The h Bar

Mr. Feynman

00:10

I don't know the book

00:24

@Amit That is only half the equations, and the paper you cited here, specifically said that this half is compatible with Galilean relativity. It just states that there are no magnetic monopoles

@Mr.Feynman why?

@Mr.Feynman That is actually not too bad. The reason is because if we really wanted to prove the maths rigorously, we could just go and look at the maths texts on each subject matter. The point of maths for physicists is to try to bridge the chasm, to give physicists the tools to phrase physics questions mathematically so that the maths people can answer them.

@Mr.Feynman Basically everybody who is great at it talks about it as a trainable skill.

Harshdeep Chhabra

05:10

what is the difference between band structure diagram and atomic orbital (or MO Theory) diagrams?

Slereah

09:14

"Dicke was also concerned about the poorly defined gravitational perturbation, caused by the observer himself. This potential source of error was well known to Eötvös. While the vibrations of the torsion pendulum were damped, the observer was far away. When the balance had come to rest, the observer came running and made the reading, before the pendulum (of period of 40 minutes) had time to swing out "

PM 2Ring

It's a lot easier if you have a video camera. John Walker of AutoCAD fame did a nice relatively low-tech version a quarter of a century ago: Bending Spacetime in the Basement

Slereah

I dunno, apparently there are giant spiders there

Ryder Rude

10:22

Will physics theories ever connect to panpsychism stuff

Some founders of QM said back then that QM supports panpsychism stuff, but since then, this belief has mostly gone away

even they backtracked on these beliefs. Like Wigner, Schrodinger, Planck. Wigner is known to backtrack

Slereah

10:50

Yes I am currently communicating with the spiritual planes for some research

Ryder Rude

12:23

Wigner, Schrodinger and Planck thought QM implied a subject-object divide in physics. But Bohr thought QM implied a classical-quantum divide.

And then Everett, De Broglie, Einstein and Bohm thought of no divide in physics, but using different theories

The greatest physicists are so much divided on the ontology of universe

Slereah

12:49

Souriau denotes the tangent of a map by $\phi^D$

bolbteppa

Einstein had no theory, the others set up 'theories' which don't make sense

Slereah

Einstein very much had theories

They were just so bad that we don't talk about them anymore

bolbteppa

What was his theory for QM

Slereah

The overdetermination theory

einsteinpapers.press.princeton.edu/vol14-trans/193

bolbteppa

4

Q: Einstein's overdetermination theory

In 1923 [1], Einstein proposed an idea for a classical theory that would explain some features of quantum mechanics, via the overdetermination of the EoM, so that only certain configurations would be available as initial values. He did not expand much on the idea or offered much in the way of exa...

Mr. Feynman

12:53

@naturallyInconsistent They're not useless or wrong, just not my cup of tea. I prefer to learn the Math I need rigorously. Not at the highest level possible, more like at a Math graduate level

bolbteppa

1923

Slereah

@bolbteppa that's me baby

bolbteppa

The guy basically discovered semiclassical QED which full QED reduces to, he is tarnished with the full rot of QM he just didn't like it

Mad

Whos here familiar with Solid state phyiscs?

what is meant with "A" Exciton and "B" exciton. Band edge exciton?

Slereah

yeah like people don't talk about the 30 years he spent on weird unified theories

Mad

12:56

i cant find decent material on it

Mr. Feynman

@naturallyInconsistent I'm a little "fatalist" over this matter. It sounds to me like an athlete saying that everyone can be the world champion with enough training. I think that altough commitment plays a decisive role, talent is also required to pursue high level research proficiently

Or even just difficult topic that are not research

bolbteppa

@Slereah Yeah but that's all classical, nobody talks about this 1923 thing apparently not even him after it

Slereah

It did not catch on

I assume he exclaimed ACH NEIN after realizing it

what was I thinking

Mr. Feynman

In other words, I don't think that anyone has the potential to make a breakthrough in Physics, Math or science in general. That sounds more like a nice fairy tale imo

Slereah

his paper doesn't even really give a toy model for why that would even be true

Mr. Feynman

13:00

So, to finally answer your question, I think that intuition can be trained but only up the individual's "limit"

bolbteppa

If you click footnote 4 it looks like he had doubts about the whole idea

Slereah

He was Einstein in the 20's, I think people just let him publish basically any hunch he had

I don't know why people think classical mechanics is easy, that shit is insane

ACuriousMind

@Mr.Feynman What does "potential" mean here?

bolbteppa

Sounds like his idea is: electrons around the nucleus are found most likely in orbitals, i.e. their initial position appears to be constrained, and Maxwell's theory is basically Maxwell equations and the Lorentz force law where the Lorentz Force Law describes the path of a particle which now seems inconsistent while Maxwell seems okay, so maybe Maxwell along with additional conditions constraining the initial conditions might be the 'real' theory

This was 2-3 years before Schrodinger's papers

Mad

https://chat.stackexchange.com/transcript/message/63779018#63779018
?

