Why isn't the universe uniform?

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King Author
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Why isn't the universe uniform?

Postby King Author » Mon Feb 15, 2010 12:46 pm UTC

So almost fourteen billion years ago, the big bang went...uh, bang, and the universe began blasting out in every direction. At first, it was pretty much all light elements, like hydrogen, then they coallesced, formed stars and began shooting out heavier elements, which themselves coallesced into planets and so forth, etc. etc. we all know the story.

So then why isn't the universe uniform? With nothing existing outside of the "cosmic egg" before the big bang, its expansion should have been omnidirectionally uniform, right? And gravity doesn't play favorites, so theoretically all stars should have began coallescing equidistantly from each other, each taking up an equal number of hydrogens, each spewing out the same amount of the same heavier elements, which should've then condensed evenly in the same manner, etc. etc. and the universe should be perfectly uniform.

So...why isn't the universe uniform? Does objectively definable and true "randomness" exist on the atomic or sub-atomic level? Or perhaps was there something outside the cosmic egg, like a structural framework of dark matter or something?

Forgive me for asking such big questions while I lack any formal training in science beyond K-12 and gen-ed college stuff.
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Re: Why isn't the universe uniform?

Postby Jack21222 » Mon Feb 15, 2010 12:53 pm UTC

I am not an astrophysicist, but I'll take a stab at it.

This is one of the questions that nobody knows for sure right now, but they suspect that quantum effects in the first moments of the universe caused it to be non-uniform. To answer your question, randomness DOES exist on the atomic and sub-atomic level. That is a well-known fact. Google the "Double Slit Experiment" for some crazy stuff. That randomness could have been the cause of every star and galaxy we see.
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Re: Why isn't the universe uniform?

Postby EmilyR » Mon Feb 15, 2010 1:13 pm UTC

Not a physicist, but I believe it's thought to be due to random quantum mechanical fluctuations immediately after the big bang (when the universe was sufficiently small that QM scale changes could have a significant macroscopic impact) that scaled up as the universe expanded.

edit -- I guess I ought to read what the second post said before replying to the first! :)

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Re: Why isn't the universe uniform?

Postby Pez Dispens3r » Mon Feb 15, 2010 1:17 pm UTC

It wouldn't at all be related to the Jurassic Park choas-math/life-found-a-way stuff, would it?

I ask only because it seems to make sense: water split won't create a uniform pattern on the ground.
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Re: Why isn't the universe uniform?

Postby Zamfir » Mon Feb 15, 2010 1:37 pm UTC

Pez Dispens3r wrote:It wouldn't at all be related to the Jurassic Park choas-math/life-found-a-way stuff, would it?

In a sense it is. Gravity on cosmic scales makes a uniform density mixture very unstable, as the slightest increase in density will be self-reinforcing until the mass collapses into stars and galaxies and clusters etc.

But that still means that you have to have some small density fluctuations in your mixture, and it's not a priori obvious that a cosmic soup should have any deviation from uniformity at all.

Once you have a mechanism for small deviations, there is still a mixing problem: areas with slightly different density might remix together on shorter timescales than gravity can collapse them to increase the difference. But this goes away as the mixture cools, and mixing becomes slower.
So in the end , you are right. For chaos you need exponential deviation from similar initial conditions, and gravity collapse provides such a mechanism.

The second part of the Jurassic Park philosophy, that such a chaotic system will always have some sort of self-organizing life-like property is simply wrong: life appears to have properties from chaotic systems, but not every chaotic system has necessarily properties of life.

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Re: Why isn't the universe uniform?

Postby Sir_Elderberry » Mon Feb 15, 2010 2:17 pm UTC

King Author wrote:So...why isn't the universe uniform? Does objectively definable and true "randomness" exist on the atomic or sub-atomic level?

