The h Bar

Slereah

00:39

Gilda Radner - Lets Talk Dirty To The Animals

►

Secret

in The Factory Floor, 7 hours ago, by Bellerophon

@Secret What if it was just a process that converted heat into light with nearly 100% efficiency?

Hmm, that got me thinking:

Does there exists a form of visible light that is not work?

as in, can there be a process which upconverts a lot of infrared with a small number of microstates into visible light with a large number of microstates such that the 2nd law still holds?

Hmmm.... I need to revise the entropy production in nonlinear optical phenomenon...

Another possibility I can think of is polarised infrared coherent light converts into a narrow bandwidth of unpolarised light of a certain colour range

any ideas?

Secret

01:07

Is there a situation where the total number of molecular degrees of freedom is not enough to surpass the total number of electromagnetic degrees of freedom such that the resulting frequencies of electromagnetic radiation are of the energy in the visible range and bound in a compact set?

Kane

04:24

if I pluck a guitar string, is the frequency of the vibration the fundamental frequency of that string?

Prathyush Poduval

yes, thats what a simple strike gives

Kane

hmm, I'm supposed to design a physics experiment for a class I'm doing and one suggestion was to do an experiment with a musical instrument.

i found this experiment: sciencebuddies.org/science-fair-projects/project-ideas/…

It's supposed to determine how the fundamental frequency changes as the effective length of the string changes

isn't it just trivial, like with different frets I can measure the frequency of vibration?

trying to decide if this would be a good experiment to carry out

@PrathyushPoduval if you've got a spare second could you check the last step of the procedure of the experiment and tell me why they calculate the speed of the wave? I don't see how it's relevant to the fundamental frequency

Prathyush Poduval

@Kane alright wait a min

@Kane Thats the method of verifying your law. Since the theory says that $\lambda \nu$ is $v$, you're substituiting the values and verifing

Kane

04:44

Oh ok, i thought the point of the experiment was to determine frequencies. but it seems to me they are measuring frequencies to determine the wave speed of each string in the end

Swapnil Das

07:29

@Blue Hi! I wanted to ask if Etoos VOD feature becomes active instantly after payment. Please reply, thanks.

Balarka Sen

07:45

The physicists are quiet today it seems

Mesentery

08:05

Hello Physics.SE! Can anybody explain me the answer to this question? The author says that something is hidden in the question. But I don't really get it

acadblock.com/electricity-and-magnetism/infinite-ladder-fjg2

Anonymous

@SwapnilDas Yes

Mesentery

11:28

Well.... I got it. Thanks!

skullpatrol

np

bolbteppa

12:54

Oh my god

Физика элементарных частиц, В.Г. Сербо. Лекция 1 | Physics of elementary particles. V. G. Serbo - 1.

►

15 lectures in Russian with English subtitles teaching from Landau vol 4 from someone whose name is recognizable

Best thing on the internet without a doubt

He is doing all the scary things from that book

Balarka Sen

@0celo7 I'm trying to transition to differential geometry

Reading ihes.fr/~gromov/PDF/1[77].pdf

Swapnil Das

@BalarkaSen Just be for a sec, does studying DG require visualising higher Ds,or is this just another internet nonsense?

bolbteppa

@SwapnilDas yes, only some people possess this ability

Balarka Sen

Visualizing higher derivatives? Well, I don't understand what you mean by that. They are not hard to make geometric meaning of.

Swapnil Das

@bolbteppa Do you?

bolbteppa

13:04

haha don't be silly nobody can visualize higher dimensions

Swapnil Das

@BalarkaSen Higher Dimensions.

Balarka Sen

Oh.

Eh, "visualization" is a vague term.

Swapnil Das

@bolbteppa Btw are you trained in mathematical physics?

@BalarkaSen seems to be :P

Balarka Sen

But anyhow I don't see what this has to do with differential geometry. You can do surface geometry, with just surfaces in the 3 dimensional space.

That doesn't require understanding of any higher dimensions whatsoever

bolbteppa

@SwapnilDas maybe, have you tried to study differential geometry

Balarka Sen

13:07

And is already sufficiently complicated.

