The h Bar

Slereah

4:00 PM

Is there a relation between the variance and the information of a PDF

John Rennie

And AVG is using around 15% CPU?

user228700

Yes.

John Rennie

I don't think that is sinister. AVG is up to something, maybe doing a scan, and that is using CPU and heating the laptop as a result.

user228700

It's been updating itself and doing all kinds of things of late, yes :-/

John Rennie

Did you download HWMonitor? That will show you the temperature inside the laptop.

Download link here

Balarka Sen

4:03 PM

@0celouvsky shrug

user228700

@JohnRennie Zip file?!

Slereah

"This formalism, as we have shown elsewhere,' was the outcome of a complicated conceptual process of trial and error and it is hardly an overstatement to say that it preceded its own interpretation, a development almost unique in the history of physical science."

Basically nobody knew what they were doing in QM

Balarka Sen

meh don't ping me. i have to stay away from this chat and be productive, or at least try to

John Rennie

@Kaumudi.H setup file - then run the setup

user228700

Slereah

4:08 PM

"For example, we might have a joint probability distribution for the political party and religious affiliation of individuals."

Odd example for a QM book

John Rennie

Yes, the high CPU is drawing a lot of power and generating a lot of heat as a result. I have basically the same laptop as you and my figures look like this:

user228700

Gah, what's the issue, then?!

John Rennie

How good is your Internet connection? If you uninstall AVG will you be able to install it again? It's about a 100MB download I think.

Kiarash

Hey everyone. I have a question! is there any classical counterpart for fermions in some sense?

user228700

I doubt if I'll be able to install it again :-/

user228700

4:10 PM

100 MB, hmm...

user228700

OK, that's manageable. Why, do u want me to uninstall it?

AccidentalFourierTransform

@Kiarash in a sense, both fermions and bosons become classical particles in the macroscopic limit

ACuriousMind

@Kiarash Not really, no.

AccidentalFourierTransform

e.g., Fermi/Bose distributions become the Maxwell distribution

John Rennie

@Kaumudi.H Well it looks like AVG is using a lot of CPU for some reason. If I wre looking at the laptop here I would uninstall AVG and see if the CPU usage and temperature go back to normal.

user228700

4:11 PM

OK. I'll uninstall it now.

John Rennie

My only concern is reinstalling it afterwards.

ACuriousMind

You can introduce "fermionic" (read: Graßmann) phase space coordinates, and that is done e.g. in the Hamiltonian BRST procedure, but these are auxiliary variables rather than representations of something physical

user228700

I don't share that concern. My #1 concern at the moment is "Oh God, please stop this heat"

user228700

"Your computer must now be restarted"

John Rennie

How is it doing? Uninstalling OK?

Good, now restart and lets see what happens after the restart.

user228700

4:14 PM

Wokay. Brb, then.

AccidentalFourierTransform

$H=p\cdot\alpha+m ß$

John Rennie

@Kaumudi.H :: John drums his fingers nervously ::

ACuriousMind

@AccidentalFourierTransform Stop making fun of my ß

AccidentalFourierTransform

never!

ACuriousMind

Hm, okay then

John Rennie

4:17 PM

@ACuriousMind is there an in joke in that equation?

Slereah

Everrett calls a probability measure $M$

Disgusting

user228700

@JohnRennie Restarting again (uninstalling all (2--3)AVG programs)

ACuriousMind

@JohnRennie The joke is the ß instead of the $\beta$.

John Rennie

@Kaumudi.H That's OK

AccidentalFourierTransform

its the Dirac Hamiltonian, and the standard notation is $\beta$ instead of ß

user228700

4:18 PM

All done!

