@JohnRennie Have you checked the definition Lubos Motl wrote in a post (which is in the photo I posted here)? This seems to me most appropriate candidate for a rigorous definition, which uses a fundamental theorem to define energy!
@Qmechanic I think it is arguable that kinetic theory is a sub-set of statistical mechanics, but by historical development and as taught it is usually treated as separate.
I even teach a limited version of kinetic theory in my intro-classes, because I think it is the most accessible really ``beautiful'' result in physics.
4-momentum is the conserved quantity as a result of a system with space-time translational symmetry, according to modern physics in Noether's theorem, all non-conserved forces are said to be the result of unaccounted for degrees of freedom and hence approximations
My understanding is that kinetics is just multi-particle quantum mechanics with a time-dependent Hamiltonian, with such high numbers of particles that you can't use ordinary QM tools, and so has not even been fully properly formulated as a theory yet, relying a lot on classical approximations, while standard statistical mechanics is multi-particle QM with a time-independent Hamiltonian, again with such high numbers of particles you can't use ordinary QM directly you need to use averages
@Akash.B your inputs largely aren't germane to the physics-directed topics being discussed. And now you're drawing flags, presumably because people don't particularly enjoy your contribution. (It would be helpful if those people used their words, of course.)
If you want to converse go ahead and join the conversation. But trying repeatedly to bring the conversation around to your personal drama doesn't seem welcome.
Anyone who abuses the flagging system will be forced to learn relativistic hydrodynamics. Or if that's considered too inhumane we could just roast them alive instead ...
@Semiclassical You don't see how a culture of speaking up when unwanted chat pops up before flagging would be helpful? I can't prove it to you, I can just testify that I've witnessed it.
A healthy room is one, in my opinion, in which people feel welcome (and even encouraged) to actually say what's bothering them, trust that tehy'll be heard, and people come to vague consensus.
@bolbteppa a system with time-dependent Hamiltonian refer to a non-equilibrium physical system? So kinetics is to describe a non-equilibrium physical system? is it an interacting system?
This assumes that the flaggers are active participating members of the room
user4704
If a user is posting a bunch of strange and nonsensical messages, talking to them, asking them to stop or clarify or whatever, is probably better as a first step then calling in what is effectively an artillery strike on them.
@Akash.B when you come back please feel free to talk in a coherent way about a notable physicist. "But Stephen Hawking" doesn't count as a useful contribution to dialogue. "But Stephen Hawking wrote X paper in which he predicted the Milky Way's central SMBH would expand drastically in the year 2020" with a link would be useful, for instance.
user4704
@Semiclassical Dubious of what? I would agree that there's probably a lot of drive-by flagging going on, yes.
@Semiclassical You can be dubious. I'm telling you, from experience in the SE network, that it's perfectly common for what I'm calling a "healthy" room to exist, and they tend to have the quality I described.
When you have large numbers of particles, you can't just set up the equations of motion for each particle separately, for example if you tried to treat the collection of particles as a stationary state problem, the more and more particles you add, the smaller the distance between distinct energy levels is, but what happens when they get within $\hbar$ distance between one another? Multi-particle QM suffers inherent quantum problems that force statistical thinking into the mix by design
Can I just say: when I respond to a flag I expect to see either a one-line drive-by profanity-laced line from a rando that got insta-flagged by a dozen people or something flagged after a conversation in which people have been asking someone to stop, then asking again, then telling them to please stop, then summoning ROs/mods to tell them to stop... The times I've come here it's been neither.
But it's not much use to just tell us that Stephen Hawking says the world will end. How are we supposed to make any useful comment on that without full information of what Hawking is actually supposed to have said?
Hawking, Musk etc... want it as protection from what the 25% or so of each countries authoritarian population will lead us to if we are not careful, as a precaautionary measure
@JohnRennie I agree that recently (say, months) it's been pretty good excepting the last few days. On the other hand, the reason I have the room starred is because of its notoriety as a hotspot within the chatosphere.
@Akash.B It would be courteous to use your words rather than dropping naked links. Something like "Stephen Hawking says we need to be off-Earth in a sustainable way within 100 years, see here [link]" makes it easy for people to converse with you without having to go do homework if they don't want.
h bar is really strange recently and I still don't understand how to deal with strangeness, for it is a whole new level over weirdness we all familar with
@Tanuj Mods can block anyone for anything. I claim it'd be more helpful if people in the room said "hey, this. This we want you to stop. Here's why...." Then bans can come, after words have proven insufficient.
@Tanuj Let me be clear: in my experience it'd be a lot more helpful if you'd said to Akash "excessive pleading and apologizing is obnoxious, it takes up space and makes it clear that you think everything's about you when it's not, please stop" rather than making an oblique comment.
@Abcd That's not spam. Spam is for overt self-promotion or posting random links. If something is not spam in that sense nor blatantly offensive, please either use your words to tell everyone what you're uncomfortable with, or, if you do not feel comfortable speaking publicly, raise a custom mod flag.
@Akash.B Stop with the short and incoherent messages. Put together a complete thought and make clear to whom you're addressing it. These little bursts interrupt others' conversation. Yes, there's a way flaggers can be identified. But only if a local elected moderator is in the room at the time. Check Meta.SE for details if you're interested. Yes, the community managers can help. But I'd say that when the room's at the point where flags are flying and speculation's abounding and you want to call in a CM... that's waaaaay too far afield of chat's purpose (supporting SE), and it's been way too…
@nitsua60 telling them to use "a few words" , if they don't want to speak about it at length , its okay , but atleast use a few words is what I was saying
@BalarkaSen I don't intend to be asking you to drop the topic of how rooms run well. If we're speculating about who flagged what then it's pointless and tends (in my experience) only to lead to more drama.
@BalarkaSen Yes, for which I'll apologize again. I'm sorry again for the mis-read and the reaction.
@Tanuj I get that, though I'll say that the reception that some of my messages have gotten (star board) seems to indicate that not everyone here's on the same page on what's good and bad to have going on.
@nitsua60 hmm there has to be a set of well defined rules as to what is good or bad , unless there are any rules , I don't see everyone being on the same page , that's where SE needs to improve.
@BalarkaSen And it's one of those where I remember mousing back and forth five or six times thinking "should I?" Which is an obvious sign that I actually should have taken my own advice and said "Hey, please stop discussion suspensions!" (At which point six people would have pointed out how I missed the joke.)
@Tanuj There can't be and won't be. It's too-complex a system to codify like that. What there can be is a practice where people are in the habit of actually saying "I think this is bad" or "I think this is good." I don't see that happening much here. And maybe it's self-directed narcissistic confirmation bias, but the stars at right tell me that it needs to be talked about more.
@JohnRennie Any idea how to share Jupyter notebooks, by mail? I got a .ipynb on my PC and I need to send it someone. Not sure if just sending the raw file will do (because I normally need to open it from the Anaconda Prompt)
@Tanuj When you find you are dividing by zero it means there are infinitely many solutions.
That's why when the question asks what the criteria are for infinitely many solutions we just need to set the determinant of the matrix to zero and solve for $k$
That's what i chose as the answer, that both statements are correct but s2 is not the correct explanation for s1, but apparently the answer is just the opposite lol
what are your thoughts on this ? I know clockwise rotation would yield a negative sign , but how do I decide about which line is the point being reflected /