Ryder Rude

13:14

@Mr.Feynman on the flip side, pretty much everyone can understand already discovered theories. This is a great feature of physics. Pure math can get too hard to even understand

bolbteppa

'Pais quotes in his book a sentence of Einstein praising in 1926 two Schrödinger's papers on quantum rules, and he adds : "It was the last time he would write approvingly about quantum mechanics."13 Actually this is not true, for Einstein wrote on many occasions positive statements about quantum mechanics.'

'In his "Autobiographical notes", written in 1946, published in 1949, he refers to it as "the most successful physical theory of our period, viz., the statistical quantum theory which, about twenty-five years ago, took on a consistent logical form (Schrödinger, Heisenberg, Dirac, Born). This is the only theory at present which permits a unitary grasp of experiences concerning the quantum character of micro-mechanical events"'

'And again, in 1953 : "I have no doubt that the present quantum theory (or better, "quantum mechanics") is the most perfect theory compatible with experience, in so far as one bases the description on the concepts of material point and potential energy as elementary concepts17"'

He clearly wrote off his overdetermined theory

Ryder Rude

@Mr.Feynman I mean math is extremely technical and precise. One wud need like years of training to follow Godel's proof of his theorem. Same cant be said for physics where u can learn GR as an undergraduate.

I think this is a great feature of physics. It does not go extremely deep like pure math

Slereah

Souriau's book is from 1997 and his notation looks like he's never seen differential geometry before

what was that guy up to

bolbteppa

currentscience.ac.in/Volumes/89/12/2035.pdf

Pages 2-3 of that seem very relevant

Ryder Rude

I think the subject-object divide school is the simplest way to make sense of QM, as we know it. This is followed by classical-quantum divide, followed by MWI, followed by Hidden variables

But simplest doesnt mean correct

The key point is "QM, as we know it"

The subject-object divide school does not modify QM postulates in the slightest

But our postulates of QM would probably change. The classical-quantum divide is the most promising in that direction

bolbteppa

13:28

From page 4 it sounds like Einstein would have become a string theorist

As well as the Kaluza-Klein discussion on 3

Slereah

probably not, Einstein didn't like objects of low dimensions

He thought that matter should be continuous

Mr. Feynman

Again, I didn't say that someone "talented" (quotation marks here because I shall expand on this to reply to ACM above) can go through it without effort. Commitment is fundamental in any case.

Regarding the second part, I think that Physics can be even terribly complicated at times and the GR example doesn't work well, because in an undergraduate course you'll only learn the basics of the basics of GR (not that graduate courses cover that much)

@RyderRude How can you say that pretty much everyone can understand discovered theories? What makes you thinking that understanding a given topic in pure Math is tougher than e.g. understanding GR?

Ryder Rude

@Mr.Feynman I mean the cutting edge theories in physics are not out of reach of everyday people. This is in contrast with pure math where only like 100 people in the world can follow the proof of Fermat's last theorem, that too after a decade of training. Math runs extremely deep.

Mr. Feynman

Just because I can remember the basic ideas of a physical theory that does not imply I understand it

Ryder Rude

Same goes for Godel's original proof

@Mr.Feynman i still think that math goes way deeper. Becuz the math of physics is a subset of pure math. Pure math has extremely obscure theorems that u wont find in physics

Mr. Feynman

13:35

So you're saying that anyone without a scientific education can understand e.g. quantum field theory?

I beg to differ

Ryder Rude

@Mr.Feynman i think anyone can learn QFT from the internet.

