certain fundamental constants). (Note: I really don't understand any of this stuff well, so if someone (Dani?) with better knowledge can correct me or clarify, I'd love to see it.) In a single-universe theory (SUT), one postulates that a particular x is selected, at random, relative to P(x) dx. In this theory, it is highly unlikely that the universe can support life (or at least life like us). In a multiverse theory (MUT), one postulates that all x are selected in parallel. In this case, our particular x will be chosen; the fact that we live in a good universe is not luck, merely natural selection. So the probability we exist is close to 1. Both these theories are more or less equally "simple" (think Kolmogorov complexity), so let us assume they each "occur" with the same or similar "probability" (i.e., p(SUT)=p(MUT)=1/2). Then we use Bayes rule: p(SUT | we exist) = p(we exist | SUT) p(SUT) / p(we exist) = (really freakin low) (1/2) / (1/2+really freakin low) = (unlikely) p(MUT | we exist) = p(we exist | MUT) p(MUT) / p(we exist) = (almost 1) (1/2) / (1/2 + really freakin low) = (highly likely) So multiverse theory is more "probable" than single universe theory. This remains true even if you wildly alter the complexity of competing theories, e.g. p(SUT)/p(MUT) = 1e6. It's true, we can never falsify SUT or MUT relative to each other. But we can make educated guesses as to which one is more "probable". And yes, this is pretty sketchy, hence my use of scare quotes everywhere. But it's the best we can do right now. Note: I computed p(we exist) = p(MUT)p(we exist | MUT) + p(SUT)p(we exist) = (1/2) 1 + (1/2)(really freakin low). [edit: just curious why I'm being downmodded. Not begging for upmods, I'm honestly curious. Did I make a mistake here?]

trapper 18y ago

They should get blossom goodchild to ask the galatic federation of light, perhaps they know :P

markessien 18y ago

The solution is too complex. Complex things don't survive, because complexity tends to decay. The universe has to be based of a very simple concept - but our minds, which are developed for earth-style biology has not yet landed on that concept. I'll consider any theory seriously that is: 1. Very simple 2. Very stable

crabapple 18y ago
The universe has to be based of a very simple concept why?
- markessien 18y ago
  Because everything we have ever observed in nature follows the exact same pattern: 1. Single instable thing exists that tends to combine with other items to form a somewhat stable object 2. The results combine with other more complex things in the same manner to create something else It's like a recursion. Something simple gets executed over and over again, each time gaining in parameters and complexity.

speek 18y ago

Isn't this a major part of string theory?

river_styx 18y ago

If I recall correctly, the "universe" is a concept meant to encompass all that exists. How then can there be multiple universes? Wouldn't the set of all universes itself exist within the universe? It seems more likely to me that "universe" here is being defined as "what we can observe", in which case these multiverses are simply the unobservable part of our universe.

r7000 18y ago
"Universes" in this context means discrete space-times with potentially different physical constants where the laws of physics would be different. http://en.wikipedia.org/wiki/Multiverse#Bubble_theory http://en.wikipedia.org/wiki/Multiverse#Bubble_theory The Many-Worlds hypothesis also implies separate "realities" ("universes"?) diverge with every quantum measurement. The word is used for convenience.
- river_styx 18y ago
  I guess that's part of my objection, really. The use of the word "universe" implies that there is only one of them, as the prefix "uni-" in Latin means "one".
lehmannro 18y ago
Back in the day "atoms" were meant to be indivisible as well. It's just relics of our language not keeping up with science.

crabapple 18y ago

there's a lot of talk of probabilities in the article but it seems hackneyed the universe has almost countless variables that can result in near-infinite states, but there is a 100% chance that one state must emerge (i.e. a 100% chance that reality exists), and it isn't clear if the alternative scenarios they describe (particles of different masses, stronger gravitational impact on stellar mass) are more probable than our own. the scientists see our state as optimal because we live in it, but why couldn't our state be suboptimal? maybe there was a potential state (never realized) that resulted in us all being omnipotent. there seems to be a bias from the researchers regarding our own state, but they haven't demonstrated that its any more or less likely than any other outcome