Dimensions are usually not a geometric obstacle. They are a topological obstacle.

Swapnil Das

@bolbteppa Lol no I'm in grade 11.

I heard people who study GR know Differential Geometry

bolbteppa

@SwapnilDas do you know what $\mathbf{A} = \mathbf{A}(x,y) = A^1(x,y) \mathbf{e}_1(x,y) + A^2(x,y) \mathbf{e}_2(x,y)$ means?

Swapnil Das

I donno what exactly this script means

bolbteppa

Ok, if you study calculus and multivariable calculus then differential geometry will seem natural

Swapnil Das

I see.

Balarka Sen

13:11

Not entirely true...

Swapnil Das

Are you a physicist?

You made reference to Landau that's why.

bolbteppa

@BalarkaSen what are colleges missing/doing wrong when they teach DG after calculus and multivariable calculus?

Balarka Sen

@bolbteppa Nothing, that is how it should be taught.

Swapnil Das

@bolbteppa @BalarkaSen Do you guys have a math ceiling?

Balarka Sen

I was objecting to the idea that differential geometry on the whole is an immediate, or a natural, idea if you know multivariable calculus. The latter is crucial to understanding differential geometry, but does not elucidate many interesting and complicated ideas involved in geometry

It's easy to pass off geometry as calculus... but computations do not elaborate ideas, which are inherently not computational

Indeed, the first page of Gromov's exposition starts by rejecting the small-scale/infinitisimal geometry, i.e., where all the calculus is.

0celo7

13:17

@BalarkaSen Gromov is insane

Balarka Sen

(The real reason is that geometry makes sense on the large-scale much widely, on spaces where the tangent space makes no sense)

@0celo7 old knowledge :p

bolbteppa

@BalarkaSen Gromov is not 'rejecting' infinitesimal geometry, he is just using the Curvature tensor as a starting point to go looking for analogues of convexity, this is nothing but applying a single variable calculus idea to more general scenarios, literally making my point for me, why make differential geometry seem complicated and other-worldly when it literally began using multivariable calculus

Balarka Sen

@bolbteppa It seems you didn't read the first page carefully.

bolbteppa

I would say the same thing to you

Balarka Sen

He's isn't using the curvature tensor as a starting point to go looking for analogues for convexity. This is what happens to people who read wikipedia all day.

He gave convexity as an example to show two definitions, one using calculus and one without.

Read again.

0celo7

13:28

Wonder what being Gromov’s PhD student is like

Meetings are just smoking a large bowl of crack

Balarka Sen

probably accurate

user228700

Hello, everyone :-) How's your Sunday going?

Balarka Sen

Hey

user228700

@BalarkaSen How's it going?

0celo7

@JohnRennie would you believe me that my desktop keeps rebooting without input from me. Is this some Windows update bullshit?

I'm not not there to reboot it but it's been rebooted at least twice

No one is in my room and no one knows the password

user228700

13:31

GHOSTS

bolbteppa

@BalarkaSen No, he showed how second derivatives satisfying condition X leads to the geometric concept of convexity, & the curvature (in terms of 2nd derivatives) has it's, in his words, "full geometric meaning remains obscure", he is looking to use the curvature to define "several significant classes of manifolds" which allow us to work directly with concepts that arise the way convexity arose from second derivatives, which "can be studied in the spirit of the old-fashioned synthetic geometry"

Balarka Sen

@Kaumudi.H Not bad. I spent all my morning on chemistry. But I am complementing the harm done with some math now

0celo7

@JohnRennie running defender full scan

bolbteppa

@BalarkaSen what is that wikipedia comment even supposed to mean

user228700

@BalarkaSen A productive day, then, cool! :-) How's Chem. coming along?

0celo7

13:32

@bolbteppa he means that you've shown no critical thought or knowledge that cannot be gained from a cursory browsing of wikipedia

bolbteppa

@0celo7 I was hoping he would admit that's what he was ridiculously trying to say not you

0celo7

He's too nice to admit it

bolbteppa

'I found a complicated advanced differential geometry paper I don't understand, and I want to use it to say differential geometry is harder than people think, and wont accept people saying the idea of differential geometry is an obvious extension of basic calculus as the inventors 200+ years ago showed because this paper!'

