The h Bar

ACuriousMind

00:00

Oh, well, to get that template to work you need to organize all the required .eps/.jpg images, too. Fixing the dvips will probably not get it to compile (but it's there, dvips right in the second line)

0celo7

I don't have any of the images either

oh wait

DVIPS

I read DVTIPS

no wonder the search function came up empty :P

ACuriousMind

::facepalm::

0celo7

I'm telling you, I'm a stroke victim, or something

ACuriousMind

@Qmechanic Oh, the vote limits count for you, too?

0celo7

@ACuriousMind ok, I'll get rid of the image stuff for now

it doesn't like \end{frame}

ACuriousMind

00:03

btw, googling any errors you get will almost always lead to a tex.SE post fixing it.

0celo7

how do I google

ACuriousMind

By typing your questions somewhere else than this chat window ;)

0celo7

oh my god now there's a longer error

this is too hard

back to Word

ACuriousMind

I guess we know now why engineers use Word.

0celo7

because we're retarded, haha, very funny

dmckee

00:06

I've never really understood the popularity of those video where some poor person makes a Class 1A fool of themselves in front of the whole world, but I think I'm beginning to get a inkling.

0celo7

@ACuriousMind holy crap I'm just deleting stuff now

nothing works

???

dmckee

Why are you looking at the aux file? You don't need to know what is in there until you understand why you might want to know what is in there.

0celo7

because I hit "goto error" and that's what popped up!!!!

dmckee

OK, here is the thing.

TeX is a programming language optimized for outputing stuff to page formats.

0celo7

I legit don't know what to google

dmckee

00:09

LaTeX is a library on top of the raw language.

When you mess up it gives you error message and you go into debugging mode just the same way you do with c or python or java or whatever language you are comfortable in.

The first rule of debugging is: only the first error matters.

3

The second rule of debugging is: it is related to what you just changed.

2

0celo7

I'm abandoning this

This is incredibly hard to use.

dmckee

The third rule of debugging is: the second rule doesn't mean you just broke it, you might have just exposed a pre-existing break.

@0celo7 No, it's not. But you have chosen to dive into the middle of a large existing project that hasn't been updated to the system you're actually using.

That's hard no matter what the context is.

Coaxing things to run in a new environment is a special skill and it is time consuming.

Bernard Meurer

@ACuriousMind @0celo7 either of you around?

0celo7

Nope.

dmckee

You are basically complaining that a template intended for the 2003 version of word isn't running right on this year's version. But that's not a surprise. I warned you about the lack of updates..

ACuriousMind

00:16

@BernardMeurer 'round and about

0celo7

I killed him because I'm yandere

Or is it tsundere?

I'm not a weeb, I dunno

Bernard Meurer

@ACuriousMind I'm having some trouble with Griffiths, he's talking about the velocity of the expectation value of x; but I don't get what that actually means

How can the expectation of X have a velocity?

ACuriousMind

@BernardMeurer Is he just taking the time derivative, or something else?

I'd expect he's just taking the time derivative.

0celo7

Does ACM know anything about quantum mechanics?

He can't even Fourier transformate a step function

dmckee

@BernardMeurer The expectation value of $x$ is a position, no? And that position can move. When it does the change in position over the change in time is a velocity.

As @ACuriousMind said, he's just taking the time derivative.

ACuriousMind

00:22

@0celo7 Pretty sure "transformate" isn't a word.

Bernard Meurer

@ACuriousMind I think that's the case yeah

But why should I care for the velocity of the expectation of x if that doesn't tell me anything about the actual speed of the particle?

dmckee

Just go with it for now. He'll expand on the implications in a couple of pages.

Bernard Meurer

Alrighty, I'll go solve my exercises

0celo7

@ACuriousMind proof?

Qmechanic

00:39

@ACuriousMind : For votes on posts and comments, yes.

ACuriousMind

There's a vote limit on comments?

For all my time spent on this site, I've never run into that one

Qmechanic

@ACuriousMind : Yes.

ACuriousMind

Do the automatic votes on duplicate comments and review comments count toward it?

0celo7

holy crap that template is from 2007

more errors

:/

@ACuriousMind where do the notes appear?

0celo7

00:57

Ok, how to start off a math presentation for a bunch of engineers...

LET M BE A PARACOMPACT HAUSDORFF MANIFOLD WITH OR WITHOUT BOUNDARY

ACuriousMind

4

Q: What would happen if photons had a mass equal to 1/100 of a hydrogen atom?

