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

00:01
@enumaris :D Is it a recreational read? or for academic or professional purposes? It sounds quite hardcore
It's geared toward 1st and 2nd year grad students
so probably not "recreational", but not so hard that it's unreadable
I have an undergrad degree in econ so that might help me a bit...(or maybe not, I haven't done Econ in ages lol)
@enumaris wha aa a a a ? Your undergrad was econ? I had no idea
You have a diverse set of skills, and knowledge
hey
reading some random things, see you guys soon
I'm finally getting back to metal after months of hiatus.
Damn this feels good!
00:09
metal? :)
Oh nice
Wish I had big speakers. I want to play this loud.
@Avantgarde you should probably consider your neighbors' peace
That's why you should have metalhead neighbors.
00:12
I would recommend head phones, but I worry you might beat your ears out with that stuff
Already wearing them.
Though I should consider buying better ones.
@Cows lol yeah...I have a double degree in Econ and Astro as my undergrad :D
Maybe you could try applying Einstein's equations to economic models?
lol
not sure it works like that :D
@enumaris with einstein, probably not. with quantum... arxiv.org/abs/quant-ph/0109122
00:15
Yeah, but who knows? Apparently path integral methods are applied in finance.
haha I'm sure there can be mathematical analogies made
But it's more applying the math to the problem rather than applying the physics to the problem.
time to clock out
laters
Yeah. Or maybe getting insight from the physical principles.
00:16
Econophysics is an interdisciplinary research field, applying theories and methods originally developed by physicists in order to solve problems in economics, usually those including uncertainty or stochastic processes and nonlinear dynamics. Some of its application to the study of financial markets has also been termed statistical finance referring to its roots in statistical physics. == History == Physicists' interest in the social sciences is not new; Daniel Bernoulli, as an example, was the originator of utility-based preferences. One of the founders of neoclassical economic theory, former...
If only we could use Born's rule to estimate the probability of a stock price jump.
From Benjamin Graham's "The Intelligent Investor" -
“Back in the spring of 1720, Sir Isaac Newton owned shares in the South Sea Company, the hottest stock in England. Sensing that the market was getting out of hand, the great physicist muttered that he ‘could calculate the motions of the heavenly bodies, but not the madness of the people.’
Newton dumped his South Sea shares, pocketing a 100% profit totaling £7,000. But just months later, swept up in the wild enthusiasm of the market, Newton jumped back in at a much higher price – and lost £20,000 (or more than $3 million in [2002-2003’s] money. For the rest of his life, he forbade anyone to speak the words ‘South Sea’ in his presence.”
mmm quantum economics
00:35
@danielunderwood "I know what my stock is worth, therefore I have no idea what it's going to be worth."
00:45
It's in a superposition of prices until the next tick, when the state collapses into a single price
You QM guys have any opinion of the transactional interpretation? I just heard of it as another one
01:09
an interpretation which relies on probability waves traveling both forwards and backwards in time seems...eccentric
I saw a reference to Putnam’s law earlier: an interpretation of quantum mechanics is believed by its inventor and up to six other physicists
I got a chuckle out of that
And you don't find the other interpretations eccentric?
lol that seems about right though
I mean, there is a certain 'conservation of absurdity' when it comes to QM
if you pick an interpretation that makes one part of it seem reasonable, then something else won't make sense
hmmm as weird as that seems, wouldn't that make time reflection symmetry happy?
I think life is complicated enough without having retrocausality.
01:25
Hey if we're going to be a little crazy, may as well go full nutters lol
02:02
Leave no stone unturned.
02:31
So I was looking around for information about dyslexia for one reason or another. It so happens that I was reading a whole lot of things and happened upon this.
There is even a question about whether one has read something like a paragraph more than once to understand it.
So people never read a paragraph more than one? Or a sentence more than once ever to understand it?
This is scary . .
 
1 hour later…
03:44
Hi guys, is there identity which relates $(\sigma_a)_{\alpha\dot{\alpha}}$ and its complex conjugate $((\sigma_a)_{\alpha\dot{\alpha}})^*$?
