Lecture 3: The Wave Function

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  • เผยแพร่เมื่อ 31 ธ.ค. 2024

ความคิดเห็น • 787

  • @anthonybrakus5280
    @anthonybrakus5280 9 หลายเดือนก่อน +90

    Big up to MIT for offering these OCW lectures. I have learned Calculus, Classic Physics, Linear and Abstract Algebra, and Quantum Physics and I didn't even have to pay late library book fees. 👍🏾 Thanks MIT, for being conscientious and gracious! 🎉💥🪅🎇🤸🏽‍♂️🕺🏿💃🏼🎆🎊🙏🏾

  • @ashlynparrott7130
    @ashlynparrott7130 2 ปีที่แล้ว +29

    Fell asleep watching a ghost hunting video, woke up and this was on my TV thanks to autoplay. I didn't even feel groggy waking up because I was so alarmed by how good of a teacher this guy is. I'm more of a molecular biology person but I think I'll continue watching these!

  • @mahinvasavada2992
    @mahinvasavada2992 8 หลายเดือนก่อน +29

    A class that ends with an applause. That is how all classes should be.

    • @TheGersonfialho
      @TheGersonfialho 4 หลายเดือนก่อน

      Not at all! Only professors with good didacts as this one deserve applauses!

    • @kingplunger1
      @kingplunger1 หลายเดือนก่อน

      @@TheGersonfialho Pretty sure the implication was that classes are supposed to be so good as to warrant applause

  • @willcatch
    @willcatch 3 ปีที่แล้ว +102

    Whoever filmed this did a great job. Panning and framing. Spot on.

    • @scowell
      @scowell 3 ปีที่แล้ว +3

      Would have been nice to see his laptop screen as direct instead of through the projector... still, a wonderful job as you said.

    • @Darthvanger
      @Darthvanger 2 ปีที่แล้ว +2

      @@scowell wow wow, we're not talking about THAT much advanced technology here.

  • @AlexTrusk91
    @AlexTrusk91 8 ปีที่แล้ว +625

    i think this kind of high quality content makes the world a better place for seekers.

    • @stauffap
      @stauffap 7 ปีที่แล้ว +34

      First you need to find it though. If you haven't figured out the value of science and scientific institutions yet you might end up "learning" "quantum mechanics" from "what the bleep" or Deepak Chopra, instead of learning it from MIT.
      The truth seems to be, that for many people it's hard to get on the right track without some type of guidance. They'll get sidetracked by conspiracy theories, fraudulent claims and various pseudo-sciences. And that may be understandable, since we haven't evolved to perceive or understand reality accurately. Furthermore our success (as a species) seems to be largely based on an accumulation of knowledge i.e. learning from other people and building upon that. So it's understandable that people can not see the value of the scientific method or scientific institutions. Scientific thinking isn't something, that has come naturally to us. It's not something that people just come up with themselves. So for most people it requires a person, who introduces them to science, leads them into the right direction, makes them ask the right questions etc. If you lack that you might not be very likely to end up here.

    • @jacobvandijk6525
      @jacobvandijk6525 4 ปีที่แล้ว +1

      You obviously missed this: 53:13. Think about it.

    • @AlexTrusk91
      @AlexTrusk91 4 ปีที่แล้ว

      @@stauffap 4 years after my comment I'm not really any further with this lecture series. But started multiple other lectures on different topics like Human Behavioural Biology from Stanford.
      I'm also thinking of finally trythe problem sets, but I guess I maybe would be hit by a wall then. So I probably gonna try it anyways.

    • @stauffap
      @stauffap 4 ปีที่แล้ว +6

      @@AlexTrusk91
      You should definately try problem sets. You never fully understand physics if you can't do the math (you might just have the illusion that you understand it).
      I meet people all the time, who think that they understand a certain topic in physics, because they have developped a more or less accurate intuition, but they fail when confronted with having to calculate something and often fail as well with their intution. The ultimate test to whether or not you understand a certain topic in physics is always doing problem sets that involve math (and preferably understanding the derivations).

    • @Abhi-mt4dn
      @Abhi-mt4dn 4 ปีที่แล้ว

      @@stauffap And can you help me abt problem sets like from where and how i should start to solve them like pre requisites and everything , i would really appreciate it

  • @mishvanzant
    @mishvanzant 7 หลายเดือนก่อน +13

    I love watching him lecture! He's so excited to show everyone "here's everything we've figured out so far, come help us figure out more!"

