Why this universe? New calculation suggests our cosmos is typical(quantamagazine.org)
quantamagazine.org
Why this universe? New calculation suggests our cosmos is typical
https://www.quantamagazine.org/why-this-universe-new-calculation-suggests-our-cosmos-is-typical-20221117/
91 comments
The fine-tuned universe is not a scientific concept though. The only hypothesis at a high level is that the constants or initial conditions of our only observable universe could have been different. However we have no data or reason to believe this is the case. We have no other universes to observe. We have no statistics about the distribution of possible constants. There are no experiments we could run.
Even the headline of this article smells bad, right? Typical as opposed to what? When I see an albino squirrel, I know that it is atypical. I have seen thousands of squirrels, and other mammals, and I have good reason to believe that an all-white squirrel with red eyes is out of the ordinary. I can calculate how many of them there are out of the population and get a ratio to operationalize my definition of "atypical". I can learn more about genetics and biology and melanin and understand an underlying cause for the condition and make predictions about albino-ness in other animals that is falsifiable through further investigation.
In this case though we just have an untestable mathematical model for 'possible universes' (whatever that means) that puts our universe near the top of some abstract bell curve. I understand that smart people made it and that it is very technical and fancy, but I also know that it is made outside of the scientific process becuase I know that we have never observed another universe, we don't have an understanding of how universes are made, we don't know what the possible bounds are for the constants of nature (because they are...constant...). So I consider this to be like a very technical art project.
The argument that god created the universe is also a fine tuning argument, but no one seems to give that one much credence.
Even the headline of this article smells bad, right? Typical as opposed to what? When I see an albino squirrel, I know that it is atypical. I have seen thousands of squirrels, and other mammals, and I have good reason to believe that an all-white squirrel with red eyes is out of the ordinary. I can calculate how many of them there are out of the population and get a ratio to operationalize my definition of "atypical". I can learn more about genetics and biology and melanin and understand an underlying cause for the condition and make predictions about albino-ness in other animals that is falsifiable through further investigation.
In this case though we just have an untestable mathematical model for 'possible universes' (whatever that means) that puts our universe near the top of some abstract bell curve. I understand that smart people made it and that it is very technical and fancy, but I also know that it is made outside of the scientific process becuase I know that we have never observed another universe, we don't have an understanding of how universes are made, we don't know what the possible bounds are for the constants of nature (because they are...constant...). So I consider this to be like a very technical art project.
The argument that god created the universe is also a fine tuning argument, but no one seems to give that one much credence.
When I asked a Jehovah's Witness who was proposing the fine tuning argument to me, "So what would a non-designed universe look like?" He just stared for a second and then said, "Are you like, a scientist or something?"
That’s not as clever an answer as you seem to think
It wasn't a clever answer. It was a very basic question. The point was that the guy who was throwing out the fine tuning argument hadn't even given it an second's though himself.
Notably, a combination of: 1) significant (improbable) information content, and 2) appearance of fulfilling a functional specification ... is taken by some philosophers as supporting a hypothesis of design.
FWIW, Return of the God Hypothesis by Stephen Meyer is a surprisingly well-argued book, exploring such support.
FWIW, Return of the God Hypothesis by Stephen Meyer is a surprisingly well-argued book, exploring such support.
On point 1, how would you know it is improbable? We're back to the initial issue of having nothing else to compare it to. Perhaps it's not improbable but in fact inevitable? Can't tell with only one example.
On point 2, it only looks to fulfill a functional specification if you beg the question. Otherwise, we're simply generating a description of what is.
Stephen Meyer is a founder of the Discovery Institute, a political group who lobby conservative issues and state as part of their mission to promote "a rigorously God-centered view of creation". That doesn't mean Meyer's work on intelligent design is incorrect, per se. But it does strongly suggest that he is starting with a conclusion and then working backward, which is the antithesis of proper scientific research. There are also plenty of eviscerating rebuttals to Meyer if his bias doesn't dissuade.
On point 2, it only looks to fulfill a functional specification if you beg the question. Otherwise, we're simply generating a description of what is.
Stephen Meyer is a founder of the Discovery Institute, a political group who lobby conservative issues and state as part of their mission to promote "a rigorously God-centered view of creation". That doesn't mean Meyer's work on intelligent design is incorrect, per se. But it does strongly suggest that he is starting with a conclusion and then working backward, which is the antithesis of proper scientific research. There are also plenty of eviscerating rebuttals to Meyer if his bias doesn't dissuade.