I know that $(\sigma_a)^{\dagger}=\sigma_a$ but when I use index notation I run into trouble when switching the order of the indices (I work with the convention $(\tilde{\sigma}_a)^{\dot{\beta}\beta}:=\varepsilon^{\beta\alpha}\varepsilon^{\d‌​ot{\beta}\dot{\alpha}}(\sigma_a)_{\alpha\dot{\alpha}}$.
vzn
vzn
04:05
@Semiclassical are you talking about RQM? its been in the headlines some lately due to some new experiments. it sounds to me like "retrodicted pilot waves." think/ suspect there is some not-extremely-complex reformulation that does not involve backward probability waves.
04:34
If there are three forces namely contact force(F),force of friction (f) and normal reaction force(N) then if one of the forces is made zero and the body remains in contact with the surface then which of the following is true:
(a)F>N(b)F>f(c)N-f>N+f(d)All of these
05:06
Please don't laugh
So things are just localized fields or whatever, and fields are fundamental
How come I can hold my phone in my hand
lol how do you get a solid from this?
Dude, the universe is next level awesome
How is this even possible
QFT isn't very good at describing bound states, so trying to understand atoms using it is a poor approach.
So an appropriate language for this will be quantum mechanics?
But QFT tells us how charged particles interact at a fundamental level, and that gives us the Coulomb potential that we can use to describe atoms.
So the charges and interactions are explained away, but bound states are not (or hard in this language)
QFT, at least in the usual perturbative approach is really a way of describing scattering probabilities.
05:12
Fascinating
That is, consider two particles coming in from infinity and interacting, then the products fly back out to infinity. QFT allows us to calculate the cross sections for the various allowed reactions.
I see
Is graph theory useful to physicists?
I think I may take a course in it since it's interesting, but it's not worth the stress if I'm not going to use it ever
I heard about some theory of gravity based on graphs at one point, but wasn't able to find too much on it. And it's certainly not a mainstream theory
They do pop up in comp sci when talking about data structures, but I'm not sure how far they typically go into the math side of things. And in 5 or so years of programming, I think I've used one all of once
05:27
I mean geometrically it seems interesting
shame it's not very applicable :/
Actually there's lattice QCD. I think that theory of gravity may have been based on lattices as well
It doesn't sound like graph theory comes up much tho
In physics, lattice gauge theory is the study of gauge theories on a spacetime that has been discretized into a lattice. Gauge theories are important in particle physics, and include the prevailing theories of elementary particles: quantum electrodynamics, quantum chromodynamics (QCD) and particle physics' Standard Model. Non-perturbative gauge theory calculations in continuous spacetime formally involve evaluating an infinite-dimensional path integral, which is computationally intractable. By working on a discrete spacetime, the path integral becomes finite-dimensional, and can be evaluated by...
Still not much, but I suppose it's more than I thought
QCD is probably more than I'd learn as an undergrad too
05:46
Yeah unless you found an elective that talked about it. I still don't know that you'd get into lattice QCD in that case. It does look fascinating to me though. I wondered a while back about the "calculus" of discretized spacetime and I guess that's it?
@danielunderwood It seems more generally to deal with discrete relations. Though most of physics seems to care about the continuous instead
06:14
Stigler's law of eponymy, proposed by University of Chicago statistics professor Stephen Stigler in his 1980 publication "Stigler’s law of eponymy", states that no scientific discovery is named after its original discoverer. Examples include Hubble's law which was derived by Georges Lemaître two years before Edwin Hubble, the Pythagorean theorem although it was known to Babylonian mathematicians before Pythagoras, and Halley's comet which was observed by astronomers since at least 240 BC. Stigler himself named the sociologist Robert K. Merton as the discoverer of "Stigler's law" to show that...
Love this
06:25
:-/
06:51
how do you feel about rejection?
