The h Bar

4:11 PM

@AccidentalFourierTransform I didn't get a secret hat :-(

@DanielSank Go participate on the site, vote something up, post a comment, whatever - you should get the "where in the world"

AccidentalFourierTransform

@DanielSank we don't know what one has to do to get the "Where in the World?" hat yet, but everybody got it today

so go and do stuff until you get it. It might take 5 min or so

John Rennie

WHAT!!!

-1

A: How does a photon travel the speed of light while it is absorbed in a molecule?

How does a photon travel the speed of light while it is absorbed in a molecule? By going round and round. Since photons always travel the speed of light and continue to exist after they are absorbed in a molecule that they hit, then what are the mechanics of a photon traveling the speed...

By going round and round?

ACuriousMind

I was under the impression the photon going round and round in a Dirac belt is what the electron is.

2

AccidentalFourierTransform

the electron thinks, therefore the electron is

John Rennie

4:23 PM

I find myself genuinely at a loss for anything to say

DanielSank

@ACuriousMind v- vote?

ACuriousMind

@DanielSank Yeah, click on those clickable little arrows

It's fun!

koolman

Hii @JohnRennie

John Rennie

Hi

koolman

Your previous hat was much better

It fit to your face

That was looking cool

John Rennie

4:38 PM

I switch the hats around just for variety. The abominable snowman is the one I like most so far.

koolman

Yeah that one was also nice :-)

AccidentalFourierTransform

4:50 PM

I have a metric $\mathrm ds^2=f^2(r)\mathrm dr^2+r^2\mathrm d\Omega$

what does my Laplacian look like?

$\Delta=\frac{1}{f(r)}\frac{\partial}{\partial r}f(r)\frac{\partial}{\partial r}+\text{angular derivatives}$?

ACuriousMind

@AccidentalFourierTransform I think the first term looks uglier, you have to compute $\partial_r (\sqrt{g} g^{rr} \partial_r)$, right?

Also, the prefactor is $\frac{1}{\sqrt{g}}$, and $\sqrt{g}$ isn't $f$ but $rf(r)$, right?

AccidentalFourierTransform

@ACuriousMind yeah, but I didn't want to compute it. I was hoping the solution "would look obvious" to some of you. My differential geometry is very rusty

oh, yes, it should probably be $\frac{1}{rf}\frac{\partial }{\partial r}rf\frac{\partial}{\partial r}$

hmm, yeah, that looks fine to me

thanks!

ACuriousMind

@AccidentalFourierTransform Well, the $g^{rr}$ is $f(r)^{-2}$ due to the raised indices, so shouldn't that be $r/f$ between the two derivatives?

AccidentalFourierTransform

wait

the determinant is $r^d$

ACuriousMind

Also note that you still need to use the product rule (I'm not sure whether you omitted the brackets out of laziness or oversight)

@AccidentalFourierTransform Oh, yeah

Well, for all I know you're in 2 dimensions, so I wasn't wrong ;)

AccidentalFourierTransform

5:02 PM

lol

oh no I forgot how to math

ACuriousMind

I have that feeling about once a month

John Rennie

5:59 PM

This duplication seems a tad suspicious:

0

Q: What is the difference between the three types of bosonic reservoirs: sub-ohmic, ohmic and super-ohmic?

What I want to understand is what the difference between the three types of bosonic reservoirs that we use in the theory of quantum decoherence: sub-ohmic, ohmic and super-ohmic beyond spectral density. and what is the interpretation of each typs !

Duplicate of:

0

Q: Difference between the three types of bosonic reservoirs : sub-ohmic, ohmic and super-ohmic

I want to ask what is the difference between the three types of bosonic reservoirs that we use in the theory of quantum decoherence: sub-ohmic, ohmic and super-ohmic beyond spectral density.

quantum-mechanics quantum-information decoherence

Apparently different users, but these questions are blatant duplicates.

ACuriousMind

@JohnRennie I think a mod flag would be a better way to alert us to suspicious things, contrary to popular belief I'm not always watching this chat ;)

John Rennie

6:19 PM

Oops, yes, sorry :-( I VTC'd as a duplicate but didn't think to flag.