Dan, rep

Emilio Pisanty

Feb 15, 2017 20:54

@DanielSank Your average rep per answer is 133?

man, I don't think I make half that number

yeah, I don't

DanielSank

@EmilioPisanty Yes, and I have the highest fraction of accepted answers for people who have written at least ~50 answers.

Emilio Pisanty

@DanielSank well, fancy being you, then

DanielSank

It's my claim to fame.

Emilio Pisanty

I should get off my ass and award more rep in bounties than you currently have =P

DanielSank

...and when someone turns to JR's rep as an indicator that his behavior should somehow specially influence site policy, I am not going to be shy about sharing my claim to fame ;-)

AccidentalFourierTransform

Feb 15, 2017 20:56

@DanielSank let me play devil's advocate here: maybe QM meant that JR is one of the most active users (regardless of his rep), and as such, his behaviour may be a good representative of the general comunity

DanielSank

@EmilioPisanty Wait what?

@AccidentalFourierTransform He's one guy though. Having a lot of use does not mean you represent the community. In fact, it's probably the opposite since most users aren't power users like JR.

Your move ;-)

...Mr. Devil.

AccidentalFourierTransform

@DanielSank E. is the user who's awarded more bounties here in PSE

by far

Emilio Pisanty

@DanielSank the total of rep I have awarded in bounties is 70% of your total rep

DanielSank

@EmilioPisanty That's amazing, but how is it related to previous discussion?

Emilio Pisanty

would take a bit, but not too much, of sustained effort to bring that up to 100%

DanielSank

Feb 15, 2017 20:57

@EmilioPisanty -_- jeez

Where U get all dis rep?

Emilio Pisanty

@DanielSank I'm just reeling off of your awesome rep-per-answer ratio

@DanielSank no idea

DanielSank

@EmilioPisanty ohhhhh

So your claim to fame is that you've given away the most rep? That's awesome!

You're a regular Robin Hood.

Emilio Pisanty

@DanielSank pretty much, yeah

DanielSank

That's a pretty sick claim to fame.

Emilio Pisanty

@DanielSank don't think I ever stole any rep

DanielSank

Feb 15, 2017 21:00

@EmilioPisanty Hmmm, ok then you're just a philanthropist.

In any case, pretty awesome.

Emilio Pisanty

@DanielSank philantropy is when it actually costs you

giving bounties above 30,000 costs you nothing

AccidentalFourierTransform

@EmilioPisanty so there is no word to describe you. Congratulations!

(there probably is some German word, though)

Emilio Pisanty

I just like to think of it as doing my bit to improve the site by putting the rep incentives where they will produce the most quality content

DanielSank

@EmilioPisanty It's a really nice idea.

AccidentalFourierTransform

you are such a romantic

DanielSank

Feb 15, 2017 21:04

Thank you again for rewarding that post about the Boltzmann constant. It was nice to see that appreciated.

Emilio Pisanty

@DanielSank it was a really good answer

DanielSank

@EmilioPisanty Thanks. Pretty sure the first place I encountered the idea that temperature is a Lagrange multiplier was in Pathria's book.

Emilio Pisanty

and also, I think the site benefits from having folks who have produced that sort of high-quality content to reach the important moderation milestones faster

DanielSank

I'm surprised, in retrospect, that Reif doesn't discuss that.

@EmilioPisanty Perhaps. I feel I don't exercise my moderation powers much at all.

i.e. I never do reviews any more.

Like, ever.

Emilio Pisanty

@DanielSank maybe not, but you're able to delve into the full review queue history and suss out bad stuff if the need comes

also see & react to deleted answers, again, if there's a need to

It would be really good to have a much bigger critical mass of 10k+ users, as measured by the fraction that do occasional moderation

particularly if we as a community managed to actually use things like the recently-deleted list on the 10k tools

actually catch bad deletions if and when they happen

DanielSank

Feb 15, 2017 21:09

See, that sounds like work.

dmckee

@DanielSank Whoa! I hadn't seen it formulated that way. Did you do a post on it? Pointer?

DanielSank

I just get so... I dunno... funky... when I do reviews.

Emilio Pisanty

@DanielSank yeah, the 10k tools could use a fair bit of improvement

DanielSank

42

A: Is the Boltzmann constant really that important?

We can understand all of this business if we visit the statistical mechanics notion of temperature, and then connect it to experimental realities. Temperature is a Lagrange multiplier (and should have dimensions of energy) First we consider the statistical mechanics way of defining temperature....

@dmckee

This is the right way to think of temperature. Statistical mechanics is a maximization problem where you're maximizing entropy.