> But it does strongly suggest that he is starting with a conclusion and then working backward, which is the antithesis of proper scientific research.
His is not scientific research, but the book IMHO is a surprisingly effective and professional weaving of philosophy, history of philosophy, popular science, and history of science toward consideration of Natural Theology.
Point 1: Shannon applies. Point 2: s/supporting a hypothesis/required to support an interpretation/
He acknowledges IIRC that we do not know ranges for potential tunings of physical constants, if that description applies. Has his reference to unexplained low entropy in the Universe been eviscerated? I can't assess his arguments about sparse solutions in protein/fold design space; if you cite a rebuttal of course I'm interested.
His is not scientific research, but the book IMHO is a surprisingly effective and professional weaving of philosophy, history of philosophy, popular science, and history of science toward consideration of Natural Theology.
Point 1: Shannon applies. Point 2: s/supporting a hypothesis/required to support an interpretation/
He acknowledges IIRC that we do not know ranges for potential tunings of physical constants, if that description applies. Has his reference to unexplained low entropy in the Universe been eviscerated? I can't assess his arguments about sparse solutions in protein/fold design space; if you cite a rebuttal of course I'm interested.
>becuase I know that we have never observed another universe
You should hang around people who do a lot of mushrooms, they can clue you in to the others, duuuuuude.
You should hang around people who do a lot of mushrooms, they can clue you in to the others, duuuuuude.
You have the anthropic principle: you can only observe a universe that produces observers. More specifically, if a universe existed that is full of dispersed hydrogen, we wouldn't be there to observe it. The universe must be fine tuned in some way, not just the constants but the very laws of physics. But this is an undecidable and therefore unscientific problem.
The reason scientists want our universe to be "typical" is that the more we can generalize our findings, the more we can make predictions. For example if we can find an equation that gives us the cosmological constant exactly, we can get rid of it as a free parameter. Not only it is philosophically satisfying, but we may also use that equation to find something else, like a new particle, maybe even a practical application.
The reason scientists want our universe to be "typical" is that the more we can generalize our findings, the more we can make predictions. For example if we can find an equation that gives us the cosmological constant exactly, we can get rid of it as a free parameter. Not only it is philosophically satisfying, but we may also use that equation to find something else, like a new particle, maybe even a practical application.
Never really understood why that requires an explanation. A universe full of life is 'interesting' from the perspective of life but that's a subjective sentiment. If the universe was only full of rocks it'd be 'fine-tuned' for rocks. If you were one big mass you'd probably think this universe is tuned awfully wrong. 'Carbon chauvinism' of the wiki page alludes to this but I think you could even generalize it to 'life chauvinism'.
Or alternatively you could ask, why isn't it fine-tuned even harder, with life in every corner? After all it's astonishingly empty in most places.
Or alternatively you could ask, why isn't it fine-tuned even harder, with life in every corner? After all it's astonishingly empty in most places.
In other words:
The puddle of water looked at its oddly shaped surroundings. Every odd curve and unnamed shape that comprised the edge of the puddle was perfectly fit by the surrounding terrain. The puddle marveled at this, such a thing was surely not chance, what phenomenon is behind this mystery? Why does the terrain surround me, a mere puddle, so perfectly?
The puddle of water looked at its oddly shaped surroundings. Every odd curve and unnamed shape that comprised the edge of the puddle was perfectly fit by the surrounding terrain. The puddle marveled at this, such a thing was surely not chance, what phenomenon is behind this mystery? Why does the terrain surround me, a mere puddle, so perfectly?
Brownian motion and the Casimir effect in the early universe should be enough to jumpstart accretion.
Seems silly to try to calculate probabilities from a sample size of 1, but what do I know.
If you have two competing theories, one requiring fine-tuned parameters and the other not, then the latter seems more plausible, because it requires less assumptions. Our universe being “typical” in the context of some theory just means that it requires less fine-tuning, and therefore the theory arguably has more merit.
But the problem is that we have no evidence to suggest that our universe is typical in the first place. For all we know there are a trillion trillion universes and ours is the only one with gravity by some fluke, and we are actually living in the least likely possible universe.
And that's the issue is this model is trying to 'work backward' and justify our universe and it's constants as being mathematically harmonious and 'typical' without having any understanding of what the actual value of 'typical' is.