John Rennie

@ACuriousMind ah. And there was me expecting something witty :-)

ACuriousMind

where I'm being generous with the word "joke"

Kiarash

@ACuriousMind yup. how have people convinced that the quantization rule for fermions is anti-commutation relationß? I read arguments in Peskin that's based on somehow similarity

John Rennie

@Kaumudi.H OK. Lets see what Task Manager and HWMonitor show now.

user228700

7%

John Rennie

4:19 PM

@Kaumudi.H 7% total? Does it show what apps are usign that 7%?

user228700

sonnet

Here is a question:
https://lh3.googleusercontent.com/-Z9DOL_rOb08/WP92t_GcWCI/AAAAAAAAVaU/RYGma3K-AFs0Er7Y2i8A_N3kTstQBimTgCL0B/h1053/4111855928331722415%253Faccount_id%253D2

John Rennie

@Kaumudi.H ah, that looks much better! :-)

sonnet

Here is my answer

ACuriousMind

@Kiarash Similarity to what?

sonnet

4:20 PM

the solution seems awfully easy

user228700

@JohnRennie Chrome, task manager etc.

sonnet

am i doing it right?

Slereah

Only one way to find out

Just apply the vectors on the matrix

John Rennie

@Kaumudi.H notice the cores are now running at a shade over 1GHz instead of flat out at 3.4GHz.

user228700

Flat out at 3.4GHz?

ACuriousMind

4:21 PM

@Kiarash The usual lore is to show that you can't quantize fermions with commutation relations because you get negative norm states, so you pick anti-commutation relations, inspired by Pauli exclusion being equivalent to anti-commutation of fermionic creation/annihiliation operators.

John Rennie

@Kaumudi.H Modern CPUs vary their speed depending on the load. The CPU in your laptop is 3GHz, but if the load is low it will throttle back to a bit over 1GHz. When the load is very high it will rmap up to 3.4GHz.

sonnet

@Slereah I'll get the linear equations back... that's it?

ACuriousMind

@sonnet Yes (that's a silly exercise :P)

John Rennie

@Kaumudi.H your original picture showed:

user228700

@JohnRennie Ah, I see.

John Rennie

4:23 PM

i.e. the cores running flat out.

Slereah

@sonnet then it's all good

John Rennie

If you look now you'll see they are running at about 1.2GHz

user228700

Ah, yes.

sonnet

okay thanks @ACuriousMind @Slereah

John Rennie

Your laptop is hereby fixed!

But ... has no anti-virus installed.

user228700

4:24 PM

@JohnRennie Yay! \O/

AccidentalFourierTransform

windows defender is all you need

user228700

My father bought Norton a few months ago.

John Rennie

At least, since I can't smell burning I assume your laptop is no longer overheating ...

AccidentalFourierTransform

why!? its worse than actual viruses

Kiarash

@ACuriousMind yea, that's true. I agree with it. just take this definition: fermions (in higher than 2 dimension) are particles that have negative representations of $S_n$ (symmetric groups). Is it possible to prove they have to anti-commute with their conjugate momenta?

user228700

4:25 PM

When we get back home, I'll ask him to put that on my laptop. Till then, I'll be sure not to download suspicious files.

user228700

@AccidentalFourierTransform What, really?!#

user228700

@JohnRennie It's not, it's not! :-D

ACuriousMind

@Kiarash I don't know what a "negative representation of $S_n$" is, but it sounds as if you're asking for the spin-statistics theorem.

John Rennie

@Kaumudi.H AVG is generally pretty good. It obviously threw a wobbler this time, but I'd be inclined to try reinstalling AVG. I can give you the password to reinstall direct from the AVG servers, but I'll do that through the mail not here :-)

Kiarash

negative 1-dimensional representation. I don't remember the theorem name

John Rennie

4:27 PM

If you want to wait till you get home that's fine, just be careful where you browse.

ACuriousMind

I have never heard the term "negative representation".

user228700

@JohnRennie :-o

user228700

@JohnRennie And what are ur thoughts on using Norton instead?

AccidentalFourierTransform

perhaps projective representation?