  • @whelan4545
    @whelan4545 9 ปีที่แล้ว +243

    love this guys passion

    • @r58302
      @r58302 10 หลายเดือนก่อน

      An absolutely perfect lecturer

  • @aussiedog5221
    @aussiedog5221 ปีที่แล้ว +32

    Six years ago, after I retired, I went through these lectures and the second semester with Dr. Zwiebach. Simply outstanding. I am back for a bit of review. Thanks Dr. Adams and Dr. Zwiebach.

    • @josephhall5681
      @josephhall5681 ปีที่แล้ว

      ;Touch and hold a clip to pin it. Unpinned clips will be deleted after 1 hour.😢hh
      O❤
      ❤❤❤

  • @weechinghwa8440
    @weechinghwa8440 4 ปีที่แล้ว +35

    Teaching in MIT is like a superstar singing on stage. Everyone claps for the good performance.. Holy moly

    • @Tikorous
      @Tikorous 3 ปีที่แล้ว +9

      People get excited when I stop speaking too, probably for a different reason

  • @annehinrichs22
    @annehinrichs22 3 ปีที่แล้ว +63

    Oh my goood, how can this be so much better than at my university?? The whole structure and order in which this is taught are just so clear!!

    • @Ne012
      @Ne012 3 ปีที่แล้ว +15

      MIT is a very prestigious university. Very low acceptance rate because they take the cream of the crop in student's. If they do that for their students you can only imagine how they select their professors.

    • @patinho5589
      @patinho5589 3 ปีที่แล้ว +14

      @@Ne012 yeah but : I went to Cambridge.. very selective on students.. terrible lecturing and teaching in general in the subject I studied which was economics.

    • @justindamirgian5977
      @justindamirgian5977 2 ปีที่แล้ว +18

      They put him in camera for a reason. I imagine they have good and bad professors also

  • @paulboro5278
    @paulboro5278 4 ปีที่แล้ว +51

    You are my favorite teacher. I watched these lectures for the first time about four years ago. Because of these lectures, I have a very good understanding of basic quantum mechanics. I just completed my post-graduation from IIT Guwahati recently. These lectures were very helpful during the last four years.

    • @IndrajitSen_TxState
      @IndrajitSen_TxState 3 ปีที่แล้ว +5

      Truth be told, your IIT professors must learn pedagogy from these professors.

    • @paulboro5278
      @paulboro5278 2 ปีที่แล้ว +2

      @itchy armpits I majored in physics.

    • @theawantikamishra
      @theawantikamishra ปีที่แล้ว

      Engineering Physics?

    • @MadScientist267
      @MadScientist267 11 หลายเดือนก่อน

      I'm never going to directly use any of this but that hasn't kept me from trying to just understand it for my own curiosity. Never know when something will appear at the edges of something else and come in handy.
      This dude has come the closest so far to getting me there 🤣

  • @lukelively4732
    @lukelively4732 6 ปีที่แล้ว +243

    I wish I took school more seriously as a kid so I could go to this school. This professor is amazing and I love his passion.

    • @bogdantokarski2798
      @bogdantokarski2798 3 ปีที่แล้ว +6

      So do I.

    • @softwareminimalist
      @softwareminimalist 3 ปีที่แล้ว +4

      Yeah, you can learn now.

    • @Darthvanger
      @Darthvanger 2 ปีที่แล้ว +14

      I've seen a few other lectures from the other teachers and I didn't like them as much as these ones.
      I think this is a gem, and we should appreciate we can watch the best of the best for free.
      It's not limited to the 100 of the smartest hardworking kids anymore and it's awesome!

    • @mississippijohnfahey7175
      @mississippijohnfahey7175 2 ปีที่แล้ว +5

      This is better though. All the learning with none of the crippling loans, egotistical teachers, or crushing deadlines! Einstein figured out SR while working as a patent clerk (though he did have a decent undergrad education)

    • @RaidenShogun1145
      @RaidenShogun1145 2 ปีที่แล้ว +2

      You can always work harder now.

  • @josephflynn9560
    @josephflynn9560 6 ปีที่แล้ว +54

    I love this so much. Trying to decide on Electrical Engineering or Physics. Did a long stint with the Marines and now using G.I. bill at a wonderful community college for freshman year. I have not been in school for a long time lol. MIT is still a dream and it feels SO good to be able to just listen. Watching these videos let's me know that I AM smart enough to sit here, even if life may not allow it right now. To be able to touch my mind to something I have wanted since I was a child is a gift and I wanted to say thank you to MIT and Prof Adams for doing this. One day, even if I am retired, I will take a degree at MIT , so stay awesome!!!!

