@PM2Ring btw real explosions involve cooling also. which reminds me, a sharp cohort cited Neumaier a long time ago but havent seen him cited in ages. think very worthwhile to look at for anyone who puzzles over interpretations/ foundations/ bohmian/ fluid mechanics etc Foundations of quantum physics II. The thermal interpretation / Neumaier arxiv.org/abs/1902.10779
@ZeroTheHero it can be done, but you have to work at it! I can think of only one person who has managed it, and he has managed to get himself suspended on pretty much every site he's joined so he's a professional! :-)
Can someone provide sources from where I can read more about fierz-pauli equation or quantum field theory approach to gravity in general? I tried searching on Google but I could not find a good review. Maybe someone can help here?
I don't know what kind of conversation takes place in this chat room, so I apologize in advance if my query is out of the topics discussed here.
@ManvendraSomvanshi it's a perfectly good thing to discuss here. However I don't think any of the chat regulars work in quantum gravity so we probably can't help much. Sorry :-(
Is it appropriate to ask a question on avengers:endgame (related to physics)? Because I have found several mistakes in the physics of the movie and I am not sure if I can discuss it since it will spoil the movie for anyone who did not watch. Any suggestions?
@ManvendraSomvanshi I would be cautious about any spoilers. Maybe create a separate chat room for that discussion, or wait a bit longer. Is it really worth discussing the science of a Marvel film? Do we expect it to be rigorous? :-)
@JohnRennie That BH antimatter question just spawned one about antimatter & naked singularities: physics.stackexchange.com/questions/477326/… I can't find a dupe target that covers naked singularities (pun intended).
@NovaliumCompany Use a voltage multiplier, like I said yesterday. But if coils are allowed, when I was a kid I made a zapper from an electromechanical buzzer & a small audio transformer, wired backwards. That is, the buzzer was wired into the transformer secondary, using the primary as output. It could make visible sparks several mm long, just from a 1.5v cell.
@PM2Ring I have no idea what happens when you throw antimatter into a naked singularity. I'm not even sure if it makes physical sense since as I recall naked singularities give you problems with causality.
@JohnRennie Me neither. I know that with a normal classical BH the singularity isn't in the past lightcone of any observer, but I don't know how it works with a naked singularity.
@PM2Ring I think the naked singularity gives us the same problems as a Norton's dome i.e. outward trajectories just start without it being possible to determine any initial conditions. In this case it's because those initial conditions would be at the singularity and that isn't part of our manifold.
@NovaliumCompany Sure, you can get a zap from an igniter. But the ones I've seen are piezoelectric: they work by mechanical distortion of a crystal, they aren't powered by a battery.
Now I come across a new term, secret symmetry. I wonder if it just refers to the symmetries associated quantum groups. I have seen the term hidden symmetries are used to refer to symmetries of this kind previously.
What kind of laser will I need to make a Michelson interferometer at home?
user351417
I think that New Alexandria's election nomination is actively harmful: if it hadn't been set up, the nomination phase would have been extended, so more people would have seen Kyle's removal and hopefully nominated themselves. But now, we have ended up with only two candidates but the system thinks we have three and things are proceeding as normal.
@Rishi Why are you suggesting the nomination phase would have been extended?
@Rishi Yes it is regrettable that so few people stepped forward to the election, but there's nothing harmful in anyone putting their names forward: you're free NOT to vote for her.
An example of online elections gone bad (from an old MUD experience of mine)
Person A is the org head. Person B disagrees strongly with a recent action of theirs, and contests them for leadership. Person C throws their hat in the mix, and Person B---caring more about getting A out---tells everyone to vote for C instead.
Person A goes on to win by one vote over Person C...with Person B receiving one vote.
(The total number of votes was something like 30. Not a huge number)
Boy was that fun :/
user351417
15:35
@ZeroTheHero I'm quite sure that the procedure is that if the number of nominees is equal to the number of positions, the nomination period is extended by a week (example).
user351417
That's why I decided that it's harmful: until now, I was under the impression that it'd be just fine if we don't elect someone with no past participation. But now it looks like the existence of that candidate has had a negative effect: it acts like a 'dummy' nomination.
