The h Bar

12:04 AM

anybody available?

1:43 AM

It's funny that they've used my name for one of the hats (feeling pride). It's horrible that /me (being Waffles) can't earn the Waffles hat. And, it gets worse when I see @KyleKanos has 19 hats including Waffles! >_<

Kyle Kanos

Why can't you get waffles?

Waffle's Crazy Peanut

@KyleKanos Because, it's a secret hat! And, I haven't yet discovered how to get it! :P

(seeing MSO now...)

Kyle Kanos

MSE makes it easy

Waffle's Crazy Peanut

Oh, yeah... Forgot that - MSE

Kyle Kanos

It's probably the easiest one to get

Waffle's Crazy Peanut

1:47 AM

Every time, there's a question - "I've found X secret hats, how to earn the others?" which gets a few dozen of upvotes, and the author earns a lot of hats for that question itself...

Next time, it's gonna be me who'll be asking that question! :D

Kyle Kanos

Yeah, just log on at 12:00 UTC and get one then ask immediately

Waffle's Crazy Peanut

> Waffles can be earned by voting on a question, editing it, and then changing your vote.

^^^ Now, all I need to do is edit one of your answers and remove my vote! :P

Kyle Kanos

Haha, good luck!

Actually, there was a minor missing word in my Christmas story answer

T Abraham

hello..

@KyleKanos sorry to disturb you but what's your recommendation regarding my chat with @Danu

Kyle Kanos

What do you mean? Seems like he suggested you start with the basics and progress onwards. If you want a second opinion, I'd suggest the same.

You can't just dive into the upper level physics courses and expect to come out alright

You need to have a formal understanding

T Abraham

2:02 AM

but what specific topics are most important 4 me to understand that article?

Kyle Kanos

I didn't look at the article

T Abraham

oh..

Here it is:

environment.harvard.edu/docs/faculty_pubs/aspuru_walks.pdf

also I am so far understanding this article:

researchgate.net/publication/…

Kyle Kanos

Looks like a lot of core QM: ket notation, Lamb shifts, effective Hamiltonians, commutators, Liouville theorem, anihiliation/destruction operators.

T Abraham

thnx... gota go

bye..

Kyle Kanos

But understanding some of those requires the basics, so, again, I recommend you to not skip the basics & dive. Start with something like Griffith's Intro to Quantum Mechanics or Gasciorowicz's Quantum Physics books and then progress to Sakurai, Shankar, or Cohen-Tannoudji

T Abraham

2:55 AM

thnx..

@KyleKanos any online resources?

Kyle Kanos

Fitzpatricks' QM

I honestly do not know how it fares compared to the other books I mentioned

And if you are at a University, check your library as I'm certain at least one of those above books will be in the stacks.

T Abraham

what about this?:

Kyle Kanos

Given the title of the link, that is an illegally obtained document containing copyrighted information

T Abraham

but I can still download it and read it...so what?

Simha

@KyleKanos Don't tell me you've never downloaded books illegally

Kyle Kanos

3:08 AM

@Simha When it became illegal in the US, I stopped downloading books

@TAbraham So you are breaking the law.

Simha

What other choice do we have ? Publishers sell ebooks for almost the same rates as the bound ones.. when clearly they should be less..

Kyle Kanos

@Simha Buying them would be the most obvious choice

The next would be getting it from your local library

T Abraham

@KyleKanos well.. it's the government's problem.. they should have taken these kinds of resources down from the Internet...

Kyle Kanos

The next would be doing without

Simha

there's no printing, binding, costs, wtc.

*etc.

Well, just imagine the rwvolution we can bring about by making ebooks affordable..

Kyle Kanos

3:11 AM

@TAbraham Actually, if the feds find out what you are doing, it'll be your problem

T Abraham

plus, after a certain point, don't books loose copyright permission?

Kyle Kanos

@Simha If I recall correctly, a few universities actually looked into iPad/Kindle/Nook-only for freshmen & turns out that a large majority of those students prefer the actual books

@TAbraham Yeah, like 50+ years if it's not renewed

T Abraham

so...