    • @yorichixX
      @yorichixX 3 ปีที่แล้ว +5

      i did bachelors in electrical engineering now i am going to switch to masters in physics!

    • @maxwellpineiro
      @maxwellpineiro ปีที่แล้ว +5

      How is it all going ?

    • @2Worlds_and_InBetween
      @2Worlds_and_InBetween 11 หลายเดือนก่อน

      I was the kid at school who said I wanted to be a Physicist when I grow up...
      (... grow up.... something I might get round to one day ;-)
      and got told, "there's no point we already know everything" by the _teacher_
      I went on to do mechanical and computer engineering with Physics /QM as the stuff I do for fun.
      but its more just a love of learning stuff
      do what you enjoy

  • @jorgecastro5834
    @jorgecastro5834 3 ปีที่แล้ว +9

    I love the way the teacher brings those abstract postulates to live. In so doing he makes quantum mechanics crystal clear. He does it so well that one can not help feeling that there can't be a better way to put it (and I have thought about it several times). This work is invaluable! Just brilliant.

  • @maurocruz1824
    @maurocruz1824 8 ปีที่แล้ว +1

    {X,P}= complete knowledge.
    Postulate 1: Wave function.
    Postulate 2: The wave function is a kind of 'generator function' of the probability that the particle actually be in certain x position.
    26:30
    Postulate 3: The states of the system are closed under linear combinations.
    Mathematica package.
    Fourier transform.

  • @FreshBeatles
    @FreshBeatles 5 ปีที่แล้ว +331

    Great lecture. Can't wait for the free pizza at 5!

    • @Andrewtmcb
      @Andrewtmcb 5 ปีที่แล้ว +3

      LMAO!!! xD

    • @NovaWarrior77
      @NovaWarrior77 4 ปีที่แล้ว +18

      Dang. I missed it by 3 years...

    • @putzak
      @putzak 4 ปีที่แล้ว +12

      The pizza is an imaginary component probably

    • @josef596
      @josef596 3 ปีที่แล้ว +2

      @@NovaWarrior77 - I missed it by 4.

    • @bzboii
      @bzboii 3 ปีที่แล้ว +4

      Wait it said free pizza at 5, not at 120…?

  • @ams1749
    @ams1749 2 ปีที่แล้ว +17

    I have my class 11 English language exam tomorrow, and here I am at 10 pm learning about wave functions,(this lecture is amazing and addictive though).

  • @nc-broadcast
    @nc-broadcast 5 ปีที่แล้ว +8

    Absolutely in awe at what Dr. Adams can do with just whiteboard and chalk. In another life perhaps I'd be in that classroom, or better yet in another world, following the Many Worlds interpretation of this beautiful subject.

  • @olekbeluga314
    @olekbeluga314 2 ปีที่แล้ว +7

    These lectures were very helpful in turning my room into a physics laboratory as I attempt to re-create the Hitachi experiment using homebrewed CRTs. It was not, however, all that helpful in subsiding my extreme existential terror. I'm going to be seeing things that go through neither both holes, nor one of the holes, nor none of the holes in my nightmares now. Thanks a lot, guys.

  • @paulmuindiwilliam2945
    @paulmuindiwilliam2945 2 หลายเดือนก่อน +1

    I'm somewhere in Kenya, and learnt about quantum computers, and I was curious. so I came across this lecture, and if i dont understand something I google it.. then i get another angle of understanding. i walk out of my house and look at the people and my relatives, i tell them about the beauty of quantum mechanics, and they just look at me like, do you have anything else to talk about, I'm like quantum computers will redefine the world as we know it... i'm just trying to understand where all this is coming from, how did they build that thing, what is the theory about it, what materials are used, where do they get them, how do they figure out the temperatures, how do they achieve that, how do they operate the thing.... well i guess it starts here, or somewhere close to here... so I'll keep on watching, going away to process everything, then come again the next day for more. this is heaven on earth!!!!!!!

  • @jesse2450
    @jesse2450 2 ปีที่แล้ว +3

    I wish there was a TH-cam channel with instructors who are obviously super interested in the topic they are teaching regardless of the subject

  • @occhams1
    @occhams1 8 ปีที่แล้ว +7

    I liked the StrongBad reference at 40:02 :) very subtle.

