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7:48 AM
8:43 AM
How did a mathematician who died at 20 accomplish more than I'll ever do
9:14 AM
Q: How to determine the isospin of a pair of nucleons?

Student404MusWhile I was reading from the book of Brussaard on shell-model applications in nuclear spectroscopy, he mentioned that isospin of a neutron-neutron pair couple to $T=1$. On the other hand, if it was neutron-proton pair, the isospin couples to either $T=0$ or $T=1$. Now, my question is I can't see ...

Why can't we somehow power the human body using electricity? Like, replace all the organs with mechanical alternatives and boom. Like, we can remove eating, drinking, peeing and pooping all together.
Unfortunately, other cells will still need food, water, oxygen... Why don't we remove the body altogether, learn to keep the brain alive, and attach it to mechanical parts?
The thing is, the brain cells will need food, water, oxygen... ahh...
We can barely put in slightly different organs as it is
it's gonna be tough to replace everything
Also scalability issues
it's hard for us to make electronic versions of human systems on the same scales
Well, the only other option is... roll the drums... AGI (and probably superintelligence)
9:21 AM
also overall we are terrible at linking things to nerves
How knowledgeable should an incoming PhD student in the field of high energy theory be?
We can't even repair nerve damages properly
The major obstacle I feel is that it takes a lot of prerequisites (like general relativity, quantum field theory, string theory) to even understand the research problems in this field: Without these prerequisites, it's extremely hard to understand the research papers in this field. And these prerequisites are generally taught in the beginning of a typical graduate program.
You should be knowledgable on the relevant classes you had before, ideally
If you are knowledgable in what comes afterward that is a bonus certainly
Part of the goal of the PhD is you learning the field
first month or so you're just reading a lot of papers and books
@Slereah Can we hook up a mechanical arm for example to the motor cortex of the brain (give it action wire and feedback wire) and see if the brain can adapt and learn to control it?
9:27 AM
I'm applying for a graduate school which asks the PhD candidates to submit a statement of interest that address the following questions in particular: (1) your area of interest ? (2) specific problems you would like to work on? (3) can you suggest some methods to deal with such problems? [This note is written beside it: The write-up should reflect original ideas. Don't write a general essay describing the area]
I mean, it should be possible.
(1) is reasonable. But is it reasonable to expect (2) and (3) from an incoming PhD student
OneNote is trash. kept crashing and then it said "some files have been corrupted, reset to restore to the previous save," did that and now it can't open anything. that is all my work for four texts. WHAT IS HAPPENING. and their so-called cloud storage has failed miserably as well. I need a drink.
(2) can be asked, although overall your thesis advisor is likely to give you your task
@NovaliumCompany Things are getting there, yes
@Slereah yay... cyborgism.
9:30 AM
Well don't celebrate too soon
As far as I know, prosthesis like that can't feel yet
So you basically lose all sensations in your arm
I'm doing proofs on vector spaces and boy am I sick of saying "construct a Gram-Schmidt basis"
@Slereah Hmm. I feel I don't have the necessary prerequisites to even understand most research problems. And now I'm being asked to pick problems that I would like to work on... Most probably it just reflects my poor preparation during my undergraduate study.
@Slereah Whom are you talking about?
@Slereah Why? I mean, can't you just make the robotic arm with some accelerometers and touch sensors?
@Knight Evariste Galois
@NovaliumCompany The tricky part is connecting it to the nerves
@Slereah $\text{caGSb}\equiv\text{construct a Gram-Schmidt basis}$
9:36 AM
@Slereah Why? What's the problem.
@Slereah He died at 20?
@NovaliumCompany they are small and many
@Knight In a duel, yes
he died the most gangsta way
@Slereah Aren't they also very adaptive (neuroplasticity). Whatever you plug in there, they should be able to adapt with it to control it, no?