@Rishi there's a lot to be said about what could have been better overall, but we have 2 good candidates & a third who indicated in comments that they'd at least care about the site if elected (which may suggest something good about them compared to the other qualified people who didn't nominate themselves)
@Rishi It's might be just because it's a pro tempore election on a beta site, but in the last engineering election, they had two nominations and appointed them directly engineering.stackexchange.com/election/1
I'm reading a book on How to talk to anyone about proper ways to make good relationships and this book talk s about how you should smile... and to make people like you, but as far as I know Steve Jobs wasn't particulary nice and yet he succeeded, how and why?
The book is called How To Talk To People, check it out and tell me if it's worth reading if you want to make it in business where you'll meet and talk to a lot of people.
@NovaliumCompany You need good business relationships. That can be accomplished in other ways besides just having good interpersonal skills. It can also help, but generally the "big innovator" types suffer a bit more on social skills, but make up for it in other ways so that it is often perceived as just "eccentric"
@Semiclassical yes, that all went rather spectacularly wrong, but I bet she still has enough money hidden away that she won't be going hungry in her old age :-)
@NovaliumCompany Bringing something to the relationship that others aren't. You don't always have to have something social to offer, but you need to have something.
@JohnRennie No, but he was diagnosed with treatable cancer and went through alternative medicines instead of proper treatment, and the general consensus is that he could have easily survived
Also worth noting that they speculate the pancreatic cancer was potentially triggered by an all fruit diet that wreaked havoc on his pancreas trying to deal with all the sugar
>According to Jobs's biographer, Walter Isaacson, "for nine months he refused to undergo surgery for his pancreatic cancer – a decision he later regretted as his health declined".[114] "Instead, he tried a vegan diet, acupuncture, herbal remedies, and other treatments he found online, and even consulted a psychic. He was also influenced by a doctor who ran a clinic that advised juice fasts, bowel cleansings and other unproven approaches, before finally having surgery in July 2004."
@Semiclassical Yeah, I agree completely. Religious crusades and stuff, that's obviously too far; but organizing into groups to work towards common goals actually can lead to some good progress. In the modern world it's basically redundant. Actively going against proven science is usually not a great call (though I can kinda emphasize with the mistrust, I don't agree with it at all)
Is it possible that both parties of the relationships building a company are socially incapacitated and that's what creates that strong bond and unification between them?
Is it possible that both parties of the relationships building a company are socially incapacitated and that's what creates that strong bond and unification between them?
I also suspect there's a limit to how much lenders & investors understand technology & technical terms, so just dumping money into "promising" entities is the norm
@NovaliumCompany successful businessmen, like Steve Jobs, tend to be very highly motivated, very confident and very focused - even monomaniac. For some reason other humans find this sot of behaviour inspiring even if they don't like that person.
Depends on what you mean by social skills. You need the right skills to be successful, but those skills are not the same ones that will make people like you.
Being rich but not liked has its upsides. You can always pay people to lie convincingly that they like you ...
Yes, you likely will need to be able to talk to people, that requires social skills. Do they need to be on par with business acumen? Maybe not, but they can't be neglected entirely
Jobs may not have been a personable guy, but he sure could deliver a speech & get people motivated to buy the next big thing from Apple
Whether or not you "need to change" isn't something strangers on the internet could or should tell you (probably similarly for books) That's on you & your experience.
@JohnRennie Maybe it hasn't been asked because the Wiki article on stellar collisions says in its very first sentence that the loss of orbital energy is due to mass loss or gravitational radiation :P
Speaking of gravitational radiation, is this comment basically correct, as far as it goes?
When black holes collide, the energy released as gravitational waves comes from their mutual gravitational potential energy. Crudely speaking, the BHs don't lose any of their internal mass. However, when considering a region that contains 2 BHs saying exactly where the mass lives isn't straight-forward. ;) — PM 2Ring9 hours ago
@JohnRennie It's now got a giant answer by JEB, which is mostly a quote from the Hulse-Taylor Nobel prize press release. Should that stuff be in a quote block?
@KyleKanos Thanks. I kind of agree re community wiki, to stop the author getting much rep from it. OTOH, I know that on SO community wiki is considered to be a deprecated feature, a leftover from the early days, before anyone could edit anything. A CW answer is unlikely to be maintained by the author, or anyone else, and that can be a worse outcome than the author picking up a few points that they probably don't really deserve. Of course, the Physics CW policy may be quite different to SO's.
Another downside of CW answers that's probably even more relevant on Physics than on SO is that it allows the author to post controversial material that's likely to attract downvotes, without the author worrying about losing rep.
I was watching a lecture on Dirac's life. The lecturer said that Dirac had rejected quantum field theory, predicted by his own equation. Why did he do so? He was Dirac, there must have been some strong reason for him to reject QFT.