It would require 5 years of dedication i guess

Mr. Feynman

(I didn't say an "official" education, though)

Ryder Rude

But intelligence is not a restraint in learning physics. This is my main point @Mr.Feynman

Mr. Feynman

Dedicating 5 years is not being uneducated

It's self education

Ryder Rude

I only mean that intelligence and talent and prodigi-nes is not a restraint in learning physics. U of course need education and time and commitment

But talent can be a restraint in learning advanced math

Do u agree

Mr. Feynman

13:39

I completely disagree. I think that advanced Physics can be as challenging as Math

Ryder Rude

So do u think that learning both are within the reach of everyday people, or do u think that both are out of reach of everyday people? This is assuming commitment and dedication from the everyday person @Mr.Feynman

Mr. Feynman

@ACuriousMind I don't know how to phrase this in a way that is really correct, so let me call it something like "sheer intelligence"

@RyderRude I think that neither is within the reach of (scientifically) uneducated "everyday people"

And certain things might be so difficult to be out of the reach even for someone who has an education in the field

@RyderRude To be clear, when you say "everyday people", do you mean people outside of science or people not particurarly talented in the field?

@RyderRude If you mean the latter, then my opinion is that the "everyday person", even with commitment and dedication (and an education), won't be able to pursue a proficient academic career

ACuriousMind

@Mr.Feynman both the general concept of "intelligence" and its heredity (i.e. to which extent it is determined by nature and not nurture) are still rather controversial

Mr. Feynman

Sure, that's why I used quotation marks and stressed that this is my opinion for the time being

My guess, if you want

ACuriousMind

blank-slate behaviorism that believes it's 100% nurture is largely sidelined, but I don't think we have good evidence to say anything else

Mr. Feynman

13:49

Might be, the human brain is terribly complicated

On the other hand, I think that at least the position according to which there exists some kind of natural intelligence is not unreasonable if we go by analogy with other human features that do depend on the genetic inheritance

Amit

Restraint is an interesting word @RyderRude, you mean hurdle? People get on all kinds of what I like to call "thought icebergs" that interfere with their progress... Einstein is perhaps a classic example

Secret

Some thoughts about the measurement problem
Why don't *experimentally*, repeated measurements of the same kind give different outcomes?

Probably the biggest mystery of quantum mechanics...
though if they do the maths will get very hard, imagine $[A,A] \neq 0$...

ACuriousMind

@Mr.Feynman I think arguing about the heritability of intelligence is somewhat of a distraction: In order to argue about heritability of a trait, we'd first have to really be sure what trait we're talking about. There's lots of people who earn a reputation for being very smart in one field and then say lots of rather stupid things in other fields.

Amit

@Secret the standard answer is that the first measurement "collapses" the state to some pure one, no?

I mean pure wrt observed basis

Secret

hmm... but if you let it then evolve a bit and then measure it again the same way, you still get the same result. That "stickiness to evolution" is probably the strange bit

Amit

14:00

"A bit" needs to be less than quite a bit :) you know what I mean..

Secret

e.g. measure a spin along z and then x give different result from x then z
But measuring a spin along z, then wait a bit, and then measure along z again, gives +1 for both measurments

Ryder Rude

@Mr.Feynman but do u think that wud be because of intelligence restraints? Or something else?

@Amit i mean stuff like "not being a prodigy". Then no amount of effort can get u to that level. So it is a limitation

Amit

@Secret Yes, but if you wait long enough or alternatively don't control the environment, even a short time will change the outcome

ACuriousMind

@Secret that's because in typical setups you don't have a time evolution that does anything to the particle after you measured it

Mr. Feynman

@ACuriousMind regarding the last sentence, that is ignorance more than stupidity

ACuriousMind

14:03

if the particle after measurement isn't free but subject to some Hamiltonian that rotates the state, even short times might change the state again significantly

Amit

@RyderRude To what level?? I am of the opinion that for accomplishments one needs a lot more work than talent

Secret

I see

Amit

Sorry i'll put it another way: the greatest talent is an endless love for a subject!

ACuriousMind

that very frequent measurement (compared to the scales of the relevant time evolution) can effectively "freeze" a state is not a mystery, nor does it have anything to do with the measurement problem. It's called the quantum Zeno effect

Ryder Rude

@Amit you can never be at the absolute top 100 in a field without being a prodigy. Prodigy+effort= top 100. Neither can be absent

Mr. Feynman

14:05

But yes, what I'm talking about is not some universal property (and here we go with categories :P), rather an inclination towards some specific field. So in that sense it's not generic intelligence we're talking about (which I wouldn't even know how to define)

Amit

@RyderRude I postulate even prodigy qualities come from attraction to a subject

ACuriousMind

@Mr.Feynman I find it hard to believe that anyone should have a specific genetic aptitude towards e.g. physics, given that physics did not exist for most of our evolutionary history