  • @dooterino
    @dooterino 9 ปีที่แล้ว +98

    9:32 When he realizes how long we've been working on quantum theory he looks like a father proud of his son's progress. If I weren't dedicated to applying physics in the more esoteric corners of computer engineering that moment alone would have pushed me into pure physics.

    • @brandonklein1
      @brandonklein1 7 ปีที่แล้ว +1

      High school senior here, I'm actually fascinated with that EXACT field!

  • @marcostala
    @marcostala 8 ปีที่แล้ว +16

    I studied Telecommunications engineering. And now I realized that I was not that far to be studying formulas to be applied to Quantum mechanics. I mean, all these mathematical functions of waves are almost the same.
    Of course it helps that I was reading and watching lots of videos about the "double slit experiment" and such, to know what are you talking about. But I never expected I would understand so much about Mathematics of the Quantum Mechanics.
    It is all about Waves.... This concept of uncertainty (given by waves) is driving me crazy (in a good way)
    This is the first Quantum Mechanics Lesson that I can "somehow" follow!
    Thank You!! Amazing Professor!!!

    • @victorfergn
      @victorfergn 7 ปีที่แล้ว

      Physicists always try to use the same math, it was the kind of math especially designed for them.

    • @ginnyjollykidd
      @ginnyjollykidd 6 ปีที่แล้ว

      The concepts are easier to understand when you know the language, like psi and B*B

  • @christofchaos
    @christofchaos 6 ปีที่แล้ว +1

    @1:00:12
    Localized particles have less localized momentum because the momenta of the composite waves are cancelling and interfering with each other. Likewise, applying energy to the particles packet of waves causes the particle to move, albeit with some uncertain probability as to the direction/speed of movement. This movement reduces the coherence of the particle, and we become less certain as to where it is located. What is being described is the movement of a particle through space, but only if the particle is a secondary reaction created by the interfering waves.
    Try to imagine the amount of waves (EM or otherwise) passing through us at any second. Now imagine these waves all form the standing particles that make us up. They are highly localized, and their individual momenta are uncertain. But when we apply a macro-force to the system, the momenta of all these particles becomes more certain, and they become less coherent in the static, localized positions they were in before. As the waves re-settle, they regroup, becoming coherent again with all the particles being reformed in a different place and once again, localized.

  • @JohnVKaravitis
    @JohnVKaravitis 5 ปีที่แล้ว +1

    58:54 VERY slick teachable moment here. THIS shows that this guy knows his shit and gives a damn that the students can see how things connect.

  • @isaacmchugh6384
    @isaacmchugh6384 6 ปีที่แล้ว +2

    This is the best TV show I've ever watched

  • @nickb4302
    @nickb4302 7 ปีที่แล้ว +20

    It's amazing how accurate certain aspects of quantum mechanics can be calculated. They're basically just determining odds and they still get the right answer based on experiment. Weird.

    • @dadestor
      @dadestor 3 ปีที่แล้ว +1

      Let me sound smart and say that is empirical knowledge 😌

  • @nkeny1307
    @nkeny1307 8 ปีที่แล้ว +62

    Watching these for fun. What a great professor!

    • @alexbillingham9593
      @alexbillingham9593 7 ปีที่แล้ว +14

      same. its completely irrelevant to my school work but its just so damn interesting

    • @financewithsom485
      @financewithsom485 7 ปีที่แล้ว +2

      Watching before 1 day of exams

    • @ismaelmelendez2710
      @ismaelmelendez2710 4 ปีที่แล้ว

      SOMMAN EDU did you pass? Are you now a quantum theorist

    • @roku6194
      @roku6194 3 ปีที่แล้ว

      @@financewithsom485 how did they go

    • @financewithsom485
      @financewithsom485 3 ปีที่แล้ว

      @@roku6194i am a software engineer now studied mechanical engineering that time this comment is 4 years back 😂

  • @Innovativemediaandproductdesig
    @Innovativemediaandproductdesig ปีที่แล้ว

    41:33 both sides of the equation are superposition in gravitational contraction

  • @sandipchakraborty184
    @sandipchakraborty184 4 ปีที่แล้ว

    MIT is the only great source of quality education which is accessible to all.Thanks really i am greatly thankful to mit for giving the world a opportunity to become capable.

  • @edwardhayes1314
    @edwardhayes1314 ปีที่แล้ว +2

    The teacher and course lecture is awesome, very professional. excellent job

  • @tanvec
    @tanvec 3 ปีที่แล้ว +3

    11:54 "Happy electrons" this guy is the Bob Ross of Quantum

  • @MrMachi95
    @MrMachi95 9 ปีที่แล้ว +8

    play ride of the Valkyrie when he asks for it, fits beautifully.

