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9:02 PM
Does anybody know of any articles or texts that describe How a magnet works ?
 
That's an article
@JohnDuffield Ok, is topology useful for cosmology
 
Anonymous
@SirCumference Heh :P
 
Anonymous
Explaining (why) magnetism isn't an easy task. There have been hundreds of papers on the topic and still people are working on it.
 
Anonymous
I mean of course you'd find the generic Wikipedia level answers if you dig the net a bit.
 
@SirCumference explain how
 
9:12 PM
@SirCumference : no, topology is not useful for cosmology. But it is useful for electromagnetism and quantum field theory. See TQFT. PS: that kiddies article doesn't explain how a magnet works at all.
 
@Blue The problem is that "why magnetism" is an ill-formed question to begin with (as are most "why" questions).
 
Doublepost deleted
 
Anonymous
@ACuriousMind Yeah, that is true
 
HOW A MAGNET WORKS

To understand how a magnet works, you need to understand that the electron doesn’t have an electric field or a magnetic field, it has an electromagnetic field. In fact it is electromagnetic field. We made it in gamma-gamma pair production, such that a 511keV electromagnetic wave is...
 
Anonymous
I think John Rennie had a good answer on this, I can't find it now
 
Anonymous
9:16 PM
At some level though, one has to take the things on faith, like most other things in physics
 
No you do not.
Faith. FFS.
 
@Blue It's not faith that physics relies on - it's experimental facts.
 
Anonymous
@ACuriousMind Those two are equivalent :P
 
Ahahahahaha, very well then
 
Anonymous
Your faith is based on experimental facts
 
Anonymous
9:18 PM
Magnetism is a class of physical phenomena that are mediated by magnetic fields. Electric currents and the magnetic moments of elementary particles give rise to a magnetic field, which acts on other currents and magnetic moments. The most familiar effects occur in ferromagnetic materials, which are strongly attracted by magnetic fields and can be magnetized to become permanent magnets, producing magnetic fields themselves. Only a few substances are ferromagnetic; the most common ones are iron, nickel and cobalt and their alloys. The prefix ferro- refers to iron, because permanent magnetism was...
 
Anonymous
The Wiki page is not bad
 
@Blue I think you mean "belief", not "faith". "Faith" usually denotes religious beliefs.
 
Anonymous
@ACuriousMind Reasonable, yes I agree
 
When you look into why a boomerang flies in a circular path, you soon find that it’s because of gyroscopic precession. Then it’s the work of but moments to find articles such as chapter 15 of Nicholas Turro’s Modern Molecular Photochemistry. In section 6 he says this: “Since the mechanics of the precessional motion of a gyroscope in the presence of gravity are of the same mathematical form as the mechanics of a
magnetic moment associated with a spinning charged body in the presence of a magnetic field , we postulate that the vector due to the magnetic moment of the quantum magnet undergoes precessional motion in an applied magnetic field”.
 
@JohnDuffield Ok is abstract algebra helpful
 
9:21 PM
@SirCumference : sure it is.
 
Sir: It depends on what aspect of abstract algebra you are talking about
 
algebra is useless
@ACuriousMind right
 
@Secret I mean, is a course or two in abstract algebra likely to help a lot with cosmology?
 
@SirCumference : algebra is helpful. I'm not so sure about abstract algebra. If it's totally abstract and there's no application at all, I don't know what it's helpful about.
 
9:23 PM
I know how a magnet works.
 
@0celo7 Yes. Groups never play a role in physics /s
 
@SirCumference Arguing against John (Duffield) is pretty hard, he's a lot smarter than you (or me)
2
 
When the particle is going around and around in a uniform magnetic field, there’s no net force on the particle. There’s a turning force, a torque, but this is symmetrical, and the motion of the particle is uniform. See Magnetic Torque and Magnetic Force from Michael Salvati at NYU physics for more about this. You can read that “in a uniform magnetic field there is no net force on the particle, but there is a torque and the angular momentum will, in some sense, precess about the magnetic field”.
 
@SirCumference That I am not sure, because I don't recall seeing even groups often in cosmology
 
@Secret Aw come on
 
9:24 PM
@ACuriousMind : sure thing. Those aren't prepared posts per se, those are excerpts from How a magnet works. Something I wrote.
 
Doesn't topology deal with manifolds?
 
It is
 
@JohnDuffield It is clear you are just posting prepared posts on the topic of magnetism instead of having a conversation. This is not engaging in good faith, stop it.
 
And manifolds are supposed to be a big deal in GR
 
@SirCumference wants to prove you wrong
 
9:25 PM
@0celo7 Wait what?
 
though I would imagine if you work with some kind of theoretical particle physics cosmology like one of my physics professor did as her research, then you will need at least a lot of groups
 
No, I just asked a question
 
but experimental cosmology? I will need to check
 
Ah, no, I only care about theoretical cosmology
The cool (jobless) stuff
 
9:26 PM
1
Q: Abstract Algebra in Relativity and Cosmology?

aortizmenaIs Abstract Algebra useful in theoretical Relativity and/or Cosmology? If so can anyone give me some examples or point me towards a good book with that emphasis if it is one? Thanks in advance.

 
Anonymous
@SirCumference Just become Hawking
 
@Blue ...in what regard?
 