Mr. Feynman

@RyderRude Yes, that is my opinion on the matter

Ryder Rude

@Amit extreme attraction + superhuman brain muslces= prodigy. This shud b non controversial :P

Amit

What made Feynman's wife complain that he solves integrals in his head all the time?? 🤣

bolbteppa

14:07

@Amit going down a dark road if this is a serious question :p

Mr. Feynman

@ACuriousMind well, not for something specific but there are traits distinguishing one field from the other being more logical, artistic or whatever

Ryder Rude

@Mr.Feynman i mostly agree, but i just think physics is relatively more in reach for the everyday person. Not that they can ever become experts. But relative to math stuff, they can get to a more satisfactory level in physics

Amit

@RyderRude I am adding an explanation for the prodigy that you don't. I say attraction from a young age to a subject + encouragement of environment and freedom to pursue it, can make one a prodigy

@bolbteppa lol 🤣 no I meant it in the best way, just his endless love for that stuff

Ryder Rude

@Mr.Feynman But not that they can contribute much or do breakthroughs

U need to be a prodigy to do that

I think if someone can learn programming or a new language as a hobby, physics learning is of comparable difficulty

Mr. Feynman

@RyderRude in that case it's just that in Math you need to learn things more methodically and you can't skip stuff

ACuriousMind

14:10

@RyderRude It is very much controversial. The core problem - once again - is that what people believe about the nature of intelligence is not some value-neutral statement of fact, but beliefs about the nature of intelligence have a long history of being crucial elements of social and moral prescriptions (cf. e.g. scentific racism, eugenics, etc.)

Mr. Feynman

@RyderRude I never said they couldn't contribute. I only talked about breakthroughs

Ryder Rude

@Mr.Feynman yes. For breakthroughs, u r right 100%. This is y i made a distinction between contributing and simply learning in my first reply

Mr. Feynman

To dumb my words down: not everyone can be a Dirac or Einstein or Feynman or Landau or whatever

Amit

I think it's quite unfair that someone had for example horrible math and physics teachers all through school and highschool, and then he meets someone that shows him the beauty of the subject say.. but by that time he also has all this bad baggage from school and he thinks "meh i just have no talent for this stuff" , see what i mean @RyderRude?

Mr. Feynman

Which isn't bad per se, I'm just stating my idea

Ryder Rude

14:11

@Mr.Feynman But ur initial comment was only about breakthroughs, yes

Mr. Feynman

Yes

Ryder Rude

@ACuriousMind but y is it controversial to say that someone can have superhuman brain muscles required for physics? People can hve sueprhuman heights or weights, etc. This is non controversial

WaveInPlace

Physics isn't a one-action business.

Ryder Rude

And muscle growth depends on genes

WaveInPlace

Sure, someone can be really good at a single task. That doesn't necessarily translate to being good at an entire discipline.

Amit

14:15

@WaveInPlace word! Look at Faraday... he had fantastic ideas that reverberate in modern physics still, yet very little mathematical capacity (owing to his background mainly)

ACuriousMind

@RyderRude it's funny you should say that because for most of human history height was not so much determined by your genetics but by how malnourished you grew up

Europeans today grow 11 cm taller, on average, than they did in ~1900, this is almost certainly not a genetic effect

WaveInPlace

The whole prodigy thing feels like it puts Einstein, Feynmann and the rest on a pedestal. They weren't successful because of their brilliant math, but because of their insights.

Slereah

@ACuriousMind I have an alternative theory

Potsdam Giants

The Potsdam Giants was the name given to Prussian infantry regiment No 6. The regiment was composed of taller-than-average soldiers, and was founded in 1675. It was eventually dissolved in 1806, after the Prussians were defeated by Napoleon. Throughout the reign of the Prussian king Friedrich Wilhelm I of Prussia (1688–1740), the unit was known as the "Potsdamer Riesengarde" ("giant guard of Potsdam") in German, but the Prussian population quickly nicknamed them the Lange Kerls ("long fellows"). == Regiment's history == The Regiment was founded with a strength of two battalions in 1675 a...

Giant invasion

Amit

Feynman and Einstein despised pedestals

Ryder Rude

Then lets just say prodigy = genes + non-malnutrition in the growing age + attraction to a subject + hard work

Only two of these things r in ur full control @ACuriousMind

Slereah

14:19

Careful I think @RyderRude is trying to get eugenics started again

ACuriousMind

so if even for such a simple case as height heritability is not as straightforward as you'd think, what makes you so certain the variation in "intelligence" we see is due to inborn differences and not other factors?

