The h Bar

@Bohemianrelativist what about e.g. Wikipedia is unclear to you?

@Charlie there are also äs and ös

it's an umlaut trifecta

Charlie

Are there any words spelled entire with letters with umlauts?

@Bohemianrelativist Also, the section just below what ACM linked on Wikipedia talks about their use in Feynman diagrams if you're interested

@Charlie not really, they're all vowels but real words need some consonants

Charlie

aww

12:14 AM

the only German word without any consonants I can think of is Ei (=egg), but it doesn't have any umlauts

Bohemian relativist

@ACuriousMind I have not read the Wikipedia; I am reading a lecture note, in which the lecturer is trying to derive the propagator.

if they're deriving a propagator but you don't know what a propagator is it's likely you're missing some prerequisites they're assuming

5 hours later…

5:33 AM

@Charlie Not unless you're a heavy metal band.

6:24 AM

Is the scri-plus and scri-minus symbol of Penrose diagrams (the future and past null infinities) from some language? What's it's origin?

Talking of these J looking thing...Got it from Carroll's book on General relativity...appendix H on penrose diagrams

6:47 AM

@ManasDogra It's an "I" not a "J".

"I" for "Infinity"

Why the curly form of "I" was chosen I don't know. I guess it just looked good :-)

@JohnRennie That makes sense

But why call "scri"..is it in some language's alphabet?

I doubt there is any deep significance to this. I suspect it's just short for "script I", where the term "script" is often used to describe fonts that look like stylised handwriting.

7:04 AM

@JohnRennie This turns out to be right!

:-)

@JohnRennie Have you read Chandrasekhar's book on black holes?

No.

amazon.co.uk/Mathematical-Theory-Classic-Physical-Sciences/dp/…

This one?

Yes...It's incredibly hard for me :( Do you have any recommendation on some introductory tetrad formalism?

Q: Resource Recommendations: General relativity, local tetrads and particle physics

To be honest I'm just an interested amateur in GR and I don't know it in the sort of mathematical depth that Chandrasekhar discusses.

I don't know the tetrad formalism at all.

Have a look at the book recommendations question and see if there are any suggestions there.

Q: Tetrad formalism

What is the current scope of doing research in tetrad formalism to understand gravity? What is the material, book I should refer for doing research on it?

I'm still self-learning general relativity. I have been a huge fan of Andrew Hamilton's amazing lecture notes on GR, black holes and cosmology. He goes through GR in pretty much full tetrad formalism. The reason he wants to do that is because some of the physics becomes much easier to understand ...

general-relativity particle-physics resource-recommendations

7:15 AM

Thanks...will check it out!

4 hours later…

Faded Giant

10:54 AM

@Charlie You should try Finnish

something like hyvää pääsiäistä

Nihar Karve

11:41 AM

Is there a way to augment Wigner's classification so that it can distinguish between, say, gluons and photons (i.e. with an internal symmetry group)?