The h Bar

12:01 AM

Later, there is a black screen with some periodic but complicated waveform. Two white lines then started to appear and then squeeze towards the middle as it slows down its movement. It is some recursive algorithm such that whenever it stops, it subtract that frequency of sine waves with that amplitude away. The waveform also obey the property where the higher the frequency component, the smaller it's amplitude

Secret

12:21 AM

6

Q: Showing that derivative of conjugate is conjugate of derivative, using chain rule

I'm trying to show that the derivative of the conjugate is the conjugate of the derivative, i.e. $\dfrac{d[f(x)^*]}{dx} = [\dfrac{df(x)}{dx}]^*$, using the chain rule. Calling the conjugate * function 'conj', we have by chain rule $\dfrac{d\ conj(f(x))}{dx} = \dfrac{d\ conj(f(x))}{d[f(x)]} * \d...

Whether you can define some notion of curl on the complex number by treating it as a vector field of its real part and imaginary part I have no idea

Secret

12:48 AM

The complex number part of this dream might be inspired from this conversation

in Mathematics, 11 hours ago, by Balarka Sen

@ShaVuklia I mean you did, you wrote $f = u + iv$, that's the same as writing $(u, v)$, which is the real function. The multiplication is the same old $(a, b)(c, d) = (ac - bd, ad + bc)$. There's no "real" interpretation of this multiplication.

8

Q: How much can we "cheat" and use vector knowledge in complex analysis?

I'm an engineering-physics student taking a course in complex analysis, and it's a little frustrating, because I see all these connections to vector calculus over the reals (especially as applied to electromagnetics). For example, if we treat complex numbers like vectors, then the Cauchy-Riemann ...

complex-analysis multivariable-calculus vector-spaces physics

I have no idea how useful or useless an expression xdz-ydz* will be

Where x and y are real and imaginary parts of z respectively

G. Bergeron

2:36 AM

@vzn I think it is pretty interesting but not yet mature. There are still a lot of vagueness floating around...

Grrrrr! Sometimes QFT makes me want to eat my hat!

(not that I wear one...)

nitsua60

3:00 AM

Apropos of nothing...

Follow this link to watch a beautiful live feed of a nesting couple of white-tailed eagles in Estonia. (Only available during Estonian daytime.)

I've learned this species of eagle ^^ builds so-called "ancestral nests," to which they return clutch after clutch, generation after generation. So it's cost-effective for naturalists to install such high-quality cameras near them.

Anonymous

A bit too high quality :P

Anonymous

What's those blue lines in the sky?

Semiclassical

Well, that was enjoyable

Just got back from an evening lecture/conversation

0celo7

accurate representation of the next two months of my life i.gyazo.com/ef23596d4b3f58084eb9223613af4ae1.png

Semiclassical

One of the people talking/being interviewed was Louisa Gilder of “The Age of Entanglement “

The other was Chad Rigetti of Riggeti Computing

Balarka Sen

3:10 AM

@0celo7 PDE's on As Fuck manifolds, eh?

0celo7

look, I'm going to flag if you don't remove that

this is a Christian chat

vzn

3:21 AM

@G.Bergeron he has certainly captured the imagination of popsci writers, maybe why hardcore physicists have some aversion... o_O quantamagazine.org/… quantamagazine.org/… quantamagazine.org/…

nitsua60

@0celo7 Please stop using "flag" carelessly. If you're bothered by what Sen said say so, say why, and make an actionable request of them. (If you're not actually bothered by it then you're adding noise to a system--flagging--whose functioning you have complained about.)

vzn

arstechnica.com/features/2017/05/… cosmos.nautil.us/feature/137/…

Semiclassical

I suspect it was tongue in cheek. or at least i hope so

vzn

lol on SE chat "f---" is a 4 letter word, found that out myself the hard way o_O :(

Semiclassical

@vzn oh hey, I've been in that mine they mention

nitsua60

3:24 AM

@Semiclassical me too. I just think it's a bad idea. It contributes (IMO) to some of theproblems that very person complains about.

Semiclassical

...and that's about the limit of my interest in that article, tbh

dark matter is another thing I don't know about and really am not interested in

vzn

@Semiclassical way cool sounds like a nice item (amongst many others) for AMA :)

Semiclassical

it was fun. unfortunately the detector they mention has been decommissioned in the last few years

vzn

@Semiclassical GB is right, think it is deep & might have to do with unification. unification is of intense interest to a wide swathe of physicists, but then again, not everyone... its sort of the ultimate Big Picture™ :|

nitsua60

Ooh, dawn light hitting the eagle's back.