WaveInPlace

Prodigies are for musicians and chess grandmasters.

Amit

You forget luck :)

WaveInPlace

Science is for the creative.

Ryder Rude

U can be attracted to a subject and do hard work. U cant reverse malnutrition in ur growth days when u r out of ur growth days

And u cant control genes except for gene editing

Which is new tech

ACuriousMind

14:20

@RyderRude Yes, but you have no idea which proportion each of these factors have, nor can you exclude other factors (for instance, how many people credit their first school teachers in a subject for instilling them with their love for that subject)

@Slereah lol

Amit

Ew genics

Maybe the genes determine in what each one is a prodigy. And it's just that at different times in different societies different types of prodigies are appreciated? Lol, I think it's a ridiculous proposal but it would make this gene business at least democratic :)

Ryder Rude

Ur idea is close to natural selection. There is no objective way to define "good traits". It depends on environment @Amit

Maybe some environments favor being dumb

For e.g. take dinosaurs

Lived for 60 mil years

Amit

Lol, that's why I said, it's grotesque / ridiculous

Ryder Rude

We got brains but we may blow ourselves up soon

Amit

I mean grotesque to think some people genes are just better at being dumb 🤣🤣

Human beings are very flexible creatures

Ryder Rude

14:30

It is hypothesized that intelligence leads 2 the demise of civilisations

Which is y there r no inter galactic aliens

They all blew themselves up

Amit

Maybe something better will come in its place

Our world lines are too short to know

Ryder Rude

There is a nice video about this

Amit

And only nature is creative

Encouraged yet?? 🥳

Ryder Rude

What Do Alien Civilizations Look Like? The Kardashev Scale

►

I wonder if a civilisation can be called successful based on its logetivity or numbers. Based on this, dinosaurs, ants and cockroaches r more successful than humans

Or maybe there is no notion of defining success

Becuz success implies purpose or meaning. Evolution has none

Amit

But maybe you need the total spacetime volume not just time? :)

Ryder Rude

14:38

Yes. Then ants r very successful

Lol

Amit

Some big fish are old timers too, no?

Crocs maybe?

Ryder Rude

Maybe evolution's purpose is to get a high consciousness level

Based on this, humans r most successful

@Amit they dont hav numbers. And they r not very dominant

High consciousness also means no other species gets to boss you

So this can be a measure of success

Humans can boss crocs

Amit

Who bosses the bacteria??

Ryder Rude

But they r barely even enjoying life

High consciousness means u can enjoy :)

Amit

You know the theory that wheat domesticated us right? Lol

Ryder Rude

14:40

Bacteria is just vibing

@Amit lol

Also, pandas did too, i guess

And they seem to be enjoying more than humans

Pandas may be the most successful creatures using this metric

Pretty much no one bosses them, and they enjoy a lot

This is ironic becuz pandas r usually called a failed species using another metric

Mr. Feynman

@Slereah You know, I've recently got interested in Halo again. We could make some Physics Spartan project...

Slereah

I have never played Halo

Not really my bag

Ryder Rude

@Mr.Feynman does hallow allow for earth life level manipulation?

Sorry, Halo seems to be some shooting game

I thought it was that universe simulator

@bolbteppa In the quantum-classical divide school, which objects are classified as classical and which as quantum?

bolbteppa

A measuring apparatus is classical, everything else is quantum

Ryder Rude

14:56

Oh

bolbteppa

Then classical physics emerges for everything the less accurately you measure

Ryder Rude

So do we just go by the effective everyday definition of a measurement apparatus, or is it made precise in the mathematical ontology of the classical-quantum divide universe that which objects are perfectly classical?

@bolbteppa

Mr. Feynman

@WaveInPlace First, Feynman is spelled with a single "n". Secondly, brilliant math? What would Einstein's brilliant math be? Differential geometry was developed earlier than GR by mathematicians. It's precisely understanding how to describe the world using that Math that made him great, not the math itself. It is that insight that I call Einstein (et al.) a genius

Now, I might be wrong about the word genius, which is controversial as we've discussed above but I want to stress that no one at all thinks those were outstanding physicists because of mathematical abilities

bolbteppa

A measuring device is an object which is described via a wave function in the semi-classical approximation, the stationary states are all semi-classical wave functions, and the wave function is always known to be one of the specific stationary states