Yes, actually. Quantum processes carry some inherent randomness, probably. If I remember correctly, experiments have shown that one of the following is false:
-Causality (things in the future cannot affect things in the past)
-Nonlocality (things can only affect the things around them, at the speed of light--no instantaneous information transfer)
-Local Hidden Variables (there are deterministic processes lying behind quantum mechanics' apparent randomness)

We usually pick the third one because the others screw up the universe even more.
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Re: Why isn't the universe uniform?

Postby Vaniver » Mon Feb 15, 2010 2:44 pm UTC

I think you can come up with a better explanation using thermodynamics and entropy- it doesn't require any quantum foolishness.
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Re: Why isn't the universe uniform?

Postby EmilyR » Mon Feb 15, 2010 3:25 pm UTC

Vaniver wrote:I think you can come up with a better explanation using thermodynamics and entropy- it doesn't require any quantum foolishness.

Still not a physicist, but if you're starting with a small, hot, very homogenous universe dosn't thermodynamics+entropy (ummm... isn't entropy included in thermodynamics?) just mean you end up with a bigger, cooler, still very homogenous universe?

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Re: Why isn't the universe uniform?

Postby Charlie! » Mon Feb 15, 2010 5:46 pm UTC

EmilyR wrote:
Vaniver wrote:I think you can come up with a better explanation using thermodynamics and entropy- it doesn't require any quantum foolishness.

Still not a physicist, but if you're starting with a small, hot, very homogenous universe dosn't thermodynamics+entropy (ummm... isn't entropy included in thermodynamics?) just mean you end up with a bigger, cooler, still very homogenous universe?

The trick is that more space means more entropy for some of the particles. If you have some particles in a small box, there are only a few ways to arrange them. But in a bigger box, there are more ways to rearrange (okay, so there are infinite ways, but I swear that the entropy scales really fast with volume. It's actually pretty kickass to derive).
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Re: Why isn't the universe uniform?

Postby MadRocketSci2 » Mon Feb 15, 2010 7:18 pm UTC

As was pointed out, gravity makes uniformity unstable. Given arbitrarily small changes from perfect uniformity, the difference would magnify with time.

Uniformity is only possible with a classical continuum. If you look at a classical gas though at some degree of scale you have to start dealing with particles, each of which must have a velocity vector pointing in some specific direction, breaking your uniformity even if the distribution overall is uniform.

If you look at a quantum gas, you can start with some uniform wavefunction for each particle with a uniform velocity distribution in all directions for each particle, but then the moment they interact, you introduce fluctuations to the velocity distributions, breaking uniformity.

That's my non-astrophysicist, non-quantitative idea of how this works.

So, to maintain uniformity, you would have to have a universe where all contained particles have no means of interaction, and a quantum perfectly uniform starting wavefunction.

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Re: Why isn't the universe uniform?

Postby Diadem » Mon Feb 15, 2010 7:23 pm UTC

Actually, the universe IS uniform on big enough scales.
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Re: Why isn't the universe uniform?

Postby Paranoid__Android » Mon Feb 15, 2010 7:43 pm UTC

Sir_Elderberry wrote:
King Author wrote:So...why isn't the universe uniform? Does objectively definable and true "randomness" exist on the atomic or sub-atomic level?

Yes, actually. Quantum processes carry some inherent randomness, probably. If I remember correctly, experiments have shown that one of the following is false:
-Causality (things in the future cannot affect things in the past)
-Nonlocality (things can only affect the things around them, at the speed of light--no instantaneous information transfer)
-Local Hidden Variables (there are deterministic processes lying behind quantum mechanics' apparent randomness)

We usually pick the third one because the others screw up the universe even more.


I just had a lecture that said that the second one was the the wrong one and that there are no hidden variables.
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Re: Why isn't the universe uniform?

Postby Kow » Mon Feb 15, 2010 8:03 pm UTC

Paranoid__Android wrote:I just had a lecture that said that the second one was the the wrong one and that there are no hidden variables.

I love how they say that with such certainty. I know for a fact that something we're not observing but might be a cause doesn't exist!
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Re: Why isn't the universe uniform?