I invite you to try it yourself
extract your own nerves, connect them to a USB plug
@Slereah I'll just plug the inputs wires somewhere in my arm-controlling motor cortrex part and the feedback wires into the arm-feedback somatosensory cortex and boom.
9:40 AM
@Slereah With whom he fought?
Things are uncertain, but apparently someone stole his gal
@Slereah It's much easier to go for the "It's not that simple" conclusion than to actually think about how it could be done, eh?
Of course it's not simple, but it's doable.
@NovaliumCompany Well, people have tried!
Successes are limited
Try again.
Increase success rate.
I do know that bionic eyes are a thing, for a start, but the resolution is fairly low
9:42 AM
@Slereah Yep, that's amazing! Also hearing devices.
@Slereah Of which country was he?
Well 1) I am not a doctor, so I would rather not do it myself and 2) Ethical boards tend to frown on human experimentation
@Knight France!
@Slereah If the human agrees, why not? It's his choice to risk his life for the greater future.
@Slereah Your paisan
@NovaliumCompany Tell that to the ethics board!
9:44 AM
@Slereah Morality and ethics are just the result of evolution's attempt to keep us alive so we can reproduce...
Kidnapping and human experimentation would make medicine and sociology go much faster, but people tend to not approve
Evolution's like: Don't kill people, they need to f*ck.
Just having people volunteer is not overall a great sign of ethical happenings, because people may not understand the risks properly or have other incentives to try even for high risks
Sam sir I think you talk about Sociology because in France it’s quite famous (because of Georg Simmel, Comte) :)
ie paying poor people to get experimented on
Trust me history has been going on for a while, we don't have a lack of examples of what a lack of ethics in human experimentation looks like
9:50 AM
I don’t know why but to me Galois Theory seems more philosophical than mathematical.
Just look up unit 731 if you don't mind the horors of history
or you can look up MK ULTRA, for a slightly more fun example
10:08 AM
@Slereah Morality is a simple mechanism that evolution has embedded in our brains so we can preserve life (and most importantly, continue it). Everything you consider immoral is something that decreases the chances of someone reproducing. It's quite simple and honestly, doing some experiments on volunteers can help with overpopulation. Humanity has a long history of not obeying evolution anymore.
What do you think about that?
I think it's a bit simplistic, but that doesn't mean we should start human experimentations :p
The fact that something stems from evolution doesn't mean we can just dismiss it
Our desire to remain alive is also such a thing, and yet you don't see me jumping off a bridge
@Slereah Of course, I totally agree with that, but in our overpopulated world, it's not unacceptable, considering the fact that it's a contribution to technological progress.
Well, if you believe it this strongly, I advise you offer yourself as a human guinea pig
@Slereah I don't want to.
Volunteers buddy.
Anyways, f*cking school time.
Cya :---)
3 hours later…
wouldn't those pages already be doing the explaining
Yes if you're smart
Bad news then
I am dumb
I guess it's basically building a bijection between two permutations?
Right, so he begins by claiming the proof is similar to the method he uses to show two permutations of $n$ things are isomorphic
An 'invariant' subgroup is a normal subgroup, i.e. a subgroup $H$ of $G$ such that $g H = H g$ which basically means you can split the group up into equivalence classes using $H$ as the class of elements equivalent to the identity
So basically, the idea is a group could have multiple different maximal normal subgroups, and each of them can have further maximal subgroups, and the number of them and the way the quotients will look will be the same up to ordering
1:09 PM
I'm afraid I'm not big on group theory
Yeah, but this is from Weyl's QM book so it's physics apparently :p
Weyl was a fake physicist
We all know he was just a mathematician
1:24 PM
That's a really shocking result no? For something as complicated as a group, the whole $12$ divides into $6, 2, 1$ or $4, 2, 1$ or $6, 3, 1$ stuff, it's like a prime factorization of a group or something
1:40 PM
Consider $C_{12} = \{e^{\frac{2 \pi i k}{12}} , \ k = 0, \ldots , 11 \}$. We note $C_6 = \{e^{\frac{2 \pi i 2k}{12}} , k = 0, \ldots , 5 \}$ is a subgroup of $C_{12}$ and $C_{12} \backslash C_6 = C_2$. We also note that $C_{4} = \{e^{\frac{2 \pi i 3k}{12}} , k = 0, \ldots , 3 \}$ is a subgroup of $C_{12}$ and $C_{12} \backslash C_4 = C_3$. The intersection of $C_6$ and $C_{4}$ is $C_6 \cap C_4 = \{0, e^{\frac{2 \pi i 6}{12}} \} = C_2$.