Emilio Pisanty

also, on the bounty-to-10k front, here's a good morsel of history

3

A: Are Born-Oppenheimer energies analytic functions of nuclear positions?

Suppose that for all $z$ in some open set $Z$ of complex numbers containing $z_0$, the Hamiltonian $H(z)$ is a compact perturbation of the self-adjoint $H(z_0)$ depending analytically on $z$. Then, for every simple eigenvalue $E_0$ of $H(z_0)$ and associated normalized eigenstate $\psi_0$, there ...

DanielSank

Feb 15, 2017 21:11

But! You have constraints: fixed energy, fixed volume, fixed particle number...

Emilio Pisanty

that bounty put Arnold Neumaier over 10k

DanielSank

Temperature, pressure, and chemical potential are the Lagrange multipliers associated to fixed energy, pressure, and particle number!

AccidentalFourierTransform

In a couple of days I'll put heather over 5k :-)

DanielSank

@EmilioPisanty You like putting people over 10k, eh?

dmckee

"Now suppose we add the constraint that the system has a certain amount of energy [...]" <== Sets off one of those "How did I miss that?!?" moments right at the top of the post.

Emilio Pisanty

Feb 15, 2017 21:12

@DanielSank have done ever since

DanielSank

@dmckee I know, right?!

dmckee

Some days I feel like a dunce.

DanielSank

@dmckee Don't. Very few physicists seem to have ever seen this idea.

I just got lucky that I read Pathria and picked up on that little note.

Emilio Pisanty

@DanielSank I once saw a public lecture by Eric Cornell that I think you would have enjoyed immensely

Core point that nature is lazy and sloppy

so it likes to maximize the sloppiness and the unlaziness

DanielSank

@EmilioPisanty Link plz?

@EmilioPisanty I had the privilege of eating dinner with him once. Friendly guy!

Emilio Pisanty

Feb 15, 2017 21:15

@DanielSank this was at ICOLS 2013, and all the other talks were posted online. I emailed after a few months to ask, and they said that he's so perfectionist that he didn't want it aired until it was absolutely spotless.

dmckee

They have it in our library here. I'll be back.

Emilio Pisanty

so nature likes to maximize sloppiness S and minimize unlaziness U

DanielSank

@dmckee What's "it"?

Cornell's talk?

Emilio Pisanty

but obviously that's a problem because being really sloppy also requires you to be very unlazy, and being unlazy isn't fun

so nature tries to minimize some kind of figure-of-merit

that goes like U-S

DanielSank

Free energy?

0celo7

Feb 15, 2017 21:17

@DanielSank He probably means Parthia.

Emilio Pisanty

but obviously that's a bit too rigid

0celo7

Forgive autocorrect

Emilio Pisanty

so you need some kind of tradeoff factor

so you minimize F=U-TS

DanielSank

@0celo7 Oh right.

@EmilioPisanty Right. So here's why I like the Lagrange multiplier picture so much:

The value of a Lagrange multiplier tells you how much better you could maximize your objective function if only you would be willing to relax the constraint a bit.

A system with high temperature is one where giving it just a tiny bit more energy would let it increase the entropy by a relatively small fraction.

So, if you hook it up to a low temperature system, it will give up energy, because the low temperature guy can raise the total entropy a lot.

By the way, this helps understand why negative temperature means something is very hot.

If $T<0$, then I always want to give away energy.

Emilio Pisanty

damn

DanielSank

Feb 15, 2017 21:22

What?

Emilio Pisanty

one of these days I'll really truly grok these things

DanielSank

@EmilioPisanty It's not complicated. I promise.

If $T<0$ that means that giving away energy raises $S$ for me.

If $T>0$ then absorbing energy raises $S$ for me.

Emilio Pisanty

oh, no, I understand everything you said

DanielSank

Therefore, if a negative temperature system touches a positive temperature one, the energy flow is from the negative guy to the positive guy.

Emilio Pisanty

I just would have been entirely unable to come up with more than 10% of it on my own, I should think

DanielSank

Feb 15, 2017 21:24

@EmilioPisanty Ah well, we all stands on the shoulders of our predecessors.

Emilio Pisanty

On looking over your answer again, I had the same reaction as dmckee

12 mins ago, by dmckee

"Now suppose we add the constraint that the system has a certain amount of energy [...]" <== Sets off one of those "How did I miss that?!?" moments right at the top of the post.

again.

DanielSank

Interesting.

0celo7

I'm still waiting for the Eureka moment

DanielSank

When I read it in Pathria my reaction was more like "Oh! Well why didn't my undergrad course just say that?" along with "Man, Lagrange multipliers are way more interesting and important than I realized when I first learned about them".

3

The h Bar

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