Postby mmmcannibalism » Mon Feb 15, 2010 8:54 pm UTC

Is it possible the cosmic egg wasn't entirely uniform? Since we don't know what happened before the big bang, it seems possible whatever came together to start it went off and formed the universe before complete uniformity.
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Re: Why isn't the universe uniform?

Postby Tass » Mon Feb 15, 2010 9:11 pm UTC

Sir_Elderberry wrote:
King Author wrote:So...why isn't the universe uniform? Does objectively definable and true "randomness" exist on the atomic or sub-atomic level?

Yes, actually. Quantum processes carry some inherent randomness, probably. If I remember correctly, experiments have shown that one of the following is false:
-Causality (things in the future cannot affect things in the past)
-Nonlocality (things can only affect the things around them, at the speed of light--no instantaneous information transfer)
-Local Hidden Variables (there are deterministic processes lying behind quantum mechanics' apparent randomness)

We usually pick the third one because the others screw up the universe even more.


Close. Experiments and mathematics have shown that there cannot be local hidden variables and therefore there is either not causality or not locality.

Einstein used much of his later years trying to construct a local hidden variable theory to preserve both locality and causality, but later Bell proved that it is impossible with his inequality

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Re: Why isn't the universe uniform?

Postby Timtu » Tue Feb 16, 2010 10:41 am UTC

Quantum fluctuations when everything was really small and hot, and everything came apart like when I try and stretch a bit of blu-tac as long as I can.

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Re: Why isn't the universe uniform?

Postby Jack21222 » Tue Feb 16, 2010 1:16 pm UTC

Diadem wrote:Actually, the universe IS uniform on big enough scales.


No it isn't. It's close, but not quite.
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Re: Why isn't the universe uniform?

Postby QwertyKey » Tue Feb 16, 2010 1:37 pm UTC

Jack21222 wrote:
Diadem wrote:Actually, the universe IS uniform on big enough scales.


No it isn't. It's close, but not quite.


I wonder what Diadem means by scales.

Perhaps if you have a universe on a big enough scale, then quantum randomisation can be neglected?

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Re: Why isn't the universe uniform?

Postby King Author » Tue Feb 16, 2010 1:48 pm UTC

Wait, randomness does factually, varifiably exist? Then determinism is objectively incorrect? But I thought determinism was the more scientific viewpoint, and free-will was the more artistic and palatable, but less factually true viewpoint...so free will is actually real? It's not just a silly human illusion?

Okay, so gravity and other forces makes things unstable such that tiny fluctuations magnify intensely and produce non-uniformity, but shouldn't any fluctuations happen uniformly? Well, I guess if there's randomness on the atomic scale, though, then no, those fluctuations wouldn't happen uniformly across and throughout the cosmic egg.

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Diadem wrote:Actually, the universe IS uniform on big enough scales.

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mmmcannibalism wrote:Is it possible the cosmic egg wasn't entirely uniform? Since we don't know what happened before the big bang, it seems possible whatever came together to start it went off and formed the universe before complete uniformity.

Oh...that makes the most sense. There's no reason to assume the cosmic egg was uniform, or appeared in a uniform way, and asking about "before the cosmic egg" is fruitless, so...
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Re: Why isn't the universe uniform?

Postby Sir_Elderberry » Tue Feb 16, 2010 2:01 pm UTC

Wait, randomness does factually, varifiably exist? Then determinism is objectively incorrect? But I thought determinism was the more scientific viewpoint, and free-will was the more artistic and palatable, but less factually true viewpoint...so free will is actually real? It's not just a silly human illusion?

Randomness doesn't imply free will. It just implies randomness. And lots of us think that determinism is compatible with free will, but that's a philosophical conundrum, not yet a scientific one. Also, it may be randomness, but it's a predictable randomness--weighted towards most likely possibilities--and for applications larger than molecules things are essentially deterministic.
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Re: Why isn't the universe uniform?