We note $C_4 \backslash (C_6 \cap C_4) = C_4 \backslash C_2 = C_2 \simeq C_{12} \backslash C_6$. The first step of the proof seems to be showing this is a general result.
@bolbteppa Can you recommend me some poems or songs which talks about past? I mean you see the opening lines of “book of my life” by Sting
**Let me watch by the fire and remember my days
And it may be a trick of the firelight
But the flickering pages that trouble my sight**
2:35 PM
@bolbteppa Hip-hop doesn’t touch the heart you know. I need something calming, if you have time please listen to book of my life by sting, or some poems from great poets like Wordsworth, Keats, Blake etc.
What's the point of making it a privilege to see separate up and down vote count when someone willing to do so can easily check it with timeline? (Even the users who aren't logged in)
The feeling of power
A: Shouldn't the timeline page be only available for members with the Established Users privilege?

psubsee2003The "view vote count" privileges is less about restricting access to the specific vote counts and more about limiting load on the servers. From Jeff's answer on Show Total Votes (or Up/Down Votes) The total vote count (score) is denormalized, but the individual up/down vote counts are not. ...

2:53 PM
@JMac thanks!
@Knight “Hip-hop doesn’t touch my heart” ftfy
3:14 PM
@Semiclassical Does it touch your heart?
3:25 PM
@Knight Here's a beautiful song about the past by the Beatles, performed by twin sisters from Austria:
3:41 PM
@PM2Ring Which is your favourite poetry?
@PM2Ring I want to ask, my school’s name is St.Michaels so should the students be called Michalites or Michaelians?
@PM2Ring hello sir!
@Knight I've never been much of a fan of poetry. I prefer songs. :)
Hi, @Yuvraj.
@Knight Hmmm. I think I prefer Michaelians.
Anybody got an idea if this is along the right lines?
Actually nvm got it
@PM2Ring I too, but some of my illiterate friends are using Michealites.
@PM2Ring Please suggest me some poetry :(
3:56 PM
@Knight have you tried The Rime of the Ancient Mariner? It is one of the best poems I have ever read.
@JohanLiebert Yeah, I really like Samuel Taylor Coleridge
@Knight The ballad of Kerrymuir
@JohnRennie Aha! What is it about?
Read it and find out!
Search results are giving for “ball of kerrymuir”
@JohnRennie Is it a poem or a song?
4:00 PM
That is another name for it. Also The Ball o'Kirriemuir.
Is it a song? By that moustache man?
@JohnRennie What about poetry? Suggest me something
@Knight Here's a silly but clever song by Annie Ross: Twisted, (Wardell Gray wrote the tune). Joni Mitchell did a good version of it back in the mid 1970s.
@Knight I'm not a huge fan of poetry to be honest. I much prefer doggerel. Anything by Ogden nash for example.
@PM2Ring I think there is a personal connection is that song with you. :-)
@Knight Maybe... :) Here's something of a more serious but surreal nature: In the Court of the Crimson King.
4:13 PM
Ooh, King Crimson :-)
Takes me back to the days of my youth.
@PM2Ring It’s great great song. Someone is writing in comments that it is about Cold War and loneliness .
@JohnRennie You might like this remix of Ladies of the Road. The actual song starts at 2:30, but the intro is interesting
People in comments are comparing it with Shine on you Crazy Diamond
For some reason I was never very fond of Islands.
