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09:00 - 18:0018:00 - 23:00

9:19 AM
Morning
 
10:10 AM
Measurements in GR is either written by people who don't write about experimental procedures or people who don't write about the math
It is a tad frustrating
 
10:38 AM
"This result is due to Whitehead."
What am I supposed to do, read the entire bibliography of whitehead?
 
 
2 hours later…
12:56 PM
@Slereah how does one make sense of AdS Poincare coordinates
In mathematics and physics, n-dimensional anti-de Sitter space (AdSn) is a maximally symmetric Lorentzian manifold with constant negative scalar curvature. Anti-de Sitter space and de Sitter space are named after Willem de Sitter (1872–1934), professor of astronomy at Leiden University and director of the Leiden Observatory. Willem de Sitter and Albert Einstein worked together closely in Leiden in the 1920s on the spacetime structure of the universe. Manifolds of constant curvature are most familiar in the case of two dimensions, where the surface of a sphere is a surface of constant positi...
 
@bolbteppa 🀷
 
1:21 PM
@Slereah what’s the result
 
@RyanUnger Geodesics fail to be minimizing either if there is another geodesic of the same length or the two points are conjugate
Might be this paper
 
That’s a very basic result...
 
Probably
 
@RyanUnger how does one make sense of (i.e. derive) AdS Poincare coordinates ^
 
1:42 PM
I don't know/care about AdS
 
what is your favorite manifold @RyanUnger
Is it the humble sphere
 
morning
 
hey
 
how's life
 
nasty, brutish and short
 
2:04 PM
"Shulgin describes going to a psychedelic conference and meeting an academic who worked in ethnobotany. He was studying a certain psychedelic plant, and was especially interested in why everyone who took that plant had hallucinations of jaguars in particular. He theorized that the plant was from the Mexican jungle, and that in some deep way our collective unconscious knew this, and so came up with appropriate hallucinations.
Another psychedelicist who happened to hear the conversation interjected β€œI synthesized that chemical a little while ago, and all I got was wiggly lines.” Shulgin left
My sides
 
@Slereah What the academic failed to mention was that you could only access and use the drug near the jaguar exhibit at the local zoo
 
The jaguar was hiding behind him the whole time
 
I think you need to establish proof of a "collective unconscious" before supposing that is the reason
 
Who said anything about collective consciousness
Maybe the jaguar is real D:
 
Maybe the jaguar is complex
 
2:12 PM
$\Huge{πŸ†}$
 
@AaronStevens Nah. You just have to call it "some deep way"; to imply that proving it is beyond our understanding; but it should be believed anyways.
 
@JMac I knew you were going to say that through our collective consciousness.
 
Guys I can't access the collective consciousness anymore
Is the server down
 
@Slereah Try turning it on and off again. Make sure to save first though.
 
I just keep getting jaguars
$\Huge{πŸ†}^{\Huge{πŸ†}}_{\Huge{πŸ†}}$
6
 
2:16 PM
Yeah, a lot of the hivemind has been getting that since the latest update. I would just hold tight, there's probably a hotfix coming today.
 
It must have sucked being in the era where you still had to do astrology to do any astronomy
You just want to work out conic sections but you still have to predict war in Austria
It's like having to write the intro and conclusion of your thesis
Ugh I don't know, just read the thesis
You'll find the return of Christ obvious enough from that theorem
 
Welcome to Physics SE! Have you tried anything so far? — Alex Robinson 3 hours ago
Comments like these are beginning to annoy me a little bit
 
@Slereah What good is studying the motions of stars if you aren't required to heavily anthropomorphize them? The only reason string theory hasn't been completely accepted is because they haven't been able to describe the strings with people-like qualities obviously.
 
@JMac Well they're strings
They're a bit...
... one-dimensional
 
Nailed the joke, matter of time
 
2:20 PM
Thank you
I'll be here all night
 
@Slereah And that's exactly why no one trusts physics anymore. If strings were 2D or 3D, and could instead be drawn like an elephant who is surfing while wearing sunglasses; it would make so much more sense.
 
Well the actual strings are 2D
You can draw trousers with them
And you can draw an elephant too, although the elephant is just $S^2$
It's just one of those bubble diagram in string theory, up to conformal transformation
(if you consider an elephant with $n$ holes, those are the vertex operators)
"You've earned the "access moderator tools" privilege! Learn more about it in the help center."
 
2:43 PM
TBH the privileged sounded like it gave more power than it did IMO. Seeing deleted questions and answers is great though.
 