07:07
If there are three forces namely contact force(F),force of friction (f) and normal reaction force(N) then if one of the forces is made zero and the body remains in contact with the surface then which of the following is true:
(a)F>N(b)F>f(c)N-f>N+f(d)All of these
Pls help me with this
07:34
@gateprep What are your thoughts on it?
making a sketch may help :-)
@DavidZ
What I feel is F=square root of(N2+f2)
now contact force cant be zero else it would jump
What else
@JohnRennie you consider yourself a "medalhead"?
@user2236 It depends on how exactly you define metal
I grew up listening to Black Sabbath, Deep Purple and Led Zeppelin. But some would describe these as hard rock rather than metal.
I think the adjective metal only became common with the NWOBHM movement of the early 80s.
07:43
hmmm
@gateprep Honestly, a sketch would be pretty helpful.
yes I have done it now say
Anyway, if $F = \sqrt{N^2 + f^2}$, do you know on that basis if any of the conditions are true?
or false?
no that is where i am stuck
OK, well take them one case at a time then. If $F = \sqrt{N^2 + f^2}$, can $F > N$ be true?
Or I guess the better question to ask first is, can it be false?
08:24
yes it might in case friction is 0
OK then: if $F = \sqrt{N^2 + f^2}$, since (a) can be false, it's presumably not the answer. Does that make sense?
How about (b)?
08:42
@JohnRennie I'd call that Precious heavy metal
:-)
@user2236 :-)
 
1 hour later…
10:09
Hello guys, I don't understand a thing about chain drives. As we see in the picture, in the first example, we need to rotate the smaller gear 5 times in order for the bigger gear to rotate 1 time. My question is what's even the point of doing this? Does it have any effect on how much the electric motor struggles? Does this gear ratio even have any practical use, except to make things easy when we ride a bike?
I know for example gears are used in cars in the transmission system to regulate the speed of the wheels, but that's all. Does it have any effect on how the engine struggles? When we are going up a hill, it's better to be put on a larger gear, because we may be going slower, but the engine won't struggle and we'll save fuel?
In your diagram the tension in the chain is constant. Call it $T$. Then the torque on the gears is $T r$ where $r$ is the radius of the gearwheel.
So the torque on the smaller wheel is less than the torque on the larger wheel.
And we can change the torques by changing the relative sizes of the two gears.
We can view the force in the torque equation as the tension?
10:24
@NovaliumCompany yes
Does this have any connection to how the motor struggles. I don't know exactly what I mean by that, but if we were to put a large gear to the motor, the motor will struggle to rotate?
That's why we make the gear chain?
To make the electric motor's job easier? It will rotate more, but struggle less?
If you consider a car then the motor normally spins very fast with a relatively low torque. By using the gears we make the wheels rotate more slowly than the motor but with a higher torque.
Is the force/tension the same in a car?
@NovaliumCompany cars don't use a chain. In a car gearbox the gears link directly together not through a chain. But the same principle applies.
Ok, so if the transmission line is put to a gear with relatively higher radius, the wheels will spin slower, but with higher torque (meaning, will be more 'powerful' and will be able to climb steep hills) but if we were to put the transmission line to a gear with small radius, the wheels will spin faster (and the car will move faster) but won't be able to climb hills because they are not 'powerful'?
10:35
Yes.
@JohnRennie Alright then, cleared some misunderstandings. Thanks so much for the help!
That's why when a car is starting to move it uses a low gear (low gear = slower rotation, more torque) then when it's up to speed it uses a higher gear. It needs the extra torque while accelerating.
:: thumbs up ::
 
1 hour later…
12:26
@vzn I was commenting as to danielunderwood bringing up the transactional interpretation, and why I don't find it appealing
A hole in spacetime sure is cool, unfortunately that does not matches experiment
(that is a crank video, be warned)
57
Q: Link to code of conduct broken?

ZetaThe recent blog post "Get to Know Our New Code of Conduct" contains a link to the new code of conduct, https://stackoverflow.com/conduct. As of 2018-08-07T05:27:38+00, that link returns a 404. Also, I cannot find any other link to the conduct yet, neither in the help center, nor in the site navi...