As we know, light has no mass. Well light having mass is the primary problem with fast(er) than light travel. Thinking about this classic, yet sad problem made me wonder, what would happen the the world if light photons suddenly had equal mass of 1/100 of Hydrogen atoms?

As usual for Worldbuilding, the top answer completely ignores the fundamental issue that massive photons would mean an exponential decay of the electromagnetic force.

HDE 226868

@ACuriousMind You do realize how much I would love for some of you to come over to Worldbuilding and correct things like this, right? Although I did see @0celo7 there recently.

Never mind; I see you commented on an answer.

ACuriousMind

01:13

@HDE226868 Yeah, I left a comment at the correct answer and a comment at the top answer.

HDE 226868

@ACuriousMind Thank you; I appreciate it.

ACuriousMind

@HDE226868 It's difficult to try to answer those questions because mostly the correct answer is "No, it doesn't work that way" or you have to write a book to cover all the possible changes and fixes to try to get something remotely resembling our world

The only author I know of who truly tries to write science-based fiction is Greg Egan, and there's some serious thought going into his books and they still probably suffer from some liberties taken to make the story work

HDE 226868

@ACuriousMind I've heard good things about Egan, but I haven't read anything by him yet.

@ACuriousMind I've answered questions like that, and I typically just go with "That's not how it works." There's no point in trying to address the rest, IMHO.

ACuriousMind

@HDE226868 I still haven't got around to reading his books set in a Riemannian universe, but Incadescence is a wonderful book about an insectoid Newton living inside an asteroid orbiting a black hole who incrementally succeeds at deducing mechanics from the strange way objects behave in that asteroid.

HDE 226868

There, are, by the way, two close votes on the question, both for "Too Broad".

@ACuriousMind That's fascinating.

ACuriousMind

01:24

But I can't imagine that book being interesting for someone not already into physics, so this explains why this is not a popular style of writing.

dmckee

@ACuriousMind Ghah! I don't have the power to downvote, but the quantity of bad physics in the answers and comments is nauseating.

0celo7

01:39

@ACuriousMind would atoms really not exist

what if the mass were reeeeeeeeeeeally small

ACuriousMind

@0celo7 Not as we know them. I haven't tried to solve the SE for a Yukawa potential, but it would have pretty fundamental impacts. Also, note that "reeeeeeeally small" is indistinguishable from no mass, which would make the question meaningless. The question explicitly says "a hundredth of a hydrogen atom", and a hundredth of a proton is not neglegible on atomic scales considering that's still an order of magnitude heavier than an electron.

In fact, that might make the decay photon+photon -> electron+positron quite viable, while the annihilation reaction would probably be heavily suppressed

dmckee

@0celo7 The maximum size of such atoms (using the 9.3 MeV mass the poster asked about) would be a few tens of femtometers. But the trick is that the potential has changed form, so a quick estimate of the energy level is not possible.

0celo7

> I haven't tried to solve the SE for a Yukawa potential

dmckee

Back to solving the Yukawa potential atom.

0celo7

Some crazy @yuggib-type has done that.

Or at least proved the solutions exist :P

And gave up after that

dmckee

01:46

The easy part is that you still get spherical harmonics. After than you have trouble. Is the solution non-relativistic?

0celo7

If you solve the SE you're gonna get a nonrelativistic thing

ACuriousMind

The Yukawa potential arises in the non-relativistic limit, yes. But it might be that the relativistic corrections one usually treats in relativistic QM become relevant far earlier.

dmckee

@ACuriousMind I hadn't even gotten that far. I was even wondering about the electron energies if bound to, say 50 fm. I think they have to be relativistic.

ACuriousMind

Another thing is that for the photons to become massive you have to have some kind of Higgs-type mechanism that gives the photon mass, and if the mass of the photon is that low, this impostor Higgs is also quite light, so you should see it at everyday scales

There's a lot of material there that could occupy a certain kind of physicist for quite a time, but it's not Worldbuilding, it's building a physical theory that is obviously not realized in nature, and who has time for that?

::waits for obligatory quip about string theory::

dmckee

::chuckles::

I think even a string theorist might balk at this if the project go too big. Afterall, they think string theory might be realized.

ACuriousMind

01:54

@dmckee That's why I stressed the obviously. No one except cranks pours work into theories that flat out contradict almost every observation you could make.

dmckee

Heck if forced to bet a bottle of 15 year old scotch on string begin being a good/bad description of the universe I'd take good just because I think the program has good foundations.

