Why Is the Universe Non-Uniform Despite Uniform Physical Laws?

[phinds]

I searched the "axis of evil" and came up with http://www.independent.co.uk/news/science/the-universe-the-new-axis-of-evil-465199.html

Fascinating. Thanks for posting that.

 

[bapowell]

"Oh, we don't know that. We just observe it happening all the time, and slapped a label on it. We call it 'Quantum Fluctuation'. If you want to hear what we do know about Quantum Fluctuation, read about it at [insert link to Impenetrable Wall of Math]."

Is this a joke? Cosmological perturbation theory is a very well-developed branch of cosmology. The theory of inflationary fluctuations, yes -- quantum in origin, is also well-understood, well-motivated, and fits spectacularly well with observations. And it has nothing to do with spontaneous symmetry breaking.

I searched the "axis of evil" and came up with this

Yes, the "axis of evil" is one of a few recent examples of potential inhomogeneity present in the universe that are manifested as a statistical anomalies in the low multipoles of the cosmic microwave background. These include a curious a alignment of the low multipoles (quadrupole and octupole -- the axis of evil), a seemingly anomalous suppression of power at low multipoles, and others (like the CMB cold spot). As far as I know, most of these result from playing the game of post-hoc statistics on CMB data sets, and don't constitute statistically significant findings. See http://arxiv.org/abs/1001.4758 for a recent summary of these anomalies in light of 7-year WMAP data. At the same time, people have come up with ways of understanding such inhomogeneities within the context of standard(ish) cosmology, through such processes as anisotropic inflation, pre-inflationary physics, nontrivial inflationary dynamics (that generate non-Gaussian fluctuations), cosmic textures, etc.

 

[willyp00]

I am going to speculate, but only on what the OP is trying to say ;) It seems to me, the discussion goes thus:

OP: "If the laws/properties/attributes of the universe are the same everywhere, why is our universe not a homogenous, static arrangement, held in perfect thermal and gravitational equilibrium by the sameness everywhere? (Like the cone, balancing on its tip?)"

"Spontaneous symmetry breaking introduces tiny variances which upset the balance, and the rest is history. (The cone has to fall; a tiny upset will ultimately tip it one way.)"

OP: "From whence come these tiny upsets, this 'Spontaneous symmetry breaking'?"

"Oh, we don't know that. We just observe it happening all the time, and slapped a label on it. We call it 'Quantum Fluctuation'. If you want to hear what we do know about Quantum Fluctuation, read about it at [insert link to Impenetrable Wall of Math]."

We started out of balance; if we didn't instability couldn't develop, no matter how sensitive stability is. It's a basis of QTF. Quantum probability means other outcomes are possible. Other outcomes, when able to interact (apparently faster than light in observations, and it only takes one of infinite possibilities), cause change. Change causes time. If everything was launched with perfect symmetry, no other outcome is possible. No change, no time. Did I take a different course than the other bloggers? It's been a long time. Taken a lot of math, but am no where near the wall (great reference!). In short, because we have clocks, we were never symmetrical. Even at the start. Just really, really close.

 

[bapowell]

Did I take a different course than the other bloggers?

Why? Do you suspect we are saying different things? I don't think that adequately addressing the OP requires a foray into philosophical musings on whether change causes time or time causes change or the use of vaguely defined notions of "symmetry".

 

[willyp00]

It is the phrase "spontaneous breaking of symmetry" that gets me. How can you break something that never was? Our universe is rattling itself into entropy like a resonance feedback loop. The tendency for all rotational inertias to align is the enthalpy counter balance. It is also the mechanics of accretion.


You do not really understand something unless you can explain it to your grandmother.

Albert Einstein

 

[bapowell]

It is the phrase "spontaneous breaking of symmetry" that gets me.

Your confusion stems from your attempts to apply "symmetry" in some grandiose way to the whole universe. That's not the right way to think of it. An example of a spontaneously broken symmetry is a pencil set on its tip and falling over, or the magnetization of a material upon cooling below the Curie temperature. The symmetries of relevance here are things like rotational and translational (geometric) symmetry. These (and many other kinds of symmetry) are alive and well in the universe (or once were), despite the vague arguments that you are making to the contrary.

Our universe is rattling itself into entropy like a resonance feedback loop. The tendency for all rotational inertias to align is the enthalpy counter balance. It is also the mechanics of accretion

And I really hope that this is a joke.

 

[thedragonbook]

Your confusion stems from your attempts to apply "symmetry" in some grandiose way to the whole universe. That's not the right way to think of it. An example of a spontaneously broken symmetry is a pencil set on its tip and falling over, or the magnetization of a material upon cooling below the Curie temperature. The symmetries of relevance here are things like rotational and translational (geometric) symmetry. These (and many other kinds of symmetry) are alive and well in the universe (or once were), despite the vague arguments that you are making to the contrary.

And I really hope that this is a joke.

a pencil set on its tip which immediately falling - Doesn't this mean that there were unbalanced forces acting on the pencil. Why else would the pencil fall? The unbalanced forces could occur then placing the pencil in that position by a human hand or the non-uniform nature of the surface on which the pencil is placed.

 

[willyp00]

It has been over 20 years since I read "A Brief History of Time", and can't quote it precisely; but it defines symmetry as I perceive it to be. I'm just trying to use common language in reference to complex subjects.

 

[bapowell]

Doesn't this mean that there were unbalanced forces acting on the pencil.

Sure. I set a pencil up on its tip. Then I push it over. I've broken the 2D rotational symmetry of the system.

 

[willyp00]

It is the instability principle. An object of infinite instability can remain in equilibrium if its environment is in perfect symmetry. Any change, no matter how small, causes the object to loose equilibrium and become unstable. Objects with greater stability require more change to loose equilibrium, as in the aforementioned reference to the Curie effect of temperature on magnetism.