did someone flip a switch too early?
ugh. if there's one thing I hate about mathematica, it's figuring out what exactly it's error messages mean
12:42
@Semiclassical case in point?
It's coming back with "Encountered non-numerical value for a derivative at t==0" in response to this:
omega = 5; beta = 2;
sol = NDSolve[{
   -1/2*D[psi1[x, t], {x, 2}] + omega^2 Cos[\[Theta]] psi1[x, t] +
     beta psi2[x, t] == I D[psi1[x, t], t],
   -1/2*D[psi2[x, t], {x, 2}] - omega^2 Cos[\[Theta]] psi2[x, t] +
     beta psi1[x, t] == I D[psi2[x, t], t],
   psi1[0, t] == psi1[2 Pi, t],
   Derivative[1, 0][psi1][0, t] == Derivative[1, 0][psi1][2 Pi, t],
   psi2[0, t] == psi2[2 Pi, t],
   Derivative[1, 0][psi2][0, t] == Derivative[1, 0][psi2][2 Pi, t],
   psi1[x, 0] == E^(-omega/2* (-(Pi/2) + x)^2),
...and the moment I finish all that time getting it in a nice c/p form, I realize what the problem is
siiiiigh
(I used \[Theta] in a place where I meant to use x)
@Semiclassical missing a ]?
@Semiclassical y u use omega and psi?
as opposed to \[Omega] and \[Psi], that is
because i wanted to c/p it without it looking like \[Psi]
a.k.a. esc-w-esc and esc-y-esc
huh, i've always just done esc-psi-esc
12:52
@Semiclassical oh, the beauties of MWEs
@Semiclassical huh
I mean, why not do esc-\psi-esc while you're at using clunky formulations =P
my favorite little example of that is the fact that esc-eta-esc, esc-et-esc, and esc-h-esc give the same result
i mean, the reason i haven't done esc-y-esc is that I didn't know about it :P
13:05
@EmilioPisanty of course, the real problem with this is that NDSolve is a black box
when it works, great
but when it gives a result I don't trust, i'm never sure how to fix it
13:17
@Semiclassical yeah, that's a problem indeed
dammit
still not quite there
I think it's improved on the original?
or maybe not, what do I know
have I just traded sharp features in one bit for more sharp features elsewhere?
is that better?
heck, is that as good as one can hope for?
 
1 hour later…
14:47
Well that sucks. I figured they would have found it. At least he gets the distinction of being the only person to win two in a week I suppose
I doubt they're going to find it.
15:30
Hi
When is the event?
Anonymous
@user2236 A part of me wishes that they lose the fields medal for a second time. It would be hilarious. :P
15:51
@Akash.B according to SE, in 9 minutes.
@user2236 not sure we really need to comment on this sort of thing here.
Afternoon
o/ @SirCumference
how've you been?
Good, you?
pretty good
16:02
Hey @enumaris
Nothing much, just finished some classes and finally have a free summer
For 3 weeks at least
I'll take what I can get
@SirCumference That seems really late to me
@heather is that... it? Are racist comments allowed when directed at 'third-world countries'? Or is the SE moderation stance so decidedly anglo-centric that it doesn't even register as offensive and inappropriate?
did summer skoo?
16:06
@BetaDecay Well yeah, but it helped to get some humanities out of the way
Not too sure if it was worth it tho...
@heather There's been several instances, involving off-PSE moderators, where the moderation stance is notoriously US- and generally anglo-centric biased. Please, please do not follow that trend.
@SirCumference Ugh humanities
I remember when I had to do those
Well for these 3 weeks, no responsibilities!
Thank god
@EmilioPisanty i apologize. i've handled this poorly both times i've been in here dealing with this, and that's not really acceptable.
16:09
There's been quite a bit of this "theft <-> third world country" linkage going around since this story happened, which is rather distateful
How're things on your end @BetaDecay or @enumaris
@EmilioPisanty I don't really mean to stir the pot and this isn't really in regard to that particular comment, but is calling a third/second world country such generally considered offensive?
