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00:00 - 17:0017:00 - 23:00

12:02 AM
@0ßelö7 Fantano in full rage mode
@0ßelö7 Any frame in the last Cory Feldman album
Lol, make Cal your avatar
@BernardoMeurer link?
I will do it
@BernardoMeurer that was he mostly drooling off while reviewing in underwears
is that what is called a rage mode?
@0ßelö7 make a Filthy Frank avatar
no, he is disgusting
12:07 AM
how about idubbbz in his green gay suit
@ACuriousMind In your answer, can you really state $A=-A^*$? Do you not need to check domains?
@0ßelö7 I'm silently assuming a finite-dimensional vector space, of course :P
God dammit I was hoping you'd figure out the general case :P
I've been working on this for a while
It isn't obvious
I got it for bounded symmetric operators
Can I be a pedant and say that if the question states that $\langle \alpha \vert A \vert \alpha \rangle = 0$ for every vector $\lvert \alpha \rangle$, that means that $A$ is everywhere defined, so there are no domain issues?
@ACuriousMind But what is the domain of $A^\dagger$?
Can the domain of $A^\dagger$ be less than the whole thing?
12:13 AM
Are there everywhere defined operators whose adjoint is not everywhere defined?
I feel there shouldn't be
@ACuriousMind Also you assumed a separable Hilbert space
So I can be a pedant too
Sure, we're on physics.SE here
@ACuriousMind Ok, so the operator definitely should not be defined everywhere then...
12:14 AM
isn't that the Riesz representation theorem
@BalarkaSen that just says $H^*=H$
@heather too late
@0ßelö7 maybe i misremembered
@BalarkaSen check my account
12:16 AM
@BalarkaSen Riesz says for $L:H\to \Bbb F$ linear and continuous, there is a $y\in H$ such that $L=\langle y,\cdot\rangle$
Feeling a strong 7, light 8 on this
@BalarkaSen is that a girl crossing her legs?
@0ßelö7 save it for your next one =)
@0ßelö7 getcho mind outta gutter boi
that's a thumbs up
12:19 AM
literally how
@0ßelö7 Hm, but adjoint of a linear operator is the same as it's dual after identifying $H$ with $H^*$ using the inner product, right?
In finite dimensions it is. Not sure about infinite
@BalarkaSen For continuous operators, yes, I think so
The trick here is that it's a possibly unbounded operator, but defined everywhere. Those are rare and very pathological
@ACuriousMind Your proof needs $A$ to be closed.
@ACuriousMind Ah, then use closed graph theorem. You need $A$ bounded.
Sorry. My downvote stands.
You downvoted me for giving an answer in accordance with usual practice in physics? Why don't you simply give the "correct" answer yourself if you care so much about this?
@ACuriousMind I don't know the correct answer.
12:47 AM
@0ßelö7 OMG, I see your green suit...
@0ßelö7 I don't know who your avatar is, but it's mildly creepy.
he's a god
@heather By the way, is it confirmed that SBA is teaching the calculus class this Saturday?
what with the weather he said there's a chance he won't be able to make it but he hopes he will be able to.
I never followed SBA on the site, so I don't know anything about his mathematical abilities.
12:52 AM
@BernardoMeurer I need linux help in T-30 mins
@0ßelö7 I'm available
@0ßelö7 What distro are you using?
@Jasper don't know, it's a server
@0ßelö7 uname -a
@BernardoMeurer thus far I haven't managed to log on
12:54 AM
Oh boi
@0ßelö7 There was once I edited my .profile file and after that I could not log into the desktop anymore.
1:10 AM
If omni directional speaker is doing 82db at 1 meter sound pressure,what is the sound power in watts?
@ACuriousMind Are you mad at me or do you want to discuss
1:27 AM
@BernardoMeurer skype
@0ßelö7 Sec
1:43 AM
@Jasper ubuntu
2 hours later…
4:07 AM
@BernardoMeurer I wasn't there and I don't know cmake. But I did think it looked interesting the one time I investigated it.
4:28 AM
@dmckee OpenCV's CMake use is disgusting
4:46 AM
Flexing like boss. Coding Branes for the lolz
k out . .
Happy Birthday Voyager - beautiful 5 minute video by the New York TImes' Dennis Overbye, Jonathan Corum and Jason Drakeford.
5:18 AM
A: Is there a mathematical equivalence between gravitational optics and quantum optics or are they mathematically incompatible theories?

WetSavannaAnimal aka Rod VanceGravitational optics is very different from quantum optics, if by the latter you mean the quantum effects of interaction between light and matter. There are three crucial differences I can think of: We can always detect uniform motion with respect to a medium by a positive result to a Michelson...