Semiclassical

3:27 AM

details on the Soudan mine experiments here: soudan.umn.edu

including a virtual tour

0celo7

why can't I be offended by Karl

vzn

@Semiclassical am more and more surprised about UMN all the time, some really world class physics going on there, but it seems very low profile. think it would be interesting to look into its history, wonder how it happened...

Semiclassical

well, part of it is location

vzn

@nitsua60 ?

Semiclassical

when you think of California universities you get Berkeley, Santa Barbara, etc.

and when you think of the East coast there's a bunch as well

MN is sort of off on its own

0celo7

3:29 AM

Trump U

Semiclassical

I'm only counting universities that still exist

(and coincidentally only ones were that were ever worth talking about)

vzn

@Semiclassical did gilder do a lecture today? or some other day? whatd you think

nitsua60

@vzn tv.eenet.ee/merikotkas.html

Semiclassical

@vzn it wasn't so much a lecture as an informal interview in front of an audience

half hour with her, half hour with Carl Rigetti, half hour for questions, half hour for book signing and informal conversation

(roughly)

They were recording it, so I'm curious if they'll post it online at some point

vzn

@Semiclassical am gonna watch that one if it gets online, encourage them to do so :)

Semiclassical

3:32 AM

well, it wasn't being held on campus but at a book place nearby

so I dunno

But I'll ask about it

vzn

@nitsua60 wont play in my ipad what is it?

nitsua60

33 mins ago, by nitsua60

Follow this link to watch a beautiful live feed of a nesting couple of white-tailed eagles in Estonia. (Only available during Estonian daytime.)

vzn

11 hours ago, by John Rennie

@Semiclassical vzn specialises in making portentous statements, but when challenged is unable to point to any concrete evidence to back up those claims.

Anonymous

@nitsua60 The view looks better now

nitsua60

@Blue the light levels may have been low earlier?

Anonymous

3:37 AM

Yeah, a bit. And the yellow lighting in the bottom right end looks nice

vzn

↑ re that: building new theories is very hard work, not for the fainthearted, impatient, or mere dabblers/ dilettantes. looking for any earnest volunteers, always welcome. there are copious details/ authoritative sci refs in my blog over ½ decade now, many cited here etc.

Anonymous

I guess those blue lines are the leaves? @nitsua60

Semiclassical

The vague portentous idea I have is whether dBB could have any bearing on the mathematics of resurgence theory (aka asymptotic series gone wild). I have at least one reason to wonder about that but I don't plan on thinking about it any time soon

Anonymous

It looks a bit strange

Anonymous

And it started twisting it's neck after long

Anonymous

3:38 AM

lol

Anonymous

I see the face now

nitsua60

@Blue oh I see what you mean now. Pine needles just in front of the lens.

Anonymous

Ah, makes sense

Balarka Sen

vzn = JD is a plausible claim

I have never contemplated that actually

Anonymous

The eagle is lazy af though

Anonymous

3:40 AM

:P

vzn

@Semiclassical looked at one of your refs on that it looked interesting, but more mathematical. yes singularities are a big/ crosscutting mystery pondered by the greats (eg feynman) and ongoing. a premiere zen question™ one might say :P

0celo7

@nitsua60 reporting: three counts of "heck" and one count of "hell" in seminars this week

Semiclassical

I guess I have two reasons, come to think of it

though one of them has a big likelihood of just being coincidence

and the other might not really gain anything from thinking about trajectories.

nitsua60

egg turning!

vzn

@Semiclassical seems like a good choice of area to make a contribution. emerging, significant, deep etc.

Semiclassical

3:43 AM

maybe.

the pitfall is that the main place people seem to want to apply resurgence theory is stuff like QCD

and uh

above my paygrade

Anonymous

@nitsua60 Ah

Anonymous

nice

Anonymous

finally

vzn

@Semiclassical "pitfall"? are you saying QCD is "above your paygrade"? btw phd sometimes called science work visa/ employment card by some.

Semiclassical

QCD is, yes. though I guess it's not so much 'above' as 'outside'

nitsua60

3:45 AM

in RPG General Chat, 34 mins ago, by Rubiksmoose

Man eagle parenting is boring. You'd think they could get Netflix (Nestflix?) at least

Semiclassical

@nitsua60 nestflix and roost

Anonymous

Heh

nitsua60

@Semiclassical that's hot

Semiclassical

by and large, though, QFT stuff is not my thing

just not something I ever had a particular talent or inclination for

nitsua60

night, all

Semiclassical

3:47 AM

night

Anonymous

Cya!