And that's the issue is this model is trying to 'work backward' and justify our universe and it's constants as being mathematically harmonious and 'typical' without having any understanding of what the actual value of 'typical' is.
What I tried to explain is that this is not really about other universes. The logic applies even if our universe is the only one. It is about the amount of seemingly arbitrary assumptions we have to make for the theory to explain our universe.
But we end up having to make other arbitrary assumptions about what happened at the very beginning of the big bang or about multiverses that we have no scientific justification in making. Calling the observed physical constants 'arbitrary' is a very mathemetician-like move. It is true that they are free variables in the sense that they cannot currently be derived--mathematical models of the universe must include these constants as hard-coded values. But the word arbitrary implies that they could have been something else, and we really don't have justification for that.
We write the modeling program and somewhere we write
It is fun to think about but it can't produce scientific results. It's epicycles, coming up with more complicated stories that over-fit for a singular observation.
We write the modeling program and somewhere we write
FINE_STRUCTURE_CONSTANT=1/137;
./my_universe.sh --fst=0.007 ...
It is fun to think about but it can't produce scientific results. It's epicycles, coming up with more complicated stories that over-fit for a singular observation.
> But the word arbitrary implies that they could have been something else, and we really don't have justification for that.
Well, we’re looking for a reasoning that would support that they couldn’t have been something else, and the article is about one way of coming closer to that.
There are really only two possibilities: Either there’s a reason why they are what they are, then we want to find that reason, or there is no reason, then in other words they are arbitrary.
Well, we’re looking for a reasoning that would support that they couldn’t have been something else, and the article is about one way of coming closer to that.
There are really only two possibilities: Either there’s a reason why they are what they are, then we want to find that reason, or there is no reason, then in other words they are arbitrary.
Both theories are assuming that the parameters are tunable. Why would we assume that?
The parameters are “tunable” because we know of nothing that would prevent the parameters from having a different value. The particular values they have aren’t a logical consequence of other known facts, and hence appear to be arbitrary. They are tunable in the sense that if they were different, no logical contradiction would arise. There is nothing that compels them to have the particular values we observe them to have. This means we have no explanation of why they have those values.
But one goal of science is to provide explanations of why the world is how it is. If we can somehow reduce the apparent arbitrariness of a parameter, or remove it completely (by having it be a mere logical consequence of something else we know), then that increases what we can explain about the universe.
But one goal of science is to provide explanations of why the world is how it is. If we can somehow reduce the apparent arbitrariness of a parameter, or remove it completely (by having it be a mere logical consequence of something else we know), then that increases what we can explain about the universe.
How do you know that the parameters are fine tuned from a single observation? Occam's razor still needs multiple observations to create the model.
They are fine-tuned in the sense that we have to postulate them as axioms, due to lack of any further reasons or causes of why they are how they are. The more we can constrain the value space from which the parameters could conceivably have been chosen, the more “typical” the actual values we observe become, and the less remains unexplained.
Sometimes Occam's Razor reminds me a little of that joke about the two economists who notice money lying on the ground.
Do we assume that our universe will turn out to be elegant because that's what we'd most prefer?
Do we assume that our universe will turn out to be elegant because that's what we'd most prefer?
In 1000 AD I live on an island of blond and left handed people, therefore the typical human is left handed blond
You’ve missed the point. If genetics would show that blond hair and left-handedness are genetically more likely (more “typical”), that would help explain what you’re observing.
I likely am missing the point, how are we proving the 1 and only sample is typical ?
That’s setting aside the whole we have limited observations of the whole universe.
Dark matter shrug, dark energy shrug
British may think otherwise.
https://en.wikipedia.org/wiki/German_tank_problem#Historical...
https://en.wikipedia.org/wiki/German_tank_problem#Historical...
I'm missing where they estimate anything from a sample size of 1. Care to enlighten me?
It was a joke, they didn't but the problem has a formula to estimate the total number from a sample size of one tank, explained in the wiki article under "One Tank" section.
It's theoretical physics. Metaphysically and experimentally, the question may be absurd, but the exercise of calculating entropy for potential universes could still yield novel understandings about the actual universe.
Silly is an excellent word to use when describing a category error, agreed.
There could also be a bias here.
Maybe cognition that develops in a cosmos and is able to reason about cosmoi is more likely to develop models of cosmoi that make their/its own cosmos very typical.
Maybe cognition that develops in a cosmos and is able to reason about cosmoi is more likely to develop models of cosmoi that make their/its own cosmos very typical.