@SirCumference doing good :D
@SirCumference I finished my A-levels in June and have been on holiday ever since
So it's been great
particularly since the mathematician whose medal was stolen is himself a refugee
16:10
@BetaDecay Neat
@danielunderwood as @Semiclassical points out, the problem is the implication "third-world-country $\implies$ theft". This shouldn't be hard or at all controversial.
Ahh I didn't even pick up that part
@SirCumference It's been a great time to study stuff that I would never have in school. Like GR
I think there's gonna be a cool bit of Deep Learning that I'll get to do in the near future...hopefully.. :D
@BetaDecay That sounds fun. What kinds of GR
16:14
what are the kinds?
Like what kind of GR concepts
@SirCumference Just the basics really. I watched all of Leonard Susskind's Theoretical Minimum lectures and flicked through MTW's Gravitation
Ultimately, I'm interested in Cosmology
So my aim was to derive the Friedmann Equations
@enumaris is your job all ML stuff or are you on the business side too? Like do they give you data and say do what you can or do you look at business processes and try to figure out what can be improved with data?
I'm more on the data side, but since the company hasn't streamlined the processes all that much (e.g. no Biz Analysts available), I have to think about the business implications as well.
but there are people who are more on the business side who actually have to apply the insights obviously
I don't generally do that stuff
my time is too valuable :P
(jk)
Ahh apparently I missed the analytics train for undergrads. I had an offer for a position when I graduated, but ended up going for something else. Now whenever I look, it seems like everyone wants someone with a PhD
Or they want someone with 10 years of data science
16:29
o.o
data science is pretty new
10 years experience is asking for a lot lol
Yeah I don't know who exactly they expect
PhDs in data science are also hard to come by since it's so new
but PhDs in CS or something is common
I guess it may be one of those "HR doesn't know the field" situations though
probably lol
Well I was saying PhD in general, though some of them do want a PhD specializing in data science
16:30
Companies like that are sometimes not worth it to work for anyways
I feel it's a lack of vision
Yeah some of the positions it kind of looks like "everyone else is hiring data scientists, so we need one, right?"
If you ask for 10 years experience, you better be recruiting for a senior level position. Or else you're just asking for someone with like no ambition who's been doing the same exact thing for 10 years...not better than a newbie who has imagination imo.
welp, the "sprained" ankle is broken \o/
I can understand asking for 10 years experience if you're recruiting for someone who's going to build out an entire data science team for you and you want to give that person a lot of free-space to do it. But then you're not asking for 10 years of data science experience, you're asking for a lot of years of management experience.
@ACuriousMind sorry to hear that
16:34
@ACuriousMind That's bad luck. Sprained and then you broke it
but then again, I guess I'm pretty biased as someone who doesn't have a ton of "experience" :P
@EmilioPisanty Thanks. On the plus side, I finally get to learn how to walk on crutches :P
@ACuriousMind what'd u do to break it?
I've "slightly fractured" my ankle before
@ACuriousMind ... count your blessings, I suppose?
but by the time an ortho guy saw it, it was already healed lol
16:35
Yeah that's true too. I've seen countless job postings where they want someone with a bunch of experience to do one specific thing. I think I'd go crazy if I was at a job where I couldn't push to do new things. But yeah I don't really have much experience either. I did make a major step in finding out that most of the stats I have learned is only applicable to unimodal distributions...which should have been fairly obvious in retrospect
@enumaris I...fell. Literally just stood up, got a bit woozy and faceplanted.
@ACuriousMind is it mean to star that?
in a friendly way =)?
=P
@ACuriousMind you uh...get woozy standing up often? Or was it you stood up way too fast?
@EmilioPisanty A bit, but I'll survive :)
16:37
low blood sugar?
@ACuriousMind good luck on your recovery
@ACuriousMind were you at Wacken? Was beer involved? :-)
@enumaris It probably was a combination of standing up very fast, having low blood pressure to begin with and it being unusually hot
@danielunderwood yeah...I just feel like experience is good for some things, but it's overrated in some other areas.