  • @mohammadkhalili3247
    @mohammadkhalili3247 ปีที่แล้ว +2

    your lecture is captivating, dear Allan! especially about superposition concept, i always just notice to math rule, but it has interesting physical meaning.

  • @santiagoarce5672
    @santiagoarce5672 4 ปีที่แล้ว +2

    Man, I love this lecturer! He's so enthusiastic!

  • @tempestvideos9834
    @tempestvideos9834 ปีที่แล้ว

    In his mind the epic depth of what he is teaching is the objective gospel. Flight of the Valkyries... Passionate dude.

  • @CHistrue
    @CHistrue 10 ปีที่แล้ว +134

    Some favorites:
    "Schrodinger's Cat, Wanted Dead And Alive"
    "Heisenberg Might Have Slept Here."
    And my own awful addition:
    "Mathematicians consider it risque when infinities cancel. Physicists are more tolerant. They do not mind if it happens during energy jumps as long as it is discrete!"
    Thumb this up if it is not completely horrible. My humor might have to be renormalized!

    • @nachik09
      @nachik09 10 ปีที่แล้ว +1

      This is awesome!

    • @CHistrue
      @CHistrue 10 ปีที่แล้ว +3

      Nachiketa Ramesh Here is one not directly related to quantum physics, but reasonably funny none the less:
      "Entropy---It may not be the first bad law to keep a good man down but it is definitely the Second!"

    • @nachik09
      @nachik09 10 ปีที่แล้ว

      CHistrue I didn't get this one. Second law of thermodynamics right? What man? How did it keep him down X(

    • @CHistrue
      @CHistrue 10 ปีที่แล้ว

      Nachiketa Ramesh Well, you know, it ruins the perfect closed system. No perpetual motion machines. I guess if I have to explain it, the humor misses.
      Should I try again?

    • @nachik09
      @nachik09 10 ปีที่แล้ว

      CHistrue Yes please!!

  • @Ztingjammer
    @Ztingjammer 5 ปีที่แล้ว +9

    Came to his first lecture thanks to 3B1B, and here I am intending to go through as much as I can from Allan Adams ❣

    • @learning4951
      @learning4951 2 ปีที่แล้ว +3

      In which video did he refer to allan?

  • @cademosley4886
    @cademosley4886 ปีที่แล้ว +1

    Now that TH-cam provides an overlay graph of the most watched parts of the videos when you hover the mouse over the timeline, I find it pleasing that that graph has two peaks, a smaller peak at 6:25 and a larger peak at 36:37. Remind you of anything? =)

  • @biohazard5702
    @biohazard5702 ปีที่แล้ว +1

    At 9:30 he just realized how crazy this science is at what he is teaching and the enormous exponential Research and knowledge we gain and how fast we went from X to y in such a small space of time

    • @biohazard5702
      @biohazard5702 ปีที่แล้ว

      I think he has add or ADHD cause I am the same when I look and notice what's Ian saying " I'am like dude whaooooo are your even realizing what you're saying"

  • @RunuJena-me6zz
    @RunuJena-me6zz 9 หลายเดือนก่อน +1

    At 32:23 he says that the momentum of the particle for the given wavefunction is p = (h_bar)(wave number) = h/(wavelength of the wavefunction) but shouldn't its momentum be h/(wavelength of the particle).Are (wavelength of the wavefunction) and (wavelength of the particle) the same thing and what does (wavelength of the wavefunction) mean?

    • @schmetterling4477
      @schmetterling4477 9 หลายเดือนก่อน

      There are no particles in quantum mechanics. That's just the worst misnomer in all of physics. There are quanta. Quanta are combinations of energy, momentum, angular momentum and charge (electric charge, lepton number etc.). These system properties get exchanged from one system to another. Take a system with one charge, massive quantum, i.e. an electron. That's about as complicated a system as we can describe with this level of quantum mechanics. A single electron, on detection, gives us only one energy and momentum value. Imagine therefor an infinite repetition of that electron. That's called a quantum mechanical ensemble. The wave function of the quantum mechanical ensemble for one defined energy and momentum value can be described by a plane wave and that ABSTRACT plane wave has a wavelength. We can recover this wavelength in scattering experiments (many electrons scattering on a crystal lattice, for instance) physically. For a single electron that wavelength is not defined. Why? Because a single quantum doesn't give us an energy/momentum spectrum. We can't predict from just one measurement what the next measurement will give us. In order to measure that spectrum we need many quanta.