I don't know how much bias the fine structure constant has on the function of cognition, but I think we can all agree that constats incompatible with higher level biological function like cognition would never produce arguments in favor of their typicality.
The answer is: A lot. When looking at fusion processes that create carbon, if the strength of the electric force (quantifiable as the fine structure constant) were just 4% different, our universe would never have produced enough carbon to create life as we know it. The limit is even tighter for the strong nuclear force - less than one percent. If you pick arbitrary constants, you'd very likely just end up in a universe that contains only protons and no higher elements. And it gets even weirder when you start looking at gravity, because most universes should actually have collapsed again long ago or expanded so fast that no elements could form. Some of these fine tuning problems can even be looked at in the absence of intelligent life, because even for a liveable universe they seem ridiculously fine tuned to support what we actually see in the sky.
I carefully chose my word "function" instead of "existence".
Give me two different universes where cognition exists but where the fundamental constants differ. Would you expect the ability to perform syllogism would be fundamentally biased to reflect the constants which brought about their existence?
Give me two different universes where cognition exists but where the fundamental constants differ. Would you expect the ability to perform syllogism would be fundamentally biased to reflect the constants which brought about their existence?
Easy. I present you two universes, one with our cosmological constant and one with a slightly smaller but still nonzero one. The differences would only become apparent over distances greater than a few billion light years or so. Out planet, solar system or even the entire galaxy would be virtually indistinguishable. But inhabitants of both would wonder how the cosmological constant got cancelled out so precisely against the QFT vacuum over so many orders of magnitude when studying the sky. No bias required.
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Yes it's called the Anthropic principle
Well, I checked all my samples and every single universe I've ever seen is identical. Right down the the atoms.
I think I need to be published!
I think I need to be published!
This comment should not be downvoted. It is entirely correct. Matches my own observations - this universe is exactly the same as all the universes that are known to exist.
Just as a hypothetical thought experiment, suppose the entire description of our universe laws of physics and initial conditions can be described with a bits string of size X. Add a few more bits to describe a specific location and time, and a few more bits to decode whatever it is that humans wrote at some time.
Then everything humanity will ever reach or know has Kolmogorov complexity no larger than this X. My intuition is that if you take X to be too small, the general "nothing's special about the universe and it's all extremely typical" argument and you must surely reach a contradiction. Surely not everything is so incredibly compressible, is it?
Physicists keep crying about fine tuning and what not, but honestly, I would be even more surprised if the initial conditions and the laws of physics were extremely small. Because we already know the laws of physics are relatively simple, I would put my bets on the initial conditions having most of the entropy.
Then everything humanity will ever reach or know has Kolmogorov complexity no larger than this X. My intuition is that if you take X to be too small, the general "nothing's special about the universe and it's all extremely typical" argument and you must surely reach a contradiction. Surely not everything is so incredibly compressible, is it?
Physicists keep crying about fine tuning and what not, but honestly, I would be even more surprised if the initial conditions and the laws of physics were extremely small. Because we already know the laws of physics are relatively simple, I would put my bets on the initial conditions having most of the entropy.
There is an easy counter model. The universe is _literally_ a real number machine, i.e. even a particular point is only describable to us in the approximate. The laws of physics get to be finite, but you can't talk about a particular location or place in time without infinite information, or you talk about it in the approximate.
>There is an easy counter model. The universe is _literally_ a real number machine, i.e. even a particular point is only describable to us in the approximate.
There is actually some debate about that, and for good reason. There are even a couple of practicing physicists looking at how predictions would differ assuming the universe has finite precision, and if I recall correctly the results from that investigation are non-trivial.
There is actually some debate about that, and for good reason. There are even a couple of practicing physicists looking at how predictions would differ assuming the universe has finite precision, and if I recall correctly the results from that investigation are non-trivial.
> The universe is _literally_ a real number machine
I am wary of this. Just because you have a good predictive model based on math, and the math can be made rigorous using ZFC / Cauchy sequences / infinite decimals / etc., doesn't mean that any of those rigorous mathematical concepts are literally running the real universe.
Personally I don't think there's any reason to believe that any numbers, even zero and one, have any existence outside of being concepts in our heads.
I am wary of this. Just because you have a good predictive model based on math, and the math can be made rigorous using ZFC / Cauchy sequences / infinite decimals / etc., doesn't mean that any of those rigorous mathematical concepts are literally running the real universe.
