The h Bar - 2015-09-10 (page 1 of 4)

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12:01 AM

Welll.... what have we got here?!

0

Q: In interpretations of QM where the wave function is real, what does that mean?

In a lot of interpretations of Quantum Mechanics they believe that the wave function is "real". But what does that mean? Are they saying that the wave function of an elementary particle (electron/photon) is a real wave, like a water wave, oscillating in space time?

quantum-mechanics wavefunction

12:13 AM

Philosophy, I'd say :P

1 hour later…

1:40 AM

chat is deaded

dw I'm here.

2:02 AM

@ACuriousMind I have indeed been abstaining, because I've never seen the distinction that the community seems to see between the OK ones and the wicked, evil ones. Left up to me I'd close them all, but the crowd seemed to disagree.

@DavidZ It could be they found their dream candidate. I got hired across sub-field boundaries a couple times (fixed-target electron scattering into low energy neutrinos into accelerator based high-energy neutrinos), but there is a risk in hiring someone that way that no one will take if the post-doc they really want presents.

@DavidZ The flexible schedule is a big deal for me. And in truth in comperable jobs in industry you still have some flexibility, but maybe not as much.

On the other hand you have more money, and a less scary advancement track.

@Danu I lived there for seven years and speak German "like a native." That was a joke.

@Danu Not even like a really bad fever?

@FenderLesPaul I'm here.

2:20 AM

Hai

I'm GR free now.

2

Q: Are pairs of events characterized by spacetime intervals even if the spacetime containing these events is not flat?

In Wikipedia, spacetime intervals are presented explicitly under the heading "Spacetime intervals in flat space"; apparently including a presentation of spacetime intervals for (all) pairs of events in flat spacetime. But is it correct and understood that spacetime interval values, $s^2$, can a...

general-relativity spacetime

What?

@FenderLesPaul You didn't convince me that I need them.

I don't believe you

How do I prove it?

idk

I decided that I don't need them.

2:28 AM

Did you donate them to the library?

Of course. I don't want to waste good books.

@FenderLesPaul It's all part of this new lifestyle that I'm trying out.

give up on things you like lifestyle?

Give up on unnecessary things.

Focus on my studies.

And you didn't even make a case for why I should keep the books!

Pretty sad.

I'm really sad now.

There is no reason to be sad.

@FenderLesPaul What are you doing tonight?

2:42 AM

@0celo7 HW :(

@FenderLesPaul We need to discuss Prop. 4.5.1 in HE...I wasn't ever truly happy with my understanding of that proof.

Wanna do that tomorrow night if you're free?

Eh what time?

I have an obligation at 10-ish.

> Donald Trump is under fire yet again after insulting the physical appearance of fellow GOP presidential hopeful Carly Fiorina in an interview with Rolling Stone magazine.

"Look at that face! Would anyone vote for that? Can you imagine that, the face of our next president," the Republican frontrunner said in the interview. "I mean, she's a woman, and I'm not s'posedta say bad things, but really, folks, come on. Are we serious?"

God damn the master strikes again.

how long would said obligation take?

Depends how many people show up!

We're putting out 3,000 flags on the HSS lawn.

2:48 AM

oh

would it end before like 12?

Perhaps, but 12 is my bed time.

oh

would Friday be better then?

Actually I should head off now.

@FenderLesPaul Probably.

mmk

I'm sick and need the sleep.

2:49 AM

night!

night

feel better

user image

Grr, it really upsets me that religion is such a big part of American politics.

I guarantee I'm the only agnostic in my political group.

Yeah it's unfortunate

3:28 AM

I started to write a comment the the most recent "I'm gonna ask a Zeno's paradox question on a physics site" question claiming that the pardoxes show the importance of empiricism in putting an end to useless chatter.

But then I realized that we have to do one every few month.

Philosophers.

@DavidZ Isn't it some times the case in academia that you get to work on what you can get funding for, which may or may not be precisely what you love?

3:57 AM

Yeah, I suppose so. I was speaking broadly - "what you love" has to be a reasonably wide net to overlap with what the funding agencies are willing to give money for, and with what the existing community of researchers will appreciate.

4:09 AM

Yup, you gotta play the bills :-)

4:30 AM

user image

4:41 AM

@DavidZ perhaps this kind of question would stimulate some interesting opinions on Academia.SE?

