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12:00 AM
@ACuriousMind Why does Heine-Borel work?
@ACuriousMind and I don't mean the proof
why does it work
what caused Mr. Heine to sit down and think bounded sets are precompact
 
12:20 AM
@JohnRennie I do hear you John but and it's true, one can learn much from seeing a canonical problem solved well. However, being the cynical entity that I am, my gut informs me that this format is not ideal for that for reasons that I can't go into here but that I suspect almost everyone understands anyhow. I've found the, e.g., physicspages.com format helpful. Regardless, I hope the best for your endeavour.
 
Anyone here comfortable enough with general relativity to tell me if I am being an idiot in this comment?
 
@dmckee Maybe
But "mass" is such a loose term
Do they mean ADM mass?
gravitational mass has no meaning in GR
 
@dmckee Do you know circuits?
I need salvation
 
@0celo7 Damn if I know. Can I ask how the mass need to make a Schwarzschild metric match the Kerr metric of a rotating object at large distance compares to the mass the of the Kerr object?
 
@dmckee ADM mass of Schwarzschild happens to be the mass in the Schwarzschild radius
 
12:33 AM
@BernardMeurer Depends how complicated we're talking. Basics, yeah. And bits and pieces of other things.
 
but that's a coincidence. Let me check my books for the ADM mass of Kerr black hole
ADM mass is basically the energy of spacetime measured at timelike infinity
 
@dmckee It's very simple, but decoders and mutiplexers are confusing me right now
 
something like that, I'd have to review it before saying more
 
@BernardMeurer Ah. Discrete logic circuits in terms of gates. Yeah, I can probably do that.
 
Kerr mass is Komar mass
 
12:34 AM
Basically I need to build a circuit that takes in 3 bits and outputs three bits. And it is a map like this
0->1
1->0
2->7
3->5
4->4
5->3
6->2
7->1
 
are there two 1s and no 6 on purpose?
(in the output)
 
so if the input ($A_0, A_1, A_2$) is dec3, the output $Y_0, Y_1, Y_2$ should be dec 5
 
@AndrasDeak There is no reason to expect the output to span the representation space.
 
sure, but all the rest seemed unique, it was worth asking:D
 
@AndrasDeak Yes, the reason is my prof said so in the problem :P
So, by building the truth table I started Identifying some patterns
 
12:37 AM
Oh ... I knew how to do those once, but it's been a while.
 
i.e. when $A_2$ is 0, $Y_0 = A_1$
 
Ok, in a stationary spacetime, ADM = Komar
Is Kerr stationary? It's not static
Damn, I don't remember these definitions
@dmckee It depends on the angular momentum
In the $a\to 0$ limit, you get the Schwarzschild metric
So you'd need to look at the metric (in appropriate coordinates)
But that's a reasonable question
Problem is, people do Kerr in different coordinates than Schwarzschild
 
@dmckee I can use MUX 4:1 and 2:1 and/or DEC 2:4, 3:8, and 4:16
 
@BernardMeurer Do you have always 1 and always 0 lines available? I seem to recall working problems with those is easier.
 
Always 1 and always 0? Like VCC and GND?
Or do you mean the EN control on the IC
 
12:44 AM
I mean can I assume the existence of an input that is always one and an input that is always 0 to the logic. On the chip those might well be VCC and a diode to GND, but that is an implementation detail.
 
@dmckee Yes, I have those lines :)
$$\begin{table}[]
\centering
\begin{tabular}{llllllll}
\hline
DEC & A_2 & A_1 & A_0 & Y_2 & Y_1 & Y_0 & DEC \\ \hline
0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\
1 & 0 & 0 & 1 & 0 & 0 & 0 & 0 \\
2 & 0 & 1 & 0 & 1 & 1 & 1 & 7 \\
3 & 0 & 1 & 1 & 1 & 0 & 1 & 5 \\
4 & 1 & 0 & 0 & 1 & 0 & 0 & 4 \\
5 & 1 & 0 & 1 & 0 & 1 & 1 & 3 \\
6 & 1 & 1 & 0 & 0 & 1 & 0 & 2 \\
7 & 1 & 1 & 1 & 0 & 0 & 1 & 1 \\ \hline
Oh, tables no worky
 
Man. It's been a long time.
 
you broke chat
 
@BernardMeurer I don't think MathJax will like a table environment, but it might process just the tabular.
 
your first row is inconsistent, though
it should be dec1 according to your original message, right?
 
12:52 AM
@AndrasDeak Yeah, I'm just saying that the row is the DEC representation of the binary
I guess the fact that the first one is the DEC of A and the second of Y is implicit
 
I'm saying that you said 0->1
 
^ that.
 