Personally I don't think there's any reason to believe that any numbers, even zero and one, have any existence outside of being concepts in our heads.
I don't get what you say in the last paragraph. Isn't the mapping of zero and one to nothing and something kind of the easiest thing (e.g. one photon or no photon)?
For the first paragraph it is my understanding that the universe is discrete/quantizied and it is not running on 'real numbers'.
For the first paragraph it is my understanding that the universe is discrete/quantizied and it is not running on 'real numbers'.
> I don't get what you say in the last paragraph. Isn't the mapping of zero and one to nothing and something kind of the easiest thing (e.g. one photon or no photon)?
You can map and mapping is useful, but the map lives in your head and isn't the territory.
> For the first paragraph it is my understanding that the universe is discrete/quantizied and it is not running on 'real numbers'.
This is a widely believed folk myth among software engineers, but it isn't supported by evidence. There are some speculative theories that try to solve some problems in physics by quantizing space, but right now they are no more empirically supported than other speculations.
You can map and mapping is useful, but the map lives in your head and isn't the territory.
> For the first paragraph it is my understanding that the universe is discrete/quantizied and it is not running on 'real numbers'.
This is a widely believed folk myth among software engineers, but it isn't supported by evidence. There are some speculative theories that try to solve some problems in physics by quantizing space, but right now they are no more empirically supported than other speculations.
Worth a read:
1. "Russell’s No Man’s Land" [0]
2. "The hollow universe of modern physics" [1]
[0] https://edwardfeser.blogspot.com/2020/08/russells-no-mans-la...
[1] https://edwardfeser.blogspot.com/2022/05/the-hollow-universe...
1. "Russell’s No Man’s Land" [0]
2. "The hollow universe of modern physics" [1]
[0] https://edwardfeser.blogspot.com/2020/08/russells-no-mans-la...
[1] https://edwardfeser.blogspot.com/2022/05/the-hollow-universe...
Mh, but I thought it was widely held that there are things such as the Planck constant which constitute bounds on divisibility. There rather seems to be no indication to believe conversely that the universe works on real numbers. Which makes at least intuitive sense that there isn't anything which contains infinite information.
There is such a thing as the Planck constant. It doesn't constitute a bound on the divisibility of space. It is a length scale below which we do not expect our current physical theories to make good predictions. See https://www.fnal.gov/pub/today/archive/archive_2013/today13-...
> Which makes at least intuitive sense that there isn't anything which contains infinite information.
There are no real numbers outside of human beings' minds. The information in a number, real or otherwise, is a theoretical mathematical concept from human minds for which there is no evidence in nature.
There is no definitive evidence that nature confirms to either continuous or discrete math at the smallest scales, but for now, if you look at theoretical physics papers, you will see integrals and derivatives, not sums and differences.
> Which makes at least intuitive sense that there isn't anything which contains infinite information.
There are no real numbers outside of human beings' minds. The information in a number, real or otherwise, is a theoretical mathematical concept from human minds for which there is no evidence in nature.
There is no definitive evidence that nature confirms to either continuous or discrete math at the smallest scales, but for now, if you look at theoretical physics papers, you will see integrals and derivatives, not sums and differences.
Am I correctly summarizing this statement, for my own understanding?
“All values in the cosmos are integers. Decimals exist to help humans make comparisons between objects.”
“All values in the cosmos are integers. Decimals exist to help humans make comparisons between objects.”
No. They're talking about real numbers; even decimal numbers (rationals) are isomorphic to integers. The reals are different.
I mean, they seem to be saying the exact opposite of that based on the usual way people talk about the "reals".
You could put all the human knowledge in a single real number and still have infinite room left.
There exists an abstract mathematical mapping, sure. However, finding the spot in the real number where that's the case may require infinite storage (you need to store the pointer) or infinite time (you start searching through the number to find what you want). It also has a halting problem where you don't actually know how you'll know when you find that data.
>Then everything humanity will ever reach or know has Kolmogorov complexity no larger than this X.
Only if it is deterministic, which certainly seems not very plausible. (You could say everything is a probability distribution, but to me it seems to get extremely complex after that, collapse?)
>Because we already know the laws of physics are relatively simple, I would put my bets on the initial conditions having most of the entropy.
Just because the laws are simply expressible does not imply they are simple. A variational minimization problem can be very easy to state (certainly that seems a good candidate for a "true" law of nature), but it can easily be as hard as a PDE!
