Why universe is not symmetrical

[Ozgen Eren]

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?

 

[Vagn]

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.

 

[Ozgen Eren]

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.

 

[phinds]

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.

 

[zoki85]

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

I think they work on it.

 

[ZealScience]

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.

 

[Ozgen Eren]

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, let's 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.

 

[Bandersnatch]

In any case, can we deduce that if there is no symmetry, there must be different physics laws on different directions. Otherwise, let's 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.

 

[Vanadium 50]

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.

 

[Ozgen Eren]

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 I am 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. I am 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.

 

[Bandersnatch]

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.

 

[Ozgen Eren]

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?

 

[Bandersnatch]

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?

 

[Ozgen Eren]

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.

 

[Doug Huffman]

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!

 

[jerromyjon]

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.

 

[Vanadium 50]

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.

 

[jerromyjon]

I don't think nature is random even in the tiniest scales.

Me either but quantum physics convincingly predicts it could be.

 

[Doug Huffman]

There is a nice paper by Andreas Albrecht of UC Davis demonstrating frequentist statistics as a sub-set of QM.

 

[Khashishi]

We can't say there was nothing in the beginning. We don't know.

 

[Ozgen Eren]

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 don't 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 got to assume there is a beginning. Otherwise science becomes just a huge stamp collection.

 

[Khashishi]

No, definition of beginning means at the first point in time. I've never seen a dictionary that defines beginning as nothing.

 

[russ_watters]

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.

 

[russ_watters]

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 don't 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.

 

[Khashishi]

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.

 

[Ozgen Eren]

No, definition of beginning means at the first point in time. I've never seen a dictionary that defines beginning as nothing.

You don't need a dictionary to know that, its obvious if you assume everything has a reason. Otherwise you are just suggesting matter was already there without any reason. If you don't believe in causation why do you do science for? You just say "thats the way it is here is the statistics" for everything.

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.

No man, I am not confusing them. Thanks for the enlightenment though.

Experiments support it.
[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.

Well of course saying something is random will work. But it destroys the scientific perception. You don't need to explain anything except doing some experiments.

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.

I will check it out, thanks. I really really wonder what made them abandon that.

 

[Doug Huffman]

Really? In the beginning was the singularity and it was good enough.

 

[ZealScience]

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. )

But there is no argument to prove that it is deterministic either. Admittedly, if you know all the degrees of freedom, you might be able to predict the motion of classical needle tips to large extent. But what about vacuum fluctuations? Even if you shield an unstable alpha-decaying nucleus from every external influence, perhaps apart from neutrinos (which only care about beta-decay anyway), I think it is still going to decay. What if the law of certain fluctuation is intrinsically probabilistic?

 

[phinds]

Me either but quantum physics convincingly predicts it could be.

No, quantum physics says explicitly that it is random, not that it "could be" random. If in fact it were shown to not be random at the quantum level, then that would disprove QM.

 

[Ozgen Eren]

No, quantum physics says explicitly that it is random, not that it "could be" random. If in fact it were shown to not be random at the quantum level, then that would disprove QM.

Is there an archive of experiments led scientists to claim randomness?

 

[phinds]

Is there an archive of experiments led scientists to claim randomness?

As far as I'm aware, ALL experiments at the quantum level demonstrate randomness. It is, for example, the basis of Heisenberg's Uncertainty Principle which says that if you make EXACTLY the same setup, you'll get different results. All this randomness was severely disliked by men like Einstein ("god does not roll dice with the universe") and others but they all got past that some 80 or 90 years ago.

As Feynman was fond of saying, the predictions of QM have been equivalent to predicting the width of the United States and getting it right to within the width of one human hair. I think we've only been able to confirm them to that degree of precision because measurement instrumentation doesn't get any better, not because they are actually wrong by that amount.

 

[Ozgen Eren]

ALL experiments at the quantum level demonstrate randomness

Where are the most significant ones are published? Is there a physics magazine or a website? Where can I at least find their titles?

 

[ChrisVer]

The most obvious non-symmetry is between matter and anti-matter. Had there been perfect symmetry, we would not be here.

Phinds got me there...

In fact the question should be why is universe so symmetric [looking at CMB]? Which leads to inflation...

 

[PeterDonis]

Ozgen Eren, we've already had a fairly extended discussion of quantum randomness in this thread:

https://www.physicsforums.com/threads/a-very-basic-question-about-heisenberg-uncertainty.786473/

There's not much point in rehashing that discussion again; you're going to get the same answers here that you did in the other thread.

Where are the most significant ones are published?

Try Googling these for a start: double slit experiment, Stern-Gerlach experiment (this is probably the simplest one, I'll discuss it a bit below), Airy experiment, Aspect experiment (the last one was a test of Bell's Theorem so it shows nonlocality, not just randomness).

The basic fact is that you can take a bunch of quantum systems that were all prepared in exactly the same way, put them through exactly the same experimental apparatus, and get different results. For example, in the Stern-Gerlach experiment, they took a bunch of electrons (actually they were silver atoms with one electron having its spin unpaired in the original, I believe it's now been redone with single electrons) which had all been prepared in exactly the same way (I'll go into that a bit more below), and put them through the same magnetic field. The electrons came out in two beams, which we can call "up" and "down". All the electrons were identical going in, yet they came out in two beams. That's quantum randomness.

Now you might zero in on that "prepared the same way" bit, because how can we know for sure that the electrons really were identical going in? Maybe there were some slight differences (the usual term in the QM literature is "hidden variables") that were too small for us to measure beforehand but which caused the electrons to split into two beams. In this particular case, the obvious "hidden variable" is the precise direction of the electron's spin axis. (Note that even on this view, the classical prediction for what should happen was still wrong: classical EM predicted that the electrons should come out in a whole range of directions, with a peak in the middle, depending on the exact orientation of the electron's spin relative to the magnetic field. There is no way to get a prediction of two separate beams from classical EM. So something has to change; the question is what.)

However, we can eliminate the above factor too, by simply forcing all the electrons going into have exactly the same spin orientation. The simplest way to do that is to take the electrons from one output beam of a previous Stern-Gerlach device, oriented in a different direction, for example left-right instead of up-down. All the electrons in the left output beam of this device have their spins pointing to the left--and we can verify this by passing them all through a second left-right Stern-Gerlach device and seeing that they all come out in a single beam, the left beam. In other words, we can execute a preparation procedure for the electrons that, by a simple test, gives us a beam of electrons that are, indeed, identical, because we can test them to be identical by re-running the preparation procedure on them and seeing that it leaves them unchanged.

And yet, even then, if we take this beam of spin-left electrons and put it through a Stern-Gerlach device oriented up-down, we still get two output beams, an up beam and a down beam. That is quantum randomness.

 

[phinds]

Ozgen Eren, I strongly suggest that you pay close attention to Peter's post and even perhaps read up a bit on the Stern-Gerlach polarization experiment yourself (not that doing so will really tell you anything Peter didn't already tell you but reading about the experiment may further dispel your lack of belief in quantum randomness).

You are in good company finding quantum randomness hard to take, but I suggest you study the experiments, get past it and move on to learn something new instead of dwelling on a point of view that isn't going to take you anywhere.