Kyle Kanos

So Griffiths' book is not 50+ years old

T Abraham

well..Look at this!:

archive.org/details/IntroductionToQuantumMechanics_718

it seems these people didn't get cuaght!

Kyle Kanos

3:18 AM

Perhaps it wasn't flagged appropriately.

T Abraham

well this website is pretty well known!

Kyle Kanos

Just because the system isn't perfect doesn't mean that it's legal

T Abraham

I expect the government to look through the entire website..

Kyle Kanos

.....why?

Do you really want a Police State?

T Abraham

meaning?

Kyle Kanos

3:20 AM

If the government is looking through entire websites such as that one, what's to stop them from looking at every website?

If they're looking at websites and find something wrong, what do they do?

T Abraham

because I assume they should go through well-known sites...

Kyle Kanos

Send the police and arrest whoever it was for whatever it was they did wrong

I never heard of the site before

Simha

But compared to bound ones, see the advantages. You can get color ebooks of high resolution instead of exorbitantly priced hardbound books, you can have a whole library of books in a sd card, eco-freindly, easier maintenance.. just to name a few.. all if ebooks are made cheaper...

T Abraham

and what about BitTorrent?

even bigger problem... but it seems the government doesn't do much...

Kyle Kanos

@Simha That assumes that the price of books is high because of printing when it's not!

T Abraham

3:22 AM

@KyleKanos heard of the Wayback machine?

Kyle Kanos

@TAbraham Mostly also illegal

@TAbraham That one I have

T Abraham

the wayback machine is from that website FYI...

@KyleKanos shouldn't the government do something about BitTorrent then?

Kyle Kanos

@TAbraham Something like this?

T Abraham

and then the NSA... I thought they know everything about what everybody is doing...

so can't they find such websites and sue them?

Kyle Kanos

@TAbraham I am glad that is (somewhat) far from the truth

@TAbraham Only if they are based in the US.

Simha

3:25 AM

@TAbraham torrents work slightly differently than other sites.. they change the source IP address every few hours.. so it becomes increasingly diffixult for any government org to keep track..

T Abraham

@KyleKanos well, Internet Archives is based in the US...

@Simha ok..I agree...

Kyle Kanos

@TAbraham So Wikipedia tells me

But the government does not actually keep tabs of every website, even "well known" ones

(the internet is bigger than you think)

T Abraham

@KyleKanos tells you what?

Kyle Kanos

@TAbraham That it's based in the US

T Abraham

yeah.. basically, it's unlikely that you'll get caught...

Kyle Kanos

3:28 AM

Feel free to believe that. I've known 3 people who were caught pirating media off the internet

One got hit hard with a $25k settlement that he's still paying off

T Abraham

fine.. you win...

anyway.. thnx for that other link..

Simha

@KyleKanos about making ebooks cheaper: but printing is one thing that adds to the cost. There's binding, transport, increase in price due to middle-men, etc..

T Abraham

that i agree with...

Simha

So what's actually coming in the way?

Kyle Kanos

@Simha No clue. And I'd be happy (now that I have a Kindle Fire) with some eBooks

But I don't think that most of the expense is in the printing, I'd imagine most of it is in the middle-men (e.g., marketers)

T Abraham

3:35 AM

i guess bcos many books in print are hard to convert into ebooks..

and maybe if people can get old books on the Internet, newer ones will come too...

Simha

that's true.. and many people believe that reading from an led screen strains the eyes..

T Abraham

also that..

Simha

and the color ebook readers are either too expensive or lack color quality..

@KyleKanos I think the reason most of those graduate students didn't opt for ebooks was because many of the quality books from earlier times haven't still been converted to digital..

Kyle Kanos

@Simha It was undergraduate freshmen, not graduate students. And if memory serves, it was eBooks straight from the publisher.

The question of which they preferred was asked after the year was over

T Abraham

chat.stackexchange.com/rooms/19520/winter-bash-secrets

Kyle Kanos

3:48 AM

blogs.kqed.org/mindshift/2012/09/…

^That's just one item I found

Not the article I remember

Simha

Interesting article, Kyle. I'll respond once I go through it..

