1. Wave Mechanics

[@lecturesbywalterlewin.they9259]

Professor Barton Zwiebach is among the very best lecturers of MIT's Physics Department.

[@mfoucault1984]

you are great as well Walter!

[@sppokharel9194]

And you are among the very best lecturers of the entire world.

[@luismontalvohiroyasu5814]

He's peruvian :)

[@llewellynhamiltoniiim.d.1057]

Excellent .......

[@nelsonmichaelvillegasjuro4362]

@@luismontalvohiroyasu5814 from FIEE UNI, me too!

[@WoNRain]

34:25 "time is not a problem anymore" Watching this at 3-40am and kinda agree with that ) Thank you very much, sir. Physics is one of the greatest thing humanity ever had

[@CommonManMTahoorH]

watching at 3:19 a.m , about an hour before fajr. Just about to offer tahajjud.

[@santiagoerroalvarez7955]

The way he smiled when everyone started clapping was so wholesome. I'm glad he can feel all of your gratitude. He really deserves it, such an amazing professor.

[@joelima8910]

Hi I’m from Japan!I wanna appreciate these lectures cuz it helps me to review this and professor explain it well and slowly so I found that I didn’t understand it well before !so helpful!thanks a lot👍

[@fernandodanielgomezcarnero6789]

A great preuvian pride!!! He inspires me to study at MIT.

[@mihoyoaccount3592]

for years to come, you will be a guide to thousands . I thank MIT for allowing such a profound individual to spread his knowledge throughout the globe. My heartfelt gratitude to you sir Zweibach, for strengthening my understanding of Quantum Physics. The applause was well deserved , Thank You!

[@victoriarisko]

So fun to watch this genius teach. As good as it gets. He clearly loves and cherishes his subject. Does he know most lectures of other professors don’t end with students applauding?

[@ganesshukri3787]

Thanks a lot Prof. Zwiebach and MIT! Even as a lecturer of this subject myself, I truly learned so much things from this amazing set of QM lectures!

[@mtripledot8910]

I love the fact that they all clapped at the end. That's so sweet!

[@cidorodrigues6087]

I'm Sido Rodrigues Brazil I really like Quantum Physics Classes. Very important to know quantum physics. Teach everything the universe knows and you gain self-knowledge about everything. Great series of really useful lectures on quantum mechanics. I am also very grateful to MIT OpenCourseWare and Barton Zwiebach... etc

[@TheZefres]

i love you MIT, thanks so much for opencourseware

[@hp127]

Thank you for this excellent series. I keep going back to them.

[@user-bq5bc7ox6j]

Lovely lecture! I come from 804 by Prof. Allan Adams, Allan is passionate, and Prof. Zweibach is totally awesome!

[@alvaroe2704]

He hurries because he must comply with the schedule, but also because he is eager to reach the next step, finishing the review and teaching the proper content of the course. This man loves what he does.

[@mississippijohnfahey7175]

It also helps keep me (and maybe other students) engaged. Slow talking makes me doze off

[@Aman-tf8bt]

These are very nice lectures,I am obliged to Professor Barton Zweibach for uploading such good lectures....

[@solounomas0]

What a pleasure!! War sehr nützlich!!

[@dilaudid]

I think if psi prime is bounded and psi is normalisable, then the current must tend to zero as x tends to infinity, which means that the whole derivative terms in the integration by parts are zero ( 46:01 )

[@CarlosBacilioZ]

Peruvian pride!

[@whatitis4872]

Didnt know Tim Matheson knew so much physics. My eyesight is sorta bad and Im like why does this dude look familiar. Then it came to me Tim Matheson. In any case, thanks Professor Zwiebach for taking the time to solve the problems in such detail. The example on teleportation was beautiful. Still trying to understand the practical intuition of the NMR. Stay safe.

[@sergeyliflandsky3231]

Can you upload quantum physics III?

[@MsHShuaib]

I think we are pushing it a bit there :P We should be thankful for everything they have uploaded.

[@JordanEdmundsEECS]

Yes please

[@manishsingh-vk8if]

It has been uploaded.

[@Acuzzio]

LOVE the video, THANKS. just a little thing: I do not like the continuos zoom in zoom out. I love when the fov is taking the whole blackboard. Too much moving.