@Blue Don't tell other users to die :P
 
I was thinking "get ALS", but yeah, death is also bad
 
Anonymous
@SirCumference Start writing pop science books :P
 
9:27 PM
@Blue Ok good
 
Anonymous
Cosmology is the best topic to attract laymen to physics
 
my thesis will attract laymen to mathematics
 
Meh, I want to expand the frontier of human knowledge
 
@0celo7 looking forward to it
 
9:28 PM
Not explain the known to laymen
 
clearly good stuff
 
@ACuriousMind : sure thing. Note that those aren't prepared posts, those were excepts from one of my "physics detective articles" called How a magnet works. I ended it with what I think Feynman should have said in the famous interview.
 
What should he have said?
 
JohnDuffield, vzn: The Labs are currently researching on Shadowbanning circumvention. It is a hard topic but if possible, anti-ghosting, which is one of the lamest way to handle a problem, will become possible at a global scale
 
@JohnDuffield I'm not interested in where it's from - but asking about a topic and then copy-pasting your responses instead of actually responding to other users shows the question was not asked with any interest in the responses to it, i.e. not in good faith.
 
9:31 PM
@bolbteppa : ACM says I mustn't post pre-prepared stuff. l
 
@ACuriousMind must one act in good faith, even when the others are known to be wrong?
 
Sigh, fine! @JohnDuffield What math beyond ODE stuff is useful for (theoretical) cosmology, or GR in general
This is the last time I'll ask the chat since I'm practically out of time to figure this out
 
You can state the jist of it in a quick sentence without copy-pastaing a wall of text
 
@SirCumference : sorry, I don't know. IMHO reading the Einstein digital papers and understanding what he was saying is the most useful thing.
 
Wait what?
 
Anonymous
9:33 PM
@SirCumference I must say, you should find someone else to give you math advice...
 
@Blue Sigh, I've asked all the mathy people here
 
Anonymous
Or cosmology advice..whatever
 
@SirCumference have I not told you
 
@0celo7 Yeah, ik. But I'm getting other opinions. You only mentioned "Calculus on Manifolds" and maybe some basic differential geometry
Sigh, tired
 
@SirCumference : if you read the Einstein digital papers you know how gravity works, then you can apply that to a black hole, and because the universe is sometimes likened to a inside-out black hole, you can apply it to that too.
 
9:34 PM
What do you mean by abstract algebra in general relativity
 
if you learn my thesis you'll be ready
 
I supposed you all have asked Slereah? He pretty much into the really crazy things in GR?
 
@JohnDuffield I want to get a career in cosmology. Reading a few papers isn't sufficient.
 
Anonymous
Why not talk to actual cosmologists? Go and talk to the cosmologists at your college. They're the best people to guide you
 
^ that also
 
9:35 PM
@SirCumference : understanding will help.
 
You can frame things in terms of rings, fields, modules, but you are just using some basic abstract algebra definitions, until you go really deep you wont be using abstract algebra
 
@0celo7 That highly depends on what you mean by "act in good faith". You shouldn't e.g. insult bad faith actors, or deliberately bait them into pointless discussions for your amusement, but you aren't required to assume good faith on their part either.
 
I emailed a theoretical cosmologist at my uni. He said "I think every physicist should know the basic undergraduate-level calculus, differential equations, and complex analysis. General relativity also involves differential geometry, but we usually teach what you need to know in GR classes.

Cosmologists are increasingly reliant on sophisticated statistics, computational techniques, and big data. So if you’re looking for classes outside PHA that might be worth taking, you might want to browse some of those"
 
Anonymous
@SirCumference Pretty solid advice I must say.
 
Though that seems more like experimental stuff
 
Anonymous
9:36 PM
Consider talking to a few more
 
Honestly, it's pretty bizarre to be worrying about abstract algebra in general relativity
 
Anonymous
And decide what best suits you
 
Anonymous
Maybe take part in research and see if you even actually like real cosmology research
 
@0celo7 Wait what?
 
You should talk to him.
He probably knows GR very well.
 
9:38 PM
@bolbteppa I think I saw groups more often than other algebraic structures in cosmology. That said, my only source of knowledge is pretty much my lecturer back in my undergrad who researches on GR cosmology stuff
 
@JohnDuffield nobody can answer the why questions to the level you're asking, if you go back to old papers and expect answers you are fooling yourself, they had ideas formulated before even the knowledge of the weak force or what relativity does to the idea of elementary particles, it's not for lack of trying, but you don't know how to derive any of the math used to discover/predict the descriptions of these physical phenomena yet use it's language, that is faith/follow-the-leader behavior
 
@bolbteppa : Shrug. I know how magnet works. There's no faith to it at all. It's a question of taking things step by step.
 
@Secret you might find some of the language of groups, rings, fields, and modules, but barely anything more than the definitions or basic ideas people pick up as they go
 
I see
 
For some reason I thought he was at ETH.
But this guy is very big.
 
9:45 PM
@JohnDuffield explain magnets in a sentence or so, just the jist, lets see if you use any weasel words or hand-waving or nonsense
 
@0celo7 Come on bro, stop mentioning the profs here
 
What does that mean
 
Again, I would've preferred if my uni was kept private
 
Did he give you a shitty grade