Kyle Kanos

There's also this one

T Abraham

2

Nanoscience and Nanotechnology

Proposed Q&A site for students, professors, and researchers to ask questions about nano-science and nanotechnology

Currently in definition.

Anonymous

4:13 AM

@Simha There are many books that one cannot afford.That's when I switch to e-books.

Anonymous

@Simha By any chance,are you in NIE?

Simha

@KyleKanos It has almost the same points we made here. I'd like to add that there's also opposition from so-called purists who argue that the emergence of ebooks will take away the 'feel' of an actual book. I tell them: Get on with it !

@Ashwin No, I am not. Are you ?

Anonymous

@Simha My friends are.I am in DSCE.

Simha

@Ashwin In response to your first comment: Everyone does that. But why not make ebooks cheaper so that everyone can buy it legally ?

@Ashwin You from Mysore too ?

Anonymous

@Simha I agree with you.

Anonymous

4:27 AM

@Simha I am from Mangalore studying in Bangalore.

Simha

Ah. DSCE ?

never heard of it

Anonymous

Dayananda Sagar?

Simha

Oh yes, I know that. never knew the full form.. :)

Anonymous

Are you doing Engineering?

Simha

It's said that the weather's gonna drop to 10 degrees odd this year.., I'm second year PUC

Anonymous

4:33 AM

Mysore is relatively colder than other cities.

Simha

Now it's not Mysore, it's Mysuru !

Anonymous

:D

Anonymous

I GTG.Bye!

Simha

yeah seeya !

Danu

7:10 AM

Good morning

Sup?

hey there

Hello, Mr. Z.

8:26 AM

Does anyone here know the typical dimensions of a u-tube ?

atleast the tube diameter ?

I just want a rough figure for some calculations..

Anonymous

u tube used in what?

Simha

8:42 AM

the ones from the chemistry lab ?

Okay nevermind... thanks !

Kyle Kanos

1:50 PM

@Danu, @JamalS: This popped up in the arXiv this morning: Tensor calculus with open-source software: the SageManifolds project

Thought you might be interested in that

Jim

N.B. This is an early Xmas gift from Kyle Kanos. Enjoy!

Kyle Kanos

Haha, that might be the best gift ever: a link to a paper

Jim

You are so thoughtful

Kyle Kanos

Also, I just found out why my laptop always wanted to tank if I ran my simulations with resolution greater than 350$^2$: My stack size was limited to about 10 MB, rather than say 65 MB

That "small" change allowed me to run a 500$^2$ simulation last night

Yay!

Jim

I ran a simulation on Monday. Came in on Tuesday to an output file that was 14.2GB of numerical data

It was then I decided to redefine my loop ending conditions

Kyle Kanos

1:57 PM

In a single file?

Jim

yes

Kyle Kanos

Nice

At (2k)$^2$ (with 8 + 1 + 2*9 variables), I get about 700 MB each output. I usually go for about 70 outputs

Jim

Suffice to say I very closely approximated a true integral. Step size approached zero

Kyle Kanos

Yay Riemann sums!

Jim

Then I tried to open the file

First time I ever overtaxed my computer's memory and it was with a .dat file

spectacular crash though

Kyle Kanos

2:01 PM

You need to learn Python or Lua for file IO stuff

Jim

No, I mean I opened it on notepad

Kyle Kanos

Also: I hate when authors use log scale with labels 1e8, 1e9, .... instead of just taking the log10 of it and labeling it as 8 9 ....

@Jim I know what you mean, I'm just saying analysis on big files like that should be done using a scripting language

Jim

I used python

you can analyze it, no problem, but sometimes I like to check out the data visually. I can usually spot problems or patterns better than my code

Kyle Kanos

Yeah, eyes are often better then bits

Kyle Kanos

2:25 PM

Ah heck, I'll give the upvote, but consider it a pre-payment. I want that additional info or I'll be forced to write a competing answer — Jim 1 min ago

I'm actually writing it now

Jim

2:35 PM

Okay, I was going to give you a day or two anyway

Kyle Kanos

Updated.

And, actually, your upvote gave me two hats :D

11

Q: What makes someone deserving of a Ph.D.?