You just assume objects like this exist or we have no theory, they exist because we know classical mechanics exists as a theory the less accurately we measure

QM is inherently tied to the existence of classical mechanics to which it must reduce to in some to-be-defined limit, it's unavoidable (despite what people want)

In other words, the wave function of it is always of the form $\psi \approx e^{iS/\hbar}$, where we directly see the existence of a classical action determining the wave function

bolbteppa

15:14

When you measure a system with wave function $\psi(x)$, before the measuring device (with measuring device wave function $\phi_0(y)$) interacts the total wave function in $\psi(x) \phi_0(y)$, after they interact you get some mess $\Psi(x,y)$, but you can Fouier expand it in the measuring device spectrum $\Psi(x,y) = \sum_n c_n(x) \phi_n(y)$, but we know after the measurement the device has to be in one stationary state (existence of CM)

so really we get $\Psi(x,y) = c_m(x) \phi_m(y)$, the $c_m(x)$ is related to the wave function of the system after the measurement, i.e. the state of the system is affected by the measurement which alters the system you measure. The fact the state changed is because they interacted. Notice 'collapse' is nowhere to be found. Notice the whole thing was described by a 'universal wave function' which MWI completely misunderstands

Technically the whole process could be described by a Schrodinger equation with some unknown Hamiltonian, but to determine all this we'd need to measure this whole system with another measuring device and so we start to go in circles

Really, the math was formalized to fit the randomness of what is found physically, you'll never find anything deep in the formalism it's all determined by the simple fact that we can't measure paths and adapt the math to this

Ryder Rude

@bolbteppa i hav a few doubts. 1. To be clear, here we are advocating the existence of perfect classical objects, and not just almost classical objects that QM can derive, right? 2. The wavefunctions of these perfect classical objects cannot evolve according to Schrodinger eqn becuz these wavefunctions can never be in a superposition of the preferred basis of measurement

3. How do we determine which classical objects IRL r described by these perfectly classical wavefunctions? @bolbteppa

WaveInPlace

15:31

@Mr.Feynman, that was my point. Those two made a major mark because of their ideas, not their mathematical skills.

bolbteppa

16:05

Have a think about it

Note I said the whole thing was describable by a Schrodinger equation

Ryder Rude

@bolbteppa I didn't understand this part : "*but we know after the measurement the device has to be in one stationary state (existence of CM)
so really we get $\Psi(x,y) = c_m(x) \phi_m(y)$, the $c_m(x)$ is related to the wave function of the system after the measurement*". This is modifying Schrodinger evolution becuz Schrodinger evolution gave u $\Psi(x,y) = \sum_n c_n(x) \phi_n(y)$

It seems like we are postulating the existence of perfectly classical objects which can never go into a superposition, so they also dont obey Schrodinger eqn

Relativisticcucumber

16:53

@RyderRude evolution doesn't have a purpose -- it's inherently stochastic. & your comments above regarding genetics are also just wrong. this is the essence of the entire nature/nurture debate, and there is substantial evidence to show that nurture/environment is just as important as genes because gene-environment interactions determine how traits manifest, the extent to which genes are activated, and overall controls the progression of development.

i think it's a bit outdated to have the aforementioned ideas about the role of genes in one's complex cognitive functions and abilities and harmful to society to propagate these types of beliefs.

Slereah

17:05

Apparently part of the whole "mass is a cohomology class in classical mechanics but not in relativity" relates to how the sum of systems of a certain mass has a total mass of their sum, but this is not true for relativity

ie two photons can have a mass together

Ryder Rude

17:28

@Relativisticcucumber ok but i did also say that evolution doesnt have a purpose a few comments before. The "higher consciousness" stuff was just me trying to find a purpose in it. But u r right.

@Slereah oh. So it's about the mass of the binding energy. But y is this related to cohomology?

Slereah

It is not.

two photons are not bound

that's because the center of mass isn't a Noether current in the relativistic setting

Ryder Rude

E=mc2 is true in relativity regardless of whether or not we consider composiste systems becuz of the free single particle relation $E^2-p^2=m^2$

But E=mc2 does get more interesting when we consider composite systems

Amit

17:53

@Mr.Feynman The funniest quote I know of in this regard "Grossmann, you must help me, or else I’ll go crazy!"

