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I recently began to study statistics and probability and I have two questions:

  1. Where does randomness come from? What is the source of randomness?

  2. Why does the randomness exist?

Is it possible to answer my question that non mathematician or non physicist can understand it?

I searched Internet for the answer but there is very little information that non mathematician or the information is for professional physicists and mathematicians.

Also please suggest books concerning my questions that is written so that non mathematician or non physicist can understand it.

Qmechanic
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vasili111
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    I don't quite understand the question. I might rather ask "where does order come from", as disorder just seems to be what one gets when one doesn't impose any conditions on the system at all. – garyp Jun 30 '14 at 16:20
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    It is pointed out here: http://arxiv.org/abs/1212.0953 that it always comes from quantum fluctuations. Even if you consider randomness that doesn't seem to have anything to do with quantum mechancis, like betting that the 10^20th binary digit of Euler's constant is 1, the randomness here still comes from quantum fluctuations in the physical processes that are involved in your brain making a choice for a particular binary digit of a particular number. – Count Iblis Jun 30 '14 at 16:28
  • possible duplicate of Are a quantum mechanical system a chaotic (yet deterministic) system? – Brandon Enright Jun 30 '14 at 17:35
  • Something is random if there is no cause that can be found that can be pointed to and said "there, that is the reason for this". So one could equally well ask why some things seem to not have causes. Or further still, why we believe that everything must necessarily have a cause. – Jim Jun 30 '14 at 17:35
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    I thibk it is more about phylosophy as about physics. – peterh Jun 30 '14 at 20:07
  • @CountIblis What the paper states is widely accepted concept among physicist or just one of the theory among others? – vasili111 Jan 12 '21 at 02:08
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    @vasili111 The argument made in the paper is controversial, but it's a realistic possibility. In physics we tend to keep an open mind about ideas that are possible. So, e.g. while I tend to agree with the arguments made in the paper, I still need to consider that perhaps quantum mechanics is itself not the ultimate truth and then the argument made in the paper would no longer hold, as it depends on the absolute validity of quantum mechanics. – Count Iblis Jan 13 '21 at 03:49

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Well, there's three different types of answers I can think of, with regards to what you asked.

One case we can have is that there's some systems that are so complicated, that if you change their initial states only slightly, the system changes drastically. This is called chaos. James Gleick's book is a good one for laypeople. Any graduate level mechanics textbook should also talk about chaos, if you're going to look for that level of understanding later on. So this chaos seems to create a sort of randomness in some physical situations. But maybe that's not what you meant.

There's also randomness in quantum mechanics, where it's not possible to know precisely two related quantities simultaneously (like the momentum and position of a particle).

Finally, there's good old experimental randomness; my physics teacher likes to think of it as "you can't know what the true result of an experiment is. You can only know what the most likely value is". For example, if you measure g (the gravitational acceleration) to be 9.8$\pm$0.01 ms$^{-2}$ (at some point on earth), you don't have the actual value of g. All you know is that the value of g is somewhere in that given range. So there's sort of a randomness to any experimental tests, because you can never know exactly what the result is.

But, as Count Iblis pointed out, all of this "randomness" essentially boils down to quantum mechanical fluctuations. It's just easier for us to think of it in terms of different concepts.

Physics Llama
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