  • @JaredAllegretta
    @JaredAllegretta ปีที่แล้ว +1

    Exactly 40:00 - a very subtle homestar runner reference.

  • @tanyadeeedmondson-wl7vi
    @tanyadeeedmondson-wl7vi 10 หลายเดือนก่อน

    Thank you all so very much.

  • @IliaToli
    @IliaToli 8 ปีที่แล้ว +25

    You guys are too awesome. I finally start understanding quantum mechanics. I am a mathematician, chemist and aerospace engineer, but not a physicist. It is particularly hard to explain quantum mechanics to me, but you are outstanding. Will write my PhD thesis in quantum chemistry, which means that I can't have enough of quantum mechanics.

    • @JimBob1937
      @JimBob1937 6 ปีที่แล้ว +1

      Ken, that's an odd statement. Obviously, in context, he is stating that a level of comprehension has personally been reached by him with enough confidence to state he is 'understanding' the current level of knowledge we hold. Obviously he isn't stating he's reached a mastery level of understanding that entirely exceeds that of all humankind to date... that would be a large assertion indeed.

    • @ginnyjollykidd
      @ginnyjollykidd 6 ปีที่แล้ว +1

      Quantum chemistry sounds awesome!

    • @NazriB
      @NazriB 3 ปีที่แล้ว

      Lies again? WTF WOF

  • @hurtcolor
    @hurtcolor ปีที่แล้ว

    43:00, 51:00, 1:00:00 (why are we uncertain about the momentum?), 1:02:00 amplitude !!, 1:12:00 fourier analysis…

    • @schmetterling4477
      @schmetterling4477 10 หลายเดือนก่อน +1

      We aren't uncertain about momentum. Momentum is locally conserved.

  • @0xaugustus
    @0xaugustus 8 ปีที่แล้ว +19

    Are the recitation videos available? Thanks

  • @youtubehandlesareridiculous
    @youtubehandlesareridiculous 10 ปีที่แล้ว +89

    What does his wife call his signature?

    • @saqlainamin1951
      @saqlainamin1951 10 ปีที่แล้ว +72

      a wave function

    • @AritraDaddy
      @AritraDaddy 8 ปีที่แล้ว +23

      Are you sure? I think he started something on the lines of My wife calls it a little gift ... ?

    • @liuculiu8366
      @liuculiu8366 6 ปีที่แล้ว +5

      this question seems like some quiz appears in the English test, the listening part. And I forgot the answer when I see the question as I always did, lol!

    • @Rockyzach88
      @Rockyzach88 6 ปีที่แล้ว +17

      Yeah it's clearly edited out for some reason.

    • @HighestRank
      @HighestRank 4 ปีที่แล้ว +1

      Rubbish

  • @Innovativemediaandproductdesig
    @Innovativemediaandproductdesig ปีที่แล้ว

    This is the one subject that still holds my attention.

  • @MrsBreeFree
    @MrsBreeFree 8 ปีที่แล้ว +3

    Really cool lecture! I am from germany and go to University here, but your Profs seems really excited to teach and he makes fun jokes, its so easy to listen to him :)

    • @AJ5
      @AJ5 3 ปีที่แล้ว

      I study at a Fachhochschule and yet I'm here watching these videos instead

  • @frede1905
    @frede1905 4 ปีที่แล้ว +5

    There's something I don't understand: I've learned that quantum wave functions can be described as a "ket vector" in an abstract vector space called Hilbert space. The position wave function, for example, used to express the probability of finding the particle at a point, can be described as a vector in an infinite dimensional Hilbert space. But we also have the wave function used to describe spin ("spinor"), and this wave function exists in a 2-dimensional Hilbert space. So my question is, what is the relationship between these two different wave functions? I've also heard that the wave function contains everything that there is to know about the particle, but I'm like, "which wave function 😭😧?" I would be really thankful if someone could help!

    • @paulryan94
      @paulryan94 3 ปีที่แล้ว +3

      The spatial wave function in the Schrodinger picture, psi, is not the same as a ket vector, | psi >. psi is the projection of |psi> onto the position basis:
      psi = < x | psi >
      | psi > holds all the information of the general quantum state and can be projected onto different basis's. That's why it's so useful. For example the momentum wave function can be arrived at by projecting | psi > onto the momentum basis:
      psi = < p | psi >
      But if you had just psi, the 'wave function', you still have a full picture of the quantum state because you can go to the ket | psi > from it.