Few days back while attending a thesis defense, one Professor was asking the defender why does he think, he deserves the degree. I was wondering since then, is there really any general answer for that? or the answer should be given describing my own work and then emphasis them how it is important...

Jim

The answer also explains honorary PhDs

btw, your update was deemed acceptable by the committee

Kyle Kanos

3:00 PM

sigh No one seems to be very competitive:

winterbash2014.stackexchange.com/leaderboard/…

User Anonymous

@DavidZ - regarding the issue of you and hats, some gentleman nailed it:

I see you have yours already. — Rob Jeffries 16 hours ago

@KyleKanos Congrats. You are a distant winner.

Kyle Kanos

@UserAnonymous Last year was quite the competition amongst some of the other members

User Anonymous

Just compare 893/626 with 21/1. Landslide

Kyle Kanos

3:16 PM

What's the first pair of numbers?

Oh

Nevermind

User Anonymous

From your link

Kyle Kanos

I see it now, total hats to users

User Anonymous

626 users from this site have earned a total of 893 hats!

I gave up on 3, because most of the hats don't really suit my identicon!

Simha

None of ours does.. but still better than some people who wear the saint lucia hat..

Kyle Kanos

Just change your identicon then

User Anonymous

3:20 PM

:P

Kyle Kanos

Ouch: myfoxdc.com/story/27648718/…

3

User Anonymous

LMAO.

Simha

!

User Anonymous

That was about John Hopkins. About another John (Rennie), his hat really suits him.

Speak of advantages of not having an identicon :(

Kyle Kanos

@UserAnonymous Yeah, it was placed rather well

I think mine is placed fairly well too

Simha

3:26 PM

@KyleKanos Changing your identicon ? How do you do that ?

Kyle Kanos

@Simha Go to your profile -> edit -> change picture

Simha

Nope. That doesn't give you an option of changing the identicon. If it did, i wouldn't have had this shit-colored identicon.

User Anonymous

4

:)

Simha

What a fit.

User Anonymous

@Simha Really :)

Kyle Kanos

3:30 PM

@Simha Hmm, it may be that your identicon is set, but changing your picture (which cna be applied to all sites) eliminates anyone from seeing your identicon

Simha

Who cares anyways, I have the advantage of wearing the Saint Lucia hat the proper way.. :D

K. Nobody gets it.. BTW, I was going through math.se and got to know that the moderator elections are underway.. when will we have ours ?

Kyle Kanos

@Simha That assumes we will have one

I think the mods do a pretty good job as it is

Simha

Woah. I thought mod elections were done periodically throughout the stackexchange.. like once in 3 years or somethin'

Kyle Kanos

I thought it was on an "as needed" basis for the smaller sites, such as ours

On SO, I think it happens every year

Simha

But do all moderators participate on physics.se ? I've seen some mods not being not active at all.. (obviously i won't name 'em)

Are you by any chance gonna stand for election if there is an election in the near future ?

User Anonymous

3:44 PM

Me? No! :P

Kyle Kanos

Me? I guess I'd put my name in the hat

But I'm not too sure I would want the job, to be honest.

Simha

Is there a minimum rep you need to have to stand for it ?

User Anonymous

@KyleKanos You should throw your hat in the ring :D

Kyle Kanos

@Simha I think it's 3000. Might be more

Here's an old Meta.SE post that suggests 7k:

5

Q: Clarifications requested on the moderator election process

I have some questions about about the moderator election process (which should be decided now, before the list of candidates is fixed and bias may start to creep in): Say the process is as simple as people voting in a CW thread (as was the case with the nominations)... Are upvotes as well as d...

discussion moderators election nominations

Simha

I'm safe.. if i do stand, i'll miserably fail at the Q&A.. and either-wise, i don't know where i'll find as much time as @DavidZ does to be a good moderator..

Simha

4:18 PM

@KyleKanos I wonder why those answers on the meta post are not made community wiki.. what does actually qualify as "community wiki" ?

Kyle Kanos

@Simha Community Wiki (CW) posts are designated by the author of the post (or by moderator approval from a flag or if the question itself is a CW).

525

Q: What are "Community Wiki" posts?