Oh! Ny bad, it should've been 0->0!
Good observation @AndrasDeak, thanks!
 
no worries, I can't be of help otherwise:D
 
Anyway, I recall that the trick is to pick out the smallest set of rectangles that are homogeneous (all 0 or all 1) and cover all cases in the output, then to figure out the logic for each one.
 
12:55 AM
Well, does it help that most of it is a reverse+cyclic shift? My hunch is "no"
 
But the data you've been given is nasty. The biggest blocks are 1x3 or 3x1.
 
what on Earth are you people doing
 
@0celo7 Digital systems
@dmckee It is nasty indeed
 
you could learn string theory instead
 
@AndrasDeak It's (2+A)%8
@0celo7 String theory won't get me as much pussy as this in the long run
 
12:57 AM
@BernardMeurer ah...
 
@AndrasDeak :P
 
mmmm
38GB used on the music app
not even a quarter done
 
but (2+2)%8==4?
 
Ah, wait. This isn't the write table.
You need three tables like
 
@AndrasDeak yes, and 4 is mapping to 4
 
12:58 AM
@dmckee Write? :P
 
@AndrasDeak OH, wait, nah I'm talking about something else
 
but you said (2+A)%8, then (2+2)%8 would refer to A==2? :D
@BernardMeurer OK then:)
don't worry about me, I'm just being nosy and curious, but it doesn't really matter if I stay confused
 
@AndrasDeak I'm just a lost freshman. I wish my course involved more Linux on calculators
@0celo7 Today my calculator played music btw
 
@BernardMeurer Has Michelle mentioned Bob lately?
 
Nope. I'm going to have to read before I can recall how to do this. And I'm suppose to be grading intro physics papers.
 
1:01 AM
@BernardMeurer wtf those things have speakers?
Or have you tortured it enough
 
@0celo7 Not more than making an analogy about bob in skinny jeans. Why?
 
it now plays music through the circuits
@BernardMeurer He's not doing well
 
@dmckee "Dear students. Your grades will be late because I have spent my weekend helping a freshman with a simple MUX/DEC problem. Love, David"
:P
@0celo7 I added a USB soundcard and connected it to speakers
@0celo7 Oh shit, what's up with the ungermaster?
 
Bad back
 
@0celo7 Ah, ageing must suck
 
1:04 AM
Yup
 
If I was a prof I'd always end my emails with "Love, Bernardo" to lure them into thinking I was a sweet prof
Then RAM THEM with some exam where they have 45 minutes to rewrite the 0.01 Kernel from scratch
 
by the time you get there all your joints hurt from all the paperwork, and you only sign BM
 
@AndrasDeak Lol, so that's why :P
 
I would love to write an analysis test
it would be 15 "easy" problems
 
@BernardMeurer I bet it played the "don't hurt me" part of this over and over again :P
2
 
1:06 AM
lol
1: Prove Cauchy sequences are bounded
 
@ACuriousMind Woke up, got out of bed, turned his computer on, just to say that :P
 
That result is so basic but there's a trick that no one knows
2: R is complete
@AndrasDeak Ok
51GB used on my new phone
40 of that is music
Still have 200GB free :)
 
@BernardMeurer I never miss a chance to link that song in the h bar :P
 
@0celo7 Dood, $\mathbb N$ is neither closed nor open
 
What does that even mean?
 
1:08 AM
@0celo7 OH
HAHAHA
 
I mean it's closed as a subset
 
That sentence doesn't make sense unless you say with respect to which topology it's not closed
 
1:09 AM
This is the topology of $\mathbb N$ to @0celo7 right now
 
it's closed as a subset of $\Bbb R$
as a subspace, it's trivially closed and open
in no scenario is it neither
@ACuriousMind Agreed?
 
good
@BernardMeurer I got a new phone with 0.25TB internal storage
how is such a thing even possible?
 
@0celo7 iPhone 7, sweet
@0celo7 NAND technology is very advanced nowadays
specially with TLC cells
 
when you pick it up and look at it, it turns on
it's watching...
 
1:13 AM
Samsung?
 
iphone
 
Dude you're such a spoiled kid :p
 
I bought it myself.
I do have a job
 
@0celo7 that's not so bad
 
hey @bernard you there?
 
1:14 AM
@0celo7 Then you're just stupid dawg :P
@Obliv Yessir
 
@BernardMeurer No argument here
 
Could you help me with some configuration settings in eclipse?
if you're not busy that is
 
@Obliv I don't use Eclipse, nor do I recommend it :/
@Obliv Ask away though, maybe I know the answer
But why Eclipse?
 
Well I'm running windows and I figure an IDE is easier to use than a text editor
 
@Obliv Which lang.?
 
1:16 AM
eclipse isn't recognizing 'cout' and I'm not sure why. It's c++
using mingw
 
Use this
It's free for students
It's the best IDE there is, I use it on Linux
Works on all OS's
@Obliv Did you declare the namespace? If not did you do std::cout?
 
