Why universe is not symmetrical

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Main Question or Discussion Point

Did scientist ever tried to explain the reason for the non symmetrical nature of the universe?

If we accept that scientific laws are same everywhere;
and there was nothing in the beginning ;
(thus symmetry of nothing, until matter is created by some sort of physics law and bigbang)

How could every angle and radius from initial beginning point today can have different particles?
 

Answers and Replies

  • #2
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Did scientist ever tried to explain the reason for the non symmetrical nature of the universe?

If we accept that scientific laws are same everywhere;
and there was nothing in the beginning ;
(thus symmetry of nothing, until matter is created by some sort of physics law and bigbang)

How could every angle and radius from initial beginning point today can have different particles?
What makes you think it isn't? The cosmological principle basically states that on a sufficiently large scale, the universe is homogeneous and isotropic.
 
  • #3
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I guess we mean different symmetries.

If everything were initially same in every direction, than universe should have been like a sphere, that's what I mean. If there is a hydrogen atom at the angle 0, radius 1km from the point where bigbang happened, then there should also be a hydrogen atom at the angle 1, angle 2, ... given that they have the same distance, 1km with respect to the initial condition.

I don't know about large scales but as far as I see, nothing is symmetrical, which is pretty weird since physics laws applies the same everywhere.
 
  • #4
phinds
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I guess we mean different symmetries.

If everything were initially same in every direction, than universe should have been like a sphere, that's what I mean. If there is a hydrogen atom at the angle 0, radius 1km from the point where bigbang happened, then there should also be a hydrogen atom at the angle 1, angle 2, ... given that they have the same distance, 1km with respect to the initial condition.

I don't know about large scales but as far as I see, nothing is symmetrical, which is pretty weird since physics laws applies the same everywhere.
There were, for reasons that are unknown as far as I am aware, very minor differences in the early universe and they became exaggerated over time, giving rise to galaxies and all the rest.

The most obvious non-symmetry is between matter and anti-matter. Had there been perfect symmetry, we would not be here.
 
  • #5
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Did scientist ever tried to explain the reason for the non symmetrical nature of the universe?
I think they work on it.
 
  • #6
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I think you do mean homogeneity and isotropy. I believe the current model assumes it at early stages of the universe. However, as they become further apart from each other, the homogeneous phase become unstable, and phase transition leads to spontaneous broken symmetry. The broken symmetry is widely observed in physics, in phase transitions, in Higgs mechanism for example.

In my perspective, the Friedman-Robertson-Walker metric based on cosmological principle is describing the universe with non interacting cosmic fluid (dust-like). But when interacting matter is introduced, there is locally broken symmetry as stated, and the gravitational effect of clustering phases decouples the surrounding from the F-R-W metric.
 
  • #7
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I think you do mean homogeneity and isotropy. I believe the current model assumes it at early stages of the universe. However, as they become further apart from each other, the homogeneous phase become unstable, and phase transition leads to spontaneous broken symmetry. The broken symmetry is widely observed in physics, in phase transitions, in Higgs mechanism for example.

In my perspective, the Friedman-Robertson-Walker metric based on cosmological principle is describing the universe with non interacting cosmic fluid (dust-like). But when interacting matter is introduced, there is locally broken symmetry as stated, and the gravitational effect of clustering phases decouples the surrounding from the F-R-W metric.
In any case, can we deduce that if there is no symmetry, there must be different physics laws on different directions. Otherwise, lets say universe was to become unstable by "introducing an interacting matter", or in any other way without breaking the physics laws as we know them (or will discover them). Then, if physics laws were the same everywhere, we wouldn't get a different kind of unstability on two different points.
 
  • #8
Bandersnatch
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In any case, can we deduce that if there is no symmetry, there must be different physics laws on different directions. Otherwise, lets say universe was to become unstable by "introducing an interacting matter", or in any other way without breaking the physics laws as we know them (or will discover them). Then, if physics laws were the same everywhere, we wouldn't get a different kind of unstability on two different points.
Not at all. The case here is the same as with a needle pefectly balanced on its tip. The laws of physics govering the needle and its surroundings are the same everywhere, yet it will not stay in its perfectly balanced state but fall to one side.
 
  • #9
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Ozgren, you are getting very close to a personal theory.

On large scales, the universe is homogeneous and isotropic - the technical terms for what you call "symmetry". On smaller scales, it is no longer the case because of initial fluctuations and the subsequent evolution, which includes interactions among the matter at these scales.
 
  • #10
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Not at all. The case here is the same as with a needle pefectly balanced on its tip. The laws of physics govering the needle and its surroundings are the same everywhere, yet it will not stay in its perfectly balanced state but fall to one side.
In reality no, there is always something that makes it fall on some particular direction, whether an air current, or maybe even the gravitational attraction of my own mass, or something like that. Because the universe is already is not symmetrical. But if you consider a symmetrical needle in very beginning, it must stay as it is depending on the physics laws we currently have.

Ozgen, you are getting very close to a personal theory.

On large scales, the universe is homogeneous and isotropic - the technical terms for what you call "symmetry". On smaller scales, it is no longer the case because of initial fluctuations and the subsequent evolution, which includes interactions among the matter at these scales.
That is why Im asking if anyone had a good answer for that before. Just large scales being homogeneous and isotropic is not enough to answer that question, because we were suppose to have a perfect symmetry. Im just saying those initial fluctuations or whatever you call them, they must be non symmetrical, since they are in general, called the physics laws, physics laws have to depend on direction. Otherwise universe would be just the same everywhere.
 