Hmm, it seems we cannot just superimpose gravitational waves to create standing waves
The above search is inspired by last night dream, which took place in an alternate version of my 3rd year undergrad GR course. The lecturer talks about a weird equation in general relativity that has a huge summation symbol, and then talked about gravitational waves emitting from a body. After that lecture, I then asked the lecturer whether gravitational standing waves are possible, as a imagine the hypothetical scenario of placing a node at the end of the vertical white line
The weird equation looks roughly like this:
$${\Large \sum}_{\alpha \text{ } \beta}^{\delta} + (forgot) = \frac{(forgot)}{(forgot)}$$
6:07 AM
[The Cube] Regarding The Cube, I am thinking about an energy level diagram like this
where the infinitely degenerate level is the lowest energy level when the environment is also taken account of
The idea is that if the possible relaxations between energy levels is restricted so that to relax from an excited state, the bottleneck must be passed, then we have a very high entropy high energy system confined in a compact volume
Therefore, as energy is pumped into the system, the lack of direct relaxation pathways to the ground state plus the huge degeneracy at higher energy levels should result in a lot of possible configurations to give the same high energy, thus effectively create an entropy trap to minimise heat loss to surroundings
6:24 AM
Hi, everyone! :-)
So in terms of The Cube, it will mean the rotational states had to somehow be protected from relaxation in the form of heat
::Realises that nobody is around and shuffles off::
@CooperCape are you around?
::No one's home and you cannot find me::
@Kaumudi.H morning :-)
6:33 AM
@JohnRennie Morning! :-) Say, which is the setup file for installing Office in the pen-drive that you gave me?
@Kaumudi.H hi, sorry for the delay - making Mum's morning coffee :-)
Ah, np :-)
If you look on the pen drive is there a folder called temp or install?
No, but there is one called "Stuff" which contains another folder named "Office 2k3".
Aha it's the folder called Office2k3. In there is a file called setup.exe. Just run that file and accept all the defaults.
6:42 AM
OK! (Y)
Once you've completed the setup you need to install Office service pack 3. There is an installer for this in the Stuff directory.
Installation in progress, thanks! :-)
@JohnRennie And what is that?
Hang on, I'll dial into my home server to check ...
How's the transition to college going?
@JohnRennie ...what?
@skullpatrol Hi! :-) I'll get back to you in a bit, sorry.
6:45 AM
np :-)
@JohnRennie I've been trying to compile OpenCV with Cuda for over 8 hours now
I want to die
@Kaumudi.H that's the installer for Office SP3. It should be in the Stuff directory.
@BernardoMeurer you have my sympathy. Trying to build large libraries on a new platform can be an exercise in frustration :-(
No, no, I meant to ask what the "Service Pack 3" is.
You're not allowed to die in Cali, only multiply @BernardoMeurer
@JohnRennie This is insane, Intel TBB has an incompatible C++ ABI with GCC 7
I can't handle this anymore
6:48 AM
@Kaumudi.H MS release service packs to fix bugs people find in Office. Service pack 3 is the latest and greatest of these bug fixes.
@Kaumudi.H Use LibreOffice, it's free and gratis!
And you know what, it even kind of works!
LibreOffice is not bad, but Office 2003 is the best office suite I've ever used.
@JohnRennie Ohh, right. I'm unable to find that, BTW. It looks like everything has installed properly because I am able to access all of the programs; Word, PPT, Excel...
It combines power and speed and small size. Later versions of Office just added cruft but no significant functionality.
@Kaumudi.H Good :-) The SP installer should be in \Stuff on the USB key ...
It's not there!
6:50 AM
If not I can bung it on my web server.
@Kaumudi.H look on swarchive.ratsauce.co.uk
You do need the service pack ...
@Kaumudi.H there is also an addon that allows Office 2003 to read (but not save) files from later versions of Office, and you probably want this too. The installer for this should also be in \Stuff (but probably isn't if I forgot to include the SP3 installer).
This is it
I'm moving to a compile-only distro
No more packages
packages break everything
Compile-only distro: download tar, untar, type make, spend next week Googling obscure compile errors.
@Kaumudi.H once you installed SP3 look on my server and download OfficeFileFormatConverters.exe. That's the converter for opening files from later versions of Office.
But NB after installing SP3 you need to reboot before installing the convertors.
Sorry about the delay; was caught up in a string of reboots.
@JohnRennie Downloading now. Thank you :-)
@JohnRennie It's easier because you can control how things are compiled
Like using -Ofast and fucking it all up :P
-Ofast destroys families
@Kaumudi.H BTW let me be the first to publically congratulate on PASSING YOUR DRIVING TEST :-)
7:01 AM
Hurricane Harvey was god compiling rain with -Ofast
@Kaumudi.H Shit, you passed the driving test?
@JohnRennie Ah, haha, thanks! :-) I received my license number via text message last night!
@BernardoMeurer Yeah, man!
I failed mine so bad now they don't me near anything with wheels anymore
@BernardoMeurer car and motorcycle! She's buying a Harley Davidson now.
I might get my license here, costs 25 bucks
Hi @EmilioPisanty, it's great that you want to help me clear out confusions. I think we have a misunderstanding here. When you say "if you really want to "understand"", I've thought you were mentioning at my questions directly to the close voter, not the question in meta. When you mention about my original post, you think that it's a hopeless mess of confusion? Why? Except being off-topic, it seems clear to understand, doesn't it?
7:03 AM
@JohnRennie ^ Lies but yes, car and scooty, without gears.
Scooter only? Not a big motorcycle?
@JohnR: Wokay, all installations are complete!
Okay, I'm downgrading intel-tbb until it works
@JohnRennie -_-
@Kaumudi.H should be all working fine now
7:04 AM
@JohnRennie And I'll check by finish my ISE project now, which has to be done using PPT.
@Kaumudi.H it was a serious question? Are there separate tests for scooters and big motorcycles? In the UK it's just one test to ride any two wheeler.
Well, of course! I dunno how to drive motorcycles with gears!
@Kaumudi.H Ah Powerpoint. I used to have to do presentations in Powerpoint. And to be fair it's pretty good.
7:06 AM
@BernardoMeurer Why, what'd you do?
@Kaumudi.H I'm just joking, I don't know how to drive civilian vehicles, never took a test
Ah, OK :-)
I can pilot a tractor like Schumacher though
@Kaumudi.H I'm a bit surprised they expect you to use Powerpoint without supplying you with a copy of the software. Or are you supposed to do it on the college PCs?
A tractor? Wow, that's an usual skill to have picked up!
7:09 AM
@Kaumudi.H I grew up in a farm dawg, I got some agrarian skills
Can you milk a cow?
Of course
@JohnRennie I s'pose they'd let us use the computers in the lab for a very limited amount of time but I think that they figure that we have access to Powerpoint softwares in one way or another.
Milking is easy, but you need practice otherwise your forearms BURN afterwards
It's good workout
@BernardoMeurer Oh, wow!
7:10 AM
@BernardoMeurer I can fly a glider, if we're boasting about driving (piloting) skills :-)
@JohnRennie Gliders don't feed families
@Kaumudi.H that seems harsh if you can't afford a laptop
@JohnRennie And they expect us all to own a laptop, of course.
I forgot to compile OpenCV with -O3
7:12 AM
OK, I gotta get on this project; otherwise, I will have nothing to show him when college reopens in a few days.
Karma!! That's what you get for rekking other chat room members! :-)
Crap, another compilation error
@Kaumudi.H Later gator
7:21 AM
OpenCV is huuuuuge
12 hours ago, by Emilio Pisanty
or as AFT would say, yyyyuuuuuuge =P
66%, so far so good
please no more errors
it's been all day
I have the build script now so no one else has to go through this
Every time it hangs for a second my heart skips a beat
Lol, it's 3.8 GB
8:10 AM
Ahhh, it seems that I've forgotten how to use PPT :-(
The last time I used the software was 4 years ago, I believe.
Wow! Why so long?
Too much time spent on JEE prep?
8:37 AM
Q: Update to Mathjax 2.7.2 please