ACuriousMind

Everyone, please be nice to each other. Focus disagreements on the matter at hand, not on personal attacks.

0celo7

@ACuriousMind Shit, if what I said is a personal attack then you've personally attacked vzn plenty of times

2

bolbteppa

13:37

That wikipedia thing is just so out of nowhere, so un-called for

user228700

@Balarka: Hello?

Balarka Sen

I agree with 0celo7's interpretation of what I said. But I have better things to do than to debunk bolbteppa's wikipedia-thoughts; I will continue this rather amusingly wrong-headed discussion on a later date.

@Kaumudi.H Chem's pretty good!

I am not super comfortable with it but it's quite alright

bolbteppa

Yeah it's really hard to dispute me when I directly quote Gromov's own paper yet you keep saying I am giving wikipedia thoughts, this is farce level

ACuriousMind

@0celo7 Knowing the people involved here, I felt it best to remind everyone before we reach the level of animosity where I'd have to actually do something.

Balarka Sen

Enough for survival

user228700

13:39

Cool! Still O.C?

0celo7

@ACuriousMind what is that supposed to mean?

@ACuriousMind also please see my windows doubt above

ACuriousMind

@0celo7 That y'all are a bunch of hotheads :P

0celo7

@ACuriousMind you have no basis for that claim

I'm the most calm person I know

ACuriousMind

@0celo7 Windows updates typically will force a restart after some time

Balarka Sen

@Kaumudi.H Yep

0celo7

13:40

@ACuriousMind Well I've been gone a month, is that enough time?

ACuriousMind

@0celo7 Uh..."some time" is more on the order of hours or days after the update

0celo7

@ACuriousMind ah, well

thx

gotta continue packing

ACuriousMind

What exactly is happening - you didn't use your PC for a month, and now after the first reboot it has restarted a couple of times?

Balarka Sen

@bolbteppa You are quoting him, but your comic digests between the quotes are flawed.

Pretty common wikipedia-symptoms, I assure you.

ACuriousMind

That could indeed be the updates, but you should see some sort of notification that tells you to reboot in X minutes or else it will restart on its own.

0celo7

13:42

@ACuriousMind I temviewered into the PC and I could tell it had been restarted since anyone last used it

which has been several weeks

anyone being me -- I don't think there's any way anyone else used it

ACuriousMind

Ah, yes, then it's perfectly possible it was an automatic restart after an update

Or some hacker is remote-controlling your PC to nefarious ends, it's 50/50

0celo7

how do I rule out the second

user228700

@BalarkaSen Wow, nice!

bolbteppa

@BalarkaSen Yeah my post was something like "one can define using the curvature several significant classes of manifolds" :) :) :) ?#@@ :p "these can be studied in the spirit of the old-fashioned synthetic geometry" ??? @ :( :( "interesting phenomenon of convexity" :\ :| ~''' alright

0celo7

^ unintelligible

ACuriousMind

13:44

@0celo7 You never can ;) If you're worried, run a thorough scan with whatever anti-virus software you're using.

0celo7

@ACuriousMind malwarebytes didn't find anything

running a full defender scan which will take some number of hours

Balarka Sen

@bolbteppa Right, now that that's out of the way: what synthetic geometry (or large scale geometry, as I said previously) means is that you have no tangent space. I.e., there's no infinitisimal calculus in the first place. What Gromov tries to do is to find an interpretation of the curvature tensor in large-scale geometry, because the local definition is not very enlightening.

He brings up the convexity example to illustrate the point that the geometric definition on the right is more interesting than the calculus definition on the left.

Nobody's claiming differential geometry doesn't have it's origin in calculus, of course it does. But the jargon of calculus obscures the bag of ideas that deserves it's own mathematical discipline, called "geometry".

