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00:00 - 19:0019:00 - 00:00

00:00
weather wise or place wise (I agree with both)
Both, yeah
I was there in the winter, and it was pretty sweat
and I was in SD in the summer, and it was great weather too
@BernardoMeurer the water in SD must be a lot nicer though
here its WAY too cold during the holidays
@Skyler I see, it's kinda cold here now
not like
ball-freezing, but it's cold
obe
obe
00:14
hi
@obe oye obe
@BernardoMeurer dafuq?
You wanna start something with me, boy?
I will destroy you. You have not even comprehended my power in trashtalking.
@DanielSank We have already started multiple things
I made Chuck Norris cry.
00:17
@DanielSank Do you want to see how responsible I am?
@BernardoMeurer sure
congratulations Trump
obe
obe
I'm probably the most irresponsible person here lmao
There is a deal on ebay to get my dream amplifier, usually $500, for ~$180. I used the money to pay a transfer application to UWaterloo and UToronto
obe
obe
@BernardoMeurer ayyy toronto
00:19
who's ready for WWIII
obe
obe
ill never need to buy coffee for myself ever again @BernardoMeurer
@BernardoMeurer wow
Good for you.
@DanielSank Am I a grownup now?
@obe Shit, I can't go there :P
no
You haven't beaten me in a lightsaber duel.
@DanielSank We both know that much like me graduating that will never happen
00:21
@DanielSank is the challenge there defeating you or inventing the lightsaber first?
@ACuriousMind I say nothing.
obe
obe
@BernardoMeurer waterloo is known for not taking transfers into compsci
or softeng
@obe CEng?
obe
obe
dunno about that
Can you figure out?
Like idk if you know someone maybe
obe
obe
00:24
I do have friends in CEng
ill ask
@obe one more coffee for you
obe
obe
just come to toronto dude
we have better research
Not in QC you don't
and you're more $$
obe
obe
pretty sure the QC profs here are more world renowned
in QI they are for sure
@BernardoMeurer if you end up going there ive got an elective recommendation for that particular uni so tell us how it goes
@DanielSank you haz lightsabers?
00:28
@Skyler You have a what?
@BernardoMeurer class that I'd recommend you taking there
@Skyler Ah! Thanks, that's nice of you to think of :)
obe
obe
@Skyler which?
@obe are you a torrontoian?
obe
obe
00:48
yea
@BernardoMeurer I am in MEFT
@Kelthar Hey
you?
MEEC :)
We should meet up sometime
yeah, sounds like a plan
00:53
I'm in my first year though
what grade are you in?
ah, I'm in the 3rd :P
Just finished first semester
Sweet, going into the masters
what path did you pick?
Btw, I'm going there tomorrow, have a quantum mechanics test xD
Idk the options in MEFT
I have not picked a path yet
00:54
I have an exam on the 30th, calc I
Since you're more experienced than me, when do the classes start again?
But my course is going to change next year, things are going to be a bit different
So Feb 20th give or take
cool
The course is going to me more flexible in what concerns the masters, much more to make the subjects combination I want
yeah
2 weeks
less if you are done with exams earlier
That's cool, in MEEC we gotta pick a specific route to go to
I regret not going to MEFT sometimes
whatever I guess
btw, I wasn't here, but I guess the conversation over the Inauguration must have been fun xD
00:57
I was just watching it on NBC with my flatmate, lol
It was okay
just scrolled a bit :P
Oh, you're just living in Lisbon for the uni?
Yeah, it's a long story
Btw, don't regret, I mean it's an experience... Maybe you'll like the course by the end of the year. Maybe you find out you want something else. But you'll know :)
obe
obe
@Skyler why do you ask
MEEC just has a lot of people who are there because they did not know what to pick
that bothers me
01:01
I understand. that changes as the year progresses though, some leave, some change, etc
Also, what's up with IST's evaluation system
it's all just exams
there are barely any projects
you can't even get extra credit on any class
Regarding MEFT, one of two things happens: Either people wanted to go to Aerospace engineering but the average didn't let them (not an issue this year anymore ^^) or they thought they wanted physics and then realize they don't and leave... usually only ~45-50 of the initial 60 remain
60? MEEC has like 220 people :(
Well, I don't know about MEEC, but I have plenty of projects all the time
I don't :|
01:04
Perhaps it is in part because you don't learn programming in first semmester if I'm not mistaken
but you must have them at SD, no?
Yeah, SD lab is hell on earth
and Chemistry lab is a meme, it's not a project
ahahah, oh yeah, Vivado and stuff
yeah, it's commonsense, chemistry sucks xD
Don't say that name next to me, I get triggered :P
My general chemistry course was absolute shit
I passed with a glorious 10.3
mine too... You're not alone at all aahahaha
Linear Algebra was really good
the prof was great
01:06
I mean, I had 15, but if you ask me, I didn't learn that much
How's he called?
Lina Oliveira
@ACuriousMind I chickened out on putting that one on my office door. My tenured colleague put t up with glee in his eyes.
and Rosa something
btw, about the extra credits in classes
I'm glad that isn't a thing
You shouldn't be "forced" to go to classes
Hm? I'm not talking about mandatory attendance
I'm talking about doing projects that you don't have to do
to be able to get extra credits if you chose to do them
01:08
ah
that's not so common, yes
I got good grades in SD, that was a surprise
Only had two subject in which it happened like that
btw, you must have heard about him, no?: 1drv.ms/i/s!AvCx1o7OEY-Yg2Ws5IOXL4nBGFyl
Huh? Who is that?
A linear algebra teacher, usually gives classes to MEEC
Well, gtg, have to rest for the exam xD cya
AH
I KNOW HIM
His exams were hard AS FUCK
01:10
see? xD
@Kelthar Good luck at the exam tomorrow!
thanks! cya around :) By the way, sent you a friend request on fb, I'm Diogo
@Kelthar Sweet, see ya!
 