Let's see if I can delete Duffield from existence
"This account is temporarily suspended because of low-quality contributions"
Apparently I have done so via time-travel
 
@Slereah I love seeing this on profiles
 
This is how professionals use Tinder, XD, LAMFO -qr.ae/T9DWUc $$\huge{\ddot \smile}$$
 
@AaronStevens I don't know why; but same.
For someone who's profile says "I read every answer with scrutiny, so be careful of what you're writing or get downvoted" you would think this guy responds better to critique... engineering.stackexchange.com/questions/31972/…
 
My powers do not extend to the engineering SE I'm afraid
 
2:53 PM
@JMac Geeze that was uncalled for haha
 
I don't believe in engineering
 
I have read neo nazis claiming such things
 
@Slereah what you just said? that offended me :)
 
Theoretical physics being due to the devilish influence of Kabbalah
 
2:55 PM
@Slereah it's always engineering....
 
@JMac I flagged the comment
 
Religion-based math tends to be fairly narrow though
It's usually just geometry and numerology
They're big on numerology
 
@Slereah There is also a religion based on mathematics...
 
Pythagorianism?
 
yessssssssssssssssss
 
2:58 PM
Not a lot of religious analysis or topology
What is the topology of god
is god compact?
 
@Slereah let's start one then XD
 
Is he a Baire space?
 
@Slereah we can derive that using quantum assumptions and hilbert space XD
@Slereah probably
Guess what gives more pleasure than reading QM?
 
Gardening?
 
@Slereah no
 
3:04 PM
the opera?
 
@Slereah no
 
Scrimshawing?
 
@Slereah no
 
Lion taming?
 
@Slereah no
 
3:05 PM
The Charleston?
 
@Slereah no
 
Well I don't know then
 
@Slereah hmmm.....
@Slereah well it's teaching, because it's so complicated that you can explain porn to your parents but explaining QM is another level shit!! XD
 
Are you teaching them lies
as people usually do in QM classes
 
@Slereah teaching lies is easier than QM.
 
3:10 PM
the tiny matter waves
 
@Slereah not waves exactly....
when toddler became a ghost^
 
@AaronStevens Yeah, I had flagged it too. I was really surprised by that overreaction from someone with that profile.
 
Shocking
Confrontational sort of person doesn't take criticism well
 
3:26 PM
@JMac I have never gotten that bad of a reaction before. But recently there was an instance where I left a comment and the reply was the same of "If you think you know better then just make your own answer"
 
@Slereah More surprised by the words "I read every answer with scrutiny, so be careful of what you're writing or get downvoted" yet they don't seem to want to put any of that care or scrutiny into their own work. Pretty ironic
 
He reads them with scrutiny bc he owns the Engineering Knowledge
Therefore you may not challenge his engineering
 
@JMac why so sad? There are tons of such people over internet. Just don't spoil your mood over it. Probably he wasn't personally well and thus he overreacted, just don't think over it. You'll feel much better if you master the art of *not giving a f**** on internet.
@Slereah BC? heheheheh XD
 
"because"
 
@AbhasKumarSinha I dont think JMac is sad. Just amused and surprised
 
3:28 PM
@AaronStevens Those ones are funny. It's like, I don't even need to know the answer to tell you what is wrong with yours; so that comeback rarely even works.
@AbhasKumarSinha It's not getting to me. It's funny and ironic.
 
@AaronStevens That's good, he should be amused with such people and share his incidents to amuse us well :)
@JMac If I were you, I'd have harshly and mercilessly trolled him for fun (ofc respecting him as a internet user)
 
@JMac Yeah. That user used to be fairly friendly to me. But lately they seem to be getting more and more frustrated with me
 
What's your crank activity over at the engineering SE like?
Do you get a lot of cold fusion and perpetual motion
and magnets
 
@JMac just add some reply like this - *Thanks for about Electrocatalytic materials, my goddamn eyes are open on the net. Now I can downvote your goddamn answer because my eyes are already open! *
@Slereah no, I've not joined yet!! (school kid)
 
@Slereah Not a lot of crank questions that I noticed when I was active there (I'd say Physics gets more); but there were some ways of thinking that seem to be popular with engineers that I did not expect. My prime example is how many people did not understand Archimedes' principle and buoyancy engineering.stackexchange.com/questions/19159/… (compare top answers to the correct one sitting at +3/-3)
 
3:34 PM
@AbhasKumarSinha hi.
 