@Kaumudi.H Im mostly joking, but I really think that Windows defender is good enough

Kiarash

S_n has only two one-dimensional representations. one is the trivial and the other sends each permutation to its sign

ACuriousMind

4:28 PM

The representation-theoretic definition of a fermion, to me, is that it transforms in a representation of $\mathrm{SU}(2)$ that does not descend to a linear representation of $\mathrm{SO}(3)$, i.e. you have the infamous "rotate 720° for a full rotation"

AccidentalFourierTransform

and that you dont need anything else

John Rennie

@Kaumudi.H In the past I wasn't a huge fan of Norton. But I haven't used it recently, and since it still sells I assume it isn't terrible.

Slereah

A fermion is a Dirac belt, as u well know

Sayeth JD

user228700

@AccidentalFourierTransform I think my windows defender just said "No antivirus software found, download online"

John Rennie

But I use AVG on all my PCs, and on all my family's PCs, and it is generally fine. I suspect this was just an isolated problem.

ACuriousMind

4:29 PM

@Kiarash Oh, so you're just saying that fermion states are antisymmetrized :P

AccidentalFourierTransform

wat?

user228700

@JohnRennie Since I don't pay them, the software keeps telling me about other updates and I keep having to re-install it, etc. It's all very confusing.

user228700

Since my dad's paid for Norton, there should be no such problems...

Kiarash

@ACuriousMind yup :P does the anti-commutation follow from this?

John Rennie

@Kaumudi.H well I was going to give you the password to install my paid for copy :-)

user228700

4:31 PM

@JohnRennie What the heck?! :-o

John Rennie

@Kaumudi.H It doesn't cost me anything - I have a site licence so I can install on as many PCs as I want for no extra cost.

user228700

What dyou mean you have a site license?

John Rennie

Site license

A site license is a type of software license that allows the user to install a software package in several computers simultaneously, such as at a particular site (facility) or across a corporation. Depending on the amount of fees paid, the license may be unlimited or may limit simultaneous access to a certain number of users. The latter is called a concurrent site license. The term "site" may not necessarily refer to a physical site or geographic location. It is simply defines a limitation on the user's access rights. The usage of the term dates back to 1950s, when mainframes limited to a specific...

user228700

Oh, wow, I didn't know that such a thing existed.

John Rennie

Do you want to try turning Defender on?

user228700

4:33 PM

OK, I'll take that password, then, if u're still willing to give it to me :-P

user228700

@JohnRennie Huh? Isn't it on by default?

John Rennie

How good is your Gran's Internet connection? Do you want to try installing AVG now?

user228700

Yes, yes.

ACuriousMind

@Kiarash Take a fermion state $\lvert \psi_1,\dots \psi_n\rangle$ generated from the vacuum by $a_1^\dagger a_2^\dagger \dots a_n^\dagger\lvert 0 \rangle$, then swap any two $a_i^\dagger,a_j^\dagger$. You get that $a_i^\dagger a_j^\dagger = - a_j^\dagger a_i^\dagger + T$, where $T$ is some term that gives 0 when acting on the stuff to the right of the $a_i a_j$. Since the state was arbitrary and the Fock space is spanned by states created from the vacuum, $T= 0$ and the $a_i$ anticommute.

AccidentalFourierTransform

CQFD.

John Rennie

4:36 PM

@Kaumudi.H OK, go to www.avg.com and click the Log in to AVG MyAccount link

Kiarash

@ACuriousMind nice! tnx Q.E.D. :)

user228700

@JohnRennie Uh huh...

John Rennie

YHM of the username and password

0celouvsky

@ACuriousMind I'm stupid. It's clearly just a number satisfying those two equations -.-

It lies halfway between the sup and inf

user228700

@JohnRennie Right. Logged in.

John Rennie

4:39 PM

Click the download link shown

user228700

@JohnRennie I'm downloading an app so that I can make phone calls from my phone again and that'll be done in about a minute. Will start this one after that's over.

John Rennie

OK, ping me when you're ready.

Slereah

What's the usual notation for a homeomorphism, $ \simeq $?

user228700

@JohnRennie Downloaded.