Don't give the other person's counterarguments a superficial look. That does not make your points stronger, just makes you seem obnoxious.

bolbteppa

@BalarkaSen so you are trying to say he is going from differential geometry concepts to non-differential, synthetic, concepts - and you are literally using a discussion of differential geometry aimed at discovering non-differential symthetic concepts to try to say differential geometry itself is hard, even by your own logic what you said makes no sense since you're not even talking about DG proper,

@BalarkaSen there is also the additional flaw in what you said in that Gromov is still just mimicking baby calculus ideas, e.g. the convexity example, or the second fundamental form (though I'm sure that can't be derived using only multivariable calculus right), adding on to the flaws in what you said

@BalarkaSen then there is the third huge flaw of why you'd throw something like this at someone who doesn't know differential geometry and is asking basic questions about it, why you'd try to make it seem way more complicated, especially using this non-DG synthetic stuff, makes perfect sense if you want to say 'I'm smart' and all others only know wikipedia level math compared to me however

Balarka Sen

Who is saying differential geometry is hard? Not being merely limited to calculus does not equate to being hard. What is this bullshit

In fact it's very easy

Geometry is easier than calculus. The fundamental basis of the first subject is pictures, and the fundamental basis of the latter is calculations

You're making awesomely lame points.

Captain Bohemian

geometry is more beautiful, intriguing, exquisite than calculus.

Balarka Sen

13:57

To illustrate that I'm not trying to sound smart, I have had my fair share of suffering with differential geometry because I don't understand symbolic logic. I understand pictures.

Most textbooks in geometry is more symbolic and analytic (or calculus-based, naively) than pictorial

That's essentially why I brought up the topic, and why I want to read Gromov's paper. It provides a more pictorial point of view, which is more suitable for me

Prathyush Poduval

@0celo7 Maybe a update issue.A simillar issue happened to me a few weeks back, right after a windows update. My laptop wouldn't reboot no matter what I did, had to reinstall a clean version of windows

0celo7

@BalarkaSen pls write my thesis

Balarka Sen

loool

Slereah

@0celo7 Is the ADM mass still a scam

0celo7

14:25

@Slereah I think it is.

John Rennie

@0celo7 Yes, Windows Update will have rebooted your PC when it installed the Meltdown/Spectre fix. That is normal behaviour.

CooperCape

ola

John Rennie

To check run eventvwr.exe, open Windows Logs/System and look for the event type User32. The event will say something like:

The process C:\Windows\system32\MusNotificationUX.exe (RATITCH) has initiated the restart of computer RATITCH on behalf of user RATITCH\renniej for the following reason: Operating System: Service pack (Planned)

0celo7

14:46

@JohnRennie I never told it to update though

CooperCape

Your computer is becoming sentient.

0celo7

@JohnRennie what?

I can't dinf windows logs/system

John Rennie

0celo7

there's no event type

John Rennie

Right click on System and choose Filter Current Log

0celo7

14:51

ok, then?

John Rennie

Set Event Sources to User32

When you click OK it will only show the User32 events, and that makes it easier to find what you want.

0celo7

ah, it did restart on the 5th

is that when the patch was pushed?

John Rennie

Yes

0celo7

ok thanks mr. computer hacker

Slereah

15:12

The relativistic quantum theory of a single particle is quite bothering me

There's many problems that should be there but I can't be sure since I have no idea what the BRST Hilbert space is like

bolbteppa

@Slereah a bunch of KG wave functions no?

Slereah

It's complicated

Because you get all the old problems of RQM if you do it naively

But I don't know how BRST quantization solves it, if it does

Captain Bohemian

I have seen the term BRST many times but don't actually know what it is, just knowing it's probably related to quantization and may be interesting.