@ACuriousMind so... academic liberals blaming climate change for everything?
16:39
@JohnRennie Sadly not at Wacken
Climate change causes broken ankles? :-)
don't remind me of the sorry state of climate change and the environment...-.-
it's too depressing
@ACuriousMind argh, not even that consolation :-(
@JohnRennie I approve. When it's all said an' done, not a bad way to go: break out of your nursing home and party hard one last time.
I just read yesterday that the EPA is lifting restrictions on asbestos use...
getting lung cancer in a couple of years should be fun
16:40
@EmilioPisanty That's one way to look at it I guess
cries in the corner
@danielunderwood Thanks :)
So I have been curious of what kind of uncertainty is involved with climate models. I feel that it would be kind of like modeling a chaotic system from a physical perspective. Though I will admit a good first step would probably be for me to look at the literature
@danielunderwood I think it's the unknown unknowns that are the big problem. The modelling is just a big finite element calculation, but how can you be sure you've included everything?
Particularly since you can only run the experiment once :-)
16:47
You could examine Venus
so, anyone care to put down bets on when the broken link on the code of conduct will be fixed?
the link doesn't conduct?
shocking
How can it shock you if it doesn't conduct?
dang, you're right
not shocking, then
67
Q: Link to code of conduct broken?

ZetaThe recent blog post "Get to Know Our New Code of Conduct" contains a link to the new code of conduct, https://stackoverflow.com/conduct. As of 2018-08-07T05:27:38+00, that link returns a 404. Also, I cannot find any other link to the conduct yet, neither in the help center, nor in the site navi...

vzn
vzn
16:49
@danielunderwood hi re transactional interpretation, have heard some about it, lately wondering if it is at all related to "two state vector formalism" TSVF which has new/ recent experimental results announced, some apparent buzz lately eg nature.com/articles/s41598-017-00274-w
Hmmm yeah never really thought about the unknown unkowns. I just figured a small difference in what was known could make a big difference. Although I suppose they have ice core samples that could make suggestions if the model works in the past
@danielunderwood with the disadvantage that your knowledge of the initial conditions for the how-it-was-in-the-past simulations is less than perfect
But I mean if your simulation ends up with all/none of the water on earth being in the form of ice 1000 years ago, then it's obviously wrong. It would indeed be tough to determine models with close predictions though
There was some fairly apocalyptic stuff on the radio news this morning suggesting we are approaching a tipping point. I was working so not really listening and don't remember the details.
As a curiosity, do we have any ability to examine the atmospheres of planets in other solar systems?
There's always something apocalyptic on the radio lol
vzn
vzn
Apr 20 at 16:34, by John Rennie
Perhaps our children would be sufficiently mutated that they could stand the heat.
On that note, the following sentences appear in the wiki page on the transactional interpretation:
"The transactional interpretation is superficially similar to the two-state vector formalism (TSVF)[7] which has its origin in work by Yakir Aharonov, Peter Bergmann and Joel Lebowitz of 1964. However, it has important differences—the TSVF is lacking the confirmation and therefore cannot provide a physical referent for the Born Rule (as TI does). Kastner has criticized some other time-symmetric interpretations, including TSVF, as making ontologically inconsistent claims."
@danielunderwood using spectroscopy, yes
(Kastner is apparently a writer/philosopher who has advocated for the transactional interpretation)
16:58
@BetaDecay hmmm I was thinking of earth-like planets, but I suppose gas giants or anything with an atmosphere could give useful data
> The authors say a total re-orientation of human values, equity, behaviour and technologies is required. We must all become stewards of the Earth.
@enumaris any chance that there are climate scientists trying to use that data?
I've not looked at either interpretation, so I can't comment on whether they've got a point or not.
@danielunderwood the data would be pretty basic, so I would guess probably not at this time
00:00 - 17:0017:00 - 00:00

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