0celo7

@Semiclassical Ugh, I have to generalize 5 pages of potential theoretic calculations to n dimensions

Semiclassical

Good luck.

0celo7

could use an em expert

vzn

@Semiclassical so whatd you think of riggetti/ gilder anyway?

Semiclassical

3:49 AM

it was fun.

vzn

@Semiclassical so did you gain any )( new affinity for QC...?

Semiclassical

didn't learn a lot about QM from the gilder part, but the history I was pretty well aware of already so I wasn't expecting to

the QC side was more informative in that regard. it seemed like a sober, realistic assessment of the field

vzn

@Semiclassical sober eh? seems like sometimes nobody working in it is sober :P gotta go look up gilders bkg, was amazed at depth of her book, seemed like she came out of nowhere & wrote the definitive history...

Semiclassical

well, she spent a lot of time on it :)

it originated from a term paper and grew from there

vzn

@Semiclassical she has serious talent, a real writer/ storyteller/ raconteur, impressive, wonder what shell tackle next

Semiclassical

3:53 AM

I think once she was put in touch with a publisher she spent another four years turning the manuscript into a publishable work

heh, one of the presenters was not-subtly urging her to write an update to her book that covers the last decade in QC

she didn't let on about her current projects, though

vzn

kind of a cipher who came from nowhere, she seems not even to have website penguinrandomhouse.com/authors/60477/louisa-gilder

Hritik

Hi, can anyone please help me understand how U=v in the nobel lecture by de Broglie ? nobelprize.org/nobel_prizes/physics/laureates/1929/…

^ Page no: 5

There seems to be a interchanging use of variable v for frequency and velocity.

Anonymous

@Hritik I don't think that's derived in the paper. Rather looks like an assumption

Anonymous

Anyhow, I didn't go through it thoroughly

Anonymous

"the group velocity of the waves in the system
xyxt is equal to the velocity of the corpuscle in this system"

Hritik

4:07 AM

@Blue I think that came from the equation above from Rayleigh but when I tried solving it I got something different. Can you try as well, please ?

Anonymous

Sorry, I need to leave now. Ask on the main site maybe.

Hritik

OK, thanks anyway

Cows

ok so I will be looking at page p. 43 scattering Amp

hmm so I get $\theta (t' - t) \psi(x') = i \int d^3 x G(x';x)\psi(x)$

Let me just try to confirm that I can be ok with the integral representation of $\theta$

$\theta(\tau) $

$\theta(\tau) = lim - \frac{1}{2 \pi i} \int \lim d \omega \frac{e^{- i \omega \tau}}{\omega + i \epsilon}$

what the duce

. . .

ok let me think

. . .

why and how

. . .let me think

eulB

4:28 AM

thonk

Cows

I mean I know what a theta function (step function is) let me look at the integral representations in this context

let me think

hehe

so one can check, but this does not tell me why this form is used

hmm

let me first look at this en.wikipedia.org/wiki/Heaviside_step_function

Heaviside step function

The Heaviside step function, or the unit step function, usually denoted by H or θ (but sometimes u, 1 or 𝟙), is a discontinuous function named after Oliver Heaviside (1850–1925), whose value is zero for negative argument and one for positive argument. It is an example of the general class of step functions, all of which can be represented as linear combinations of translations of this one. The function was originally developed in operational calculus for the solution of differential equations, where it represents a signal that switches on at a specified time and stays switched on indefinitely....

close with small cigar

Balarka Sen

5:31 AM

Aesop Rock - All Day Nike + Original Run (Continuous Mix)

►

Wow holy shit

This is unflippingreal

Cows

6:23 AM

yeeehaaa good playlist

This stuff is epic. Would listen to this while coding tomorrow!!

Novalium Company

Guys, what are kets and bras in QM. I tried looking around, but I still can't get it.

G. Bergeron

@vzn Yeah, on that part he is rather prone to premature public declarations. And it comes back once in a while as if new.

@NovaliumCompany state vectors and their duals

Novalium Company

I'm a beginner in QM, and what is a state vector?

G. Bergeron

Or elements of the Hilbert space (ket) and elements of the dual of the space, aka functionnal linear (bra).

Novalium Company

... never mind.

G. Bergeron

6:27 AM

You should learn some abstract linear algebra

before learning QM

Novalium Company

ok.