Some questions and answers are marked Community Wiki and are owned by a Community Wiki user. Why have Community Wiki posts? How do Community Wiki posts work? How does a post become a Community Wiki post? How can the Community Wiki status be removed from a post? Return to FAQ Index

support faq community-wiki posts

Simha

4:36 PM

Thanks for the link Kyle ! Its almost 12 in this part of the world.. so.. adios !

Danu

5:17 PM

@KyleKanos cool, thanks! However, I can't program, so guess I won't be using it much :P

Kyle Kanos

@Danu Read my lips (okay words): L E A R N

:D

Danu

I'm in a math.phys. degree. Ain't nobody got time for side studies

Kyle Kanos

It's not side studies if it helps your career!

Danu

Still side studies. There's so much I could do that would help my career, if I had time :P

Kyle Kanos

New plan: stop sleeping

2

Also: if I get 5 more votes, I'll have rep-capped 2 days in a row :)

JamalS

5:29 PM

@KyleKanos: See my comment to your derivatives answer.

There's two more :)

Kyle Kanos

@JamalS: I was about to respond

But here's probably better

I know there's going to be loads of deviations from the "typical" notations I give

Listing them all would be a huge endeavor! I think I'm going to add a catch-all "there's many more, be sure to take note what you're reading!" to the end

JamalS

@KyleKanos Why not make it a Wiki answer?

Kyle Kanos

I dunno

Guess I could do that

JamalS

Would be nice... :)

Kyle Kanos

But do I lose the rep for doing that?

JamalS

5:36 PM

I don't think so, but it's worth checking the help thingy on the site.

Kyle Kanos

Found it

6

Q: How do questions marked community wiki AFTER you answer impact rep upon recalc

I did a search, and checked the FAQ, and checked out the questions which came up as related from the title, and still have nothing on this. But if this is a dupe, please close it and point me at the right question. :) (I say this because it feels like it SHOULD be a dupe; I just couldn't find it....

discussion reputation community-wiki reputation-recalc

Answer: nope

JamalS

Yay!

Yeah, that makes sense. You shouldn't receive reputation for work other people contribute to your answer, but you should for the original answer.

Kyle Kanos

I'm leaving a comment about how it's moving to CW, could you upvote it so people can see it (otherwise it'd be buried)

JamalS

Upvoted.

dmckee

@Simha One moderator essentially withdrew from service and eventually was removed from the list. The rest of us have more and less active times.

JamalS

5:39 PM

So I just edit it myself now?

Kyle Kanos

@JamalS Yessir!

I still need to find a question to ask so I can get a new hat (maybe 2 if I know the answer)

JamalS

5:52 PM

@KyleKanos: Thanks!

Kyle Kanos

No problemo!

And I think I've got my question

JamalS

@KyleKanos: That thing about Johns Hopkins has happened with Cambridge.

Kyle Kanos

Another ouch!

I wonder how that sort of thing happens

JamalS

A few years ago they sent out acceptance letters to students who had been rejected, I think even before interview.

That's like the reverse of a mock execution, but just as bad, at least it would be for me...

@KyleKanos: What's ya question?

Kyle Kanos

Even as a fan of American Football, I find this funny:

15

Q: What’s a “handegg”?

What’s a handegg? NOTE: This question is primarily related to the etymology of a compound noun which is not in The Dictionary. There is a hat this year called “Handegg”, given out for a posting that reaches a score of +7. But here’s the problem: the word handegg does not occur in the Oxford En...

etymology slang history connotation winterfest

@JamalS You'll see in a moment when I post it ;)

JamalS

5:57 PM

@KyleKanos Oh, I know, it's a GR question? I bet it is.

Kyle Kanos

@JamalS Sadly, it is not

JamalS

:(

@KyleKanos: Type faster, man, type, type!

Kyle Kanos

6:20 PM

Posted

JamalS

@KyleKanos: Hmm, not really qualified to answer that one

Kyle Kanos

Haha, doesn't matter!

skullpatrol

6:35 PM

►

Physics Meta

6:52 PM

-1

Q: How many publishing-physicist are there in the world?