Just a thought pal.

Perhaps so, though SE sites aren't really meant for collecting opinions

True.

2 hours later…

6:44 AM

@Danu A logical theory could describe many things that are not "real" (as we can using common language). And a model in logic is "an instance" of the theory (i.e. an instance of the sentences of the language for which certain sentences, the axioms, are true). That makes sense, and can be adapted to the particular case where the instance of the logic theory is our description of physics. Therefore (our description of) physics is a model of a certain logic theory.

This obviously does not mean that the nature is a mathematical model itself. But I like this concept of model (maybe because I think as a mathematician) more than saying that an "abstraction", the mathematical description, is a model of physics (because the abstraction encompasses more cases than the specific case)

Nevertheless, I know the terminology commonly used by physicists, for I used it many times myself. And it is also understandable, simply I like the other way around better ;-P

7:39 AM

@0celo7 We were talking about personal problems, not being sick. In any case, even then (this is from memory, I haven't had a fever since I was like ~10) I would sleep, just have really strange dreams.

@0celo7 You did??? :( I would've paid you to send them to me.

@yuggib Only our description is. Physics itself is certainly not guaranteed to be, and I think many of us don't believe it is.

I think it's still better to say that the description (mathematical) we use is a model of the world than vice versa.

8:39 AM

@KyleKanos Any chance you could help me importing auto-comments? The add-on is only giving me 2, and "importing" new ones doesn't actually work for me :\

9:21 AM

Guys

Let's form a band

It will be called Einstein and the Evidence

9:39 AM

@Danu Yes, but you are only able to give a human-made formulation of physics; it is not an entity by itself. I know that the things that we observe exist independently from the description we give to them, and that it is not the point. The point (and I agree it is a silly one, but I enjoy this type of stuff) is that the formulation itself in human terms (i.e. physics, if you wish) it is reasonably assumed to be a model of some logic theory, i.e. a language with rules and axioms.

If you wish (and it is accepted mathematical terminology), the logic is the syntaxis; the model the semantical interpretation of it.

And that again gives strength to the fact that physics (the model) is the thing that gives meaning to the structure/language (the logic theory)

@Slereah JD can bring the "Evidence" :D

@yuggib This sentence makes no sense to me

Furthermore, I find this high-brow rephrasing of things more obfuscatory than useful.

why? these are common terms when talking about language

Oh no are we doing philosophy

one thing is the structure of the language, the other is its meaning

9:46 AM

The Meaning of Meaning

the language seen as a series of symbols may have rules, but do not have meaning

and it is "more general", in the sense that you can give different meanings to each series of symbols, keeping the same rules

Define: meaning

but then

What is meaning

user image

define, "define"

The Meaning of Meaning

The Meaning of Meaning: A Study of the Influence of Language upon Thought and of the Science of Symbolism (1923) is a book by C. K. Ogden and I. A. Richards, Magdalene College, University of Cambridge. It is accompanied by the two supplementary essays by Bronisław Malinowski and F. G. Crookshank. Although the original text was published in 1923 it has been used as a textbook in many fields including linguistics, philosophy, language, cognitive science and most recently semantics and semiotics in general. The book has been in print continuously since 1923. The most recent edition is the critical...

good book

9:53 AM

@skillpatrol anyways, in mathematics, you give meaning to a language if you write a model of it. It is quite clear what the definition of a model is, nevertheless it is also quite clear that a good deal of vicious circling is involved

absolutely

I do not want to defend mathematical logic at all costs; but it is a quite serious and intersting discipline

...yes

I'm finally going to be writing an answer to my most interesting question.

...not a real answer in the usual sense, though.

nice

10:19 AM

0

Q: question put on hold for no clear reason

I believe that the question linked to below meets all the criteria for homework questions listed at the Physics Stack Exchange meta site, and that therefore it has been inappropriately put on hold. In a comment I left on the question I asked the people who did this to explain their actions and th...

10:31 AM

vote for this^ to be put on hold for no clear reason :D

10:42 AM

@skillpatrol You like to live on the edge? ;)

@PhysicsMeta So much to comment on this, haha

I prefer sweet emotion

Janis Joplin - Ball And Chain (Amazing Performance at Monterey)

I'll see your Janis Joplin and raise you The Machine

@skillpatrol Just compare the singing; It's clear what's more interesting ;)

Ya can't top the Cambridge boys from the UK

Game Over

:P

10:52 AM

@Danu Of course I didn't get rid of the books. I wanted to see @FenderLesPaul give a reason why I should keep them, though.