[@Superchhatrapati]

wonderful lecture ....................enjoying very much

[@MetalThatRoxUrSox]

I loved this video. Thank you for posting!

[@saidurrahman2341]

i love the chalkboard class.

[@NamanJoshi-pi4bn]

Since february 2020, everyone does!

[@eitanas85]

?any chance to upload solutions of the problem sets Massachusetts Institute of Technology (MIT)

[@yanovoyair5129]

una carta de amor . peru

[@viswavijeta5362]

Playlist Length: 36 hours 11 mins

[@zhangotheraccounthoward495]

Does anyone know where one could find the solutions to the practice problems given on the website? If anyone’s knows it would be greatly appreciated if you could tell me as I can’t seem to find it anywhere.

[@notsoslimshady4315]

What are the prerequisites to this course ?? I mean which mitocw course to do before this one ??

[@mitocw]

The Prerequisite listed in the syllabus says: "To register for this course, students must have completed 8.04 Quantum Mechanics I with a grade of C or higher." See the course on MIT OpenCourseWare for more information and materials at: ocw.mit.edu/8-05F13. Best wishes on your studies!

[@engrsmukhtar]

@@mitocw Wow! You also answer learners questions. Awesome.!.

[@cool7914]

I am a chemistry professor ,But my favourite subject is physics and i love quantum mechanics.

[@jacobvandijk6525]

Not thrown out of the department yet? ;-)

[@darrellrees4371]

Excellent video. I can't believe this has been here over a year and no one has commented.

[@عليجاسبحسين]

This professor is creative.

[@livingtonsam9968]

I was actually stuck on getting an intuitive understanding for the usage of complex numbers until you explained it

[@EarlWallaceNYC]

At 1:01;13, what are the implications of the duality between Completeness and Orthonormal-ness? I love how Prof. Zwiebach asks (and answers) questions I am about to have. Even in review stuff, he blows my mind.

[@schmetterling4477]

At the level of physics nothing. The mathematical proofs for these things are non-trivial and outside of the scope of physics lectures. In general things are also not as simple as physicists like to pretend. It does, however, not matter. The usual physics potentials that can be treated with this level of theory have, as far as I know, non-pathological solutions, so we can pretend that the shown formulas are all there is.

[@physicsboy3108]

Which book did they follow for Quantum Mechanics sir????

[@mitocw]

There are two required books: Griffiths, David J. Introduction to Quantum Mechanics. 2nd ed. Pearson Prentice Hall, 2004. ISBN: 9780131118928. Shankar, Ramamurti. Principles of Quantum Mechanics. 2nd ed. Plenum Press, 1994. ISBN: 9780306447907. See the course on MIT OpenCourseWare for more info at: ocw.mit.edu/8-05F13. Best wishes on your studies!

[@physicsboy3108]

@@mitocw ok done!!! Stay blessed 💝

[@bijayjha3309]

Anyonefrom india here can go to watch hc verma:an experimental physics teacher quantum mechanics ...he can make you feel the physics. ..as professor walter does...both are marvellous. .. :Believe me..

[@tomlavelle8518]

Thanks for the awesome work!

[@not_amanullah]

This is helpful ❤️🤍

[@18SV]

Do anyone have solutions for assignment questions posted on the course site ?

[@schmetterling4477]

You are supposed to solve those yourself. :-)

[@sagarbhat7932]

7:55 how do we know that a1 and a2 are complex?

[@not_amanullah]

Thanks 🤍❤️

[@satheeshart]

Let’s share our thoughts on the message of the video.

[@NicolasSchmidMusic]

how would I have studied QM if I was born 10 years earlier? Your videos teach me everything I need

[@schmetterling4477]

You would have gone to the library and got a textbook on the topic.

[@lambda2693]

@@schmetterling4477 burned

[@kimberlynferrer2009]

I have a class Discussion about wave mechanics im a student then do i have to discuss too that far?

[@maxt774]

Does 8.05 have path integrals?

[@umerhayat1590]

Thanks a lot...

[@Mark467]

Hi +MIT OpenCourseWare. First off thanks for putting this stuff out there online for free! Do you guys have a video on Physics I #8.01?

[@putinscat1208]

+Mark467 Look up Classical Mechanics MIT. They also have Electromagnetism.