John Rennie

OK, it should have downloaded AVG_Protection_806.exe. Click on this to run it.

user228700

4:44 PM

Yes, yes :-) Installing now.

John Rennie

Don't accept the defaults! I'll talk you through the options.

user228700

Oh, um, OK...

0celouvsky

@Slereah approx.

Simeq is homotopy

John Rennie

@Kaumudi.H Is it at the "downloading installation component" stage?

Bernardo Meurer

@JohnRennie WHERE

WHERE DID YOU FIND IT

user228700

4:46 PM

@JohnRennie Logging in now...

ACuriousMind

@JohnRennie I'd bet it's at the "Kaumudi accepted the defaults and is trying to reverse the process" stage :)

0celouvsky

...

John Rennie

@ACuriousMind :-)

user228700

@ACuriousMind No :-P Thankfully, he warned me in time.

John Rennie

@BernardoMeurer the cookie butter?

@Kaumudi.H Logging in now?

user228700

4:48 PM

It asked me to log in and it's installing now...

John Rennie

You accepted the defaults. Oh well :-)

Bernardo Meurer

@JohnRennie Yes

user228700

@JohnRennie Huh? I did?! >.<

Bernardo Meurer

@Kaumudi.H You accepted the default configs for a Windows install?

user228700

Dang it, is there a way to reverse this?

AccidentalFourierTransform

4:49 PM

no, you now have four new toolbars

Bernardo Meurer

Nope

You just sold your soul

ACuriousMind

Okay, now my earlier comment is appropriate ;)

Bernardo Meurer

@ACuriousMind Lol, you cursed her

John Rennie

@Kaumudi.H It's OK, let it complete and we'll see what we've got.

At this screen:

You wanted the custom installation

Bernardo Meurer

Wait

All of this is to install AVG?

I used Avast back in the day

It was okay but it always blocked my binaries

John Rennie

4:51 PM

@BernardoMeurer the AVG installtion is one click if you just want the default settings ...

user228700

@JohnRennie Uuuuugh.

0celouvsky

I use avast

John Rennie

@Kaumudi.H It's OK. It's just that a default installation adds things lie the firewall that are unnecesaary.

Bernardo Meurer

No antivirus can protect you from Windows, that's the shame

John Rennie

You can always disable the unwanted bits once the install has finished.

user228700

4:52 PM

OK, I've messed something up :-/ The installation stopped 'cause I thought I'd be able to reverse the process and closed the window.

John Rennie

You know, it's a long time since I did end user support and I'm remembering how much I used to love it :-)

user228700

@JohnRennie I take it that u're being sarcastic? ._.

John Rennie

Ah, you spotted that :-) Yes, it's the lowest form of wit. Oh well.

So where did we get to. Has the AVG installation been aborted?

user228700

@JohnRennie :-P Nah, I'm sarcastic (irl) all the time and I don't feel bad about it if I'm not being mean.

John Rennie

If you run Task Manager does it show any processes called avgsomething?

user228700

4:55 PM

@JohnRennie Yes. And now I don't know what to do 'cause I don't see an option to continue.

user228700

@JohnRennie Yep.

John Rennie

avgsetupx.exe?

user228700

Actually no, no setup. avgpro something.

Bernardo Meurer

Oh

user228700

Ah, there's one named "instup32*" something and that one's description says AVG Antivirus.

Bernardo Meurer

4:57 PM

You downloaded the free trial of AVG Pro?

John Rennie

@BernardoMeurer no, it's the paid version.

Bernardo Meurer

@JohnRennie Who pays for antivirus?

John Rennie

@Kaumudi.H Are the processes using any CPU? Is the disk light flickering?

@BernardoMeurer I don't use free condoms and I don't use free AV.

0celouvsky

I just read that math education is racist and taught from a privileged white perspective

user228700

@JohnRennie Yes to both.

0celouvsky

4:59 PM

Is that true?

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