I was never a Pink Floyd fan

@0celo7 Send them to me, though :D

Outside of "personal interest," there's really no reason to have them.

@Danu Danu on ignore (everywhere)

@0celo7 There is no reason for anything outside of personal interest.

I've never listened to a pink Floyd song

AFAIK

10:53 AM

:O

4 mins ago, by skill patrol

I'll see your Janis Joplin and raise you The Machine

start here^

I'll pass

0celo7 on ignore (everywhere)

@0celo7 I think it's good practice to at least give things a try.

As weird as it may seem, there is a pretty big chance you won't be into the music you love right now in about a year (maybe 2)

please, this is a physics channel

Only physics songs

Tom Lehrer CHEMISTRY element song

-_-

chemistry has misery in its name

10:58 AM

The Renormalization Group Play Physical Revue 2013 @ UIUC

@Slereah Blurgh

@MichaelA.Gottlieb We can talk here, if you like. It's a bit more direct that commenting, and comments are traditionally not intended for extended discussions.

Perhaps even better, I can create a separate chat room for this discussion.

chat.stackexchange.com/rooms/28984/…

11:25 AM

@skillpatrol If you'd like to ask me a question, just do it here. Or make a separate chatroom for it.

@Danu nah, it wasn't that important...

@Danu I thought you didn't like hard copies

I can send you Weinberg G&C. Amazon delivered two copies for some reason.

@0celo7 Cool! I don't dislike hard copies, I just think the prices are a rip-off.

They are.

I've received most of my books for birthday, Christmas, etc.

So I thought that, if you're getting rid of em anyways, I'd just pay for your shipping to me :D

11:29 AM

Springer MyCopy is pretty great though.

@0celo7 Is that your access to springer books?

Yeah I can get any Springer book for $25.

Oh, cool

Except for German ones because they saw no need to buy that collection.

@Danu SRGF in that picture is a MyCopy one. It's only a paperback, but it beats the outrageous hard copy price.

I wish Cambridge did that. I'd buy that Twistor book in a heartbeat.

@0celo7 I wish that all publishers did that. I'm gonna look into whether I can get this too.

11:32 AM

@Danu The physical copy is $25. I can get the ebooks any time I'm on the campus Wifi.

@0celo7 I guess they don't do it for Europe. I don't see a MyCopy button

Oh, I found it! Not for every book, but for Lee's Smooth Manifolds book they have it :D

in English Language & Usage, yesterday, by Danu

@tchrist I guess reading textbooks on mathematics induces certain peculiar reading habits ;)

great comment btw

@skillpatrol Thanks.

"Satellites don't exist. All transmissions we receive are made possible by triangulating ground towers and dishes. "

I knew it

11:49 AM

Ok, I think I have the flu.

I'm sitting here, not moving, not hot, and I'm sweating.

@0celo7 Good way to lose weight :D

I'm jelly

Water weight is trivial.

I need some paper towels or something.

go get some antibiotics

Uh, I have class until 2

Also the flu is a virus

Thanks for drawing my attention to MyCopy @0celo7

11:55 AM

It's the least I could do

thank @FenderLesPaul for telling me about it

NbCeID 8
http://www.sciencedaily.com/releases/2015/09/150908132807.htm
Looking for lightweight ones?

@Danu Aren't you way beyond Lee?

@0celo7 That book contains a lot of stuff.

It's great as a reference.

Also, no, I'm definitely not "beyond" Lee in any sense.

I see.

user54412

@0celo7 This is America! If antibiotics aren't curing your virus, you're just not getting enough of them.

12:08 PM

I wish Springer had something on twistors...IDK why but I want to learn about them

0

A: How does one correctly interpret the behavior of the heat capacity of a charged black hole?

The paper pointed out by Daniel's comment gave me a starting point to find more literature on this topic and do further research. After a while, it became clear to me that my question is actually an unsettled (research) question. Therefore, a definitive answer cannot really be expected. Nonethele...

Finally wrote an answer @ChrisWhite perhaps this is of interest to you.

user54412

@Danu I'm already reading it.