[@consecuencias.imprevistas]

+Mark467 They had but were taken down from their channel. You can still find them on the internet

[@putinscat1208]

Marty McFly They are on KZbin. Oh, 'MIT Physics', will get you Physics I & II.

[@JustNow42]

He don't seems to know about Hilbert spaces.

[@amaraojiji]

Defining function as vector over infinite amount of dimensions is kinda strange. You can do this for countable infinity (rational numbers), but what about irrational ones?

[@Pferdekopfnebel]

I believe this was just to illustrate what is happening there. The L2-inner product is kind of a generalization of the dot product in finite dimensions. Allowing complex functions this leads to the Hermitian inner product that was used in this lecture.

[@amaraojiji]

***** Without proper defining what is 'vector over continuity', it can cause rather strange issues at corner cases. Like what is state of 'vector relationship' of functions sin(1/x) and cos(1-1/x)...

[@Pferdekopfnebel]

amaraojiji Can you explain a little more what you mean? I don't understand what you are hinting at.

[@RalphDratman]

The first half of this particular lecture is excellent -- I might even say stellar. Seldom have I observed such good teaching. But then in the second half the lecture goes too fast with too little explanation, beginning with time-independent eigenfunction solutions of the separated space equation. Around this time Prof. Zwiebach seems to tire. That he did so is not so surprising, because he exerted himself very hard, and to great effect, in the first half. I think introducing the ramifications of functions seen as infinite-dimensional vectors requires more than half a lecture to put across properly. Further to introduce orthonormal eigenfunctions using integration by analogy with the dot product seems too much to swallow in one sitting if the student has not encountered those concepts before. Without some minimal introduction to separable PDEs with Fourier-series solutions, some of the second half of the lecture might not make much sense.

[@consecuencias.imprevistas]

Check the reqs for this course @ OCW, all the things you mention are taken care of

[@gaspardsagot628]

I'm always surprised American students seems to learn that a vector has coordinates. In France we are first taught the abstract axioms of a vector space, inner product, etc; and then only are examples mentioned. This makes things like "functions are vectors" completely trivial, because yes, they check out the axioms.

[@RalphDratman]

I think the French approach is much better. When I was in university-level physics, it bothered me quite a bit that vectors were handled so casually, and in contradictory ways.

[@pragjyotishbhuyangogoi8363]

'Mathematicians can invent crazy functions'- Barton Zwiebach.

[@UnforsakenXII]

I always wondered why it can't be that the operator acts on Psi star when looking at expectation values instead of A acting just on just psi. Is it should be the same right? If it's an observable, it's hermitian and thus, you should be able to flip the order? Or is it different?

[@whatitis4872]

Physicists notation, more precisely one physicists (Dirac) notation is very confusing, Though practically mnemonic for some manipulations that are not used that often and are a lot harder to write the real way. Its like if you changed the whole english language so that then the word supercalifragilistic world be short and then other more often used words become ugly and long. I think the math notation is much clearer. When dirac says and |psi> the mathematician says and u since psi and phi are simply vectors. A is an "linear" operator on vectors and < , > is a sort of dot product that eats two vectors and is linear wrt vectors but not truly linear cuz how it acts on scalars. In any case is a complex number and = * ie the complex conjugate, Now on a certain basis in continuous case this is realized as = integral f(x) g(x)* dx and you stick to this def. You could have chose to define = integral f(x)*g(x) dx. the first way is genuinely linear in first entry while the second way of defining is genuinely linear on second entry. Now either convention you choose, A is hermitean which means = see how you write this in the f, g notation see if that helps. If A is not hermitean, then you got trouble is not = and thus has unclear meaning I'd say. Also strictly speaking f, g are not u and v since f, g are the coefficients of u and v in some basis, but for our purposes here essenuially f=u and g=v

[@whatitis4872]

I Noticed something else look at your question. , Let S mean integral. If = S f g* dx then = S (Af) g* dx which is equal (if A herm) to = S f (Ag)* dx buit notice in second case A acts on g and then, its conjugated Now if Af = hf where h is a fixed function of x, notice A wont be hermitean unless h is real valued consider this case and see if that meakes it clearer.

[@UnforsakenXII]

@@whatitis4872 Thanks. That comment was 3 years old however. : )

[@whatitis4872]

@@UnforsakenXII Yeah I only read it now wasnt sure if youd answered it or if youd thought it in this way.. In quantum one always learns new things when one looks at old stuff. I recently put a video on tunneling on my youtube channel something I hadnt thought about in 10 years.