Only if it is deterministic, which certainly seems not very plausible. (You could say everything is a probability distribution, but to me it seems to get extremely complex after that, collapse?)
>Because we already know the laws of physics are relatively simple, I would put my bets on the initial conditions having most of the entropy.
Just because the laws are simply expressible does not imply they are simple. A variational minimization problem can be very easy to state (certainly that seems a good candidate for a "true" law of nature), but it can easily be as hard as a PDE!
The point about determinism is correct, but since wavefunction evolution is unitary, the universe is fully deterministic. Only if you take some interpretation that there's real physical process of measurement which we don't understand and is indeterministic you can get randomness.
But maybe if you subscribe to multiple worlds interpretation then the hardest part might be specifying which universe you're in, which would require number of bits proportional to the time since the big bang.
But maybe if you subscribe to multiple worlds interpretation then the hardest part might be specifying which universe you're in, which would require number of bits proportional to the time since the big bang.
> The point about determinism is correct, but since wavefunction evolution is unitary, the universe is fully deterministic.
A problem: if you consider the contents of the universe (and the precise state of the contents at a given snapshot in time) to be part of "the universe", you have the hard problem of consciousness to tend with (in that humans are a part of the universe, and they rearrange its contents on a regular basis).
> Only if you take some interpretation that there's real physical process of measurement which we don't understand and is indeterministic you can get randomness.
Randomness is not the only means to achieve a non-deterministic universe, there is also the possibility of non-deterministic forces being in play, like human activity.
Of course, one can assert that human cognition is deterministic (no other option may even be available in some cases!), but science strongly suggests that simply asserting something to be true does not necessarily cause it to be true (though it does often cause it to appear to be true to pre-trained instances of human consciousness, a phenomenon which science has well demonstrated).
Abstractly(!), humans seem to be in a very similar cognitive state as they were when they ran on sub-perceptual religious axioms.
https://ell.stackexchange.com/questions/155593/meaning-of-th...
A problem: if you consider the contents of the universe (and the precise state of the contents at a given snapshot in time) to be part of "the universe", you have the hard problem of consciousness to tend with (in that humans are a part of the universe, and they rearrange its contents on a regular basis).
> Only if you take some interpretation that there's real physical process of measurement which we don't understand and is indeterministic you can get randomness.
Randomness is not the only means to achieve a non-deterministic universe, there is also the possibility of non-deterministic forces being in play, like human activity.
Of course, one can assert that human cognition is deterministic (no other option may even be available in some cases!), but science strongly suggests that simply asserting something to be true does not necessarily cause it to be true (though it does often cause it to appear to be true to pre-trained instances of human consciousness, a phenomenon which science has well demonstrated).
Abstractly(!), humans seem to be in a very similar cognitive state as they were when they ran on sub-perceptual religious axioms.
https://ell.stackexchange.com/questions/155593/meaning-of-th...
> Only if it is deterministic, which certainly seems not very plausible.
A collapsing quantum state is so far the only proposed process which would result in a nondeterministic universe. The problem is that absolutely nothing is known about it, and everything around it is fishy.
I personally think that the concept of the universal wavefunction makes more sense.
A collapsing quantum state is so far the only proposed process which would result in a nondeterministic universe. The problem is that absolutely nothing is known about it, and everything around it is fishy.
I personally think that the concept of the universal wavefunction makes more sense.
It’s also possible that our __models__ are simple, but the underlying reality is not, so as long as there exists some error after sufficient evaluations it is safe to say that our model’s complexity is less than the universe’s.
Yes, I agree. It is definitely possible that the underlying laws are extremely complex and there is absolutely no simple way to state them.
But what I think is really interesting that this extreme complexity can only be found in extremely large and small scales. E.g. Newtons laws are phenomenal at predicting the universe at "human scales". The systems which can arise in Newtonian physics can be extremely complex, but their descriptions are usually very simple. Deviations from Newtonian predictions either are very small or arise only at large/small scales.
But what I think is really interesting that this extreme complexity can only be found in extremely large and small scales. E.g. Newtons laws are phenomenal at predicting the universe at "human scales". The systems which can arise in Newtonian physics can be extremely complex, but their descriptions are usually very simple. Deviations from Newtonian predictions either are very small or arise only at large/small scales.
