Were the physical constants chosen randomly by Nature? Were the physical constants chosen randomly by Nature or it was determined by some source of… matter(?).

I really don't have idea. If you could help me it'd be awesome.
 A: No-one knows the answer to this, so the best I can do is describe some of the ideas. Bear in mind this is all speculative so take it with a pinch of salt.
In our existing tried and tested theories the fundamental constants are put in by hand and there is no mechanism for them to vary. However the idea that constants might be variable goes back as far as Dirac.
Many experiments have looked for variation in the fundamental constants, but so far without success. Examples include the Oklo natural reactor and many astronomical studies looking for changes in the fine structure constant.
The most concrete proposal for variable fundamental constants comes from string theory. This requires six of the spatial dimensions to be compatified so we don't see them. This compactification can occur in many different ways, at least $10^{500}$ according to the landscape idea, and each different compactification will result in different fundamental constants. Whether this really describes our universe is currently a highly contentious issue.
A: No one knows. But it is clear that the constants have miraculously "good" values to allow stars to form, fusion to last billions of years, and so forth. If they were just slightly different, none of this would have happened, and conscious life would not have emerged. Therefore, there would have been no one around to observe and study the Universe.
This has led to the suggestion that rather than referring to "the Universe" as I did above, we should refer to "our universe", and there might be other universes with different values of the fundamental constants, but no one around to see them. A different version of this is the suggestion that the Universe is unimaginably bigger than what our telescopes can see, and different regions have different values for the physical "constants", which actually aren't constant, but actually vary over extremely long distances.
It is unclear if or how either of the above ideas might ever be tested. The one thing we can be sure of is that some undiscovered physics is lurking there, somewhere.