2 hours later…
03:00
We need a thorough Q/A on how a laser works.
obe
obe
03:55
@DanielSank do it
 
2 hours later…
05:56
@BernardoMeurer actually I can only find one spare. I must have given the other away.
I was using the spare amp on my PC for gaming, but it was more hassle than it was worth, which is why it's now packed away in a storeroom.
06:18
1 message moved to Trash
07:01
@JohnRennie good morning (^ム^)
why tensile young's modulus of bone is more than commpressive
@Ramanujan I have no idea I'm afraid. I don't know anything about bone and its mechanical properties.
user228700
07:30
@JohnR: Good morning :-)
how to find a minimum of $x^2+y^2$ under the condition $x^3+xy+y^3=1$
@Kaumudi.H Morning :-)
user228700
@Ramanujan You do realise that he's not an answering machine, yes? Would you go up to somebody and ask them a random question without any context whatsoever?
user228700
Ah, u edited your message.
Actually I can't remember how you do constrained minimisation problems like that ...
07:34
> I hang around in the chat room and I'm happy to answer questions there as well. Just ping me if you want my attention.
user228700
@Ramanujan Well, sure but why should that deter you from being nice?
Being nice?!?
user228700
Yes, why are you shocked?
I think Kaumudi just meant it looked like the question came out of nowhere, rather than saying something like "Hi John, are you busy? If not could you help me with this?"
user228700
^ Exactly.
07:37
But I'm not fussed and I would help you with the question if I could remember how do do it.
Sadly, much of the maths I learned at school I've since forgotten.
user228700
@JohnRennie I know that you don't mind :-) Still, it's not very nice to do that and I simply wanted to point out that to him.
I would take the equation $x^3+xy+y^3=1$ and write an expression for $x^2+y^2$ at every point along the curve, then minimise it. But I can't immediately see how to do that for an expression you can't easily write as $y=f(x)$.
Kaumudi have you done that sort of constrained minimisation?
So derivative is not involved? Like f'(x)=0
user228700
@JohnRennie Not that I can remember but I'm trying...
In mathematical optimization, constrained optimization (in some contexts called constraint optimization) is the process of optimizing an objective function with respect to some variables in the presence of constraints on those variables. The objective function is either a cost function or energy function which is to be minimized, or a reward function or utility function, which is to be maximized. Constraints can be either hard constraints which set conditions for the variables that are required to be satisfied, or soft constraints which have some variable values that are penalized in the objective...
07:40
@JohnRennie thanks for link
Actually it was question on maths SE
Nevermind someone has answered
Ah, hang on.
user228700
@JohnRennie Oh, no, I have. The nature of the constraint sort of threw me off but yes. hang on...
$x^2 + y^2$ is just the distance from the origin.
So the question is effectively at what point does the curve $x^3+xy+y^3=1$ come closest to the origin.
Nice!
user228700
^^ Yep, very nice :-)
07:44
Hi Pato. I don't think you can post here until your rep reaches 20.
I assume you're interested in discussing the difference between QFT and the Schrodinger equation.
user228700
Hmm, what does the equation $x^3+xy+y^3=1$ represent? .__.
@Kaumudi.H a curve
user228700
Dude.
user228700
What kind of curve is my question!
@Ramanujan I think the general approach to questions like that is to use Lagrange multipliers. In this case i would start by sketching the curve and the answer should be obvious.
07:52
user228700
Thanks :-) How the heck are we to determine which point is farthest from the origin?!
There is no point on that curve farthest from the origin.
OK so the nearest point to the origin is when $x=y$ in which case you need to solve $x^3+xx+x^3=1$ to find the value of $x$ and therefore $y$. Then calculate $2x^2$
user228700
Ah, ur question is minimum, not maximum.
@JohnRennie I don't think so.
user228700
07:55
@JohnRennie How did u ascertain that the point would lie on the line $x=y$?
It seems the points on the x and y-axes are nearer than the bulge
just because it's symmetric through $x = y$ doesn't mean it has to have the minimum there. just a local extremum
Well that's easily calculated.
