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Apr
16
comment Why have our eyes not evolved to see “gluons”?
Also, I find "there's a lively discussion going on about whether this is on topic" hard to reconcile with you mod-closing the question. IMHO, mod powers should only be used in cases where a clear policy exists, and in this case I really think that's not the case.
Apr
16
comment Why have our eyes not evolved to see “gluons”?
@DavidZ I think you might have some kind of mistake while moving the conversation to chat - that chat room contains duplicates of the comments above, but not the ones that were made after them.
Apr
15
comment Why have our eyes not evolved to see “gluons”?
@ACuriousMind done, but honestly I think complaining about it is doing something about it. At the very least, it enables other users to realise that the opinions of the close voters are not those of the entire community, which I think is pretty important actually.
Apr
15
comment Why have our eyes not evolved to see “gluons”?
Closing this question would be a disaster. The issue doesn't really seem to be that it lacks physics content (it's about gluons for pity's sake!) but rather that it also contains biological content. It's irritating enough to keep closing questions based on philosophical hair-splitting about which things count as "physics" and which don't, but if we also start closing questions based on containing applications of physics to other fields then we're just completely lost as a community.
Apr
11
comment Symbolic dynamics of a multidimensional system
@DavidZ would you remind locking the question as well then, in that case? If there is dispute it should take place on meta. Close votes are meant for implementing policy, not deciding it, but often they get used as a vote for what the policy should be instead. That's happening here I think, and we should not let policy be determined this way. (I myself do not have the energy to start another meta post though. I only wanted to attract good answers to a decent question.)
Apr
11
comment Symbolic dynamics of a multidimensional system
@ACuriousMind is that really true? It doesn't complain if I click on "close", though obviously I haven't gone all the way to actually attempting to cast a close vote. Anyway my intention is not to abuse anything, just to draw attention to questions I think stand out as decent, productive and on-topic, especially in cases where this seems to be in dispute.
Apr
11
comment Symbolic dynamics of a multidimensional system
Posting a bounty in an attempt to counteract down votes and close votes. We absolutely should not be hostile to well formed technical questions like this, especially when it's under the guise of a philosophical nitpick about "physical content," whatever that is.
Mar
29
comment Spaceship split near event horizon
@Neil there is no contradiction. The event horizon is a point of no return, and if you pass it there is no way you'll ever make it back again. Eventually, no matter what you do, you will fall into the singularity. It's just that there isn't a sign to tell you that you've gone past it. Spaghettification and the event horizon are quite different issues - it's the spaghettification that disappears for a big enough black hole, not the point-of-no-return nature of the horizon.
Mar
29
comment Spaceship split near event horizon
@Neil the magnitude of tidal forces depends on the mass of the black hole. For smaller ones, yes, you'd be spaghettified long before you reached the event horizons, but for big ones like the one at the galactic centre the tidal forces at the event horizon are negligible - you would experience it as a region of space like any other.
Mar
2
comment Why is entropy additive?
@SaudiBombsYemen ah, I see. But when you sum over A and B, they are equal after all. (It that isn't clear, let me know and I'll post an answer.)
Mar
1
comment Why is entropy additive?
I'm pretty confused, because it looks like you start by assuming that $P(S)=P(A)P(B)$ and then show that it contradicts an assumption that $P(S)\ne P(A)P(B)$, which of course shouldn't be surprising. Have I misunderstood what you're trying to show?
Feb
14
comment Why are magnets in form of hollow sphere not a magnetic monopole?
Other possible duplicates physics.stackexchange.com/q/18115 physics.stackexchange.com/q/15655
Feb
9
comment How can a product of Bra and Ket be a scalar if they are matrices?
+1 because that way of visualising matrix multiplication is way better than the much more awkward one I've been using all my life up to now.
Feb
2
comment Reference for statistical mechanics from information theoretic view
I added another Jaynes reference, which I consider one of the best - I hope you don't mind
Jan
19
comment What are alternative ways to think about transfer matrix as used in Ising model?
Oh, either's fine! I can probably work through it myself, but if you have time to put some information in the answer it might be helpful. (I just figured out that if you use the convention that stochastic matrices left-multiply probability vectors then you have to use the left Perron-Frobenius eigenvector of $T$, which is what was holding me up.)
Jan
18
comment What are alternative ways to think about transfer matrix as used in Ising model?
This is an excellent answer and taught me something I needed to know. I'd really like to know more about the general case, in which the transfer matrix might not be symmetric.
Jan
15
comment What would be the implications of a Penrose Universe?
There are some studies of cellular automata on penrose tiling lattices, which might have something of the flavor of what you're asking for. If I get a chance I'll see if I can dig up some papers.
Jan
15
comment At an instant, does a system of gravitational charges exhibit equivalent behavior to a time-reversed system of like electric charges?
@endolith in GR, yes, that's true. I suppose I assumed we were in the Newtonian approximation. In the full GR case, playing the video backwards will still result in an apparent attractive force, it's just that the reversed gravitational waves will increase the energy in the system rather than decrease it over time.
Dec
31
comment What will a glass look like in 500 years?
I'm not an expert (maybe there's someone here who is) but I believe it's debatable whether glass is really a "slow liquid" rather than a solid. But even if it is a liquid, I think it will takes a lot more than 500 years for it to flow appreciably.
Dec
22
comment Is simulating the entire universe possible?
@KyleKanos I think it's entirely clear that it's asking about whether there are physical limitations that would prevent it, not about what humans can conceive. (I've edited to change the wording.)