@ChrisWhite It may also be a bit disappointing.

user54412

@Danu That Figure 5 is pretty much what I was trying to sketch here

@ChrisWhite Ah, nice. I guess you probably had a good understanding of the situation, then.

(I didn't understand what you were doing)

user54412

12:19 PM

it wasn't a very good sketch on my part

I'm actually currently finding more relevant papers, so I may update the answer sometime soon.

user54412

I still feel like the more "fundamental" question here is why T(M) at constant Q has a local maximum, i.e. why do charged black holes start to get colder once you remove too much neutral mass?

user54412

Hmm. Can you remove neutral mass?

You can phrase it the other way around (about dropping in neutral mass)

:P

user54412

I think I've wondered this before -- does Hawking radiation depend on charge? Will it tend to neutralize (or extremize) a charged black hole?

12:24 PM

@ChrisWhite It tends to neutralize, according to my professor.

chat.stackexchange.com/transcript/message/24003217#24003217 @JohnDuffield

user54412

@Danu For all Q/M values? Nothing funny happens as you cross $\sqrt{3}/2$?

@ChrisWhite He didn't address this specifically---He was ranting against people who dare even consider extremal black holes.

@0celo7 : if you want me to give serious answers then ask proper questions on the stack exchange. They won't get closed down. Meanwhile: photon momentum is resistance to change-in-motion for a wave propagating linearly at c, whilst electron mass is resistance to change-in-motion for a wave going round and round at c. That's it. It's that simple. That's why E=mc². You go from energy to momentum to mass by dividing by c. There is no cosmic treacle.

:O

you wrote an equation

12:35 PM

Well, more of a formula

still, a step up from drawings

@Slereah we have argued for hours on that distinction in the math room :P

next ask them the difference between an axiom and a theorem

Prepare for more fun!

you can also try asking the difference between a QM interpreration and a QM formalism here

nah, I don't need another suspension thanks

@Slereah ::readies pitchfork::

::lights torch::

::rolls in tar barrel::

Damn it, can't find the feathers.

where is rigor when you need him?

12:41 PM

average discussion of quantum gravity :

user image

So fellas, anybody want to talk physics? Anybody got any little questions? Apart from that guy who's done with me.

which one

@Slereah Is the joke "image not found" or did you mess up? (clicking the link gives a 403)

user image

Not sure I get it

12:43 PM

how about that one

user image

That one I like :D

And now you reminded me that Abstruse Goose hasn't updated in ages :(

Anybody want to talk about why you can't quantize gravity?

No.

Anybody want to talk physics?

I do.

12:48 PM

I cant see anything from you on physics SE, so I can't see what you're interested in.

Haha, I just got a revival badge for answering my own question.

@Danu You haven't got self-learner yet, though :P

Woops, don't know how I accidentally addressed that message to John Duffield; fixed now.

@ACuriousMind GIMME :P

@Danu : pity there's big issues with that. Like a black hole can't be charged. Note that "there are two horizons" is a well-known hypothesis rather than a well-known fact.

Nooo

12:55 PM

@JohnDuffield You never got to that part of GR, did you? Einstein died before they found them, sadly.

What have you done @Danu

@JohnDuffield Furthermore, your second sentence is completely irrelevant to the post.

@Danu : I'm afraid some of what you take for granted re black holes flatly contradicts general relativity as described by Einstein. If some modern author explained why, that wouldn't be a problem, but they don't. And you don't even know that there's any issue.

abstrusegoose.com/secretarchives/epilogue-376

Nooo

@JohnDuffield Yes, Einstein failed to understand black holes. Sadly.

1:00 PM

@Danu: I don't like the "WORK IN PROGRESS" note at the top of the answer. Like "Edit:" it's meta information that's worthless to the reader at present and disrupts the flow of reading.

::Braces for accusation of German-ness::

@ACuriousMind I was about to remove it.

(Or is it Germanity?)

I have it there while I'm editing, but I'll probably only edit again tomorrow.

@ACuriousMind : You are similar to the most evil german man to ever live

Otto von Bismark

@ACuriousMind Done.