[@UnforsakenXII]

@@whatitis4872 That's very true. I was just getting into quantum 3 years ago but now after having done some string theory research, going back at everything, it's really amazing how much new stuff you can pick up.

[@HamId-zq3um]

La physique quantik s'inspire des nombres complexe pour exprimer et comprendre les phénomènes relativistes.

[@sergeyliflandsky3231]

In which course do you teach the DIrac equation? Can you upload this course as well?

[@ilkertalatcankutlucan3257]

+Sergey Liflandsky it sin 8.04

[@sergeyliflandsky3231]

+ilker Talat Can KUTLUCAN But they haven't uploaded this yet, have they?

[@mitocw]

+Sergey Liflandsky We have, here's the playlist: kzbin.info/aero/PLUl4u3cNGP61-9PEhRognw5vryrSEVLPr. See the course on MIT OpenCourseWare for more information and materials at ocw.mit.edu/8-04S13

[@sergeyliflandsky3231]

+MIT OpenCourseWare This is Quantum Physics I. The topic I was asking about was the Dirac equation which is not in the scope of this course. It seems that Dirac's equation is not covered even in Quantum Physics II. I was asking of you to upload Quantum Physics III ,or whatever the name of the course which is the natural continuation of Quantum Physics II. Thanks :)

[@sergeyliflandsky3231]

+ilker Talat Can KUTLUCAN I have watched the entire playlist and I'm now finishing watching Quantum Physics II. I meant the Dirac equation not the Schrodinger equation. Dirac's equation is never covered in a standard introductory course to quantum mechanics. Usually it is covered in the third course on the subject.

[@alexperez4007]

Barton zwiebach = UNI Lima Perú.

[@aireshbhat3534]

Is he holding a chalk holder or a huge ass chalk???

[@henryprzygocki4662]

huge ass chalk

[@pierrejeanes]

damn I would like to have this teacher loco

[@milesharris5657]

me 2

[@princhikalita518]

luv it.. thnq u sir

[@dannymiranda6785]

Orgullo peruano...

[@AliAli-yn1ks]

Thank you

[@SphereofTime]

33:17

[@richrocks231]

proud peruvian

[@saraluciaescobedoarcovedo2609]

chido

[@milesharris5657]

thanks for education pal ur a great old grandpa

[@litoboy5]

cool

[@andrewtran6669]

Why am I here? I'm not even in Introductory Physics 1 yet

[@samonellasgayclone1054]

maybe just like me, you wanna head to the cool part

[@lol-ws6qn]

Why the eff did I go to community college?!

[@drbonesshow1]

lol88787 To join the community and join the smoking club.

[@vibhatkumar2589]

His accent matches with bihari bhojpuriyan accent here in India... 😂😅, Very helpful though

[@HamId-zq3um]

dx

[@davidsweeney111]

yea!!! w a v e m e c h a n i c s !!!!

[@TheGamingg33k]

Damn I honestly got lost after 40 mins. Went too fast and hard.

[@santiagoerroalvarez7955]

Don't blame yourself, this was actually review of 8.04, so he blazed through it. You can always chech that series out! kzbin.info/aero/PLUl4u3cNGP60cspQn3N9dYRPiyVWDd80G

[@clashclan4065]

Wth

[@chavoyao]

If you use a potential which is 0 for each rational and 1 for each irrational you are going to have a complicated mathematical discussion and no physics at all. We need to rescue physics from that abysm where mathematicians have buried it.

[@conoroneill8067]

Eh, not really. The rationals have Lebesgue Measure zero, so the potential in this case the potential would be identical to a potential of 1 everywhere. Also, that's a strawman of the kinds of problems mathematical physicists ask in the first place.

[@paulg444]

The guy is a gifted lecturer, but he never presented the reason why the Schrodinger wave eq. captures the reality of Einstein and De broglie. He simply states it as axiom.

[@alvaroe2704]

I guess that approach you are asking for is included in Quantum Physics I (8.04), at least in the 2016 one (also available on KZbin)

[@schmetterling4477]

It doesn't. The Schroedinger equation is a toy system. It is not a proper physical theory.

[@AndreAmorim-AA]

zed

[@AliAli-yn1ks]

Thank you