0celo7

I've never seen the relativistic electron stuff AFAIK.

Books always talk about but no one does it.

Bernard Meurer

Yo

0celo7

@BernardMeurer $f:A\subset\mathbb{R}\to\mathbb{R}$ is continuous at $c\in A$ if $\forall\epsilon>0$ $\exists\delta >0$ s.t. if $|x-c|<\delta$, $|f(x)-f(c)|<\epsilon$.

Bernard Meurer

@0celo7 on mobile, send pic plox

0celo7

01:59

You should be able to read LaTeX.

Bernard Meurer

I no longer own a PC

Yeah but there's a reason we render latex in the first place

dmckee

Of some interest: arxiv.org/abs/1210.5886

ACuriousMind

@BernardMeurer oO Did recompiling your kernel go horribly wrong somewhere?

0celo7

@dmckee Not even TeX

dmckee

Yeah. It's pretty icky. But sometime you just have to put up with that.

0celo7

02:02

@dmckee I'm working on the beamer crap

Bernard Meurer

@ACuriousMind My RAM was en route to death for a while and now I'm too broke to buy new ram

ACuriousMind

:(

0celo7

Time to write this presentation.

Hmm, how the heck do I write this

Do these people even know linear algebra?

dmckee

> "Since the SE with the Yukawa potential has no exact solution [...]"

0celo7

Proof?

dmckee

02:04

Is this a well know fact? They don't give a reference.

0celo7

Oh my GOD

Is that the standard font

how do I kill it with fire

ACuriousMind

@dmckee I'm not even sure how one would begin to prove such a thing. "exact solution" is a notoriously slippery term

dmckee

@0celo7 The beamer instructions include a section on controlling the fonts...

ACuriousMind

Some people call an unholy mess of Bessel functions an "exact solution", others would not.

0celo7

@dmckee oh really, where do I find that?

dmckee

02:07

In the table of contents, I suppose. I haven't read them in nearly a year.

0celo7

Eh...you ruined it

Whatever

dmckee

@ACuriousMind I'm OK with anything that converges in a sensible number of terms.

Usually sums of Bessel functions are that well behaved.

0celo7

@ACuriousMind I solved the problem of the vibrating membrane "exactly"

dmckee

That the statement seems to cry out for reference, and there isn't one.

ACuriousMind

I bet they just looked around if anyone had found a solution, and when they didn't find one, they just put that there to make their result seem more impressive

dmckee

02:10

Reasonable.

ACuriousMind

And "Does not appear in XY's great table of solutions to differential equations" is a rather sketchy looking "reference", I'd not write that, either

Although I'd bet @Slereah knows some paper computing energy conditions for classical solutions to the Yukawa potential SE, or something like that :P

0celo7

@ACuriousMind Why?

SE is nonrelativistic

why would anyone do that

ACuriousMind

That was a joke :P

0celo7

Germans don't joke.

ACuriousMind

This one does, and he also goes to sleep now

0celo7

02:15

Good night.

ACuriousMind

Good night

0celo7

Just as I begin algebra homework

You're evil

Sir Cumference

03:09

-7

Q: Dark Matter Revealed

Many theorize what the Universe would look like if it were to ever be observed. The matter called "Dark" is identical to the matter called "Grey".Coincidence? https://www.youtube.com/watch?v=TZFk7_nhqQQ Nervous system in the human brain look familiar? Question-With the authenticity or integri...

dark-matter

Gibberish

0celo7

03:24

@ACuriousMind How does one show that the nascent delta function, the Gaussian thing, actually becomes the delta function?

Hari Prasad

Is Zero Even? - Numberphile

►

James Rowland

05:19

@Ocelo7 to show a function $g(x,\epsilon)$ is a delta function you need to confirm the property $I=\lim_{\epsilon\to 0}\int dx f(x)g(x,\epsilon)dx=f(0)$.

For the Gaussian delta function first change variables $x\to x/\sqrt{\epsilon}$ so $I=\lim_{\epsilon\to 0}\int dx f(x\sqrt{\epsilon})e^{-x^2}dx/\sqrt{\pi}$.

Lastly if $f$ is well behaved we can use the dominated convergence theorem to show $I=f(0)$. The integrand converges pointwise to $f(0)e^{-x^2}$ and $f$ is assumed to be well behaved, i.e., smooth enough and not too divergent, thus allowing us to use the dominated convergence theorem.