    • @frede1905
      @frede1905 3 ปีที่แล้ว +2

      @@paulryan94 Thank you for your answer, but the question I asked above was answered on physics stack exchange right after I made my comment. So it's no longer something that confuses me :). Here's the link to the question and answer on the site, if you're interested:
      physics.stackexchange.com/questions/560132/wave-function-as-a-ket-vector-in-a-hilbert-space

  • @zevikan8638
    @zevikan8638 9 ปีที่แล้ว +4

    proved to be a major help in understanding the uncertainty principle : )

    • @kehaarable
      @kehaarable 3 ปีที่แล้ว +2

      but how can you be sure?

  • @ogradus
    @ogradus 3 ปีที่แล้ว

    1:17:00
    I think the Geiger counter messed with the camera and microphone for a second based off the angle of that plate while you were reading it.
    Cool!

  • @jackgude3969
    @jackgude3969 ปีที่แล้ว

    1:17:08 - I love how happy he is as he says "It's got uranium in it!"

  • @david203
    @david203 5 ปีที่แล้ว

    If there are two peaks in an otherwise zero wavefunction (just before 46:24), yes you can say that on average the position is between the peaks. But each measured position can only be at one of the peaks, not between them. This is like saying the average side of a tossed coin is in between head and tail: it is not literally true. In fact, I would say it is misleading to talk about an average value when the data points are all in only two or three specific places. "Average" implies that data tends to occur near the average value, at least in English descriptions. If we are talking about Normal Distributions, then 'average" (mean) has a very specific meaning, of course. But two peaks are not a normal distribution.

  • @TheDiabolocraft
    @TheDiabolocraft ปีที่แล้ว

    I had quantum physics classes in 2018 taught by some brilliant nutter who couldn't teach a class to save his life... Smart but just terrible. What a great time it was

  • @anyuru
    @anyuru 3 ปีที่แล้ว +2

    38:30 "This is what quantum mechanics is all about"
    *pulls down board and shows "Free Pizza"*

  • @daveconerly1450
    @daveconerly1450 4 ปีที่แล้ว +9

    This was one of my professors at MIT a while back. The class was exremely hard. He was a genius of course. .
    He talked pretty fast when teaching. . If for any reason you got behind , it was almost impossible to catch up.

  • @hasanshirazi9535
    @hasanshirazi9535 6 ปีที่แล้ว +29

    When the Prof. rubs the chalk off the black board, doesn't it go into his open coffee bottle?

    • @grandpaobvious
      @grandpaobvious 4 ปีที่แล้ว +3

      Chalk is nontoxic when consumed in moderation.

    • @hasanshirazi9535
      @hasanshirazi9535 4 ปีที่แล้ว +3

      @@grandpaobvious Yes, may be Calcium in it is even beneficial for the bones!

    • @shivam1996able
      @shivam1996able 4 ปีที่แล้ว +27

      if youre paying attention...the chalk is already in the coffee bottle, and also not in the coffee bottle

    • @abderrahimbenmoussa4359
      @abderrahimbenmoussa4359 3 ปีที่แล้ว

      There is.probably a function to assess that

  • @cbk41
    @cbk41 9 ปีที่แล้ว

    Dr. Benedict Gross from Harvard stated in his Abstract Algebra lectures that you could never know enough linear algebra.
    Seems like the big point of the decomposition of wave functions into their linear combinations and superposition helps to illustrate both of their points.

  • @nanoprehistoric
    @nanoprehistoric 6 ปีที่แล้ว +16

    17:30 the moment i realized that he wrote his own name as a wave function! Hahaha

  • @dalenassar9152
    @dalenassar9152 7 ปีที่แล้ว

    @ timestamp 8:05, the proper pronunciation (of De Broglie) is DEE-BROY. Rhymes with LEE ROY.

  • @jordaneleniak
    @jordaneleniak 3 ปีที่แล้ว

    I paused the video and started Ride of the Valkyries for the III postulate. Definitely added something to it.

  • @artistpw
    @artistpw ปีที่แล้ว

    Really love the content available on youtube.

  • @MrBoxinaboxinabox
    @MrBoxinaboxinabox 10 ปีที่แล้ว +18

    Was that a homestar runner reference at 40:00?

    • @teammoof
      @teammoof 10 ปีที่แล้ว +6

      Yes it was. Nice catch.

