The h Bar

10:00 PM

Shouldn't the diff geo notion of torsion be the same as the "GR" notion...since GR is just basing it off diff geo (btw GR takes a torsion-free connection as an assumption, so there's no torsion in GR)

Balarka Sen

it's not available on my country either

Secret

Of course barbara probably cannot see my message because of what happens in maths chat

good night

@BalarkaSen i think it's only available in the uk

ACuriousMind

@Mithrandir24601 I can report this video isn't available in Germany, either

Mithrandir24601

:( It's such a good video

good night

10:03 PM

brb sending open letter to bbc on behalf of the h bar

Sir Cumference

Does anyone speak GR?

enumaris

I might

good night

@SirCumference greek?

Mohammad Areeb Siddiqui

how deep is leonard susskind's theoretical minimum?

good night

does the minimum part not answer your question?

ACuriousMind

10:09 PM

@MohammadAreebSiddiqui About 5 feet deep (more seriously, I'm not sure what exactly you want to know as an answer to that question)

Mithrandir24601

There are other parts of that episode where it has a fight with a small shark :)

0celo7

@SirCumference Some.

Mohammad Areeb Siddiqui

XDD expected that, i mean in the first few pages he talks about how this is not a big fat mechanics book and provides just enough knowledge for the subject

how much is this just enough?

good night

depends what you wanna do

Sir Cumference

@enumaris Welp, this might be asking a bit much, but would you be willing to skim this short paper a little? It suggests that the entire Universe is at least 47.8–170 billion Gpc in diameter, even though we obviously can't observe anything beyond the observable universe

Basically I'm hoping someone could explain simpler what is happening

enumaris

10:12 PM

distances in GR are tricky

anything non-local in GR is tricky

are they talking about the co-moving distance?

0celo7

"topology scale"

Have I mentioned that I hate physicists?

Sir Cumference

It doesn't even say whether it's comoving or proper

What...?

Cows

Hi

enumaris

0celo hates us

:(

Sir Cumference

@SirCumference sigh *47.8 Gpc

Cows

10:13 PM

I am nervous about tomorrow. I have an interview

at 2 pm, technically "a phone conversation"

good night

@0celo7 alright name one other physicist that says topology scale

i don't think that's even acceptable in physics

0celo7

then I hate the field for not deleting these guys from arXiv

Sir Cumference

@0celo7 Welp, is it wrong to trust a paper less if it's in a journal with a low IF?

Cows

@SirCumference what is IF?

Sir Cumference

@Cows Impact factor

Impact factor

The impact factor (IF) or journal impact factor (JIF) of an academic journal is a measure reflecting the yearly average number of citations to recent articles published in that journal. It is frequently used as a proxy for the relative importance of a journal within its field; journals with higher impact factors are often deemed to be more important than those with lower ones. The impact factor was devised by Eugene Garfield, the founder of the Institute for Scientific Information. Impact factors are calculated yearly starting from 1975 for journals listed in the Journal Citation Reports. ��2...

Cows

10:16 PM

oooh

Sir Cumference

A measure of how many citations it gets a year

> journals with higher impact factors are often deemed to be more important than those with lower ones.

0celo7

@SirCumference the most prestigious journal in my field has an IF of 2

those numbers don't mean anything

Sir Cumference

@0celo7 Right.

0celo7

there's another with 2.375

maybe I'm in the wrong area

enumaris

well Nature would be like the highest IF I think

0celo7

10:19 PM

nature is like 41

enumaris

isn't Nature like at IF of 100 or something

right

Sir Cumference

Well, the only reason I found the paper is because Wikipedia's page for the Universe lists the size as "at least 156-554 billion light years" in the infobox

Universe

The Universe is all of space and time (spacetime) and its contents, which includes planets, moons, minor planets, stars, galaxies, the contents of intergalactic space and all matter and energy. While the size of the entire Universe is still unknown, it is possible to measure the observable universe. Halpern and Tomasello calculated the observable universe using data from European Space Agency's Planck satellite, estimating it to be 90.68 billion light-years across, 0.7% smaller then previously thought. The earliest scientific models of the Universe were developed by ancient Greek and Indian...

enumaris

something much higher than like the Physical Review ones

0celo7

which is the popular one?

Phys Rev A?

ACuriousMind

@0celo7 Once you have forsaken GDP, there's no way back :)

enumaris

10:19 PM

Phys rev A-D are on different topics

Sir Cumference

@0celo7 Does "your field" refer to a math field or physics field?

0celo7

@SirCumference Math/Math.phys

enumaris

I don't think any of them are significantly more popular than any other except insofar as whether that field is more popular than the other

0celo7

Both publish in the Journal

enumaris

Phys rev X I think is the paper for the "cool" stuff?

0celo7

10:21 PM

I work on Riemannian geometry in a GR context so it's really hard to place me

enumaris

You mean Lorentzian geometry

:P

0celo7

no

Mithrandir24601

@enumaris But then the likes of Nature, by it's very, erm, nature, publishes a good number of e.g. biology papers, which on average, get more citations than the average physics paper

0celo7

@enumaris please give me the benefit of the doubt

I know what Lorentzian geometry is -- and while I know a lot of it, I'm not working on it

it's completely different

enumaris

why are you working in Riemannian geometry in GR? GR explicitly uses a Lorentzian metric

0celo7

10:22 PM

spacelike hypersurfaces are Riemannian manifolds.

good night

@Mithrandir24601

guys I found it

why doesn't it load

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