Slereah

@Amit I relate

Amit

@Slereah Maybe you also need a mathematical advisor? :D

Slereah

I usually just use @ACuriousMind

Amit

ahah, makes sense

Mr. Feynman

@WaveInPlace Again, when did anyone in this discussion say they did because of mathematical prowess? When people call them geniuses they are talking about their ideas

@Slereah best AI on the market tbh

Ryder Rude

18:03

Einstein was crazy good at math too

His ideas still stood out more. People better than him at math cudnt come up with those ideas.

ACuriousMind

@Mr.Feynman just wait until I start charging for API access!

Ryder Rude

Physics breakthrus require 10/10 creativity and 8/10 math skills.

I think

ACuriousMind

@RyderRude You really need to stop just pulling these claims out of thin air

There was enough prior work on similar ideas that it spawned the relativity priority dispute

"great man theory" is an outdated view of history, both political and scientific

Ryder Rude

@ACuriousMind I more meant GR when i said that

ACuriousMind

@RyderRude ...why do you think it's called the Einstein-Hilbert action? Because no one but Einstein came up with it, right?

Ryder Rude

18:13

But u r right. I also dont believe in "one person changed the history" narrative. It is compeltely false

@ACuriousMind i have read that story. Actually, Hilbert was reading Einstein's papers for years leading upto his final paper

ACuriousMind

for someone who doesn't believe in it you're saying a lot of stuff that sounds as if you believe it :P

Ryder Rude

When Hilbert published, Einstein had already worked out pretty much everything and released it

He was just a bit late in releasing the action

I think he was late by 3 days

@ACuriousMind i really dont believe it one bit :P. There is no one who turns the world around in a day

Slereah

@ACuriousMind According to Some Fellow, the kinetic term of the Lagrangian relates to the presymplectic potential

Do you happen to know how

ACuriousMind

18:28

nope

Slereah

Mysterious

Ryder Rude

In GR, we cant always choose the co ordinates to make the metric globally minkowski. But in symplectic geometry, can we always choose co-ordinates to make the symplectic form globally the simple one?

Silly Goose

are quotient groups important concepts for physics; particularly quantum mech?

i saw that they are used in rep theory but it seems only in intermediary steps when one is processing a representation into irreps

Slereah

18:44

Sure

Plenty of groups are quotient groups

Rotation group is the quotient of the spin group

Lorentz group is the quotient of the Poincaré group by translations

etc etc

wait is that true I'm not sure

Silly Goose

hm i guess i don't know what the action of quotient groups looks like

because that makes it sound like you treat a group modded out by a normal subgroup as just ignoring the normal subgroup when acting with the group

but then it is simpler at least in the poincare case to say we act with the homogenous lorentz subgroup of the poincare group

Mr. Feynman

@ACuriousMind I expect some premium subscription for regular users :P

Silly Goose

the highest tier of subscription allows one question about qm interpretations every 7 years

ACuriousMind

@SillyGoose note that, in general, you do not have that $G/H$ is a subgroup of the original $G$

Slereah

It is sometimes not a group at all

Silly Goose

18:55

:0

not a group bc the operations are not well defined? or other reason?

ACuriousMind

it happens in the Poincaré/Lorentz example because the Poincaré group is a semi-direct product $\mathrm{SO}(1,3)\rtimes \mathbb{R}^n$ and when you quotient out one factor out of a product you get the other factor

@Slereah of course the quotient of groups by normal subgroups is a group

that's why we require the subgroup to be normal

Slereah

Well you didn't specify a normal subgroup :p

Silly Goose

oh sorry i meant normal subgroup

ACuriousMind

4 mins ago, by Silly Goose

because that makes it sound like you treat a group modded out by a normal subgroup as just ignoring the normal subgroup when acting with the group

they did

Silly Goose

i thought quotient group wouldn't mean anything if you didnt mod out by normal sub group

Slereah

18:57

The past does not exist

Silly Goose

bc the normal condition implies the group operations are well defined

er is necessary

@Slereah is this the Spin group which si the double cover of $SO(3)$?

