The h Bar

WillO

02:48

I'm a day late with this, but Andy Capp was extremely popular in the US, and there was a time when comedians, politicians, etc knew it was safe to assume that everyone in the audience knew who he was.

PM 2Ring

06:12

@WillO Interesting! Thanks for that info, Will. I suppose Andy Capp is a pretty good parody of a stereotypical working-class English bloke of the era.

Slereah

08:18

For the purpose of the Book I am looking at the CIA's website's declassified documents because I know they occasionally have hilarious documents related to GR

Slightly terrifying that people this stupid have jobs with so much power

I mean I know that just having people internally writing stupid document doesn't mean they're doing much about it, but still, somewhat worrying

cia.gov/readingroom/docs/CIA-RDP96-00792R000400330013-4.pdf

ACuriousMind

08:34

what's the fourth vertex of that tetrahedron

Slereah

I assume it is to be discovered by a giant grant from the CIA

I'm not an expert in secret projects but apparently there was a whole a whole CIA thing about SCALAR ELECTROMAGNETIC WEAPONS

Which was some panic about the soviets having some kind of secret weapon made of new physics

I'm not sure how big of a thing that was but they wrote a few document on the matter

ACuriousMind

also I can't really find anything about this "japan psychotronics institute" or "inomata shuji" that isn't linked to that CIA document

Slereah

A secret, I assume

ACuriousMind

are you sure this isn't just some psy-op by the CIA :P

Slereah

Or more likely it faded away from history as some random crank most likely would

ACuriousMind

08:39

like, "unclassifying" some completely bonkers documents to make the world think you're incompetent doesn't sound like the most absurd strategy to me

Slereah

I'm kind of trying to look a bit into the history of GR cranks, but it's not as easy as you'd think!

They don't tend to remain long in the popular consciousness

@ACuriousMind I think the mindset of thinking the CIA can't possibly be incompetent or have incompetent employees is much more dangerous!

I don't think overall the spooks involved in it are particularly smart

Sorry if I hurt your feelings, CIA operative monitoring this chat :(

ACuriousMind

@Slereah sure, but you can have both incompentent agents and someone who's clever enough to try to make the world think you're even stupider than you actually are!

Slereah

I mean those people still exist now

You always have some weirdoes working in government organizations publishing stuff like that

Probably too big of an organization to monitor everything published by everyone

The harder part is to try to guess what's important

I don't think those things were ever a particularly big issue because there's only a few documents and mostly written by the same people

ACuriousMind

I guess when you're a large organization there's not a lot of reason not to employ like one guy who looks into all the cranks :P

Slereah

I mean you've worked into companies

Have you always felt like the company is always reactive to your needs when something is wrong

ACuriousMind

08:45

lol

Slereah

I've been waiting for weeks for someone to fix an in company app

The power of Klein Gordon

ACuriousMind

I got a new laptop this week and I've spent 3 days trying to combat the stupid IT management software to allow me to install the stuff I need to actually do my work

Slereah

I do wonder where one could find cranks in like the early 20th century

The earliest GR crank I can think of is Heim

and that was like in the 50's

ACuriousMind

I think the distinction hasn't always been so clear?

you can only tell someone is a "crank" when there's a strong, self-consistent "orthodoxy" that they're in obvious disagreement with

otherwise you just have people making up hypotheses

like, believing in phlogiston today is crackpottery, but a few hundred years back that was an acceptable stab at a theory

Slereah

Yeah but you know

Sometimes you can tell just by looking

I know the nuance between a crank and just someone with an idiosyncratic theory

But sometimes there is no such nuance

Sometimes there are spirits involved

Fadeev-Popov ghosts

ACuriousMind

08:52

@Slereah but the main thing there is the formatting and word choice, right?

because modern science has converged onto a particular way of formatting and phrasing things

Slereah

Well this was the 1930's, people didn't have LaTeX or Words

so it is harder to tell

ACuriousMind

you can't "tell just by looking" when looking at stuff that's a 100 years old because that convergence was weaker back then and you aren't as familiar with the conventions from back then

Slereah

I dunno, I've read my fair share of it :p

But yeah I can't think of that many cranks that are that old and still well-known

But maybe I could find out by looking at the bibliography of other cranks

maybe they maintain their own traditional lineage

IIRC 't Hooft has a list of GR cranks somewhere on his site

Although finding anything on 't Hooft's website is even more challenging than finding top secret documents

webspace.science.uu.nl/~hooft101/…

That's the one

he doesn't name names, though

Oh wait there is one : god-does-not-play-dice.net

chakalov.net/SEM.pdf

Amazing

"Three years ago, a friend of mine asked whether he could learn spacetime engineering without the hassle of learning my “crazy stuff”."

Vixra doesn't even have a search engine

Although I think overall cranks don't like citing even other cranks, for the most part

They are more of the make everything yourself type

One early crackpot idea for relativity seems to have been the theory of autodynamics

imbAF

09:40

In my lecture we were told that , when we say that an equation is not Lorentz covariant, it means that under a LT the left and the right side of the equation transform differently.
Different in what sense? Like they do not equate each other anymore? Or if you try and solve each side, you'll get different results/values, when considering a scenarion?

Slereah

Although I think it is one of those things were a lot of the crank theories claiming ancient roots is like the theory was proposed by serious people in ancient times, but cranks latched onto it recently

nickbros123

10:12

Is real analysis ever useful in physics? One of my physics prof said its not but it's one of my vices ig, it's extremely fun to study

Slereah

Depends what you mean by real analysis I guess

Obviously plenty of physics is real analysis

nickbros123

@Slereah there's only one kind, no? The one in Rudin principles of mathematical analysis?

