Should you know vector calculus well. Some linear algebra. Physics-wise, a good understanding of E&M is necessary in general. You should know some statistical mechanics and thermodynamics for the astro sections.
From what you've told me, a few Google and Wikipedia searches here and there should be all you'll need.
@abt: I suggest to not go for weinbergs as a first book. just like jackson for electrodynamics. take something else before and than tacke these books. takes less time and effort and you have read 2 books
@abt well... just remember that a course like in shankar is (at my institution) a year-long three quarter course. I think the same can be said about zee.
@abt I don't recommend thinking in terms of contributing here but, rather, in terms of trading here. Don't be afraid to jump right in and write an answer to a question that you don't quite know the answer too. As odd as that may seem, you'll find your most valuable answers are those you aren't quite sure of when you take an interest in the question, focus your mind, do a bit of research and/ or calculation, and the write the answer to the best of your knowledge and ability.
@AlfredCentauri I agree. I wrote an answer on quantum mechanics yesterday. First time on a non classical mechanics topic! I was very pleases. But I also asked any willing chat members to proofread just in case. quality assurance since I'm a novice.
@StanShunpike I believe it is the case that answering interesting questions here is an excellent way to gain or refine you knowledge of the subject so keep it up. That what I mean by trade; ideally, you and some (if not all) of those that read your answer benefit from your effort. I actually have a lot more to say (write) about this but another time...
Currently, when a moderator deletes a user all of the user's votes are removed along with the user himself. I was pretty surprised at this behaviour when I first heard about it, and I don't think it is a good idea to throw away all of the votes just because the user is deleted.
Votes are locked ...
It would make sense for two kinds of deletion, one with vote-removal, one without. If the user is deleted for good faith reasons (wants to leave the site, rage-quit, &c), then we keep the votes. If the user is an obvious sock/troll/etc, delete them. — ManishearthMar 28 '12 at 13:40
That'd be a good plan, but do not believe it's active
@ACuriousMind Nakahara says Dirac spinors are sections of $(D,\pi,M,\mathbb{C}^4,\mathrm{SL}(2,\mathbb{C})\oplus \overline{\mathrm{SL}(2,\mathbb{C})})$ but this errata list says to remove $\overline{\mathrm{SL}(2,\mathbb{C})}$. If this is correct, can you please explain why Nakahara made the error?
(Or at least why you think there could be confusion.)
My intuition tells me that a Dirac spinor should be a section of $(W,\pi, M, \mathbb{C}^2,\mathrm{SL}(2,\mathbb{C}))\oplus (\bar W,\pi, M, \mathbb{C}^2,\overline{\mathrm{SL}(2,\mathbb{C})})$ where a right-handed Weyl spinor is a section of $(W,\pi, M, \mathbb{C}^2,\mathrm{SL}(2,\mathbb{C}))$.
I haven't really looked at quantized electromagnetic fields yet (only phonons) so I'll say sure, sounds good to me! Or. not. I mean
"a unit of excitation of a mode of the electromagnetic field" is a photon. A photon. So it does say plenty about what you're talking about. It's a rather long phrase.
"@Jimmy360 do you refer to nerds creating negative using metal plates in vacuum or creating and the measure negative energy?"
@DanielSank I'm reminded of this: "All the fifty years of conscious brooding have brought me no closer to the answer to the question: What are light quanta? Of course today every rascal thinks he knows the answer, but he is deluding himself." A. Einstein
@alarge The review was actually good, they just said it needs to be 3D and that it's not novel enough of a method for that journal. The problem is we know we need to do 3D but we started with 2D and are trying to write up what we ahve
It's pretty tough to "get started" with a method, it seems like everybody expects the very first paper to have every imaginable feature in it
The method isn't novel enough for a journal about methods, but the results aren't novel enough for a journal about the results... the only thing that is novel is getting the results with the method
I've had several papers rejected, happens to all, especially if you aim high. Twice the rejection was due to very poor reviewers, so I just resubmitted those to the same journals with long cover letters explaining my disagreement (because I really thought the papers best fit those journals). Eventually both were actually published.
But peer review is basically about luck anyway. If you think you have a chance at one of the top journals, you submit it there. If/when it comes back, you submit it to tier 2, then to another tier 2, then to tier 3 etc. until you, by luck, get referees that ok the paper. It helps if they know you in real life or have big egos: if they don't understand the paper they'll ok it rather than tell the editor.
Which is to say that I don't have much respect for the peer review system nor the grants-by-impact-factor metrics.
@0celo7 I have no idea what your notations mean. I'd say that that a Dirac spinor transforms in a representation of $\mathfrak{sl}(2,\mathbb{C})\oplus\mathfrak{sl}(2,\mathbb{C})$, and that the bundle it is a section of is simply a vector bundle with that (4D) representation space as its fiber.
I once met a guy whose job it was to go to different trade shows/expos and basically find all the Chinese vendors infringing on their patents with their "new" products. That was for a company of course, not academic.
@Jiminion If you have a patent in India, can someone else in another country use the technique and not care? How does it work anyway? I remember going to some seminars on this topic, but can't remember anything else except it was basically too complicated and you should consult a lawyer.
Inconsistency in tags: singularities says to use singularity when talking about GR black holes and the like, but singularity is a synonym of singularities. What happened here? (@Qmechanic, since you're the tag overlord, as it seems ;) )
@alarge I did work with a lawyer. I think the patent is protection from people in that country using the technology. I had an item pending in Europe as well, but eventually dropped it as the costs were too high. The US effort also went South - repeated challenges, etc.
Many resources state that light skin/pale skin absorbs more UV than dark-colour skin. Doesn't black absorb maximum radiation?
For an example, see this article:
Natural selection therefore favored a genetic solution to that problem by evolving to a pale skin that absorbs UV more efficiently.
@DavidZ Yeah, me neither. But someone seemed to want that difference once, and someone else seems to have made it a synonym without fixing the tag wiki. I wasn't sure which version we wanted.
@ACuriousMind : Most likely at some pt the tag was pluralized, but without the corresponding update of the tag wiki. You (and other editors) are welcome to fix the tag wiki (and btw any other inconsistency, you come across). Else I will do it eventually.
@ACuriousMind : In my opinion the tag should cover all types of singularities, i.e. from naked to non-technical usage, infinities, GR, non-GR, you name it.
@ACuriousMind I see the same upon first loading, but I can scroll to the left (or simply press Home) and see the rest. If you can't do it then it's a bad [bug] but if you can I'd class it more as a quirk than anything else.
I don't care about reputation and I also don't care about down votes. But still, I care more about the latter. I'm sure there is a utility theory that allows for encompassing that.
Is there any quick, easy way to include a "What level are you at (or background reading have you done)" in the greyed out text in the ask question box? I can move this to SE meta if needed.
Apologies if this is a periennal topic, asked by every newbie like myself.
the secret to finding these is going to the home page of the SE, then scrolling way down to the bottom and using the "chat" link in the footer; that gets you a list of chat rooms linked to that SE site
@DavidZ three questions: (1) i am correct I am not supposed to paste images of sections of a text but use latex, (2) if so, why? What's wrong with images, (3) is this just a physics SE thing or do all the exchanges from upon images?
Many resources state that light skin/pale skin absorbs more UV than dark-colour skin. Doesn't black absorb maximum radiation?
For an example, see this article:
Natural selection therefore favored a genetic solution to that problem by evolving to a pale skin that absorbs UV more efficiently.
Is there any quick, easy way to include a "What level are you at (or background reading have you done)" in the greyed out text in the ask question box? I can move this to SE meta if needed.
Apologies if this is a periennal topic, asked by every newbie like myself.