This is just a formal statement of the intuition that the Gaussian function filters out the value of $f$ near the origin. When the Gaussian is very narrowly peaked, more narrow than any variation of $f$, we can just replace $f$ by its value at the origin.

GPhys

06:23

I was texting my school friends in the classes I was missing pictures of the NSLS-II and RHIC :D

John Duffield

08:13

@ACuriousMind : the mass of a body is a measure of its energy-content. In the simplest case a body is something "at rest" in front of you. A photon propagates at c, so it's never at rest, so rest mass does not apply. But when you trap the massless photon in a mirror-box, it's effectively at rest, and it adds to the mass of that system. Then when you open the box, it's a radiating body that loses mass.

See arxiv.org/abs/1508.06478 by van der Mark and (not the Nobel) 't Hooft. The inference is that photon momentum is resistance to change-in-motion for a wave propagating linearly at c, whilst electron mass is resistance to change-in-motion for a wave going round and round at c.

user116211

@JohnDuffield: o/

John Duffield

@user36790 : that's E=mc². Note this bit: The kinetic energy of the body with respect to ($\xi,\eta,\zeta$) diminishes as a result of the emission of light, and the amount of diminution is independent of the properties of the body. Moreover, the difference K0 − K1, like the kinetic energy of the electron (§ 10), depends on the velocity.

user116211

@JohnDuffield Huh?

John Duffield

@user36790 : Whilst a photon has energy-momentum, mass doesn't normally apply because it's a wave propagating at c, and you can't accelerate it like a cannonball. But you can slow it down in say glass, whereupon it exhibits a little effective mass. When you slow it down totally by catching it in a mirror-box, all of the energy-momentum is exhibited as mass. It's resistance to change-in-motion, it's the flip side of wave momentum.

user116211

(－‸ლ)

user116211

08:24

@JohnDuffield: WTF! I just gave you a formal hi! and you are pinging me with what?

John Duffield

With E=mc². Amazingly a lot of people just don't understand it. Even Newton understood that gross Bodies and Light were convertible into one another.

And now I have to go.

user116211

@JohnDuffield ha! That's better. Bye.

The Dark Side

@user36790 lol

user116211

@TheDarkSide: o/

user116211

@TheDarkSide an epic shit. JD does whatever he likes.

The Dark Side

08:30

:)

@ACuriousMind lol

innisfree

10:26

Anyone know what "the ordering lemma" might refer to exactly? The context is a discussion of the linear dependence of matrices

ACuriousMind

@innisfree No idea, can you give a bit more context?

ACuriousMind

Hm... the part that you identified as "entirely speculative" is kind of common knowledge in physics, so that may be a bit of a mischaracterization. — David Z Mar 3 at 16:58

lol, the Worldbuilding physics tag is a goldmine

"Is it possible for a skelecopter to fly?" would make a good viXra paper.

innisfree

11:03

I was working on an excercise that the 16 gamma matrices, gamma_5 etc form a complete basis. I did it my way, then looked at the answer, which was similar but referred to that lemma

ACuriousMind

It's probably a strange name for some gamma matrix identity, because I'm pretty sure that's not standard linear algebra terminology

innisfree

Hmm OK thanks

Qmechanic

11:22

@0celo7 : Incidentally, I recently answered that question, echoing James Rowland's above comment.

David Z

@EmilioPisanty did your ping get taken care of?

ArtOfCode

@DavidZ I think @Qmechanic handled it. See this room for details.

David Z

Ah yeah, all set then.

Could have been done with flags, but whatever :-/

Emilio Pisanty

@DavidZ I have to say I'm very jumpy with flags at the moment

particularly when they result in wholesale comment deletion of a user that's already saying he's being censored

David Z

Well, that's not a consequence of the flag, really, it's a consequence of the fact that the user is posting terrible comments

Emilio Pisanty

11:32

@DavidZ Yeah, but if it starts a campaign against me saying that I'm the big bad wolf censoring people, then it escalates the situation instead of helping to defuse it

David Z

If that came up, we (mods) would take the blame for deleting the comments. We sometimes leave little notices that we've deleted comments, anyway.