  • #11
Bandersnatch
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But if you consider a symmetrical needle in very beginning, it must stay as it is depending on the physics laws we currently have.
But it's not true! If you had the needle surrounded by a perfectly symmetrical distribution of molecules, in a short time the random motion of these molecules would break the symmetry and push the needle to one side. It's the same with gravitational interaction on cosmological scales.
 
  • #12
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in a short time the random motion of these molecules would break the symmetry and push the needle to one side
Do you mean the quantum sense of randomness? Like any of its atoms not having a defined position, appearing here and there, sort of thing?
 
  • #13
Bandersnatch
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Do you mean the quantum sense of randomness? Like any of its atoms not having a defined position, appearing here and there, sort of thing?
That's a large part of it. You need only the tiniest divergence from the equilibrium state to cascade into full-blown symmetry breaking, and the quantum nature of the world on the smallest scales is always going to supply such tiny nudges.
But also, you need to consider the processes that you think preceeded the equilibrium phase. Is there any reason why they ought to output a perfectly balanced setup, and not one with inherent deviations from symmetry? On the large scale, it may look homogenous and isotropic, but it's just a statistical effect. Why would it need to be so on the smallest of scales as well?
 
  • #14
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That's a large part of it. You need only the tiniest divergence from the equilibrium state to cascade into full-blown symmetry breaking, and the quantum nature of the world on the smallest scales is always going to supply such tiny nudges.
But also, you need to consider the processes that you think preceeded the equilibrium phase. Is there any reason why they ought to output a perfectly balanced setup, and not one with inherent deviations from symmetry? On the large scale, it may look homogenous and isotropic, but it's just a statistical effect. Why would it need to be so on the smallest of scales as well?
Because I assume there is some causation in physics rules, I don't think nature is random even in the tiniest scales. (Saying it is random is easy, but in any case there is this possibility that we just can't see the connection. If someday, someone really proves it to be random, then we can just throw away all equations and live with a huge statistical data. )

I guess even in quantum physics, Bohmian Mechanics suggest causation by breaking locality.

And if there is causation, that means laws are local, directional, not universal.
 
  • #15
Doug Huffman
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Because I assume there is some causation in physics rules, I don't think nature is random even in the tiniest scales.
Ahh, predestination and determinism! Read Popper (no historicist prophesy for freewill) and Smolin (no determinism for randomness). The root is in the fallacy of the dialectic, thanks Plato - NOT!
 
  • #16
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As the physical laws go, we have to assume they are consistent to get "way back when" all the matter formed after the big bang. You can't cut off your nose to spite your face. The laws worked backwards from now is what lead to the HBB theory in the first place. You can't then take a theory based on an assumption and "start over" from the big bang and try to change the rules... You'd have to work backwards from now with variable laws and try to work back to see what the start would look like, and perhaps the picture would look very different.
 
  • #17
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Because I assume there is some causation in physics rules, I don't think nature is random even in the tiniest scales.
Well, you're just wrong then. Nature is fundamentally probabilistic.
 
  • #18
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I don't think nature is random even in the tiniest scales.
Me either but quantum physics convincingly predicts it could be.
 
  • #19
Doug Huffman
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There is a nice paper by Andreas Albrecht of UC Davis demonstrating frequentist statistics as a sub-set of QM.
 
  • #20
Khashishi
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We can't say there was nothing in the beginning. We don't know.
 
  • #21
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Well, you're just wrong then. Nature is fundamentally probabilistic.
How can you ever be sure something is probabilistic. Even if you set up the same experiment and get a different result, there is a chance that you are missing some independent variable and the experiments are not the same. Or when you see an electron suddenly do a weird thing, there might be a cause that you are missing. Saying something is random is the easiest answer, its like religion(as questioning is meaningless) combined with statistics(as you do hundreds of experiments and generalize). I dont claim I found a way to explain, I just think its a wrong attitude if you want to do science.

We can't say there was nothing in the beginning. We don't know.
Thats basically the definition of beginning. If you assume there is a scientific reason for everything exist today, you gotta assume there is a beginning. Otherwise science becomes just a huge stamp collection.
 
  • #22
Khashishi
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No, definition of beginning means at the first point in time. I've never seen a dictionary that defines beginning as nothing.
 
  • #23
russ_watters
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In reality no, there is always something that makes it fall on some particular direction, whether an air current, or maybe even the gravitational attraction of my own mass, or something like that. Because the universe is already is not symmetrical. But if you consider a symmetrical needle in very beginning, it must stay as it is depending on the physics laws we currently have.
I think you are confusing laws with conditions. F=ma is a law, but the numbers plugged into it are conditions. So a 2 kg mass accelerates differently from a 1 kg mass based on the same force because the conditions are different, not the law.
 
  • #24
russ_watters
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How can you ever be sure something is probabilistic.
Experiments support it.
Even if you set up the same experiment and get a different result, there is a chance that you are missing some independent variable and the experiments are not the same. Or when you see an electron suddenly do a weird thing, there might be a cause that you are missing. Saying something is random is the easiest answer, its like religion(as questioning is meaningless) combined with statistics(as you do hundreds of experiments and generalize). I dont claim I found a way to explain, I just think its a wrong attitude if you want to do science.
[Shrug] If the theory works, it works. In science it is more wrong to assume the existence of something for which there is no (or worse, contradicting) evidence.
 
  • #25
Khashishi
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Ozgen, physicists have carefully considered the possibility of "hidden variables" and aren't merely cavalier in asserting that quantum mechanics is random. Read this for a basic overview http://en.wikipedia.org/wiki/Hidden_variable_theory. We can't ever completely rule out hidden variables, but there are strong causality and thermodynamics reasons for believing that they don't exist.
 

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