> Newtonian physics can be extremely complex, but their descriptions are usually very simple
IIRC Constructor theory builds on this, in a way, it defines some very basic and simple building blocks out of which the rest of the laws that govern our universe.
https://en.wikipedia.org/wiki/Constructor_theory
IIRC Constructor theory builds on this, in a way, it defines some very basic and simple building blocks out of which the rest of the laws that govern our universe.
https://en.wikipedia.org/wiki/Constructor_theory
Either that, or reality is inherently quantum and the entropy of an evolving unitary wave function (well, the entropy of any given amplitude) basically goes to infinity.
> Surely not everything is so incredibly compressible, is it?
I like your line of thinking and I'm actually quite excited about this recent shift in physics to a more information-theoretic line of inquiry.
Is it fair to state a corollary of your question this way? Given a complete description of some hypothesized universe/multiverse generator (essentially the next layer down that we are actively trying to discover), the Kolmogorov complexity (or some variation of K-Complexity) of this description must be greater than the K-complexity of any generated universe.
In my view, it would be very weird if this were not true. And (to me) it would be even weirder if this K-complexity was some large number but still less than infinity.
I like your line of thinking and I'm actually quite excited about this recent shift in physics to a more information-theoretic line of inquiry.
Is it fair to state a corollary of your question this way? Given a complete description of some hypothesized universe/multiverse generator (essentially the next layer down that we are actively trying to discover), the Kolmogorov complexity (or some variation of K-Complexity) of this description must be greater than the K-complexity of any generated universe.
In my view, it would be very weird if this were not true. And (to me) it would be even weirder if this K-complexity was some large number but still less than infinity.
You could have an incredibly simple universe generator that just produces universes with random laws of physics and random initial conditions. From our human point of view that's indistinguishable from a highly sophisticated universe generator, since we can only observe the successes (or rather only one, that by our definition is a success)
> My intuition is that if you take X to be too small, the general "nothing's special about the universe and it's all extremely typical" argument and you must surely reach a contradiction. Surely not everything is so incredibly compressible, is it?
This sounds similar to saying, "This photograph can be expressed in this small number of bits, therefore it's not special." Why does one imply the other?
This sounds similar to saying, "This photograph can be expressed in this small number of bits, therefore it's not special." Why does one imply the other?
We don’t know that the universe is discrete, hence a description in a finite number of bits, and Kolmogorov complexity, may be inapplicable.
This line of reasoning assumes that all physical processes are deterministic. If they are not (as is the current mainstream belief) then I don’t think that line of reasoning would stand. Instead, the current state is the result of that initial set of inputs, and countless other nob-deterministic dice rolls.
Also keep in mind that everything assumes the equations are Lipschitz in order to guarantee uniqueness of the solution given specific initial conditions. But this is too optimistic.
y’=y^(1/3)
with y(0) = 0
has an infinite number of solutions.
y’=y^(1/3)
with y(0) = 0
has an infinite number of solutions.
It gets far worse if it is not an ODE, but a PDE, there a uniqueness criteria is somewhere between "for this PDE in this extremely special case with these extra assumptions ..." up to "?????".
The universe appears chaotic, in that outcomes have sensitive dependence on its initial conditions. Even if all laws of physics are deterministic.
So for there to be a wide range of possible things happening from the initial starting point (including you and I having this conversation right now), IMO it follows that a complete description of the initial conditions would have to be absurdly (infinitely?) large to cause the universe to replay to this exact moment if you started it all over again.
In other words, the size of X would have to be extremely large… so I think I agree with you.
(Edited once I realized that myself and OP are likely in agreement.)
So for there to be a wide range of possible things happening from the initial starting point (including you and I having this conversation right now), IMO it follows that a complete description of the initial conditions would have to be absurdly (infinitely?) large to cause the universe to replay to this exact moment if you started it all over again.
In other words, the size of X would have to be extremely large… so I think I agree with you.
(Edited once I realized that myself and OP are likely in agreement.)
> Then everything humanity will ever reach or know has Kolmogorov complexity no larger than this X
No. Information complexity does not obey conservation laws. The initial rule for generating the Universe is simple, but as time goes on information complexity only increases exponentially. It's a singularity of information complexity and we are at the center of it.
(This is the real reason, by the way, why aliens don't exist and Fermi's "paradox" isn't really.)
No. Information complexity does not obey conservation laws. The initial rule for generating the Universe is simple, but as time goes on information complexity only increases exponentially. It's a singularity of information complexity and we are at the center of it.