Once things get to a certain point, defusing is no longer an effective strategy

I actually haven't looked at the comments you're talking about (I think) but I'm talking about rude/nonconstructive comments in general

Emilio Pisanty

@DavidZ To be fair you did do that

But it somehow (no idea how, really) got to the point of this comment physics.stackexchange.com/q/241595#comment530130_241595 and this answer physics.stackexchange.com/a/242048 and this chat.stackexchange.com/transcript/message/28066332#28066332 and this chat.stackexchange.com/transcript/message/28066682#28066682 comments in chat

David Z

@EmilioPisanty And I think we're considerably more likely to do it in a case where any of the people involved seem to be mad and looking for a target for their anger

oh dear... "self-appointed guardians of the orthodoxy" :-P

ACuriousMind

@EmilioPisanty Everytime I hear someone complaining about being "censored" on the internet, all I can think of is this xkcd

3

David Z

@EmilioPisanty That would definitely be the point at which defusing is no longer useful, if you ask me.

Emilio Pisanty

11:39

@ACuriousMind Yeah, but I'm the one getting called out by name for no other reason than attempting to improve one question and answering what looked to be a more localized one.

ACuriousMind

@EmilioPisanty I really think that, if you want to avoid that, the only way to do that is to not engage in the first place.

David Z

Yeah, I was thinking the same. It's unfortunate, but that's how life on the internet goes. There is always a risk of offending someone and getting insulted for it.

Emilio Pisanty

@ACuriousMind Yeah, that was the original plan, but then that thing with plans and contact with the enemy and all that.

David Z

We try to minimize that by holding people to standards of behavior and making sure the existing content sets a good example, but there is no foolproof system for preventing it in the first place.

FWIW we've seen worse :-P

Emilio Pisanty

@DavidZ Yeah, I know. It's surprisingly upsetting, though.

David Z

11:42

Yeah, I get that. After you go through it enough times you stop caring.

...not that I necessarily recommend that, on second thought

Emilio Pisanty

@DavidZ Hmmmm.

Anyway, I'm off for lunch.

user54412

0

Q: Why should Einstein and Jordan frames be equivalent?

Einstein and Jordan frames are related by physical rescaling of the vielbein, is it correct? Why are they considered equivalent?

general-relativity metric-tensor

user54412

I couldn't figure out what this question was asking. So I clicked on the wiki link. And now I'm more confused.

user54412

Both allude to some confusion without even saying what they're talking about.

ACuriousMind

It would help if they gave a proper definition for a start :P

Sir Cumference

12:11

Is the electromagnetic force weaker on particles like quarks, which have 1/3 or 2/3 charge?

ACuriousMind

@SirCumference weaker than what?

Sir Cumference

Hmm...is the electromagnetic attraction between an up and down quark weaker than that of a proton and electron?

ACuriousMind

Yes.

Although - you have to beware that the masses are different

Sir Cumference

All right, thanks

ACuriousMind

So, yes if you just mean the numerical value of the force, otherwise it depends on what you mean.

Sir Cumference

12:17

Well, what if there were a particle with the same mass as an up quark, but an electric charge of +1. We then had its antiparticle around. Would the attraction between them be as strong as the attraction between an up and down quark?

ACuriousMind

@SirCumference No, it would be stronger. That's the (classical) definition of electric charge, it tells you how strongly the object reacts to electromagnetic fields.

Sir Cumference

As opposed to what definition?

ACuriousMind

Well, in quantum theory you can't really speak about forces, so this language doesn't make sense anymore

But after you introduce interactions and coupling constants, you see again that the charge essentially adjusts how "relevant" the electromagnetic field is to the behaviour of the charged object.

John Duffield

13:19

@SirCumference : nobody has ever seen a free quark. They aren't what you think. See the Wikipedia article and note the picture.

0celo7

Maybe the quark love each other

And never want to be separated

John Duffield

@SirCumference : also note where it says "a proton is composed of two up quarks, one down quark and the gluons that mediate the forces 'binding' them together." Now take a look at the Wikipedia gluon article: "as opposed to virtual ones found in ordinary hadrons". Then see anna v's answer here: "Thus virtual particles exist only in the mathematics of the model ".

Hari Prasad

@0celo7 what happens if we seperate them

ACuriousMind

You can't. Nothing can overcome the force of love.

Hari Prasad

@ACuriousMind what if a down quark finds someone better

ACuriousMind

13:26

They're not monogamous.

Baryons are happy threesomes, can't you see?

Hari Prasad

what does this image say?

John Duffield

You can't separate those quarks because they aren't three billiard balls held together by gluonic springs. And the proton isn't a mess of quarks and gluons either, ready to spill out like beans from a bag.

Hari Prasad

Does it mean that the energy I input to separate the quarks is absorbed and creates new quarks rather than separating quarks.