Slereah

BRST quantization is quantization of constrained systems

Like gauge theory and such

Because if you quantize those normally, you get a lot of states that should describe the same state

bolbteppa

@CaptainBohemian this is great on brst disconzi.net/Research/BRST_and_Gauge_fixing-Martin_Rocek.pdf

Slereah

15:19

Careful tho

There are spooky ghosts

I do suspect that the whole negative energy solution thing is taken care of by BRST, since I think those are related by a symmetry?

since it's part of the reparametrizations that switch the time orientation

I'm not sure how it works with Malament's theorem though

If the Hilbert space is close to just $L^2(\Bbb R^n)$ that should go against it for any state of compact support

bolbteppa

Hmm, the BRST operator is the Klein-Gordon operator, so physical states satisfy $Q |\psi> = (\partial^2 - m^2)|\psi > = 0$, i.e. negative energy solutions unavoidable no? There's no difference from what you get in the Dirac method of quantization for a point particle

Slereah

Well there's that Thing you can do IIRC

Where you define the Hamiltonian differently on the positive energy and negative energy sector of the Hilbert space

I don't know if that happens though

But I think positive energy states and negative energy states are the same under reparametrization

Under a reparametrization that does $t \to -t$

hence they might just get identified in the final Hilbert space?

I dunno

bolbteppa

I don't see any of this in the 'brst point particle' section of the string books I've skimmed anyway

That's interesting about the reparametrization

Slereah

There aren't a lot of really detailed things on the topic

arxiv.org/pdf/gr-qc/0511088.pdf

This is probably the most detailed account of the theory

Maybe I should write the dude once I learn BRST quantization

bolbteppa

15:38

Did you check his other paper

arxiv.org/pdf/gr-qc/9806058.pdf

Slereah

I did

It's basically a shorter version of his thesis

bolbteppa

Wait, even though positive and negative time may be equivalent under a reparametrization, it's the energy $\varepsilon^2 = \pm \sqrt{p^2+m^2}$ that leads to anti-particles

Slereah

Well I don't care so much about the energy as I care about the inner product

I don't mind the energy being negative, I mind the probability being negative

But I need to learn BRST properly to be sure about what all of this means

bolbteppa

I never seen the point particle quantization until string theory so I may be confused on this, if you blindly just applied Dirac quantization to the relativistic point particle action you'd end up with the Klein-Gordon equation

Slereah

Well you do see point particle quantization a lot in like

Phase

15:45

The Physics SE was made before Area 51 right? How did they decide back then what stackexchange sites should be set up?

Slereah

Historical quantum stuff

But the big issue is that the inner product can lead to negative probabilities

Also there's the Malament theorem on more recent issues for it

The wavefunction obeys the Klein Gordon equation fine, but some states have negative probabilities

bolbteppa

It's kind of amazing first quantization of a relativistic point particle leads to the second quantization of a spin 0 particle

Slereah

Well not really

Since the Hilbert space isn't the same at all

although you can do QFT with point particles

but then it's complicated

bolbteppa

@Slereah that's what he says happens here though:

books.google.fr/…

Phase

@BalarkaSen LoL isn't that bad

bolbteppa

15:54

What's 'not really' about it?

Phase

Just /muteall

and have a fun time

Slereah

@bolbteppa Well I mean there's a leap you have to do in between

bolbteppa

@Slereah I guess when he applies the constraint as a differential operator to a wave function

Slereah

The difference between the two is that in RQM it's a wavefunction

While in QFT it's an operator

bolbteppa

No in RQM it can be an operator, in Non-Rel QM it can be an operator if you want it to be

On page 8 he re-interprets the results he gets via Dirac's method using BRST, just a couple of sentences, need to think about it more

Slereah

16:07

could be I suppose

There's so much QFT stuff out there

bolbteppa

So much basic qft stuff we all should know, e.g. renormalization, brst, qcd, ... that's impossible

Slereah

So much stuff just to understand the basics of string theory

bolbteppa

nevermind superstring theory...

Slereah

really I don't even know all I need to know about classical mechanics

bolbteppa

They say you never really learn a subject until you teach a course on it so I guess/hope it's okay to keep forgetting basic stuff :p

Slereah

16:13

Well you know, most students aren't that into asking questions even then :p

vzn

@0celo7 thx very much for vote of confidence, admire your own top record for "contrarianism" ~71x last count :) o_O :P physics.meta.stackexchange.com/questions/10193/…

@Kane nice find, really like this general site idea & have been looking for something like it a long time, although wish there was more college level stuff, and a discussion forum. open/ tabletop experimental science lives! weakly! :) sciencebuddies.org

vzn

16:34

@Secret kind of a (vague) zenlike question and therefore unanswerable. however! did remind me of this recent experiment in the news that claims "reverse time" and to see heat flow from cold to hot. all kinds of weird findings like that lately pushing conceptual boundaries of QM it seems!