Postby doogly » Tue Feb 16, 2010 2:32 pm UTC

Locality is preserved in qft. What it means is that if you have any two operators acting on a field, [A(x),B(y)]=0 whenever x is not in y's past or future light cone. Replace [ ] with { } for fermions. You could take another definition for 'locality,' like 'something that would bug Einstein,' but that is highly imprecise. This version is the one in Sir Elderberry's list.

And Vaniver, quantum fluctuations are not foolishness. They're what we get. Thermodynamic fluctuations would not be sufficient to explain what we see. If you start with quantum fluctuations at the very early universe and then inflate them (as in http://en.wikipedia.org/wiki/Inflation_(cosmology) ) you get what we see. There are some reasonable alternatives to inflation, but pure thermo wouldn't do it.
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Re: Why isn't the universe uniform?

Postby Yakk » Tue Feb 16, 2010 4:39 pm UTC

First, 'cosmic egg' that 'expands into nothingness'?

That doesn't match common big bang models. In fact, there is no evidence that we can see with any instruments that there was a nothingness to expand into.

We have models that track the visible universe (all billions of light years) down to a really small spec in radius. At the small spec sizes, even with low entropy there are enough quantum fluctuation to generate some kind of "most amount of uniformity" that is non-trivial. When that small spec expands extremely rapidly, these small amounts of lack of uniformity grow. Gravity, as noted, starts magnifying these small amounts of lack of uniformity, and you get galaxies condensing out of what is mostly void.

Still, you need that initial lack of perfect uniformity that the quantum theory provides: without it, thermodynamics would have nothing to "sink its claws into" in order to produce clumping.
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Re: Why isn't the universe uniform?

Postby gmalivuk » Tue Feb 16, 2010 6:22 pm UTC

Kow wrote:
Paranoid__Android wrote:I just had a lecture that said that the second one was the the wrong one and that there are no hidden variables.

I love how they say that with such certainty. I know for a fact that something we're not observing but might be a cause doesn't exist!

They say there are no *local* hidden variables with such certainty not because they haven't observed it, but because they are mathematically certain.
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Re: Why isn't the universe uniform?

Postby King Author » Tue Feb 16, 2010 7:42 pm UTC

Sir_Elderberry wrote:
Wait, randomness does factually, varifiably exist? Then determinism is objectively incorrect? But I thought determinism was the more scientific viewpoint, and free-will was the more artistic and palatable, but less factually true viewpoint...so free will is actually real? It's not just a silly human illusion?

Randomness doesn't imply free will. It just implies randomness. And lots of us think that determinism is compatible with free will, but that's a philosophical conundrum, not yet a scientific one. Also, it may be randomness, but it's a predictable randomness--weighted towards most likely possibilities--and for applications larger than molecules things are essentially deterministic.

Hmm..."predictable" randomness doesn't sound random. To my semantics, "random" by definition excludes prediction. Well, you know what I mean. If you flip a coin and say "it'll either be heads, tails, or land on it's edge" that doesn't mean a coin flip isn't random; you've just listed all the possible outcomes. Nor would correctly "predicting" a random outcome make it non-random, for example if I predict the scores of the next Lakers game and I'm correct, that doesn't mean that was the inevitable outcome, I just got lucky.

And by "for applications larger than molecules, things are essentially deterministic" you mean physical processes, right? Like, when a star will die, which way a laser will reflect when it hits a series of mirrors, stuff like that, yeah? Not people's decisions and so forth?

By my semantics, however, determinism and free will are indeed exclusive, because determinism says that a person's actions are inevitable and set in stone (from the beginning of the universe, it was always inevitable that I'd be here, typing this sentence at exactly this moment, thinking these thoughts, at this time, in this way), while free will says they can choose any given action (even though admittedly, most people behave very predictably the vast majority of the time). Saying determinism and free will are compatable smacks of post-diction to me, not prediction proper. That is to say, you can take the life of Joe Anybody and look back and say that any given major decision he did was inevitable given his past experiences, yet at the time, even if you had all the knowledge of those past experiences, you couldn't have predicted what he'd do, nor can you predict what he's going to do next in the present. Well, again, you know what I mean. You can fairly safely predict a person will wake up and go to work any given weekday, but that's not determinism.
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Re: Why isn't the universe uniform?

