The h Bar

bolbteppa

1:25 AM

Reggelicious

Starting to make sense of these trajectories

Slereah

do they just zoom by

bolbteppa

The hydrogen atom energy levels can be written as $E_{n,l} = K^2 = \frac{1}{(n+l+1)^2}$, (where $K = \sqrt{2mE/\hbar^2}$ arises in the Schrodinger equation naturally). The outer-most line is the $n = 0$ case of $l$ plotted against $E$, next line is $n = 1$ etc...

States with fixed $n$'s and different $l$'s are like different states of an electron. I posted above a diagram of the isotropic harmonic oscillator with the same thing going on, but straight lines.

Mesons, which have no simple 'Coulomb potential schrodinger equation' that we can just solve and then list the energy levels, still satisfy this kind of behavior, only now (relativity) different mesons i.e. different actual particles are the nodes on the line of fixed '$n$' with different $l$ values, plotted against $k^2$, which in relativity is now $E^2 - p^2 = M^2$ hence those $J = \alpha M^2 + b$ plots

Since there's no simple Schrodinger equation we can just set up and solve, people worked backwards from this idea that we know the spectrum, lets find the equation/theory which gives this spectrum, and lo and behold they got bosonic strings somehow

They zoom by from node to node I guess :p (but fixed along the same line)

Still pretty jarring to think of getting different particles along these lines, would you call the $l = 1$ and $l = 2$ states of an $n = 4$ electron different particles...

Secret

4:32 AM

well in a way...

since elementary quantum particles have no substructure, changing its quantum numbers is the same as changing the type of particle, so it is intuitive to me that different states can be identified as different particles

Yuvraj Singh...

6:45 AM

Morning to everyone :-

Slereah

8:56 AM

morning

Emilio Pisanty

josephsteinberg.com/…

@ACuriousMind a job offer for you

ACuriousMind

10:08 AM

Dec 3 '19 at 17:26, by ACuriousMind

I firmly believe COBOL is the future

Slereah

@ACuriousMind unfortunately true

COBOL is like the appendix or catholicism

A relic of another era that we cannot get rid of

My holy neural network is generating theological insights at a speed unmatched!

Pretty slow, but I assume much faster than the usual writing of holy books

ACuriousMind

@Slereah Careful, lest it produces a second TempleOS

Slereah

Also hopefully it won't gain consciousness and become god

"In the beginning God created the heavens and shut the gates of the Universe. Open to God! Go on before the wisdom; provide those with eyes. He is good, as recorded in the Docum, and besteth over the wisdom. Believe on a Promised Day; be determined in a righteous anger. Bar the gates of the Protected Field; call the greater done. What this state of the glory of the Almighty is to the divine being, so much the better!"

Even the universe is under quarantine now

John Rennie

Does anyone actually understand reciprocal lattices, or do people who work in solid state just get good at bluffing?

Slereah

who knows

ACuriousMind

10:23 AM

all understanding is bluffing :P

Slereah

I once quoted that von Neumann quote about people not understanding mathematics and just getting used to it on the math channel

they got very angry

John Rennie

A student has just asked me about reciprocal lattices because they baffled him completely. The best I could offer was to say me too.

hand wave, hand wave, Fourier transform, hand wave, hand wave

Why is solid state physics soooooooooooooooooo hard?

Slereah

Were it not it wouldn't be physics

ACuriousMind

@JohnRennie I mean, they're just the Fourier transform of the "real" lattice. In my experience many people are just rather bad at explaining that and try all sort of "intuitive" explanations that fall apart if you look at them too closely

Slereah

there's no physics field for matching block shapes into holes of the same shape

John Rennie

10:29 AM

@ACuriousMind that's easier to say than it is to intuitively grasp :-)

Slereah

If you wanted to intuitively grasp something you should have gone into making stone tools

ACuriousMind

There is no intuition (except that gained simply from familiarity with it) - it's a pretty abstract construct

I mean, this part of solid state physics is basically using all sorts of statements from Pontryagin duality but rarely mentions that because math might scare people :P

John Rennie

They are already scared - trust me on this :-)

ACuriousMind

I remember also being frustrated by these lattices because you were expected to compute all sorts of stuff in them without a really satisfying explanation of why it worked because the lecture didn't like proofs that were longer than two lines

@Slereah Not sure - is there a good intuition for the correct shape of a stone knife? :P

Slereah

@ACuriousMind sharp

ACuriousMind

10:35 AM

I know an archaeologist who will not shut up about the surprising intricacy of the different ways you need to shape the stone for different purposes if you get him started on it...

Slereah

Sample from the holy network : "Every step of the way, a mountain will grow taller and taller, like a piece of the boulder, where the head of the caveman is. When the caveman will be forty, the body of his wife will become like a shield of gold, and his head like a campfire."

Wise words

ACuriousMind

It almost makes sense until you try to understand it :P

Slereah

I mean

It makes about as much sense as the holy texts it is made from

It's no less nonsensical than say, Revelations, or the Nostradamus prophecies

"It is the time of the darkening moon, his eyes shine with a darkness that none can describe.
When the children will be seven years old, the virgin when she will be about four hundred years old.
When the caveman is eight hundred years old, and when he will be seventy, he will all that time govern the land, excepting the valley of the mountain, which the mountains are. Then he will lead his people from the valley, to the land northward.
There they will live for forty generations, excepting the hills, and mountains built up by the water.

The caveman gospel

I had to exclude some holy texts because I wanted texts to be mostly readable by modern viewers

So no Pyramid Texts, Book of the Dead, Rig Veda or Zend Avesta

user434058

11:28 AM

-3