user228700
What kind of a function is $x^2+y^2$ anyway?
well what does it equal?
$r^2 = x^2 + y^2$
07:59
It measures squared-distance of origin from $(x, y)$.
user228700
Alright, I'm going to move on from this. Multi-variable calculus is not there in my syllabus.
It's a paraboloid centred on the origin
paraboloid = parabolic shaped bowl
@Kaumudi.H yeah,i was also just looking :D
too bad, multivariable calculus is the real deal
@JohnRennie i seem to be missing something there john, isnt that a circle
not a paraboloid
08:00
For a fixed $r$, sure
user228700
^
Graph of $z = x^2 + y^2$ in R^3 is paraboloid
Graph of $z^2 = x^2 + y^2$ on the other hand is a cone.
user228700
@Balarka: Do you regularly work with complex numbers?
@Kaumudi.H it comes up a lot in physics, especially upper div
@BalarkaSen I get $x \approx 0.6573$ when $x=y$ and that gives $z \approx 0.86$ i.e. $\lt 1$.
08:01
not regularly, but I do.
user228700
@Skyler Yes, I know :-)
user228700
@BalarkaSen Well, I found an excellent series about them on YouTube. I dunno if this series is far too basic for you but here:
@JohnRennie Hmm. You seem to be right that the min is on $x = y$. Strange!
Thank you, thank you :-)
08:04
No,minimum can be at more than one point,it may be guess until he prove why …
user228700
There are a total of 13 videos, each one more complex than the last. So, you might want to skip the first few...
@Kaumudi.H I don't really want to watch it though. But thanks.
user228700
OK.
personally I like the geometric visualization of complex numbers on the number plane
@Ramanujan it's obvious from the graph that there is only one minimum
@Kaumudi.H I imagine Balarka Sen probably knows about complex numbers already :-)
08:05
@JohnRennie but does he complex analysis?
user228700
For anybody else who is interested but is also sceptical about whether or not to watch the series (lest they're too basic), here:
@Skyler Have you read any of Balarka Sen's posts here?
that question was a bit more tongue in cheek, i am trying to work my way back up
Anyhow I need to work for 15 minutes or so ...
08:07
Riemann surfaces are excellent
08:36
> thus for a system in equilibrium , the value of bulk modulus is always positive.
Which kind of equilibrium?
@JohnRennie do you have some time ?
Yes, what's up?
^what kind of equilibrium?
@Ramanujan I've no idea. Have you got a link to the original statement?
@JohnRennie lacking in physics :(
A positive bulk modulus means that when you compress something the pressure goes up i.e. is resists compression. And when you stop compressing it the increased pressure will make it expand again.
But suppose the bulk modulus was negative. That means when you compressed the object its pressure would go down not up.
And the more you compressed it the more its pressure would go down. So it would just shrink away to nothing.
That's why any system with a negative bulk modulus is unstable.
08:52
@JohnRennie ? Increase in pressure and decrease in volume
The bulk modulus is $$K = -V\frac{dP}{dV}$$
A positive bulk modulus means that if you compress something, i.e. reduce the volume, the pressure goes up.
Which is kind of obvious. If you compress a gas its pressure increases, and if you let go of the gas it expands again.
$\huge{:(}$
2
I have to head off for a bit.Back in an hour or so.
09:10
I am totally fascinated by how many down-votes this has attracted.
two each on the question and answer.
It's a perfectly harmless post.
I can only assume the same two people exercised the down-arrow here.
09:51
@DanielSank it wouldn't be so bad if people said what they objected to. I suppose people fear retaliatory downvotes.
@DanielSank Those are the exact words the naked physicist used :P
Though I do agree it's weird you got downvoted twice
10:27
in a concave lens
how is OF = FC?
isnt PF is supposed to be equal to FC?
10:57
$$ \huge{\int )::(}\int$$
@Secret What on Earth are you trying to make?
Oh
I am just super bored and frustrated as I keep making careless mistakes when I try to elucidate the symmetry of some integrals
I assumed you were trying to make some kind of artwork with LaTeX...
well, you can call that some kind of lovecraftian creature, I guess, since it has 4 eyes at the centre
@Secret Also, if you wanted it bigger, ya could've used \Huge instead of \huge :P
11:01
$$\Huge{\int )::( \int}$$
much better
@Secret Also pretty sure \Huge and such don't require curly brackets