Postby Sir_Elderberry » Tue Feb 16, 2010 7:58 pm UTC

King Author wrote:Hmm..."predictable" randomness doesn't sound random. To my semantics, "random" by definition excludes prediction. Well, you know what I mean. If you flip a coin and say "it'll either be heads, tails, or land on it's edge" that doesn't mean a coin flip isn't random; you've just listed all the possible outcomes. Nor would correctly "predicting" a random outcome make it non-random, for example if I predict the scores of the next Lakers game and I'm correct, that doesn't mean that was the inevitable outcome, I just got lucky.

Imagine rolling three six sided dice. The most common result will be 10.5, and you'll get a bell curve around that. That doesn't mean it isn't random. That's the sort of predictable-ness I mean.
And by "for applications larger than molecules, things are essentially deterministic" you mean physical processes, right? Like, when a star will die, which way a laser will reflect when it hits a series of mirrors, stuff like that, yeah? Not people's decisions and so forth?

Well, I mean that quantum randomness doesn't enter into things. Computing someone's entire brain as a deterministic system would therefore be possible but ridiculous.

By my semantics, however, determinism and free will are indeed exclusive, because determinism says that a person's actions are inevitable and set in stone (from the beginning of the universe, it was always inevitable that I'd be here, typing this sentence at exactly this moment, thinking these thoughts, at this time, in this way), while free will says they can choose any given action (even though admittedly, most people behave very predictably the vast majority of the time).

Here's how I see it, which may not adhere to the actual philosophical definitions of terms, I apologize. I would agree with an idea of "quantum determinism"--that is, not all initial conditions will end in the same ending conditions, but we could predict the probabilities of different ending conditions ("decisions" in the psychological sense, I guess) according to the strict laws of quantum mechanics. In a sense, then, the brain is somewhat analogous to an extremely complex, organic computer, in that it takes input (in the form of sense data) compares it to programs/instructions (memory, pre-existing structures) and gives out an output (in the form of decisions, thoughts, actions). "Free will" in the traditional sense seems to almost imply dualism. People can choose any action at any time, but they will choose only one, and which one they actually choose is "determined" by initial conditions. You have free will, yes, but it's subject to causation.
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Re: Why isn't the universe uniform?

Postby gmalivuk » Tue Feb 16, 2010 8:29 pm UTC

Sir_Elderberry wrote:Imagine rolling three six sided dice. The most common result will be 10.5

If you *ever* get 10.5 by adding integer numbers of dots, you're using some kind of math I'm not familiar with. :-)
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Re: Why isn't the universe uniform?

Postby hawkmp4 » Tue Feb 16, 2010 10:01 pm UTC

gmalivuk wrote:
Sir_Elderberry wrote:Imagine rolling three six sided dice. The most common result will be 10.5

If you *ever* get 10.5 by adding integer numbers of dots, you're using some kind of math I'm not familiar with. :-)

This made me laugh out loud in my computer science class. Shame on you.
Sir_Elderberry, I believe you mean the expected result would be 10.5.
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Re: Why isn't the universe uniform?

Postby Sir_Elderberry » Wed Feb 17, 2010 12:22 am UTC

Haha, yeah, I was in class and therefore had to keep alt-tabbing to something that looked like work. (Hey, I never said it was a standard d6. Just a six sided die. Maybe it's numbered weird.)

Incidentally, my dice don't have dots.
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Re: Why isn't the universe uniform?

Postby Zamfir » Wed Feb 17, 2010 8:25 am UTC

Sir_Elderberry wrote: (Hey, I never said it was a standard d6. Just a six sided die. Maybe it's numbered weird.)