@Slereah 2 magnets and 2 balls...
@yuvrajsingh hi bro! :)
 
Engineering relativity questions are even more fun
 
Do you know India, s top research college other than iit iisc, iiser.
 
like the whole buoyancy/relativistic contraction problem
 
@yuvrajsingh niser.
 
3:35 PM
or the relativistic runner over a grid
 
@JMac I remember you complaining about that before haha
 
I'm an engineer, but apparently to many of them; buoyancy is just some magical property of submerged objects; and not the result of hydrostatic forces acting on all surfaces of an object. I just don't get how you can defend archimedes' principle so much without understanding how it's formulated
 
Other than this.
 
3 mins ago, by Abhas Kumar Sinha
@JMac just add some reply like this - *Thanks for about Electrocatalytic materials, my goddamn eyes are open on the net. Now I can downvote your goddamn answer because my eyes are already open! *
uh sorry, wrong one!
 
3:36 PM
@yuvrajsingh then not sure
@Slereah You are Indian? You watch these kinda videos?
 
No
 
@Slereah ah okay, just that is very indian thing.... :O
 
As the song implies, it's also a very Russian thing :p
 
@AaronStevens hello :)
 
Not that I am russian either
 
3:38 PM
@yuvrajsingh Hello
 
I am studying thermodynamics, these days what is the meaning of disorder, actually.
 
@JMac Archimedes was a famous magician
 
a mathemagician
 
@yuvrajsingh It is a subjective term. Usually "disorder" just means "more random" (but even that is fairly colloquial).
 
3:40 PM
@AaronStevens He actually manifested the principle of buoyancy on Earth when he said the magic word "Eureka!" before that spell, buoyancy wasn't a thing.
 
I would honestly move away from that word
 
@AaronStevens yes he once made his pants dissappear in public after he discovered buoyancy
 
@JMac I always tell people before Newton there wasn't a way for us to remain on the ground
 
^ this is true, I didn't believe that first
 
How do I relate it with entropy.
 
3:41 PM
Don't end up like Archimedes
 
@Slereah can you derieve $F=ma$ using some very very very very basic assumptions, (ama tryin)
 
Stabbed for standing for geometry
 
@yuvrajsingh Less formally, more entropy means "more disorder".
 
@AbhasKumarSinha What assumptions
 
@Slereah any
 
3:42 PM
I mean if you don't define forces, this isn't even a law
it's just a definition
 
@AaronStevens is correct
 
@Slereah Using Schrodinger's Eqn
 
Can elaborate, because it, s making me crazy
 
Using Schrodinger's equation you just use the time derivative
 
@Slereah time independent ones...
 
3:43 PM
ie for a time-independent Lagrangian, $$\dot{A} = [H, A]$$
 
commutator
Therefore, $$\dot{x} = [H, x] = [p^2/2m, x] = p/m$$
 
@Slereah ?
 
If you don't know quantum mechanics this may not be the best question
 
I got $F$ on one side and to reduce to $ma$ to other side, by limit $\hbar \rightarrow 0$ drives me crazy....
$[,]$
 
3:45 PM
@AaronStevens from school days we taught study, entropy is the measurement of degree of randomness.
 
@Slereah ugh!! I think there is some bug here
[,]
 
@yuvrajsingh Yes, that is a less formal way to explain it
 
yes...
Is that happening to others too?
@Slereah just type [,] in the chat and press enter, then what's that loading for?
 
But many of the physicist on the site says it is not correct. Way to explain it.
 
3:48 PM
@yuvrajsingh I wouldn't say it isn't correct... it just isn't very precise. "Disorder" is a subjective term.
 
OK, so why we relate entropy with temperature,.
 
Entropy is roughly the number of ways you can get a given macroscopic quantity from microscopic quantities
Consider for instance a quantum system composed of two harmonic oscillators
With a quantum state $|n_1, n_2 \rangle$
 
whenever I type this '[,]' in the chat, the chat loads something and then the next moment it stops... Should I report it?
 
I'm lazy so just assume $H = \hbar \omega (n_1 + n_2)$
Imagine that you measure the energy of that system, macroscopically. So you only get the total sum.
 
@yuvrajsingh Well "why" is because it is useful and we can do it
 
3:52 PM
There's only one way to get $E = 0$ : $n_1 = n_2 = 0$
But for instance, there are two different ways of getting $E = 1$ : $n_1 = 1$ or $n_2 = 1$
As the number of particles increase, the number of combinations you can get for a given macroscopic quantity increases
This is basically what entropy expresses
And it gives you basically the probabilities of a configuration given macroscopic quantities
 
Aah, that, s very well explained, I do noT know, but i Remember there is one more definition given by clausis @Slereah do you remember that.
 