Physicists create quantum experiment where time moves backwards / mother nature network

Phase

I'm just waiting for the day that the silly idea of "quantum mechanics" is discarded and we can move forward and model things as they truly are: oobleck fields

Narcissus jewel

@vzn 71 times, that's truly impressive.

I wonder who does hold the record

Loong

16:56

different chat room

vzn

@Phase guess you are joking but googling that leads to a fluid dynamics wikipedia pg.

Non-Newtonian fluid

A non-Newtonian fluid is a fluid that does not follow Newton's Law of Viscosity. Most commonly, the viscosity (the measure of a fluid's ability to resist gradual deformation by shear or tensile stresses) of non-Newtonian fluids is dependent on shear rate or shear rate history. Some non-Newtonian fluids with shear-independent viscosity, however, still exhibit normal stress-differences or other non-Newtonian behavior. Many salt solutions and molten polymers are non-Newtonian fluids, as are many commonly found substances such as ketchup, custard, toothpaste, starch suspensions, maizena, honey, paint...

Phase

well oobleck is a non newtonian fluid

It's cornstarch and water iirc

airomyst

can someone help with an answer to this question?
https://physics.stackexchange.com/questions/378501/closed-packing-and-dislocation-in-metals

vzn

← now wonders if spacetime fluid could be modelled as nonnewtonian fluid :P

Slereah

17:18

I don't think anyone really did spacetime as a fluid

Might have worked for Einstein-what's his name gravity

with the scalar field

but with a tensor field I don't think that's doable

although of course you have the spacetime simulations with fluids

I don't know what kind of fluids they use

Slereah

17:44

"Because we have a grading and a derivation we can consider the cohomology of this complex, called BRST cohomology"

Not cohomologies again ;w;

bolbteppa

I keep forgetting the basic logic of this: consider the decay of one particle into any number of particles, if $w_{fi} = |S_{fi}|^2/T = (2\pi)^4 \delta^4(P_f - P_i) |T_{fi}|^2 V$ is the transition probability per unit time for one particle $|i>$ to decay into $|f>$, why multiply $w_{fi}$ by $\Pi_a \frac{V d^3 p_a}{(2 \pi)^3}$ to say $dw = (2\pi)^4 \delta^4(P_f - P_i) |T_{fi}|^2 V \Pi_a \frac{V d^3 p_a}{(2 \pi)^3}$ is the probability for decaying?

Slereah

@bolbteppa are you also the dude asking for this on ##physics :p

bolbteppa

Yeah, it's driving me nuts

Seems like a general thing about continuous distributions

i.e. $w_{fi}$ makes no sense

Phase

18:00

Didn't mean to even do that

bolbteppa

If the states were discrete it would make sense

Continuous probability distributions, need to multiply by $dx$ volume elements all the time, zero at any one point etc... it just seems disgusting

haha

vzn

18:13

@Slereah yeah have been looking into that lately, was surprised, new angle for me, found some major connections of fluid dynamics to cosmology (thx semiclassical!), saving up links for next blog on that. btw did you ever look at tenev/ horstemeyer paper?

Slereah

I did not

ACuriousMind

@bolbteppa It's not a transition probability, it's a transition probability density. If $f(x)$ is a probability density then what you need to integrate to get actual probability is $\mathrm{d}P = f(x)\mathrm{d}x$. The $2\pi$ are just annoying factors from some Fourier transforms.