@Knight Pink Floyd & King Crimson were contemporaries. A lot of people liked both bands, but there was also some strong rivalry. I suppose King Crimson were a bit more intellectual and "arty", but Pink Floyd had more commercial appeal and success.
4:26 PM
@PM2Ring King Crimson was a band or a single man?
@JohnRennie Me neither, but I enjoy the humour abd wildness of Ladies of the Road
@Knight that's not a simple answer :-)
They are a band, but arguably the main man always was and continues to be one person - Robert Fripp.
^ That
Although I don't think Fripp ever had much input on the lyrics.
Red is probably my second favourite KC album. The first being ITCOTCK of course.
@JohnRennie hahahahaha. Was he rich like Waters?
4:29 PM
No. King Crimson never had that much success.
@PM2Ring John sir told me that Waters wrote all the lyrics of Animals, so isn’t Waters a clear winner?
I think Fripp is reaonably well off, but not a multimillionaire like Waters.
I think Brits have a habit of liking their paisano :-)
@Knight personal wealth is not terribly reliable guide. Taylor Swift is richer than Waters and Fripp put together :-)
@JohnRennie Of course. :) I do like In the Wake of Poseidon, apart from the penultimate track, which drags on for too long (IMHO), and it's a blatant rip-off of Gustav Holst's Mars, the Bringer of War.
4:32 PM
Taylor Swift is more famous because she is a woman.
In the Wake of Poseidon is so similar to the first album. It's good, but it feels like they used all their best ideas in the first album and ITWOP was the leftovers.
My all-time favourite KC track is Starless
Yes, which curiously is not on the album Starless and Bible Black. That confused me as a young prog rock fan.
Yeah. It took a while for Fripp to be convinced about Starless, so it didn't make it onto Starless & Bible Black
Did you use to listen songs on radio? As in your time (I’m not sure about PM2RING) Internet wasn’t there
4:37 PM
@Knight Back in the 1970s in the UK there weren't many music stations. Basically just BBC radio one, and that mainly played chart records.
If you were interested in anything non-mainstream there wasn't much of interest on the radio. You had to buy albums.
Oh! Means many singers were left unheard
Which brand of shirts or trousers do you wear? @JohnRennie @PM2Ring
Be careful that may show how rich you are :-)
Anyone (other than me) keeping track of coronavirus? 1850+ dead. worldometers.info/coronavirus
@Knight I'm a major scruff. I wear tee shirts and slacks unless I'm forced to dress smartly.
@JohnRennie Which brand of T-Shirts? Tommy Hilfiger, Allen Solly, Louis Philippe, Nike?
Unbranded. I generally buy Fruit of the Loom as they seem to wear well.
4:47 PM
You’re lying:-)
I'm going to slump into my armchair and digest lunch. See you all tomorrow.
@JohnRennie Do you have a 6000$ suit?
@Knight I don't think I own anything worth $6000. Well, except for the house.
@JohnRennie Here's an Aussie prog rock track that had commercial success. The recorder was played by a guest, Bon Scott, from the band Fraternity. Bon went on to become the 1st singer of AC/DC.
@Knight he is a millionaire
4:49 PM
@JohanLiebert We know :-)
He is very rich
Rich with knowledge (richest)!
I wonder if kidneys are worth $6000 on the black market.
Probably not 60 year old ones :-)
@JohnRennie They do.
@JohnRennie they are worth more than that.
@JohnRennie I cannot say anything about brain
4:51 PM
@Knight well there you go then, I do own something worth $6000 :-)
@JohnRennie you own a brain worth trillions!
@Knight I'd be surprised if brains were worth anything. You can't transplant a brain. Or at least, not yet.
@JohnRennie I can wait
They probably don't even taste good. I've eaten lamb's brains and they were very bland.