For instance if you have some energy $E$, you'll find that it's much more likely that every particle has an energy distributed around $E/n$ rather than a single particle having energy $E$
Clausius' definition of entropy is pre-statistical mechanics, IIRC
It's just defined by other quantities, $dS = \delta Q / T$
 
@Slereah @AaronStevens can I say universe is homogenous every where, and ordered.
 
Look to your left
Look to your right
Are you seeing the same things?
 
4:01 PM
No.
Actually I was referring to the concept of heat death.
 
Raise your hands if you hate snow.... :'(
 
@AbhasKumarSinha Depends on the context
 
@AaronStevens very cold, I'm almost frozen
 
Oh no
The original Pauli-Fierz theory is in German
Ach
 
4:14 PM
Find a translation
I really want to read that
 
1
Q: Work done while compressing an ideal gas

Ramanujan_Ο€Today in our chemistry class we derived the pressure-volume work done on an ideal gas. Our foremost assumption was that $$P_{ext}=P_{int}+dP$$ so that all the time the system remains (approximately) in equilibrium with the surrounding and the process occurs very slowly (its a reversible process) ...

Am I missing something here, or is this trying to assume pushing a book is like compressing an ideal gas?
 
No way
 
Apparently the idea was:
"The theory of particles of arbitrary spin was initiated by Fierz and Pauli in 1939 [6],that followed a field theoretical approach, requiring Lorentz invariance and positivity of the energy. After the works of Wigner [7] on representations of the Poincare group, and of Bargmann and Wigner [8] on relativistic field equations, it became clear that the positivity of energy could be replaced by the requirement that the one-particle states carry a unitary representation of the Poincare group."
https://arxiv.org/pdf/hep-th/0409068.pdf
From the Fierz one:
"In the discussion of the secondary conditions (1.3), we made use of the existence of a rest frame for each plane wave. The existence of the rest frame is essential for the entire conclusion, and the case m= 0 must therefore be regarded as a degenerate boundary case. We shall, therefore, regard the case of vanishing mass as a separate one."
Wigner method snuck in already
 
4:24 PM
@Slereah programming skills?
 
@AaronStevens last idea clear things very well. I have one more question just a small one.
 
"B.L. van der Waerden in Groningen"
 
:52601612
 
Powerful name
 
4:26 PM
@yuvrajsingh Ok
 
Why we include the word free in Gibbs free energy.
 
@Slereah that's a leopard
 
@SirCumference No jaguar-specific emojis so far
 
@Slereah have seen my question. Do you have any idea.
 
@yuvrajsingh It is the only energy that is "free to use" in a sense
 
4:29 PM
@AaronStevens lol? never expected that....
@AaronStevens really free?
 
@AbhasKumarSinha the energy from which you can extract work
 
@Slereah what that means?
 
ie if you produce $30kJ$ of heat, you won't get $30kJ$ of work from it
 
@Slereah so what free has to do with it?
 
@AbhasKumarSinha it is not bound to escape away as unusable thermal energy
Don't get too hung up on words
 
4:33 PM
OK, it, s accidentally written.
 
Ah that's a bad quality
 
the best physical examples are nonphysical situations
 
@SirCumference The magician is Archimedes
@yuvrajsingh Well it isn't an accident
 
Why, since it is just a logic, and someone added a word free infront of it, because of that logic.
 
that is far from the worst naming that physicists have used
 
4:38 PM
@SirCumference Electromotive force?
 
@AaronStevens that's a good example
also variable star designations are atrocious
In astronomy, a variable star designation is a unique identifier given to variable stars. It uses a variation on the Bayer designation format, with an identifying label (as described below) preceding the Latin genitive of the name of the constellation in which the star lies. See List of constellations for a list of constellations and the genitive forms of their names. The identifying label can be one or two Latin letters or a V plus a number (e.g. V399). Examples are R Coronae Borealis, YZ Ceti, V603 Aquilae. == Naming == The current naming system is: Stars with existing Greek letter B...
 
That Fierz paper seems really good, need to think about this whole $(f+1)^2$ component business properly
 
Anybody now a youtube channel who, as trust worthy, and right explanation on thermodynamics.
@AaronStevens
 
@yuvrajsingh you're better off with a textbook
youtube channels aren't usually top quality
 
Do you have any refer book. @SirCumference
 
4:41 PM
@yuvrajsingh I don't know what you mean. I didn't pick random videos. I picked channels that have a history of producing correct, high quality videos.
 