Just spaces
hello
welcome food for thought
r u excited about trump?
nah, I'm not interested in politics
u?
11:13
yeah I'm excited
I love politics though
the science of organising humans to achieve maximal productivity
poli sci
:-)
yeah
hi swapnil
11:20
good u
good
When 40% don't vote, it doesn't mean much to me.
11:32
what doesn't mean much?
why does it matter how many people vote?
just politics, in general
I think the fact 40% don't vote is a reflection that people aren't interested in politics
as opposed to being a reason to not be interested in it
yup
join the crowd
I'm interested in it because it has the potential to have a real impact on people's lives
like the world will be different under Trump than Hiliary
so I'm interested in understanding what the differecnes are
and those who understand their environment (physical, social etc.) will thrive
hi @Kaumudi.H
how r u
I heard trump used Twitter a lot
user228700
11:36
@Ken: Hey :-)
user228700
I'm good, thanks. What about you?
yeah he does
he's very hip
i'm gud 2
just chilin watching the tennis
user228700
How's the website coming?
it's Aus Open season
user228700
@Kenshin Nice.
11:37
na been too busy to do much on the website
but it does have like 120 questions
user228700
Oh, OK. That explains why you haven't been around as much.
user228700
Do u play tennis?
yea
I played for 10 years or so but I don't play much now just for fun on occasion
user228700
Oh, wow, I see. I play badminton sometimes.
oh yeah that's fun too
i was the badmintong school champ
user228700
11:40
Wow. Cool :-)
user228700
Say, how's the climate over there this time of year?
boing atm
boiling
like 30-35 celcius
up to 40 in melbourne some days where the Aus Open is at
but it's ok if I stay inside with the aircon on
user228700
40?!
user228700
Wow.
yeah
yeah on Tuesday the tennis players had to play in that heat
user228700
11:42
We had 42 once but it's usually never that high.
yeah 40 is rare her too
average is about 30 atm with a few 35 days
and like 1 40 day a month in summer time
If stress is directly proportional to strain,then can we say strain is directly proportional to stress?
@Ramanujan yes
user228700
@Kenshin That's still a little crazy, wow.
11:44
Then Young's modulus = strain/stress?
x = (1/k)y
let j = 1/k
then x = jy
thus if y is proportional to x, x is proportional to y
Also you can think about it as a graph, if y is proportional to x you can draw a straight line on a y vs x graph that passes through 0
if you plot instead x vs y, it will still be a straight line passing through 0
user228700
Oops, @Ken: Bye :-)
tata
12:35
.
12:54
Note: k is a nonzero constant. If k=0 there would be "variation."
14:14
hello
14:24
Howdy
14:41
> Our solar system has moved in a higher energetic space, and/or the Nemsis system, aka Nibiru/ planet X, causing our Sun tot shine brighter with white light instead of yellow. Note that therefor the Moon and Venus are brighter.
Is there a reason why the esoteric guys love to call the whatever life force or agent in their worldivew "energy", even though it is not really energy as understood in physics?
From some of the low quality PSE questions, they seemed to commonly attribute this to electromagnetic radiation, but EM wave behave nothing like what their worldview defined as "energy"
I always puzzled at what they are thinking. Even in the context of their worldviews, there seemed to be no consistent notion of logic behind how they define things
@Secret Because, in everyday language (not just that of esoteric crackpots!), "energy" is a much more vague concept than in physics. Just ask someone with no formal training in physics what the difference between energy and power is.
yeah they just use them interchangeably, and most ordinary people seemed to have this notion that if something has more power, it is stronger, more resilent, (insert bunch of suitable terms)
Yes, that's because that's what "power" means in ordinary language. They're not wrong, they are simply not aware that everyday language and technical usage differs.
14:58
Sometimes it gets confusing when your audience is full of people with diverse backgrounds, and then it happens there are some words that most of them use, but mean completely different things to them, resulting in the need to sort of act as a translator to phrase that word n times in the context of their fields
 