... in passing, and got to wondering what a "coaching institute" is. The obvious explanation is that it is a private tutoring service gussied up in a fancy name. Anyone know if that is the case or there is a better explanation?
@ManvendraSomvanshi Naively plowing ahead with QFT generates all kinds of mathematical headaches which require a lot of infrastructure to resolve (when they can be resolved at all). Search term "renomalization".
Easy to get dispirited about that. Especially early on.
@dmckee In India there are these messed up coaching institutes that 'prepare' students for an entrance exam called JEE (entrance in an engineering college). These institutes are very famous (at least in India).
They just throw information at students that is to be replicated in the exam.
The exam is actually very hard. And due to high competition many students join these institutes.
@dmckee Isn't the Dirac sea considered to be the first field theory. Or at least kind of a proto-field theory?
@dmckee yes that is correct. But these are not ordinary tutoring services. These institutes earn in millions. Just wiki FIITJEE.
@ManvendraSomvanshi Feynman was able to change that attitude in Brazil 6 decades ago. See v.cx/2010/04/feynman-brazil-education But I fear that the problem in India is just too big and has too much momentum for the system to be changed without some kind of miracle.
so is the temperature of a black hole horizon uniform? I guess it's impossible due to relativity. does this mean that temperature is not well defined for a black hole? Therefore its mass?
I'm curious. What would happen if there were only 2 nominations for filling up two vacant mod positions, when the nomination deadline ended? Would those two people become mods directly without any voting?
For an undergrad interested in theory, would it be more beneficial to take differential geometry than topology? Also, what are the math courses that are probably most beneficial to prioritize for physics?
@thermomagneticcondensedboson You can assign a Hawking radiation temperature to a BH, but it's kind of meaningless, since the BH is sitting in a bath of thermal radiation (the CMB) that's at least a billion times hotter. Also consider the HUP as applied to the position of the event horizon. But of course we need a quantum gravity theory to talk honestly about this stuff. Even Hawking radiation may be fictitious, since it was derived using a semi-classical model that some people consider rather dubious.
@kylecampbell You'll need both, although differential geometry probably a bit sooner than topology. (Lie) group & representation theory don't hurt, either. Most math appears somewhere in physics, and "theory" is really broad. A condensed matter theorist will do very different things from a general relativist.
@KyleKanos Isn't that a possible loophole? I mean, just in case there's one less nomination than the no. of vacant positions, and a rather unqualified user spots this and makes the nomination right before the nomination deadline ends (so that his nomination can't be cancelled) ? Isn't there some way to prevent this from happening?
I suggest taking the math that seems interesting to you, rather than slogging through it out of some imagined necessity for physics. Most physicsts manage perfectly well without much in the way of formal math :P
@SDFG The way to prevent this is for enough people from the community to nominate :P
Honestly, if really no one except a completely unqualified user nominates, you should be worried about the state of the site, not about the soundness of the election system.
@ACuriousMind True that. But this would only lead to a further downward spiral. And the situation isn't limited to no nominations. I mean, even if there's just one nomination less, that's a chance for a biased user to get the diamond. You're telling me there's really no way to prevent this? :O
They happen whenever SE and/or the mod team of the site feel think it would be a good idea. It depends on the site, but I'd guess for most sites it's less than 1 every 2 years
Thanks for the advice @ACuriousMind. I think you're right about taking what you're interested in! Since I'm interested in both of them, I guess I was wondering what be more useful in physics. I think the topology course where I am is quite theoretical though, i.e., group theory is a pre-req whereas differential geometry would be more immediately applicable to something like GR. Although, most of the GR I've been exposed with just uses tensor analysis that can be learned with the physics.
Also, lie theory is a grad course that requires group theory (with finite groups) as a pre-req, which I just can't fit in.
I also don't immediately see the usefulness of group theory in physics if we're not talking about continuous symmetries... Although it's cool on it's own sometimes.
@kylecampbell Finite groups can also appear in physics (e.g. crystal point groups or any other discrete symmetries) and their representations theory is a good preparation for Lie theory - many of the formulae are "just" the sums from finite group theory turned into integrals
@kylecampbell The permutation group comes to my mind as particularly important.
@NovaliumCompany "Reasonable people adapt themselves to the world. Unreasonable people attempt to adapt the world to themselves. All progress, therefore, depends on unreasonable people." George Bernard Shaw