@yuvrajsingh this is the one used in my uni's class
 
@AaronStevens how stupid I am.
 
@yuvrajsingh You are learning new things. That doesn't make you stupid. Lack of knowledge isn't the same thing as stupid
 
Yes. sure. Is word zero in math also have some sginficance in history.
 
"word zero math"?
 
4:47 PM
@yuvrajsingh I don't understand the question
 
what do you mean by "significance in history"
 
Actually rearing '0' is zero in hindi it refer to shonay
It was before in the old Indian sculpture, it written that word shonay mean
Something which neither can be separated, nor be divided, it is the origin of everything.
@AaronStevens @SirCumference
 
i have no clue what that means
sounds philosophical
 
What it means, is in Hindu vedas (old holy books)
They already discover zero.
Which has the meaning that we use in today mathematics
 
@Slereah some of the number of components argument physics.mcgill.ca/~yangob/symmetric%20tensor.pdf
 
4:54 PM
@SirCumference are you from Ukraine
 
Are you a engineer or physicist
 
physicist
speaking of which i gotta get back to studying
 
In which field.
 
mathematical physics or astronomy
haven't decided which
 
5:00 PM
Are you a UG.
 
Same here.
I am asking a question which is totally irrelevant to the site. But still will trump come again.
@SirCumference
 
@yuvrajsingh President of US?
 
Yes.
 
@yuvrajsingh Are you asking if he will be reelected in 2020?
No one can answer that
 
5:16 PM
Yes, we in India can predict that MODI ji will come back with 100% assuring, and he did that.
 
@yuvrajsingh Just saying you predicted something with 100% and it happened doesn't mean you actually predicted it to 100% accuracy
 
Search on Google, about the interview of people India before the election. Every body has his point view. I am just asking that.
What you think.
I think that, s the freedom of speech, and democratic nation should provide their citizen.
 
@Slereah Nice wiggly lines you got there
 
@yuvrajsingh Well for sure US is divided politically
So I don't think anything can be predicted
Just look at the 2016 election. Everyone thought Trump was going to lose
 
Nice........,
 
5:27 PM
@AaronStevens Hello :)
 
@user8718165 Hello
@yuvrajsingh Why do you ask?
 
It, is easy I was reading an article on new York times, so
 
@yuvrajsingh What is easy?
 
@AaronStevens how are you?
 
@user8718165 Alright. Trying to get things done to finish my PhD, but things aren't working out like they should
But that has happened at all points in my research....so I am used to it haha
 
5:39 PM
@AaronStevens you are doing a PhD? Wow!!!
 
@user8718165 Eh anyone can attempt a PhD. I am not very impressive yet haha
 
@AaronStevens Things not working out like they should is exactly how these things are supposed to go.
 
@JMac there is a graduate student in a biology lab we collaborate with that seems to have everything go right for him
It is a running joke in our labs now
 
@AaronStevens I would keep a fairly wide radius around him, for everyone's safety. If things are going that well, odds are they will spontaneously combust any day now; for the sake of balance.
 
@JMac I think I am the balancing combustion
 
5:44 PM
@AaronStevens okay :) Can I ask you a question?
 
@user8718165 Of course. I can't promise an answer though
 
@AaronStevens No...no worries at all. Almost everybody was saying that Mr. Trump would lose 2016 elections right? But did majority of the people just change their mind? I mean the people who were saying were the ones who were voting. Sorry If its a silly question :(
 
@user8718165 It was probably due to incorrect polling methods, as well as a huge push from the media against trump
So there was a sort of illusion that there was no way Trump could win
 
@AaronStevens Thank you for telling. I didn't know that... I was just thinking that people literally were sharing their opinions.
 
@user8718165 There is no way to determine the entire voting population's opinion before an election
 
5:53 PM
@AaronStevens yeah...Got it now :)
 
I do not know, that us people are very shy, to express their views on a such a important discussion. @AaronStevens
 
@yuvrajsingh There are many outspoken people. There are also people who prefer not to discuss it. I don't think you can paint all US citizens as one way when it comes to expressing political views though
 
Let erase it, I was just wanted to know, that what local people think about it.
Good night. :) to everyone
 
@user8718165 There might have also been an effect of people who supported Clinton not going to vote since they believed she was for sure going to win anyway. Although I cannot back that statement up with actual data
 
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