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location Baltimore, MD (USA)
age 24
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2nd year graduate student at Johns Hopkins University in Physics. I'm primarily interested in particle theory and mathematical physics. I have some interest in pure mathematics, especially geometry and topology, and outside of particle physics in other fields including cosmology, topologically protected phases in condensed matter physics, and information theory.

I haven't had much time for this site recently. It's rather difficult to use this site to ask research questions, and it seems there are many people here who are capable of and willing to answer the basic questions which are very common here. If someone starts a new research-level Q&A site about physics (either on SE or elsewhere) I'd be interested in participating.


Apr
26
comment If randomness doesn't exist, how come the universe isn't a perfect sphere with predictable distribution of matter?
Back to probability, I don't think there should be a consistent notion of a "random pick from [0,1]" in the way you are claiming. Such a thing is an abuse of language, as are random bit sequences. A Vitali set isn't an event, so there's no reason to expect it to have a probability. I don't see any paradox with that. It is true that this notion of probability and the physical one are somewhat different, but I don't see a problem with that. If you want to continue this discussion, let's move it to chat, because it's become entirely irrelevant to the topic of the question.
Apr
26
comment If randomness doesn't exist, how come the universe isn't a perfect sphere with predictable distribution of matter?
It is definitely not true that any ring I am interested in is countable; take for instance $\mathbb{C}^n$ with the direct product. Most of the explicit examples I'm interested in could be dealt with by countable choice, but for both categorical and practical reasons it it's far easier to just deal with all rings.
Apr
25
awarded  Commentator
Apr
25
comment If randomness doesn't exist, how come the universe isn't a perfect sphere with predictable distribution of matter?
I don't totally understand what you mean, and I definitely like AC (otherwise how will I know that my rings have maximal ideals?). Personally, I'm of the opinion that random numbers/sequences are essentially abuse of language, but if I translate what you are saying into my language then I think what you call 'pure randomness' is what I would just call randomness, which in my book is a fundamentally physical (i.e. nonmathematical) concept. But in any case I don't think there's any more need for discussion of it here.
Apr
25
comment If randomness doesn't exist, how come the universe isn't a perfect sphere with predictable distribution of matter?
@Anixx I don't see how the two are asking the same question. They seem different both in focus and in the OPs' levels of understanding. I believe that the standard test is something like 'if the answers on a previous question would also constitute complete answers to this question'. If I take, say, Joe's answer on that question and apply it here, it doesn't seem to answer this question or be at an appropriate level.
Apr
25
comment If randomness doesn't exist, how come the universe isn't a perfect sphere with predictable distribution of matter?
This is a nice answer. It addresses the heart of the question succinctly, though my answer is more in depth on some tangential issues.
Apr
25
awarded  Supporter
Apr
25
comment If randomness doesn't exist, how come the universe isn't a perfect sphere with predictable distribution of matter?
Also, I'm not sure what the phrase "pure randomness" means. What makes a particular distribution purely random by your definition?
Apr
25
revised If randomness doesn't exist, how come the universe isn't a perfect sphere with predictable distribution of matter?
added 88 characters in body
Apr
25
comment If randomness doesn't exist, how come the universe isn't a perfect sphere with predictable distribution of matter?
Nowhere that I can find did the OP say he wanted a jargon-free answer. Even if he did, a certain level of jargon is useful to know, and most of it was clearly explained. I've added an explanation for the particular phrase in question.
Apr
24
comment Angular Momentum Addition Theorem - Sanity Check
Yes. If you pick $j_1$ to be the larger of the two then it's unnecessary.
Apr
24
answered Angular Momentum Addition Theorem - Sanity Check
Apr
24
answered If randomness doesn't exist, how come the universe isn't a perfect sphere with predictable distribution of matter?
Apr
24
comment In the known universe, would an atom not present in our periodic table exist?
Neutron stars are bound states, but for me the question of whether or not they are nuclei is more subtle than that. Neutron stars are composed of quark matter, and so I can't consider them nuclei which are bound states of nucleons in my definition. Of course some of the physics is the same, but a neutron star has at least as much in common with a star as with a nucleus.
Apr
24
comment In the known universe, would an atom not present in our periodic table exist?
@lurscher: Neutron stars are bound by entirely different physics, namely gravity, from the strong interaction in nuclei. As such, I don't really like thinking of them as large atomic nuclei. As for whether or not the island of stability is hypothetical, I more meant that the idea that some particular nuclei will have extremely long half-lives, on the order of decades or longer, which would be necessary for applications.There are definitely confirmations that there is an island of stability, but exactly how stable the most stable nuclei are is still open as far as I know.
Apr
24
awarded  Teacher
Apr
24
awarded  Editor
Apr
24
revised In the known universe, would an atom not present in our periodic table exist?
added 3 characters in body
Apr
24
comment In the known universe, would an atom not present in our periodic table exist?
I don't really understand why you claim there is no other possibility (unless you are an astronomer, because then of course they are metals by your definition). Perhaps you are claiming that these high-Z elements certainly would not have the properties of any known nonmetals, which I agree with, but it isn't at all obvious to me that they should be similar to known metals either. I decided to change dubious to unobvious, because that's more what my sentiment is, but I definitely don't think it's obvious.
Apr
24
comment In the known universe, would an atom not present in our periodic table exist?
I don't think that's as obvious as you are claiming. As far as I know, most high atomic number elements that have been synthesized have been in small quantities, so that we can't really study their bulk properties. Cn is known to be a metal, but other elements with Z>108 are not known. One can try to use theory to predict that these elements should have the properties of metals, but in the particular regime nuclear chemistry becomes increasingly important to consider and results from condensed matter theory are questionable without experimental demonstration.