4:54 PM
@JohnRennie Fried human brain is tastier than you think! 😂 😂
@JohnRennie Why did you do that? If (God forbid) you get Lamb’s brain then who would help us
@Knight Yes, I used to listen to the radio when I was younger. I still do, from time to time, but mostly small community stations, not commercial ones, and I usually listen to them via the internet.
In the mid 1970s, the Australian government broadcaster (the ABC) launched an alternative AM rock station 2JJ, which became an FM station JJJ a few years later. They played all sorts of stuff you'd never hear on commercial stations. But I stopped listening to them in the late 1990s because they played too much rap for my tastes.
@JohanLiebert :-)
@PM2Ring Rap? I thought you had a tender heart :)
@Knight BTW, I'm a year or two older than John Rennie.
4:56 PM
@PM2Ring OH! You never disclosed it! My God
@PM2Ring I used to think that you were around 30! Quite a surprise.
@Knight I have a very low tolerance of rap & hip-hop. But I do own a copy of this album, which has a few brilliant tracks: en.wikipedia.org/wiki/Hypocrisy_Is_the_Greatest_Luxury
@PM2Ring At your time I think Alan Turing was not that famous but you chose him as your inspiration. You’re good you’re something :)
@JohanLiebert I wouldn't mind being 30 again... I turned 60 last year.
Announcement: Three scores 1 year ago PM2Ring sir was born and with his great intellect he is helping guys like me.
5:04 PM
@PM2Ring correct me if I am wrong. I have observed that many (high rep) users here are quite active on stack overflow. It might be because they are in the field of scientific programming or something related. Is there any specific reason for this?
@JohnRennie You also had the "pirate" stations, though... if you were in the right location to receive them. Some of the best presenters / programmers on 2JJ had been on those pirate stations before coming to Oz.
@JohanLiebert I'm not sure, but there are quite a few scientist types on Stack Overflow who aren't employed as programmers, but who do write code for their science work.
5:32 PM
@EmilioPisanty That looks like undeleting to delete-by-flag instead to me.
@ACuriousMind What would be the point of that
@AaronStevens delete-by-flag (i.e. with a rude/abusive or spam flag) feeds certain automated blocking systems that a manual delete doesn't
Ah yeah, that makes sense
hmm, i gotta find something to learn after college
i've only been thinking about physics/math these four years
5:47 PM
More physics and math?
welp that'll probably be the case :P
but like i don't wanna get too narrow in what i know
Then don't :P
6:13 PM
@JohanLiebert Beat Saber is really fun. I own a pretty low-end VR setup and Beat Saber. The biggest hassle is having a small apartment and having to move stuff when I want to play standing games like that.
6:39 PM
@JohanLiebert I made it across the Hong Kong border two days before they started doing two weeks of required quarantine. >150million Chinese citizens now under lockdown. Crazy.
@dsm so you were traveling there?
@dsm anyways, be safe be healthy.
7:04 PM
@Knight mine personally, no. But that’s a sample size of one.
I’m quite confident there are people for whom hip-hop can be emotionally-engaging
7:22 PM
@Semiclassical I've definitely been emotionally engaged by it before. I haven't listened deeply to it in awhile; but when I used to listen to it more there were quite a few songs with an emotional impact on me.
7:33 PM
Sometimes when tutoring calculus I come up with some convoluted puzzles
What is the function $f(x)$ such that $\frac1x\cdot f'\left(\frac1x\right)=x\cdot f'(x)$
Where $f'$ is a derivative with respect to $x$
Maybe I should say a function; I am not sure if the function I am thinking of uniquely is like this :P
Yeah there are infinitely many answers actually
And constant functions don't count :P
7:54 PM
@JohanLiebert Indeed, really interesting time to be over there. Vast majority of the shops, restaurants, roads, and public transportation was empty by the time I was leaving. Felt like a ghost town. In good health though, cheers
A: Meaning of matrix elements

dsmRead these expressions from right to left. Your expression $\langle\phi|Q|\psi\rangle$ can be read as "the amplitude of finding the $|\psi\rangle$ state in the $|\phi\rangle$ state after measuring the observable $Q$." Mapping this onto your spin example, $\langle S_z;+|S_x|S_z;+\rangle$ is the am...