I tried std::cout it doesn't work. declaring the namespace doesn't work either lol
omg..
it works now.
 
See, I have this effect on computers
 
Wtf.. lol @bernard u have the magic touch
THANKS MAN.
 
@BernardMeurer they scream in pain?
 
1:19 AM
@0celo7 nuff said (OK, might be bogus, but this one's legit)
 
user218912
@0celo7 you bought an iphone 7???
 
@Obliv Love ya
@0celo7 They work in fear that I'll try and fix them
 
@obe I was in the mall looking for some new shoes (@BernardMeurer) and thought it was time to upgrade
 
user218912
@0celo7 which colour?
 
@0celo7 What was your old one?
 
1:20 AM
5s
 
@0celo7 Wanna give it to me?
 
I sold it to pay for apple care, sorry
@obe matte black
 
@0celo7 Dang it
 
user218912
coool
 
user218912
i want jet black :(
 
1:21 AM
no you don't
 
user218912
why
 
it get scratched
so you have to put a case on it
and that just defeats the purpose
 
user218912
you're right but it still looks cool
 
@BernardMeurer jk it was my bd present, but I did pay for it
 
@0celo7 I knew it!
That shit cost 900 bucks dawg
ain't no uni job that pays for that
You'd have to work a decade
 
1:23 AM
Um.
I did pay for it using my money.
 
@0celo7 That someone gave you?
 
user218912
then how is it a bd present?
 
No, from my job
 
doesn't getting a new iphone involve ritually camping for three weeks?
 
user218912
you bought yourself a bd present?
 
1:24 AM
@obe I'm getting reimbursed
@AndrasDeak only if you get it day 1
 
user218912
ok
 
@0celo7 like all the cool kids, eh?
 
I got my iPhone 4s day one
back in the day
 
@0celo7 Spoiled
 
heh:D
 
1:25 AM
I camped for 15 minutes
 
user218912
I have a galaxy s5
 
@BernardMeurer was my first phone
 
You payed for somebody to camp for you, didn't you?
 
@0celo7 Mega-Spoiled
 
@BernardMeurer Was my 5th phone
@AndrasDeak Yeah, a servant
 
1:25 AM
@0celo7 Called it
 
knew it!
 
One of the shoe shiner boys
 
user218912
@0celo7 I can't believe I made it this far in QFT, I'm basically halfway done the course and I have an A+
 
user218912
I deserve an iphone 7
 
good job
 
user218912
1:26 AM
thanks :D
 
@obe not from me, I dropped too much money today lol
 
user218912
lol
 
user218912
I'll beg my parents.
 
user218912
lol...
 
user218912
that's sad right
 
user218912
1:28 AM
I don't have a job
 
@0celo7 My music wouldn't fit on your phone
 
how do you have more than 0.25TB
unless you just have a lot
that's cheating
 
Oh shit, it would
 
lol
rekt
 
user218912
I can live off 32gb
 
user218912
1:30 AM
I only listen to like 15 songs...
 
I need to make my phone not watch me
how do I do this
 
@0celo7 Get another phone
 
Do you want mine?
 
user218912
@0celo7 what?
 
1:31 AM
when you pick it up and look at it, it turns itself on
which means the camera is on all the time
or at least when you pick it up
 
@bernard puu.sh/s1gmr/c02dc0c594.png you think there should be more configurations than this?
 
user218912
oh
 
@Obliv Please try CLion dude
Eclipse is nuts
 
good night
 
@bernard I'm in too deep..
 
1:33 AM
@Obliv Really. Don't
Also, that's what she said
 
ALL I NEED TO DO IS WRITE A PROGRAM THAT CHECKS IF DD/MM/YY THE DATE ENTERED IS SUCH THAT YY = MM * DD
AND I HAVE TO GO THROUGH ALL THIS BS
 
@Obliv Use
Clion
Or go install Linux and be happy
 
python with datetime
 
@AndrasDeak lol
 
actually i'm going to try editplus really quick I think it should compile fine.
 
1:36 AM
@AndrasDeak Time to figure out what my reddit password is.
 
@Jim When you are around could you, please, make us a private room. I have some things I wanted to talk to you
 
user218912
@0celo7 this scattering stuff is difficult
 
yes it is
there's a reason why physicists are smarter than mathers
QFT filters out the <125 IQ crowd
 
@BernardMeurer Private rooms are for moderation purposes only, Jim cannot create one.
 
Dammit, @ACuriousMind halp plox?
 
1:39 AM
At least if by private you mean "not readable for others"
 
@BernardMeurer check texts
 
@ACuriousMind Yes. are you on Skype?
 