1 hour later…
16:27
[On integration] The reason why many differential equations are often striaghtforward when the solution involve sines, cosines and exponentials, and why integrals where the integrands are products of the aforementioned are relatively easy, is because they have a cyclic symmetry:
in Mathematics, 21 mins ago, by Secret
[Integral symmetries] Cauchy Riemann theorem like analogues in reals:

$$\frac{d^n}{dx^n}f=\lambda\int^{(m)}fdx$$

(where $f=\sin, \cos,e^x$ (possibly more?),$\lambda \in \mathbb{R}$)

For example

$$\int x^n \sin x e^x dx$$
Consider

$(uv)''=u''v+2u'v'+uv''$

Plug $u=\sin x$, $v=e^x$. Then

$(uv)''=-uv+2u'v+uv$

Note how the antisymmetry of $\sin x$ wrt the functional $()''$ results in cancellation. Hence

$(uv)''=2u'v$

Now it is easy to check that $\cos x$ is also antisymmetric wrt $()''$ thus we could have start with $u' =\sin x\implies u = -\cos x$. Hence
In short, functions like sine, cosines and exponentials give the same result when differentiating them n times as when integrating them n times
Therefore after integrating them a certain number of times, it warps back and becomes differentiation. This is the real analysis analogue of the cauchy riemann integral formula where integration can be done as differentiation
17:04
Hi @ACuriousMind o/
17:49
@Danu heyhey
18:12
@ACuriousMind I'm bored to death.
rob
rob
@Danu Death? sounds harsh.
Life is harsh sometimes...
@Danu Taht's sad; alas I cannot entertain you as I'm preparing a party
@ACuriousMind Have fun :)
18:37
@Danu Thanks :)
18:57
@danu what's up
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