Is this correct?
@dsm I think I am thrown off by your wording a little bit
8:17 PM
@AaronStevens Sorry, it's 4am over here and I'm sleep deprived. Didn't want to get into normalization because the question was aimed at interpretation, but I see that wasn't a good approach. Deleted the post because I didn't want to go down the path of editing when I should be asleep. I appreciate the comment
Modulus with negatives is weird. Like -29 mod 4. 4 * -7 = -28, therefore, the number 1 should be the answer, but it's 3... wtf?
@NovaliumCompany You need to preserve the signs! The answer should be -1, which mod 4 is the same as 3
the difference between -29 and -28 is 1, isn't it?
-28 mod 4 is 0
@NovaliumCompany No, -29 - (-28) = -1
8:23 PM
@ACuriousMind Sorry it's a bit late. Soo, the answer should be -1, not 3.
Well, -1 and 3 are the same mod 4, and by convention we choose to represent numbers mod 4 with 0,1,2,3, so both -1 and 3 are "correct" as being the same as -29, but 3 is the conventional choice.
Nailed it
@ACuriousMind 3 is not the difference between -29 and -28, -1 is.
@NovaliumCompany ...so?
@ACuriousMind So -29 mod 4 is -1. I don't understand where that 3 comes from.
8:27 PM
@NovaliumCompany 3 is the difference between -29 and -32.
You seem to be using an idiosyncratic definition of what "mod 4" means.
@NovaliumCompany -29 is 1 less than a multiple of 4
so it is -1 mod 4
It is also 3 more than a multiple of 4 (-32 + 4 = -28) so it is also 3 mod 4
The way I do it is: what integer you can multiply 4 by so to end up as close as possible to -29. Now take the difference between -29 and that 'as close as possible' number
@NovaliumCompany Now follow that procedure with the exception that your result has to be positive.
{... ,-11, -7, -3, 1, 5, 9, 13, ...} are all equal mod 4
8:30 PM
The closest positive number to -29 is 1, so what do I multiply 4 by, so to end up at one... is that it?
@NovaliumCompany Then there you've made a conventional choice to represent 3 mod 4 as -1 mod 4 (note that this procedure also gives -1 for 3, since 4 is the closest 4-multiple to 3 and 3-4 = -1).
I am confusion
@NovaliumCompany The value that you calculate is conventionally positive (i.e. not -1)
Whatever you're reading that says 3 is the answer has made a different conventional choice (and much more common one)
Oops, I picked the wrong equivalence class
8:34 PM
I got it.
@JMac this helped
So to end up at a positive result, the number I'm subtracting from -29 must be greater than -29. So if I choose -30, I can't multiply 4 by a solid integer, but I can do so with -32.
-32 is not greater than -29 by traditional definitions of "greater than" :P
sure but it works for the modulus to be positive
@NovaliumCompany It just depends on which number you subtract from the other
So take the example of -14 mod 2. I can do 2 * -7, which yields a difference of 0. I don't remember the answer being that :P
oh nvm
the answer is that.
Of course -14 = 0 (mod 2) - all even numbers are zero modulo 2.
8:43 PM
Oh, you can use the modulus operator in Python to distinguish between even and odd numbers, coolio
Can all odd numbers be 0 "modd" something :P
if x % 2 == 0:
print("bruh, it's even")
8:59 PM
Anyone attempt my calculus "riddle"?
@AaronStevens I wrote it down, thought to myself, man I haven't really done any calculus in awhile, then got sidetracked.
So I don't know how you want to count that.
@JMac Yeah, I honestly don't know if there is a nice way to solve it
It's not a complicated function though

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