@bernard okay editplus works. It's basically atom except without all the fancy stuff you mentioned before
screw eclipse.
 
don't Skype without me pls
 
@Obliv Use. Clion. Ir makes C++ reasonable
 
1:40 AM
I'll use my new headph...shit
 
user218912
lol
 
I'll use Skype on my phone
After I remember the password
@heather ;(
 
user218912
can I join too? I'm pretty lonely :'(
 
No. I need to actually talk to the man
Or, message at least
 
check your damn texts
 
user218912
1:42 AM
guys let's do a skype call for fun
 
user218912
plz :(
 
@BernardMeurer After I have reset my password, I will be, and I would prefer messages over a call
 
Hah!
 
@ACuriousMind Thanks. I can't call right now, lucky you :P
 
@0celo7 I always forget my Skype password, that's almost a ritual by now :P
 
1:46 AM
@ACuriousMind I'm resetting mine right now lol
I changed it the other day to something I could remember
@obe I can't find any good wallpapers
 
user218912
for your phone?
 
si
 
user218912
what do you like?
 
pokemon
 
@Jim Nevermind that, just send me an email when you can, meurerbernardo@gmail.com. @ACuriousMind Can attest it's a legit reason :P
 
user218912
1:51 AM
do you really?
 
@BernardMeurer Right, there are totally no brain-eating potatoes involved
 
user218912
I've been using ice cave wallpapers @0celo7
 
Yes, I love pokemon
@ACuriousMind can confirm
@BernardMeurer is the i7 at a new resolution?
 
An i7 is a processor, how can it have a resolution? :P
 
user218912
@0celo7 ice cave
 
1:53 AM
no, apparently not
@ACuriousMind iPhone 7, smartass
 
@0celo7 Nope
@ACuriousMind Depending on the i7 it comes with a built-in graphics chip that has a recommended resolution
rekt
 
lol
@obe uhhh
 
user218912
 
user218912
cool wallpaper
 
2:03 AM
@obe We will skype if you talk
 
Hmm. Anime wallpapers
 
2:16 AM
@BernardMeurer let's skype about QM
@ACuriousMind can watch and comment
 
@0celo7 Yep, gimme 5 mins
 
Ok you can help me with my bullshit EM homework
@ACuriousMind ?
 
@0celo7 Ready, skype bitch
 
hold on let me clear some RAM
I'm using 15
 
user228700
2:38 AM
Hi everyone :-)
 
user228700
Belated Happy Halloween..? :-P
 
belated?
what day is it in India o.o
 
user228700
1 Nov.
 
Mind = blown
Are you guys a day ahead of us?
 
user228700
Wtf, no!
 
2:41 AM
It's October 30th where i live
Right now
 
user228700
Oh, crap, sorry, it's 31st. Happy Halloween :-P
 
Tomorrow is the 31st I'm pretty sure
Ok, ok
My world was falling apart for a second
 
user228700
Sorry about that :-P
 
user228700
@JohnRennie: Morning :-) In the following post, I had asked about the K.E of photoelectrons in the PE:
 
user228700
3
Q: Kinetic energy of photoelectrons

KaumudiI came across the following question: A photon of energy $h\nu$ is absorbed by a free electron of a metal having work function $W<h\nu$. Then: The electron is sure to come out The electron is sure to come out with kinetic energy $h\nu-W$ Either the electron doesn't come out or it ...

 
user228700
2:44 AM
And u wrote that the formula is actually given by $K.E=h\nu -W- \delta E$ where $\delta E$ is the energy lost by the electrons due to scattering.
 
user228700
But I googled the definition of the term work function and found that it is the catch-all term for the total energy required for the electron to be ejected-doesn't this include the energy lost due to scattering?
 
user228700
If we use the above definition of work function, the equation $KE_{max}= h\nu -W$ makes sense. This, as u see, is the $KE_{max}$ and not simply $KE$. Hence, the $KE$ of an ejected electron can vary b/w 0 and $KE_{max}$
 
user228700
(The probability that an electron will be ejected with a kinetic energy given by $KE_{max}$ is next to 0, correct?)
 
What's the distribution look like?
 
user228700
I...dunno. Lemme google it.
 
user228700
2:53 AM
It has used strange terms that I'm not familiar with :/
 
user228700
I found (an oversimplified version):
 
user228700
 
user228700
(Wow, zero come out with $KE_{max}$. Not very surprising, I guess)
 
user228700
Anyhoo, @JohnRennie: Thoughts?
 
@Kaumudi strange graph lol
no graph looks that nice
 
user228700
3:08 AM
@0celo7 Yeah :-P Emphasis on the word oversimplified.
 
 
2 hours later…
user228700
4:59 AM
This is why u should never google ur symptoms-now I think I have narcolepsy aah!!
 
Narcolepsy? You fall asleep all the time?
 

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