ACuriousMind

what

Slereah

Some people will differentiate real analysis from say calculus

even though that is just part of real analysis

nickbros123

To be clear, In my earlier message I was talking about the real analysis found in rudin and other textbooks. I know that calculus is widely applicable in physics every nook and cranny

Slereah

10:27

More complex theorems of real analysis are often used in physics yes

I don't know if your professor would qualify it as "real physics" whatever that means but they certainly do

ACuriousMind

unless you're looking at a different Rudin than I am it's also just differentiation and integration?

physics certainly uses stuff like Stokes' theorem

Slereah

People do estimates on bounds of differential equations, they have to work out if solutions exist, the stability of solutions, etc

Not really my area of expertise but that is a thing

Ryder Rude

10:44

@PM2Ring it has great vibes

@PM2Ring great lyrics. all of them can sing well

Ryder Rude

10:59

@PM2Ring i had never heard of sequence accerelators. it is a very cool idea

en.m.wikipedia.org/wiki/Series_acceleration

@PM2Ring i dont know programming myself. it seems like u r very experienced with approximations

@Slereah Tesla was also a crank about relativity

He said that it was wrong

Slereah

That he was, but mostly the very boring reactionary kind

Ryder Rude

yes

In some sense, "illusions" also exist because we wouldnt be talking about them if they didnt exist. they are real to the observer. this causes the problem of classifying different types of existence

illusions just dont exist in the same sense that the objective reality exists. the mathematical universe resolves these issues. it defines mathematical state of the universe give by physics as the "objective universe" that exists

in the mathematical universe, illusions can be traced back to bits in the brain of the observer. that is their entire existence. now u may ask "dont other things too exist as bits in the mind"?

yes, but the other bits in the mind have a source in the objective mathematical universe. the illusion is sourceless. it is a bit in the brain that is a misleading representation of the objective universe

but it is a bit that nevertheless exists

bolbteppa

12:16

Today is Green function day

Sanjana

13:14

In the arguably the most well known proof of the identity $\nabla^2 1/r=4\pi \delta(r)$ we invoke the divergence theorem at some stage to get the $4\pi$...How is the use of the theorem justified when the vector on which it is applied does not have a continuous derivative at $r=0$?

I know a more satisfying alternative proof which is basically regularizing the singularity and killing the cutoff at the end of the calculation, but how is that particular derivation justified?

ACuriousMind

it isn't :P

Sanjana

:(

Slereah

I think if you want to bother using Stoke's theorem for distributions you'll have to delve into the theory of currents

which is not a lot of fun

Sanjana

@Slereah heard 'bout it the first time :o

Slereah

The theory of currents has the misfortune of having a name that's pretty hard to search for without getting other results

Current (mathematics)

In mathematics, more particularly in functional analysis, differential topology, and geometric measure theory, a k-current in the sense of Georges de Rham is a functional on the space of compactly supported differential k-forms, on a smooth manifold M. Currents formally behave like Schwartz distributions on a space of differential forms, but in a geometric setting, they can represent integration over a submanifold, generalizing the Dirac delta function, or more generally even directional derivatives of delta functions (multipoles) spread out along subsets of M. == Definition == Let...

Sanjana

13:23

Nice

.btw... Is Dirac Delta function the only distribution which satisfies the sifting property $\int dx f(x)\delta(x-a)=f(a)$?

I mean if I have $\int dx f(x) g(x-a)=f(a)$ then is $g(x)=\delta(x)$ guaranteed?

ACuriousMind

formally that integral doesn't really mean anything

A distribution is defined as something that assigns numbers to functions

so $\delta$ as a distribution is simply defined by the rule $\delta[f] = f(0)$

and you can note that for any actual function $g$, $f\mapsto \int f(x)g(x)\mathrm{d}x$ defines a distribution

hence the notation

Slereah

For instance if you have two functions $f, f'$ which are identical except on a set of measure 0, they define the same distribution, since those integrate to zero

ACuriousMind

so simply by what a distribution is, yes, any distribution that assigns $f(0)$ to any $f$ is the $\delta$ distribution

Sanjana

Oh...so if I define a distribution by $g[f]=f(0)$ then $g[f]$ has to be $\delta[f]$ simply cz it's the definition of $\delta$ function and none other can take it's place?

@ACuriousMind Oh ok...thanks

Slereah

Distributions are linear functionals, after all

Ryder Rude

13:31

@Sanjana if u take this to be the definition of dirac delta, then yes. however, if u take the limit of Gussians as the definition of Dirac delta, then there are non-Gaussian stuff too can can yield u this propery $g[f]=f(0)$

Slereah

If you have two distributions that give you the same thing, $f[\phi] - f'[\phi] = 0$ and therefore $(f' - f)[\phi]$ = 0

Ryder Rude

but conventionally, $g[f]=f(0)$ is the definition of Dirac delta

nickbros123

@Sanjana one of my profs gave me an elaborate proof, using big big words that I didn't understand (action of a distribution, compact support, etc etc) nothing went into my head but I was quite assured a proof exists

I haven't reacted to this answer because I don't yet understand the mathematics, evaluate it for yourself, perhaps useful. I am quite content for now with the "cutting the space into a ball around origin and tking a limit" idea. math.stackexchange.com/a/4719423/1118236

Ryder Rude

@bolbteppa google doesnt show it

but green's functions are very important

Sanjana