Physics Meta

0

Q: Looking for PDF

I am looking for a PDF file of a physics document for my research which used to be freely available online on the author's website, but the website no longer seems to be working and there are no contact details for the author (as he has retired). Is there a suitable place on here to ask if anyone...

discussion

bolbteppa

vzn

@bolbteppa hey it would be interesting to hear more on this, wonder if there is a ref that focuses on explaining as much of DG as possible from multidimensional calculus pov...? seems like an excellent topic for a speaker session eh? whaddya say? :) physics.meta.stackexchange.com/questions/7783/…

ACuriousMind

18:23

@bolbteppa Basically, yes - the momentum states are not actual states, actual states are wavepackets like $\lvert \psi \rangle = \int f(p)\lvert p\rangle \mathrm{d}p$. So when you compute the probability amplitude for an actual state, you get $\langle \psi_1 \vert \psi_2\rangle = \int f_1(p) f_2(q) \langle q \vert S \vert p\rangle \mathrm{d}^3 q \mathrm{d}^3 p$.

Where $\mathrm{d}A = \langle q \vert S \vert p\rangle \mathrm{d}^3 p \mathrm{d}^3 p$ is the "infinitesimal amplitude" you get from attaching the right differentials to the density $\langle q\vert S \vert p\rangle$.

bolbteppa

@vzn if you mean DG proper then you have Schaums amazon.com/Schaums-Outline-Differential-Geometry/dp/0070379858 and Kreyszig amazon.com/Differential-Geometry-Dover-Books-Mathematics/dp/… and Forsyth archive.org/details/lecturesondiffer00forsuoft if you mean DG with a focus on tensors for GR then Dirac does it in about 15 pages amazon.com/General-Theory-Relativity-M-Dirac/dp/069101146X

basically by treating $4$ space as embedded in higher dimensional space, or you can read this amazon.com/Vector-Tensor-Analysis-Applications-Mathematics/dp/… and do what Dirac does using vector fields including their basis vectors to make things far simpler

@ACuriousMind have you got a reference doing it that way?

vzn

18:41

@bolbteppa thx! have schaum outline on QM, like it. amazon.com/Schaums-Outline-Quantum-Mechanics-Outlines/dp/… plz keep spkr session in mind, am sure others could benefit from your insight into these & other areas :)

ACuriousMind

@bolbteppa Doing what what way?

That certain "amplitudes" are actually densities when "states" of continuous variables are involved is everywhere in QM, just consider that the wavefunction $\langle \psi \vert x \rangle$ is a density too.

bolbteppa

Yeah no nevermind, that makes sense

Very cool, very obvious point I should have seen

eromod

18:59

@ACuriousMind Can I ask you something, please?

ACuriousMind

@eromod Sure

eromod

@ACuriousMind Do electrons have infinite energy? I heard they are like waves sometimes, do the waves slow down eventually or non-stop,infinite?

ACuriousMind

No, nothing has infinite energy

eromod

so if I left an electron in vacuum for a billion years, eventually it would slow down?

all by itself

ACuriousMind

What do you mean by "slow down"? If you put it in a vacuum without anything to interact with, it will remain in the exact same state as you put it in.

eromod

19:06

Oh so waves dont need energy to exist?

Slereah

19:28

"Because Q is Hermitian and its square is zero but Q itself is nonzero, this means the vector space of all states prior to the cohomological reduction has an indefinite norm! This means it is not a Hilbert space."

Hm

I guess that would explain it

vzn

@eromod sounds like concept of "particle decay". there are some more "exotic" theories of particle decay that suspect eg particles thought indefinitely stable like protons may have a decay but "probably not observable/ detectable"... ie much longer than age of universe etc...

Bernardo Meurer

@ACuriousMind My heart is a vacuum

Balarka Sen

rip rip

we have a sadboi here

Bernardo Meurer

@BalarkaSen Yes

I'm a sad boi

I'm on level 5 sadness right now

It's the level where you sit on the corner of your room on the floor in fetal position reading tarski

Balarka Sen

That's actually really heart wrenching

Bernardo Meurer

19:42

Level 6 is where I typeset analysis problems listening to death grips

Balarka Sen

As the kids say nowadays, "Cool story bro"

Bernardo Meurer

(That's where that exercise list came from)

Balarka Sen

Some of the problems there are p dope

Bernardo Meurer

@BalarkaSen You might enjoy this science4all.org/article/homotopy-type-theory

I know right? I really like that list

It can train you both in the hand-wavy part with those shitty limits and derivatives

and the conceptual part with some of the integrals and the proofs

@0celo7 If I double major in maths is it the ultimate proof that U.S. higher education is entirely broken and is now meaningless?