Slereah

Yes

Conversely so(3) is the quotient of the spin group

ACuriousMind

To (not) answer the original question: I feel like asking whether "quotient groups" are relevant in physics is a question like where "subtraction" is relevant in physics :P

quotients are simply an elementary operation you can have in the math, you can't really seperate it from the rest of group theory

Silly Goose

what does one mod out by in that case? it seems like one would want to mod out in such a way to collapse the two elements in Spin to the one element it corresponds to in SO(3)

ACuriousMind

@SillyGoose the center

Slereah

19:01

@ACuriousMind what if you did a direct sum of group by its negative instead

Silly Goose

hm i see i guess i don't see it as much as subtraction but probably because i do not look for it :P; but okay quotient groups it is

ACuriousMind

You have generally that a Lie group $G$ with fundamental group $\pi_1(G)$ has a universal cover $\tilde{G}$ such that the kernel of the covering map $\tilde{G}\to G$ is isomorphic to $\pi_1(G)$ and that kernel is central in $\tilde{G}$

Silly Goose

oh okay i was thinking abt the kernal of the homomorphism between the two but i was trying to see why that would give the desired result

well that is the only normal subgroup i know would definitely exist in this case :P

Mr. Feynman

@SillyGoose I have a feeling that in the next update that topic will be banned

Silly Goose

subscription revoked

is this use of the word cover the topological use

like "open cover"

or i guess it is just a set related notion :P

ACuriousMind

19:06

@SillyGoose it's the topological use of covering space

Mr. Feynman

After some years since I played Halo, I decided to play the MCC

It's time to kill some Covenants

Silly Goose

ohhh okay this is starting to make more sense

so the elements of $\tilde{G}/G$ are the fibers $f_x = \{y \in \tilde{G} : \pi(y) = x\}$ where $x \in G$. which is precisely what we want.

Mr. Feynman

@ACuriousMind Have you ever played Halo?

Silly Goose

well how nice that works out :D

ACuriousMind

@Mr.Feynman I have, but only in local co-op with a friend

Mr. Feynman

19:11

Oh, so you used to be a Spartan

ACuriousMind

Patch notes:
- Removed ability to ask about quantum interpretations due to high cooling costs
- Responses should now contain 10% less snark
- Still looking for the cause of the bug that makes some users experience a ':P' added at the end of every response

2

Amit

lol, this AI generates its own release notes!

Mr. Feynman

@ACuriousMind And like for every update I download in my life, now it's time to complain

Really, I'm an update boomer

When I played R6S it took me weeks to accept they nerfed or buffed operators

Amit

Now not only programmers are in danger, but product managers too

Silly Goose

@Mr.Feynman should operators in quantum mechanics be buffed or nerfed?

Mr. Feynman

19:16

Anti-unitary operators deserve a buff, no one plays them fr

Otoh, unitary operators are too overpowered

Sounds like Wigner's patch didn't work as expected

ACuriousMind

@SillyGoose the identity operator needs to be nerfed. I mean, every vector is an eigenvector? Come on!

Mr. Feynman

We should write a book "QM for gamers"

ACuriousMind

20:39

@Mr.Feynman ...wouldn't it have to be a game and not a book? :P

bolbteppa

21:04

@RyderRude Not modifying anything, the sum was a single term the whole time

Mr. Feynman

21:20

@ACuriousMind I can write, I can't design a game but if you can... :D

ACuriousMind

oh, I could program a game - don't know about designing it, so far all my hobby projects in that direction faltered when I had to actually figure out what the game was going to be like

Amit

There's quantum chess (I was sure I mentioned it here once, but can't find in chat history)

ACuriousMind

in one case I spent a few weeks trying (and failing) to figure out a format for writing branching dialogue that I'd have liked

Mr. Feynman

21:43

@ACuriousMind if the game is heads or tails I can too :P

Anyways, you don't need to see in a game explaining QM. So no design

Slereah

How fun

Obviously one of the character should be Wigner's friend

Mr. Feynman

22:03

@Slereah the human playing is Wigner's friend

The character is the observer in the lab

Slereah

If you want a relativistic game just pick that experiment where some guy runs towards a barn with a giant pole

It sounds like it could be fun

Amit

22:22

Was there an older terminology for what we now call Killing vectors?

Slereah

Mr. Killing is from the 19th century

It's pretty old

Amit

Yes, but am I wrong that older texts don't mention them? Or maybe they were considered too advanced once?

Slereah

I would guess they probably called them infinitesimal isometries

Or something to that effect

4

Q: Who first introduced the notion of Killing vector field?

Does anybody know who that first introduced the notion of Killing vector field? Thanks.

ho.history-overview

Amit

too bad the question doesn't end with "..into GR?" :)

Slereah

I know that people used Killing vectors in GR pretty early on, or at least symmetries

The paper on stationary spacetimes is from like 1917

arxiv.org/pdf/1003.3202.pdf

Mr. Lie talked of infinitesimal transformations

Although presumably in norwegian

Amit

22:39

Okay thanks

Silly Goose

23:54

bloop

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