ACuriousMind

@HariPrasad It's supposed to convey a classical model of how confinement works (and is thus not really what the theory says). The strong force law is linear, not an inverse square like electromagnetism, so separating the quarks takes more and more energy. When there is enough energy in the separation, it is enough to create a quark-antiquark pair, and those then bind to the two quarks.

Hari Prasad

@ACuriousMind OK i understand

ACuriousMind

13:35

The issue with this model is somewhat that it is derived by treating the quarks as static, but the idea of creating them from energy would need a dynamic quark field. Confinement is notoriously hard to show in the full theory, although much progress has been made.

John Duffield

@Hari Prasad : no. You can easily produce two-quark pions by colliding 3-quark hadrons together. IMHO to really understand the real reason why gluons are virtual and why you can't separate those quarks, you have to think partons.

ACuriousMind

(that picture has nothing to do with partons)

John Duffield

It does, in that quarks and gluons are parts, not particles in their own right.

0celo7

@ACuriousMind Never forget that.

John Duffield

@ACuriousMind : it does. Remember that the gluons in a proton are virtual. There's something there, but there aren't any actual gluons flying back and forth, just as there aren't any photons flying back and forth between the electron and the proton in the hydrogen atom.

ACuriousMind

13:42

No one is claiming the gluons are anything other than virtual here. I'm surprised at your seemingly indefinite supply of straw for your opponents. Okay, not really surprised.

Hari Prasad

Patrons and Quarks : Both models describe the same thing from different perspectives?

John Duffield

@ACuriousMind : the point is that the zigzag lines in this depiction represent the gluons, but they're virtual. So you have to redraw the picture.

ACuriousMind

I didn't draw that picture, so I don't have to redraw it.

Sir Cumference

@JohnDuffield Of course nobody has every seen a free quark

They require so much energy to separate, doing so would actually make another quark

Hari Prasad

What is the half life of proton?

Sir Cumference

13:47

I'm asking about the electromagnetic attraction between particles with integer and fraction charges

ACuriousMind

@HariPrasad The partons are a phenomenological model designed to explain and predict high energy collisions. The quark come from the fully formed quantum field theory. So yes, they are different perspectives of the same thing - baryons and mesons.

Sir Cumference

And pretty sure we've all seen the picture with the quarks, antiquarks and gluons in the proton

0celo7

@ACuriousMind I think that the gluons are real.

Sir Cumference

@0celo7 That's good.

John Duffield

@SirCumference : nobody has ever seen unicorns either. Or fairies. And guess what, in low-energy proton-antiproton annihilation, you don't see any quarks or any gluons. So where did they go, and where did all that fundamental strong force go?

ACuriousMind

13:50

@0celo7 Stop trolling :P

0celo7

I also think that the quarks are 2.3MeV, etc. gluons in a closed spinor configuration.

Sir Cumference

@JohnDuffield So what's your point?

That has literally nothing to do with what I was talking about.

0celo7

I mean, what kind of magic would it be for quarks to just randomly appear?

ACuriousMind

@SirCumference You'll notice that's a pattern with him :P

0celo7

There's no magic.

Sir Cumference

13:50

@0celo7 Pretty sure it's all magic

Science is magic

0celo7

@ACuriousMind So what's the FT of a periodic function?

John Duffield

@SirCumference : it does, because you've never seen a fractionally charged particle.

Sir Cumference

@dmckee First rule of debugging is: do not talk about debugging

Second rule of debugging is: do NOT talk about debugging

ACuriousMind

@0celo7 Huh?

0celo7

@ACuriousMind Is it just the sum of partial Fourier transforms over the periods?

With some overall factor?

Like for Laplace transforms?

ACuriousMind

13:52

I don't understand the question

The Fourier transform of a periodic function is either a sequence of Fourier coefficients or a Dirac delta comb, depending on your point of view

0celo7

Yes

I'm asking why

but I might as well prove it

myself

@ACuriousMind Oh, it's easy

Just turn the function into a Fourier series and transform the exponentials

ACuriousMind

well, I know that :P

0celo7

I have no evidence of this

Hari Prasad

isites.harvard.edu/fs/docs/icb.topic1146666.files/IV-8-QCD.pdf

0celo7

Hmm, maybe I should derive the Heisenberg uncertainty principle using Fourier transforms

> where the canceled term vanishes because the wave function vanishes at infinity.

yuggib

13:59

@0celo7 T__T

0celo7

@ACuriousMind But you said $L^2$ functions need not vanish at infinity

Transcript for