Luc J. BourhisPhysics.stackexchange currently uses 2.7.1 with the config TeX-AMS_HTML-full which is affected by a visual glitch on both desktop and mobile version of Safari under latest OS, \vec{x} results in the arrow displayed too far to the right (issue #1737). This has been fixed in 2.7.2. Thanks.

9:15 AM
Q: Homework questions on mobile phones

Countto10I have never used the app for this site, but if you ask a question on a mobile phone, there is no homework guidance box, as there is on the full site, due to screen size limitations. I think it's a safe asssumption that many students are using their phone to place their homework questions, in wh...

9:38 AM
@0ßelö7 I don't really care for the functional analytic technicalities in this case - of course this statement needs some additional assumption to hold rigorously in the infinite-dimensional case, but I'm 99% that that's not what the OP wants to know (and, judging from the comments and other failed attempts, the "simple" version of the statement seems to confuse enough people already :P)
@Kaumudi.H If he keeps speaking at that tempo he's going to suffocate from not breathing enough ;P
@Kaumudi.H You can always use the Open or Libre Office variants if you can't get PPT itself (I don't know how close they are to the original, though, haven't used PPT in ages)
10:17 AM
Q: Chat does not support latex input

alloThe chat does not show LaTeX, not even in the comments which were moved to chat and had working LaTeX in the comments section.