1:01 PM

@Slereah *Bismarck

#reckt

Who was the most evil german scientist

I guess either the Zyklon B fellow or the jewish science guy

possibly the german nuclear program one

Philipp Lenard, the jewish science guy

that's the one

@Slereah I don't think there's that much "evil" about working on a nuclear program, per se.

depends how enthusiastic you are about using it, I suppose

Yup

1:07 PM

Kurt Diebner was the guy

"Diebner was rounded up on 2 May 1945 as part of the Allied Operation Alsos, taken to Huntington, England and interned at Farm Hall, with nine other scientists thought to be involved in nuclear research and development. The nine others incarcerated were Erich Bagge, Walther Gerlach, Otto Hahn, Paul Harteck, Werner Heisenberg, Horst Korsching, Max von Laue, Carl Friedrich von Weizsäcker, and Karl Wirtz."

Scientist stealing

In the USSR they had a special gulag for scientists

Hm, what was it called

I forget

Sharashka

that's the one

"The results of the research in sharashkas were usually published under the names of prominent Soviet scientists without credit given to the real authors, whose names frequently have been forgotten."

My god

They became grad students all over again

@Danu The physics of mathematics just doesn't sound right...

@Danu : I beg to differ. And I will add this: when I point out something Einstein said which doesn't tie in with something Paul Davies said, don't dismiss Einstein out of hand.

Ditto for guys like Penrose. OK gotta go.

later pal

"But if you examine the results of Alexander's instruction, you will see that he educated the Hyrcanians to respect the marriage bond, and taught the Arachosians to till the soil, and persuaded the Sogdians to support their parents, not to kill them, and the Persians to revere their mothers and not to take them in wedlock."

Plutarch just called persians motherfuckers

@JohnDuffield Einstein didn't believe black holes exist, did he?

If that's true, then that is enough to dismiss his opinions on black holes :P

"Einstein denied several times that black holes could form. In 1939 he published a paper that argues that a star collapsing would spin faster and faster, spinning at the speed of light with infinite energy well before the point where it is about to collapse into a black hole. This paper received no citations, and the conclusions are well understood to be wrong."

1:18 PM

:D

Burn

baby

Burn

Can you imagine, if someone of his stature (compare e.g. Witten within the HEP community) publishes a paper and it just doesn't get any citation at all? Ouch.

Before someone else points it out, note that all of Witten's uncited papers are either conference proceedings, popular writings or less than 4 months old.

if I cite Einstein's paper, will he feel better

1:35 PM

@ACuriousMind Does "effective action" fall under "perturbative"

@0celo7 No, although I'm guessing you're talking about the "low energy effective action" of string theories, about which I know too little to be able to tell.

@ACuriousMind You might think I'm stupid then. I still don't know why people are going on about "string theory is only defined perturbatively" when BBS manages to go 600 pages and does not cover string perturbation.

@0celo7 Does BBS tell you how to compute amplitudes?

What does "string theory is only defined perturbatively" mean

@ACuriousMind They mention it in chapter 3, but never calculate one.

@0celo7 It means that the prescription for how to calculate amplitudes is only defined by the perturbative sum over all worldsheet topologies.

1:40 PM

Ah

Ok that's true

And this perturbative sum is not an expansion of something like the path integral, as in QFT, but the definition.

So what they're saying is that there isn't one single path integral or whatever in string theory

Ahhh

And...that's a problem?

eq. (3.111) in BBS

now why is there no way to write it nonperturbatively

is it a fact that there is no way to write it nonperturbatively or has no one figured out how to do it

@ACuriousMind I don't understand the third objection...I thought string theory determines the background

@0celo7 Yeah, because perturbation series are generally expected to be only asymptotic, i.e. they diverge after a certain number of orders.

good le morning

You can't really define an interaction by something that's not really expected to converge

1:45 PM

I see

@0celo7 I think we just have no clue how.

and what is the fourth objection in full

@0celo7 Which third objection?

Are you quoting from BBS?

@ACuriousMind in the xkdc thing

or is that abstruse

yeah that's goose

abstruse

1:46 PM

user image

@0celo7 nLab is your friend ;)

"You can also just ignore any science assertion where 'quantum mechanics' is the most complicated phrase in it."

heheh

@ACuriousMind I only quote HE randomly

@ACuriousMind what

ELI5

@0celo7 The usual QFT perturbation series is an expansion around the "classical free background" where $\hbar = 0$ and all coupling vanish.

jesus, what on Earth does any of this mean ncatlab.org/nlab/show/…

no books I have discuss this

@ACuriousMind ok

so?

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