Given that I can't even do division

Avantgarde

@BalarkaSen youtu.be/p8C-J-Yudy8

Balarka Sen

19:48

@BernardoMeurer Nice article!!

I have to read this in full

Bernardo Meurer

It's really dope, I stopped halfway through

math.wisc.edu/~miller/old/m771-10/kunen770.pdf

cs.unibo.it/~dallago/FICQRA/esslli.pdf

These two are in line too

Balarka Sen

@Avantgarde My headphones are lost but interesting visuals

@Bernardo damn dawg you're really going down the logic rabbithole aren't you

Avantgarde

@BalarkaSen You missed the best part then :(

dmckee

@eromod You seem to misunderstand what energy. Waves carry energy. Moving particle carry energy. Neither consumes or loses energy without interaction.

Bernardo Meurer

@BalarkaSen Yeah, I quite like this stuff tbh

I had a blast reading Tarski

I want to get Lemmon but I don't have $$

dmckee

19:53

Living on the surface of a planet messes up peoples intuition for physics because frictional forces are ubiquitous.

So you come to an understand that things tend to "slow down" if left to themselves when what they really do is slow down relative things they are rubbing against.

Balarka Sen

When life gives you Lemmon, you have no $$ to buy it

dmckee

But you have posited something that is rubbing against nothing.

Bernardo Meurer

Lol

Actually it's Mates I really want

amazon.com/dp/019501491X/…

Balarka Sen

Damn the definition for the type of integers is really involved

This is beautiful

The next section is where the fun is at!

0celo7

Fuck my metabolism is too good

I’m falling asleep on 3 cups of coffee and a monster

Balarka Sen

20:01

Don't toot your own horn. It's rude.

parvin

on a capacitor connected to a battery, how can one plate indicate charge to the other plate while there is an insulator in between?

0celo7

@BalarkaSen I need some cocaine. Please help

parvin

@BernardoMeurer Is it useful for computer science students too?

the book i mean

0celo7

@BernardoMeurer Rebecca is getting a math degree that’s a complete joke

parvin

good for Rebecca

Bernardo Meurer

20:04

@parvin Who are you? And not really

@0celo7 Lol, mean, but true

@BalarkaSen That article is the shit :)

Balarka Sen

I'm done reading. Good article.

parvin

does any one know about capacitor?!

on a capacitor connected to a battery, how can one plate indicate charge to the other plate while there is an insulator in between?

Balarka Sen

Proofs = paths, proofs between proofs = homotopy of paths, Voevodsky = good man, rest in peace

Bernardo Meurer

Lol

@parvin Look, to solve any electronics problem just lick the circuit. if you die, the solution doesn't matter, if you don't, you're not studying interesting circuits

Balarka Sen

Brilliant

Bernardo Meurer

20:17

@BalarkaSen Only you appeciate my art

Captain Bohemian

20:46

@Slereah is BRST quantization used in loop quantum gravity, which is a gauge theory?

Slereah

Probably???

CooperCape

21:07

Yo

parvin

21:22

@BernardoMeurer wut?!

dmckee

21:54

@JohnRennie @KyleKanos The OP of physics.stackexchange.com/questions/378401/… seems to be serious about getting to the conceptual heart and has made a serious effort to edit to that effect. Care to take another look?

Physics Meta

22:44

-1

Q: Purpose of homework tag?

Recently I saw many homework posts rejected. I don’t think I’ve ever seen a decently upvoted homework question. Why is this so? Perhaps it is better to remove the homework tag altogether?

discussion tags homework

0celo7

23:21

@BernardoMeurer I’ve always been a big fan of the suicide solution for everything

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