11:06 AM
@PhysicsMeta Really? ::sigh::
11:58 AM
Humanity’s message sent to Voyager yesterday: "We offer friendship across the stars...."
Apparently, they want to first make sure the aliens aren't stronger, and only then take over their civilization
What is the definition of exterior derivative?
@0ßelö7 Nice suit.
@BalarkaSen hm?
Was just complimenting your gravatar.
It's your all time best
12:11 PM
Nah, his best imho was the raider head band guy.
12:28 PM
The whistles go WOOOOOOO
12:38 PM
I think it's still on your network profile?
@skullpatrol Yeah, one of my extensions broke my chat
Fixed it tho
12:43 PM
Anything new?
Football starts tonight.
@skullpatrol American football or...?
NFL, yes.
1:03 PM
> On loan until 07/21/2018
Probably a prof.
1:53 PM
@Qmechanic shouldn't this get migrated to hsm rather than straight-up closure?
Q: Why were the SI-unit prefixes chosen to be a multiple power of 3?

crezefireWhy were the SI unit prefixes, i.e. \begin{align} \mathrm{giga} && 10^9 \\ \mathrm{mega} && 10^6 \\ \mathrm{kilo} && 10^3 \\ \mathrm{milli} && 10^{-3} \\ \mathrm{micro} && 10^{-6} \\ \mathrm{nano} && 10^{-9} \end{align} chosen to be a multiple power of 3? Edit: Although this questio...

2:05 PM
@Mithrandir24601 amazon is evil. I bought a book for research and when I went to check on the shipping info, I saw the price doubled
the next person who wants it is screwed
You could turn around and sell it for triple: screw on to others as amazon would screw on to you :P
@EmilioPisanty : Possibly. I just feel uneasy about undeleting & migrating a post that OP self-deleted.
@Qmechanic I think it's quite reasonable to assume OP deleted because they thought it was unwelcome
which it isn't, much
You can leave a comment explaining what's happened, and OP can re-delete on HSM if they want to
2:21 PM
@EmilioPisanty : Ok. Done.
@Qmechanic Glad to hear it.
@Qmechanic hmmmm, wait. I meant migrate and then comment.
but oh well
it's the thought that counts :P
@skullpatrol hmmmm
no, it's the thought and also the action =P
2:32 PM
Absolutely, pal.
[The Cube]
9 hours ago, by Secret
user image
I think I will made a PSE later asking about this
But first, I need to figure out how to formulate it
@BalarkaSen I agree, this is the goat avatar
@ACuriousMind So you're not the least bit curious what the minimal conditions you need for the result to be true are?
2:51 PM
@Qmechanic seriously, though, is it clear to OP how to proceed if they want the question migrated?
While a grid of 64 round independent objects can potentially have 64 sets of rotational energy levels, and we also know that the degeneracy of rotational energy levels are $2j+1$
@0ßelö7 What? That's just typical :/
@Mithrandir24601 thankfully, the book is obscure enough that the price will go down before anyone else tries to buy it lol
3:07 PM
Well... Hopefully... I find it hard to trust big online retailers when it comes to things like this for some reason :P
the major challenge is how to restrict the possible relaxation pathways so that in order to relax back to the ground state, at least one lower rotational level has to be passed, thus creating the bottleneck shown above
It's like that moment when I first discovered that supermarket fruit/veg and meat doesn't taste as good as the greengrocer's or butcher's but is also more expensive
Mithrandir, do you know of the types of possible pathways for rotational energy levels to relax?
@Mithrandir24601 in what world is supermarket stuff more expensive than hipster stuff
0celo, do you know of any solutions from the top of your head that describe the collision of two gravitational waves?
Since gravitational waves are qudrupolar, nonlinearity will mean they cannot just superimpose on each other, but I am not sure what the collision look like ad whether the result is still wave like
3:23 PM
No idea, sorry
I would check a gravitational waves book, I don't know much about them
Chris White did...
ok nvm, thanks
3:58 PM
@0ßelö7 Bristol :) Tesco opened a shop on an independent street near where I live and there were riots outside it as a result
I'm really not kidding - I can get the best fish I've ever had at about half the price it would be in a supermarket
@Mithrandir24601 Do you have bazaars in the UK ?
Here people rarely go to supermarkets to buy groceries, meat, fish, fruits, etc :P
I have just read QED-Feynman. What should I read next? anyone?
That sounds like a pop-science book :P
@Blue yeah, although we don't generally call them as such and there can also be open air stalls as well
4:12 PM
@SpaceOtter Classical Fourier Analysis by Grafakos
@John Rennie (From 9 hours ago oops... ) I am now...
Though I have a feeling I know what this would be about :/
4:27 PM
Hello my droogs
@Slereah hiya
want to do the honours?
Q: Dot product formula proof

