Lecture 13: More on Scattering

[@LydellAaron]

8:10 - coherent state, 49:56 - resonant nodes within system with stability at higher energy frequencies. 53:00 all the scattering parameters are encoded in the A ,B, C, D transmission and reflection coefficients.

[@schmetterling4477]

Yes, except that it's a lot more complicated in the 3d problem.

[@LydellAaron]

@@schmetterling4477 I believe you. Do you have any links or references to a 3D model of scattering parameters, or is this something we have to derive from the geometry of the problem?

[@schmetterling4477]

@@LydellAaron I wish. I don't have a good intuition for it myself. The problem starts with the observation that even classical scattering on an electrostatic 1/r potential leads to an IR divergence. I am not a theorist, so please don't nail me to this, but my understanding is that the source of all these problems lies in the fact that these potentials are scale-invariant, i.e. no matter how far we zoom out or in, a 1/r potential always looks the same after we change the effective distance and energy scale. There are advanced mathematical tools available to deal with that (e.g. renormalization, conformal theories), but they are, as far as I know, neither easy to calculate nor do they have simple intuitive mental models. Or maybe they do, for someone who has studied the theory of scale invariant systems (which are also a key to the thermodynamics of phase transitions, for instance). The results for the case of quantum field theory (logarithmic running mas/energy etc.) can be found in many textbooks, of course, but how to get there without the detailed calculations is not in my repertoire of mental models. At least not yet.

[@brabantstad384]

my love for this teacher is never ending

[@zphuo]

@30:00 The understanding of R could reference to Griffiths Q2.34. @49:00 is a very usefully deduction.

[@atticusw11]

At 39:02 the values for C and B are incorrect; the correct values are C = (k2-k1)/(k2+k1) and B = (2k2)/(k2+k1). The values for R and T are still correct as written

[@vedantkashyap5703]

1:04:31 it will be (k^2 + k'^2)^2 ; a whole square on the brackets

[@SudarakaMallawaArachchi]

Why aren't the lecture notes beyond lecture 8 not available in the OCW website? :(

[@DDDelgado]

38:00ish what about tunnelling?

[@adnon2604]

1:20:30 I really love this story

[@raghavendrakaushik1691]

Hilarious story at the end! This lecture covers the technical details of tunneling nicely. A video of Science Asylum explains how Quantum Tunneling is required for nuclear fusions to happen inside the sun! Do Check it out!

[@volcanic3104]

Where are these optional problems that are discussed in the beginning? I can't seem to find them on the website

[@NaveenShettyind]

It would be nice if we can get lecture script for this specific lecture.

[@brabantstad384]

It would be nice if you stopped touching my mother

[@usmanmuneer6143]

I think its available at the OCW website

[@not_amanullah]

Thanks 🤍❤️

[@kirisameinsu]

where i can get the notes of this and coming lectures?

[@mitocw]

You can find the materials on MIT OpenCourseWare at: ocw.mit.edu/8-04S13. Best wishes on your studies!

[@aeroscience9834]

"You know, France..Cheese..."

[@xrisku]

hey, check out the Nehru Jacket! :)

[@hassan.javaid]

You mean a waist coat ... :/ ... Nehru is not the only one wore it and also not the first one.

[@ShubhamBhushanCC]

@@hassan.javaid Dude come on

[@youtubeshortsanycontent]

Is this meant to confuse us ? 1 and 0s?

[@STEM671]

ZENER DIODE; REVERSE BREAK DOWN RATINGS DUE STRUCTURAL ANALYSIS

[@prashanthp5948]

If b goes zero seems like the wave Is moving right in time, but an energy eigen state should not move in time right? I couldn't get this part ,could someone please help me

[@usmanmuneer6143]

Energy eigenstate can move in time; the probability density function of the energy eigen state shouldn't move... and it doesn't. Its just rotating like a rotating spring, it looks like its moving but its just rotating. Superposition of such eigenstates, however, would move.

[@CHistrue]

I'd sound more coherent in talking about quantum physics but my wave function has scattered!

[@CHistrue]

CHistrue Why so few viewers? I do not understand a whole lot but I am still hanging on every word in hope of learning something!

[@HT-rq5pi]

+CHistrue They all left after reading your jokes (jk).

[@CHistrue]

***** I thought levity added to the energy of the photons to finally break them free of their shells? They don't call it "levity" for nothing, right?

[@chitresguria4722]

is he supposed to say every new thing in the office hours?? crap

[@MinecraftworksRUS]

48:15

[@Cezannest]

1:15:20

[@thecaptainindia9790]

Hey that's an indian coat 😂

[@not_amanullah]

This is helpful ❤️🤍

[@arcticbloxx]

Hi

[@alpteknbaser7773]

💐

[@rupeshknn]

Totodooo

[@muhtasimminhaz9151]

Doo-doo-doo

[@JA-it4bg]

That idiot student toward the beginning caused him to start writing squares (^2) on the transmission and reflection coefficients... They are not "norm squares", they are the absolute value of a ratio of the probability currents. Am I wrong? Now I don't know whether to discredit everything else in the rest of the lectures. It manifests badly at around 26:46 and towards the beginning after he goes on about coherent states... I guess I'll have to switch to Zweibach's lectures instead and start from scratch.

[@JA-it4bg]

Thank God I finished it out and he realized the typo @ 35:36

[@JA-it4bg]

@E sorry for the insult buddy

[@chaoticstorm8145]

Chill out. People make mistakes, no need to call him an idiot, especially considering hes going to one of the best schools in the world and you're not