I was looking up Michio Kaku's blog specially the article "So You Want to Become a Physicist" and in that I have found that according to his statistics 30,000 physicists are part of American Physical Society (APS) that said, I assumed that an publishing physicist may probably do physics for 50 - ...

discussion soft-question

Kyle Kanos

7:03 PM

@SeanAllred: You'd be proud: I'm using emacs on a cluster right now (and finding it frustrating that I have to keep searching for commands)

Sean Allred

7:35 PM

@KyleKanos cluster?

Kyle Kanos

Supercomputing cluster

Specifically Stampede: portal.tacc.utexas.edu/user-guides/stampede#overview

JamalS

8:25 PM

@KyleKanos: You're at the university of Texas?

Kyle Kanos

Negative

UT just hosts the cluster I use

I'm at Clemson:

Clemson University

Clemson University /ˈklɛmsən/ is an American public, coeducational, land-grant and sea-grant research university located in Clemson, South Carolina, United States. Founded in 1889, Clemson University consists of five colleges: Agriculture, Forestry and Life Sciences; Architecture, Arts and Humanities; Business and Behavioral Sciences; Engineering and Science; and Health, Education and Human Development. As of 2013, Clemson University enrolled a total of 16,931 undergraduate students for the fall semester and 4,372 graduate students and the student/faculty ratio is 16:1. The cost of in-state tuition...

Sean Allred

That's my CS prof's alma mater!

Kyle Kanos

I'll be my alma mater soon ;)

Sean Allred

@KyleKanos Ah, so operating over ssh?

Kyle Kanos

Doubly so, actually

Stampede is part of the XSEDE network, so you have to SSH into XSEDE and then SSH over to Stampede

Sean Allred

8:35 PM

Hahaha nice :)

JamalS

@KyleKanos: Where are you going to go after that?

Kyle Kanos

I've got an interview coming up at Wells Fargo for a quantitative finance position

If not there, some other industry job. General Electric & Boeing have facilities near me that I would apply for

JamalS

@KyleKanos: You're going to be a quant?!? Nooooo! Be a researcher, Kyle :)

Kyle Kanos

That's another alternative. Apparently Los Alamos is interested in me

JamalS

@KyleKanos: That sounds promising; I remember reading about Los Alamos from Feynman's autobiography.

@KyleKanos Just to put you off finance: A friend of mine graduated from Cambridge with a Ph.D. in mathematics; he was interested in quantum computing and artificial intelligence. He was hired by Goldmann Sachs in Hong Kong, and half way through they changed the project he was working on, and just made him manage their codebase. Long story short: he quit out of misery.

Kyle Kanos

8:45 PM

To be honest, maintaining code wouldn't be too bad. I thoroughly enjoy messing around with codes

user54412

I recently talked to someone I know at Goldman, and they said in the last couple years salaries for new people have gone way up, and workload has gone down a bit, since they are now competing with Google and all these Silicon Valley startups for the brightest young people

JamalS

@ChrisWhite: So? Salary <<< work.

user54412

In making a "meaningful" contribution to the world, perhaps? But $250,000/yr to work less hours than a grad student is awfully enticing...

JamalS

@ChrisWhite It's unfortunate professors aren't payed that much.

Kyle Kanos

Something like 45% of all quantitative analysts make between 100 and 200k per year

Another 20-something% between 200 and 500k

JamalS

8:51 PM

There's also a bonus potentially.

Kyle Kanos

Of course, those in that higher bracket are usually working at hedge funds where salaries are higher than with banks

user54412

The wealthiest professors I know get almost all their money from outside consulting -- whether it's quantum physicists advising hedge funds, statisticians analyzing nuclear power risks, or general relativists making Hollywood movies

3

Kyle Kanos

There's one faculty here who commented to me & my classmate about us keeping "bankers hours" because we were leaving at 5 (to go to a sub-departmental party). Dude comes in between 11 a and 1 p and then goes home at 6 p. Teaches 0 classes. WTF is he talking about :/

JamalS

@ChrisWhite: If I'm a string theorist, will people seek me for outside consulting?

user54412

@JamalS possibly? It's not like my quantum physics prof researched anything related to finance.

JamalS

8:55 PM

Well, that's good news.

hwlau

9:24 PM

@ChrisWhite will they consult quantum prof. anything related to brain?