(This is the real reason, by the way, why aliens don't exist and Fermi's "paradox" isn't really.)
What do you mean by "information complexity"?
Quantity of information absolutely does follow conservation laws, at least in quantum mechanics.
Quantity of information absolutely does follow conservation laws, at least in quantum mechanics.
Same thing as the Kolmogorov complexity the original poster mentioned. It corresponds to entropy somehow, so I don't think quantum mechanics is on topic here.
Does this assume the/a universe is deterministic?
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Wouldn't a probability model also suggest our universe, galaxies, and solar system are all probably.... typical?
The probabilities of trillions of galaxies suggest it is more likely we are 1 of many, rather than 1 of 1.
Just because, for example, an ancient tribe in Europe lived in the north and might never see others because they're 100's of miles away - doesn't mean the tribe is 1 of 1.
The probabilities of trillions of galaxies suggest it is more likely we are 1 of many, rather than 1 of 1.
Just because, for example, an ancient tribe in Europe lived in the north and might never see others because they're 100's of miles away - doesn't mean the tribe is 1 of 1.
Some models suggest we might be fairly early, probably somewhere in the first 10-25% of space faring species.
Maybe we are special, for example space around our solar system is emptier than usual, maybe due to a super nova blasting stuff away. But chances are we are not all that special, just in an early part of the game where nobody expanded into our neighborhood yet
Maybe we are special, for example space around our solar system is emptier than usual, maybe due to a super nova blasting stuff away. But chances are we are not all that special, just in an early part of the game where nobody expanded into our neighborhood yet
>Some models suggest we might be fairly early, probably somewhere in the first 10-25% of space faring species.
I’d like to see some sources for this, because this sounds like unscientific, unprovable drivel.
I’d like to see some sources for this, because this sounds like unscientific, unprovable drivel.
[1] is the first paper Google spewed out, though I think there is newer work. I'm on mobile though, so can't check. The basic idea is to figured out how many stars that may support space faring civilizations have formed, and how many will form in the future. Add in some delay for planets and life to form, and account for the death of the star, and you can estimate how many such species should spawn over time, and thus tell if we are early or late to the party (assuming all assumptions are somewhat right)
1: https://ouci.dntb.gov.ua/en/works/7PgprAO9/ https://arxiv.org/pdf/1606.08448v2.pdf
1: https://ouci.dntb.gov.ua/en/works/7PgprAO9/ https://arxiv.org/pdf/1606.08448v2.pdf
Our star system isn't typical. Most stars are red dwarfs.
Perhaps we’re overdoing the copernican principle at this point? It’s weird how researchers internalize that to the point they can’t even fathom that anything about existence is special.
IMO that well is dry and our future breakthroughs will come from focusing on the observers of the universe.
(Thanks for attending my Ted talk)
IMO that well is dry and our future breakthroughs will come from focusing on the observers of the universe.
(Thanks for attending my Ted talk)
Specialness requires explanation, or alternatively it’s just a fluke. The latter is unsatisfactory, so we’re looking for explanations, and if there are none, or they again require special assumptions, then the natural conclusion is that there is no specialness.
Some amount of specialness is normal. If our place in the multiverse can be described by 1000 random normal-distributed variables, you would expect 50 of those values to be at least two standard deviations away from the mean, and 3 variables to be three standard deviations off.
Of course we don't know which ones, so assuming any one thing to be normal is the best approach. But looking at the big picture, there are bound to be flukes. Not having any would be an even bigger fluke
Of course we don't know which ones, so assuming any one thing to be normal is the best approach. But looking at the big picture, there are bound to be flukes. Not having any would be an even bigger fluke
How confident can we be about what other potential universes might be like with different fundamental constants? Maybe if we pick one constant and vary it slightly, we can reason that there would be less carbon, but how do we know that some other combination of parameters wouldn’t create some other phenomenon, unknown in our universe, that could act as the substrate of life?
Especially considering we may not know what all the parameters are.
Especially considering we may not know what all the parameters are.
It's typical. Typical of all the other cosmoses out there.
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This doesn't seem to be an answer to why the fundamental constants are set for an interesting universe with stars and atoms that do chemistry. Not ones full of dispersed hydrogen, or one big mass, or ones with uninteresting chemistry where nothing happens. See "fine-tuned universe".[1] Still, it's a step forward.
[1] https://en.wikipedia.org/wiki/Fine-tuned_universe