Which brings the next interesting question in probability theory:
Suppose you got a weird-numbered die from Sir Elderberry. What is the expected result from three throws?

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Re: Why isn't the universe uniform?

Postby King Author » Thu Feb 18, 2010 12:22 pm UTC

Sir_Elderberry wrote:
King Author wrote:Hmm..."predictable" randomness doesn't sound random. To my semantics, "random" by definition excludes prediction. Well, you know what I mean. If you flip a coin and say "it'll either be heads, tails, or land on it's edge" that doesn't mean a coin flip isn't random; you've just listed all the possible outcomes. Nor would correctly "predicting" a random outcome make it non-random, for example if I predict the scores of the next Lakers game and I'm correct, that doesn't mean that was the inevitable outcome, I just got lucky.

Imagine rolling three six sided dice. The most common result will be 10.5, and you'll get a bell curve around that. That doesn't mean it isn't random. That's the sort of predictable-ness I mean.

Your choice of metaphor is sublime; I design tabletop RPGs. Anyway, I see what you're saying now.

Sir_Elderberry wrote:
King Author wrote:And by "for applications larger than molecules, things are essentially deterministic" you mean physical processes, right? Like, when a star will die, which way a laser will reflect when it hits a series of mirrors, stuff like that, yeah? Not people's decisions and so forth?

Well, I mean that quantum randomness doesn't enter into things. Computing someone's entire brain as a deterministic system would therefore be possible but ridiculous.

So, quantum randomness doesn't scale -- just because quanta are truly random, that doesn't necessarily mean that any larger system constructed from many tiny quanta will have any of that randomness. I see.

Sir_Elderberry wrote:
King Author wrote:By my semantics, however, determinism and free will are indeed exclusive, because determinism says that a person's actions are inevitable and set in stone (from the beginning of the universe, it was always inevitable that I'd be here, typing this sentence at exactly this moment, thinking these thoughts, at this time, in this way), while free will says they can choose any given action (even though admittedly, most people behave very predictably the vast majority of the time).

Here's how I see it, which may not adhere to the actual philosophical definitions of terms, I apologize. I would agree with an idea of "quantum determinism"--that is, not all initial conditions will end in the same ending conditions, but we could predict the probabilities of different ending conditions ("decisions" in the psychological sense, I guess) according to the strict laws of quantum mechanics. In a sense, then, the brain is somewhat analogous to an extremely complex, organic computer, in that it takes input (in the form of sense data) compares it to programs/instructions (memory, pre-existing structures) and gives out an output (in the form of decisions, thoughts, actions). "Free will" in the traditional sense seems to almost imply dualism. People can choose any action at any time, but they will choose only one, and which one they actually choose is "determined" by initial conditions. You have free will, yes, but it's subject to causation.

Actually, except your conclusion, I pretty much agree. I often describe my views on free will precisely as "people can choose to do anything, but what they actually do is often predictable." My philistine of a sister could suddenly start reading Sartre and buy an easel and start painting, and stop wearing so much make up and living and dying by whether her douchey boyfriend likes her or not, but it's so unlikely you can essentially write it off and "predict" her behavior.

Our difference, I think, comes from the respective importance we give the fact that it's possible for anyone to do anything. You seem to write it off entirely because it's so unlikely. But precisely because it's possible (even if it's ridiculously unlikely), I say determinism isn't ultimately true. You might be able to deterministically predict the gross behavior of masses of people, given enough information about them, but this is merely due to the constraints of life limiting the choices people have and the choices they ultimately make. In other words, the ability to predict people isn't because the human mind is deterministic, it's because of the way we live our lives. I mean, on any given day of the week, probably no American will suddenly decide to abandon his materialistic life, fly to the Himalayans and become a sherpa. It's not because his behavior is pre-programmed, that his mind is deterministic, it's because odds are, he wouldn't be able to handle that kind of life and he knows it. The fact remains, however, that he can do that if he wants to, so determinism is out.