Sofia

10:11 PM

@KyleKanos: Am I permitted to post a question and answer by myself?

ACuriousMind

@Sofia Yes, you are. There's even a checkbox for Answer your own question when you ask a question

Sofia

@KyleKanos: Fine!

Phonon

10:30 PM

@ACuriousMind hey, I wrote an answer to that interaction question, with the hope to clarify things a bit more(basically building on your answer)... do you think it'll help the OP as it is?

ACuriousMind

@Phonon I have just started to read it :)

@Phonon: Two nitpicks - you do not define what the $M_m$ are, and self-adjoint is a stronger statement than Hermitian, and it is self-adjointness that observables must fulfill.

Phonon

@ACuriousMind alright thanks, will fix it

ACuriousMind

@Phonon: Additionally, I disagree with "This should clarify that a measurement is by definition nothing but an interaction between an external physical system and the quantum system under study." To me (and von Neumann/decoherence people), a measurement is an interaction with a special kind of time evolution. There are interactions which are not measurements (most interactions between quantum system do not produce decoherence, after all)

Phonon

@ACuriousMind yes indeed, I had clarified on this difference further in the answer (augmented systems), but you're right as it stands in that paragraph it's not entirely correct

Huy

10:45 PM

I'm trying to reproduce a result from years ago, which was a derivation of the quantum Zeno effect. Namely, I started by showing if $$H = \hbar \mu \begin{pmatrix} 0&-i\\i&0 \end{pmatrix},$$ then $$e^{-\frac{i}{\hbar} Ht} = \begin{pmatrix} \cos \mu t & -\sin \mu t\\ \sin \mu t & \cos \mu t \end{pmatrix}.$$ I don't know if it's just me being too tired, but the i's cancel and then I don't manage to get $\sin$ and $\cos$. Did I make a mistake in my notes or are my calculations right now incorrect?

Phonon

@ACuriousMind at least I managed not to use collapse hahaha :pp

@ACuriousMind loved these two (1, 2) recents xkcds ;D

ACuriousMind

11:02 PM

@Phonon Hehe...it's the download folder for me, but yes :D

Phonon

@ACuriousMind oh man, for me it's really My Documents that is like that... :( such a mess, never get around to fixing it!

ACuriousMind

Nah, Every file that I create is neatly named.

Just the downloads are terrible, and they get named before they get sorted :P

Phonon

:DDD

ACuriousMind

Yes, I am a bit compulsive when it comes to my file and folder structures :D

Phonon

Worst is when you have a folder of papers with names like: 0211443v5.pdf, 1-s2.0-S0009261400012070-main.pdf... LOL, I literally facepalm myself everytime I have to go through them

ACuriousMind

11:05 PM

Yeah, I really hate the ArXiv for the names of its PDFs ;P

Best name currently in my download folder: E4FB23E8AD9F7C3573EA40174E3E0665.pdf, competing with 10665221_1396256293997757_6128123913373482386_n.jpg

Phonon

hahahahhahaha

:DD at least different file types :DDD helps a lot already haha

ACuriousMind

Yeah. But I still have to open every pdf to find out what it is and how it should be called. The pictures are easier^^

@Phonon: Your second xkcd is (to me) reminiscent of the early, often weirdly melancholic ones. Good to see Randall return to his roots ;)

Phonon

@ACuriousMind hahaha yeah idd :Dd

ACuriousMind

Btw, WHERE IS YOUR HAT? ;)

2

Phonon

:DD don't even know how to get one...

ACuriousMind

11:16 PM

All the non-secret ones

Phonon

so beautiful the background in this page

lol I only have this ugly cake and candles one... how does this qualify as a hat? :DD

@ACuriousMind btw isn't it weird that we don't have $\ket{}$ in SE? has to do with included packages of MathJax?

ACuriousMind

11:36 PM

@Phonon Half the "hats" aren't hats. There are shirts, and lamps, and waffles :D

@Phonon I think it's because none of the "standard" math packages like amsmath defines this, you need something like braket, which is not included in MathJaX AFAIK

Phonon

@ACuriousMind ah yes, makes sense

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