G. Bergeron

Then QM is just seeing physical states as vectors of a special vector space (Hilbert space) with linear operators (= matrices) representing time evolution and measurements. So infinite dimensional vector spaces and the associated theory of linear operators on them is kind of a necessary prerequisite

John Rennie

@NovaliumCompany it's simpler than G. Bergeron is making it sound because he is using technical language, but it will take a little while to explain ...

G. Bergeron

@JohnRennie LOL, but you'd agree linear algebra is kind of an obligatory prequisite?

especially when one is considering the bras and the kets...

John Rennie

@G.Bergeron bear in mind Novalium is 15 years old

I think you can get the basic idea without having to do a LA course.

G. Bergeron

6:33 AM

hmm, ok

John Rennie

But yes I absolutely agree that understanding LA is the best way, by far, to understand QM

G. Bergeron

hence the ''... never mind.''

Novalium Company

@JohnRennie I know it will be hard, but I am not giving up.

John Rennie

@NovaliumCompany I have to work for about half an hour but I'll be available after that if you want to pursue this

G. Bergeron

@NovaliumCompany Is your goal to get a feel or an intuition for the ideas or get to ''use it everyday''?

Novalium Company

6:36 AM

I would like to get to the main ideas in quantum mechanics and computing, since I see a big future potential in it.

G. Bergeron

what's your current background in math?

and physics?

Novalium Company

@JohnRennie I will be going to school soon, so I'll be here Saturday and Sunday.

@G.Bergeron I am 15. I think that explains enough :D

G. Bergeron

@NovaliumCompany I don't know your past nor what is typical in your country

Novalium Company

Bulgaria

and I've learned Classical Physics through watching Khan Academy vids, and so on...

G. Bergeron

What are your learning in math?

Like functions, trigonometry, algebra?

Novalium Company

6:38 AM

That's my main problem. My math is for a 15 year old.

But I am ready to learn it, together with QM.

G. Bergeron

which is?

Novalium Company

Which is what?

G. Bergeron

Understand it's a bit beyond me and I don't remember what I knew at that time

Novalium Company

Oh, well, I can't tell you what I know, because our 'titles' in our student books are in Bulgarian.

G. Bergeron

Have you done calculus?

Novalium Company

6:40 AM

Yes... I guess :D

G. Bergeron

like derivative / integrals?

dx/dt and the like

Novalium Company

I'm learning Integrals

G. Bergeron

ok

and polynomials and the like is fine? Like finding zeroes.

Novalium Company

I like to do it this way: I'm reading a Quantum Mechanics book, and whenever I don't understand so math concept... etc, I google it or ask for help here.

I don't know the titles in English, but I think I know polynomials.

G. Bergeron

like 4 x^2 + 3x -3

Novalium Company

6:42 AM

Yes...

I know these guyz :D

So yeah, any more questions? Cause I have to go to school.

G. Bergeron

Oh

THe next one was about real numbers

like 3.454634534621.....

Novalium Company

I know them.

G. Bergeron

@NovaliumCompany Cool

Well good day if you have to leave, if I'm around I'll help, now that I know what to start from

@vzn Also what's a hardcore physicist?

Novalium Company

Thanks. The community here is very good, and everyone is so kind and ready to help. Here is the book that I am following: ffmgu.ru/images/2/24/… I am at 'Creating Your Own Vectors in Hilbert Space' and I'll finish it soon.

So see you later @G.Bergeron and @JohnRennie

Prathyush Poduval

7:38 AM

@NovaliumCompany Griffiths is a very good book for QM. He introduces all the mathematical ideas and techniques in the book too.

If you’re interested to learn linear algebra separately, you can look into Sheldon axled, it’s a pretty awesome book

Anonymous

8:28 AM

@PrathyushPoduval For some reasons I don't like Griffiths at all. Firstly, it starts too early with the Schrodinger's equation. Secondly it does give a good introductory background in the Hamiltonian and Lagrangian formulations unlike Shankar.

John Rennie

Damn the torpedos, I'm going to have another coffee!

Emilio Pisanty

8:46 AM

@Cows still confused?

Shing

too board?

0

Q: What's a good book on experimental methods for physics?

I have read many books which can guide one in becoming a better theoretician but I haven't come across many books that help one become a better experimental physicist. For some reason the history of science favours the theoreticians and while I admire Lev Landau, Henri Poincaré and Albert Einstei...

experimental-physics resource-recommendations

Emilio Pisanty

@Shing looks fine to me

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