F2NDCIf two vectors $\vec{A} =A_x\hat{i} + A_y \hat{j} + A_z \hat{k}$ and $\vec{B} =B_x\hat{i} + B_y \hat{j} + B_z \hat{k}$, have angle $\theta$ between them then the dot product (scalar product) of $\vec{A}$ and $\vec{B}$ is $$\vec{A}\cdot\vec{B} = |\vec{A}||\vec{B}|\cos \theta$$ $$\vec{A}\cdot\...

'fraid not
House keeping to do
@Slereah long time no see
Not me, I can see all the time
Well at night I mostly keep my eyes closed
But I could open them any time
@EmilioPisanty *honors
4:35 PM
Fortunately my trials are nearly through
@0ßelö7 no, I don't think so
Only 5 weeks of that dumb web development clas
though at least I have applied my skills to a worthwhile end : samuel-lereah.com/articles/Physics/…
Though beware, guy in San Francisco, I have google analytics on!
I can see your every mooove
my QFT and GR courses are using opposite metric conventions rip in pieces
@Slereah "site title", what a postmondernist site name :P
the GR convention is the correct one
4:45 PM
@ACuriousMind It goes well with the opening blurb of the front page
according to @ACuriousMind when we figure out M theory we will know the right signature
it will be the GR one
Does M theory even use a signature
there is a metric
I thought string theory did it all in a Riemannian way!
4:46 PM
I'm still not 100% sure what the site title should be
Not too whacky because it's partly a thing to show off to employer
But still catchy enough
@Slereah Hm? The strings move in a 10d Lorentz target spacetime.
Likewise, the branes of M-theory move in a 11d Lorentz target spacetime
@ACuriousMind How are talks even supposed to work. I don't think I can do more than 3 reasonably detailed proofs in an hour
I thought the target space wasn't real :p
@ACuriousMind wait, there are two different backgrounds?
so spacetime is 21 dimensional?
@0ßelö7 I've never seen a talk about an advanced topic where a "reasonably detailed proof" of anything was given
4:47 PM
this is getting out of control
@0ßelö7 Ehhhh, no
M-theory and the five string theories are dual descriptions, you're not supposed to apply two of them at the same time
@ACuriousMind me neither
I don't understand how talks work
They don't.
I was at a talk yesterday that was supposed to have a detailed proof
it was completely derailed by some professor who didn't believe a calculation
@ACuriousMind actually I take back what I said. It's 50/50
the topology talk had a full proof but it took 45 minutes
Basically most talks are just good to take away a bunch of buzzwords you can look up if your interest was aroused by the content
4:50 PM
He could have just said to see the proof in Steenrod
If the speaker is really good and the prerequisites align with what you know you may even take away some osrt of actual high-level understanding of the topic :P
@ACuriousMind I edited my question that was put on hold but I doubt I put it in a format that was 'on-topic'. If it's unsuitable just close/delete if you can...
@ACuriousMind that's what my advisor said
@ACuriousMind that's what I want to do
But I don't know how to cram all of it in one hour (or multiple hours for that matter)
@0ßelö7 That's the ideal, but it's not something you shouild expect from the average talk, imo.
And it also depends on the topic and how well it lends itself to hand-wavy short descriptions that nevertheless convey things like proof sketches
That's why it is best to work in humanities
"Well maybe people are bad???"
4:53 PM
@ACuriousMind I want to give a talk on my GR work first. That can be hand-wavey. But I also want to present my program for Sobolev spaces and elliptic regularity, which is reasonably original. But the devil is in the details there.
@CooperCape I'm afraid not, you're still just asking us to check whether or not what you wrote there is correct - such questions are not a good fit for the site, since the potentially correct answer "Yes, that's right" is too short to even submit as an answer
Close it then - is it a bit cheeky to ask if it is? :/
@ACuriousMind Two of the people don't know anything about $\psi$do's, which is an issue.
@CooperCape It is already closed - you should be able to delete it yourself if you want to. (And yes, what you wrote there is correct)
Okay - apologies for the inconvenience... and thanks :p
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