I guess ultimately, I define determinism by what's possible while you define determinism by what occurs, and given those starting points, both of our conclusions seem reasonable.
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Re: Why isn't the universe uniform?

Postby gmalivuk » Thu Feb 18, 2010 12:56 pm UTC

We've discussed free will before, and mostly concluded that it's probably an incoherent notion whether you believe in a fundamentally deterministic universe or not.
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Re: Why isn't the universe uniform?

Postby Sir_Elderberry » Thu Feb 18, 2010 2:16 pm UTC

Actually, we seem to be discussing different types of "determinism". You're talking about the idea that you can predict the behavior of the human brain based on psychology. When I say that the human brain is "deterministic" I mean on the molecular level. Anyone is free to choose whatever they want, and individual people are really quite unpredictable. Nonetheless, at the basest level, their brains act in accordance with physical law. Of course, the brain as a system is such an extraordinarily complex thing that prediction of its behavior from reductionist principles is still more or less impossible, in the sense that there's probably not enough computing power in the universe. So I believe in a nearly-total free will in the same sense you do, but it arises from purely physical interactions and is therefore subject to physical law. I think we should take further discussions of free will to PM.

So, quantum randomness doesn't scale -- just because quanta are truly random, that doesn't necessarily mean that any larger system constructed from many tiny quanta will have any of that randomness. I see.

Well, let's return to the dice analogy. As you add dice, the bell curve gets steeper. The chance of a 10 on a d20 is 1 in 20, but it'll be increasingly more likely to hit 10 on 2d8, 3d6, 5d4...Similarly, the more quanta you have, the more likely you are to have all the randomness just end up canceling out. That randomness is still present--there's a nonzero chance of my atoms spontaneously teleporting to the moon--but it gets pretty negligible, which is why it took us until the 20th century to notice it.
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Re: Why isn't the universe uniform?

Postby Yakk » Thu Feb 18, 2010 6:30 pm UTC

The die analogy is reasonable, but you do have to understand the scale.

Imagine if each atom was a d4 that "rolled" every second. It uniformly and randomly returns 1, 2, 3 or 4.

If we took 200 grams of carbon, and we observed the average value of the dice from that volume every second, the observed value would fall between 2.5000000001 and 2.499999999 in basically every observation if we observed it for a trillion years.

Average together enough random processes, and the macroscopic thing looks like a constant. Even if you start looking at it via a microscope, you don't see anything but uniformity -- because even at microscopic scales, there are a ridiculous number of carbon atoms!

Now, imagine if instead of a few moles of atoms, you had a handful of atoms. And imagine if you took those atoms, and you said "copy paste zoom!" -- ie, you took a clump of 10x10x10 atoms, and you copy/paste/zoomed by a factor of 10^7.

Now you have 10^8 x 10^8 x 10^8 atoms -- roughly the same 200 grams (give or take an order of magnitude or two). But at the moment of copy paste, immediately after the 'die is rolled', the measured average of the property on the 200 grams of carbon will vary quite noticibly from 2.5 -- the 95% confidence interval is (approximately) +/- 0.2.

And when you pull out the microscope, the structure is very non-uniform, because you took the original randomness and duplicated it into huge clumps.

The theory goes that cosmic inflation -- a huge fast copy/paste/zoom thing -- took the quantum flux that happens on small scales, and boosted it up to universe-sized scales. This resulted in clumps that where beefy enough to cause galaxies and clusters of galaxies (etc) to form.
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Re: Why isn't the universe uniform?

Postby feedme » Thu Feb 18, 2010 11:35 pm UTC

At Popsci.... http://www.popsci.com/science/gallery/2 ... celerators
As the Brookhaven National Laboratory proved this week, it's possible -- at least briefly.

Scientists announced Monday that in a quark-gluon plasma, achieved by smashing gold nuclei together at 99.995 percent of light speed, quarks briefly lost their ability to tell right from left.

This anomaly, which breaks the laws of physics, lasted a billionth of a billionth of a billionth of a second. A similar phenomenon, called symmetry breaking, is thought to have occurred shortly after the Big Bang and upset the balance between matter and antimatter, leaving the universe with more matter.


Could be part of the explanation?
Also, I'm confused about the phrase "breaking the laws of physics"

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Re: Why isn't the universe uniform?

Postby mmmcannibalism » Fri Feb 19, 2010 12:15 am UTC

Also, I'm confused about the phrase "breaking the laws of physics"


Breaks the current laws of physics as humans have defined them is how that should probably be read. Its similair to how objects moving near the speed of light breaks the newtonian laws of physics.
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Re: Why isn't the universe uniform?

Postby feedme » Fri Feb 19, 2010 2:56 am UTC

mmmcannibalism wrote:
Also, I'm confused about the phrase "breaking the laws of physics"


Breaks the current laws of physics as humans have defined them is how that should probably be read. Its similair to how objects moving near the speed of light breaks the newtonian laws of physics.


Aren't there theories to allow that?

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Re: Why isn't the universe uniform?

Postby Sir_Elderberry » Fri Feb 19, 2010 3:37 am UTC

I think he's saying that an object moving a significant fraction of c acts differently than Newton would predict--thus "breaking the laws of physics". The point he's trying to make is that nothing really breaks the laws of physics. That's the point of "laws of physics" after all. Rather, things "break the understood laws of physics".
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Re: Why isn't the universe uniform?

Postby Hoofed Plover » Fri Feb 19, 2010 3:40 am UTC

King Author wrote:I mean, on any given day of the week, probably no American will suddenly decide to abandon his materialistic life, fly to the Himalayans and become a sherpa. It's not because his behavior is pre-programmed, that his mind is deterministic, it's because odds are, he wouldn't be able to handle that kind of life and he knows it. The fact remains, however, that he can do that if he wants to, so determinism is out.


There's a problem with what you wrote here. It's a bit like saying "If I push this first domino, the others will probably fall over. The fact remains, however, that the dominoes wouldn't have fallen if I hadn't pushed the first one, so determinism is out." Sure, you can imagine another universe in which your American wanted to start a new life, and in that imaginary universe, he would. But in the real universe, he doesn't want to, therefore he doesn't do it. Seems pretty deterministic to me. I think the issue here is that people often think of wanting as some sort of magic that exists above the physical world, when in actuality desires are purely physical phenomena (albeit incredibly complex and interesting ones, of course!), and obey the laws of known physics. Specifically, desires are directly caused by something (another desire, some thought, or a sensory experience), and that something is caused by something else, and somewhere in that chain of somethings we get to a cause that arose from outside the mind. Of course, our brain doesn't retain all the information that would allow us to trace every one of our thoughts and desires to its external origin, so we are left with the illusion that our mind is the ultimate cause of our actions, and that's where this whole idea of "free will" comes from.
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Re: Why isn't the universe uniform?

Postby Yakk » Fri Feb 19, 2010 1:58 pm UTC

So one of the ideas of physics is that the laws of physics as we know them are scale, tempurature and pressure sensitive.

Given a sufficiently hot and dense environment, the forces we describe as distinct ... end up being one force. It is just that under low pressure and temperature conditions, they look like 3 very (well 4, but nobody has pulled this off with gravity yet) forces. By low-pressure, I'm including pretty much everything outside of the big bang, and maybe the occasional supernova core/neutron star core/high energy collision type situation (I don't know if mere stellar cores are sufficiently hot/dense).

In essence, the laws of physics we use are cold-and-sparse approximations to the "real laws", much as newtonian mechanics is low-velocity low-gravity low-acceleration approximations to relativity.

But we have models for what our laws are the approximation of (at least in the merging of 3 of the 4 fundamental forces into one). Still, saying that these experiments "break the laws of physics" is somewhat reasonable, as it does break the "low-temperature/pressure" laws

That make sense?
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