    • @domainofscience
      @domainofscience 7 ปีที่แล้ว

      Haha yes it was! I wondered the same thing. Where are the consummate V's?

    • @Taricus
      @Taricus 6 ปีที่แล้ว

      Nope. It's a dramatic orchestral piece. He means it'd make it seem epic while he lays down the postulate.

    • @HighestRank
      @HighestRank 4 ปีที่แล้ว

      Unlikely, though it probably was, depending on your prior ecology.

  • @jagergaming2281
    @jagergaming2281 5 ปีที่แล้ว +12

    when the wavefunction is your signature

  • @xazau-
    @xazau- 8 หลายเดือนก่อน

    This guy is good! A lot better than any of the physics classes I took!

  • @Ne012
    @Ne012 3 ปีที่แล้ว

    So thankful now of all the hard work I put into Fourier series and transforms and convolution that I can do these problem sets.

  • @LeonardGimson-zf7ry
    @LeonardGimson-zf7ry ปีที่แล้ว

    Very great professor, very interesting way to teach

  • @RyanDeGreg
    @RyanDeGreg 17 วันที่ผ่านมา

    7:00 he uses the word 'parsimonious' which means stingy and unwilling to spend money. I think he means to use the word 'harmonious.'

  • @thewaytruthandlife
    @thewaytruthandlife 9 ปีที่แล้ว

    13:20 dX*dp >= h-bar shows us just how non localised matter is. from that moment on that this was written down it should have been understood that matter behaves non local .....in contrast to what classical physics states/shows

  • @nemethma
    @nemethma ปีที่แล้ว

    20 years ago I had these same types of classes. No clue what was going on at the time. Now I get it. Maybe can go get that A I was looking for!

  • @Mohamedkassr
    @Mohamedkassr 10 ปีที่แล้ว +3

    Prof.John Admis, I couldn't express my thanks for your awesome lecture. Wave fns / Fourier series and transform notes. Also you're ready to any questions. Thanks :) for all things

  • @BandhanGoyal
    @BandhanGoyal 6 ปีที่แล้ว

    At 59:53 - there need not be a wavelength for a momentum (unless we are presuming it a wave beforehand). E.g. A cyclist riding a bike has a momentum but no wavelength. Please clarify.

  • @oldfire3107
    @oldfire3107 4 ปีที่แล้ว +2

    At 35:25 when he explains about the doubt that the student had, he talked about light waves superposing, but isn't light wave function always real. Is there an example of a complex wave function for photons?

    • @aidanstanford6742
      @aidanstanford6742 4 ปีที่แล้ว

      I honestly don't know an exact answer to this question as I have not researched it enough. If I had to guess I could say that any real function can be thought of as the real part of a complex function. Therefore there could be a complex function for a photon. It would also not hold up intuitively if not every particle's state could be explained with a complex psi.

    • @jaurandt
      @jaurandt 9 หลายเดือนก่อน +1

      The answer to your question is that no quantum wave function is ever completely real. Wavefunctions are complex, always. If you are referring to real "light waves" as described by Maxwell's equations, those are not a proper description of "light" as it apparently works in reality. If I'm wrong, someone can let me know.

  • @NarenLumpkin
    @NarenLumpkin ปีที่แล้ว +1

    Good Dr., are you implying light is simultaneously part, particle. beam, as well chunk?

  • @AnuragPradhan101
    @AnuragPradhan101 8 ปีที่แล้ว +27

    Why I'm feeling that this lecture is not in continuation with lecture 2 ,since in lecture 2 he didn't discuss polarization !

    • @RedTriangle53
      @RedTriangle53 8 ปีที่แล้ว +10

      he's referring to the group class held by the other professor, not the previous lecture. A group class is more like the classes you have at high school level and lower, in that you do problems and ask questions and sometimes they go through things on the blackboard.
      Edit: they might be using a different system than what I am used to, but I am at least fairly certain that he was talking about something similar.

    • @financewithsom485
      @financewithsom485 7 ปีที่แล้ว

      Anurag Pradhan from Miami

    • @Rockyzach88
      @Rockyzach88 6 ปีที่แล้ว +3

      Polarization was just an analogy of how the box discussion.

  • @SecularSerenity
    @SecularSerenity 3 ปีที่แล้ว +2

    Episode 1: Wow! This is awesome.
    Episode 2: Okay this is a little tough.
    Episode 3: Maybe a community college dropout needs a deeper background to understand this...
    Can't wait to watch episode 4.

  • @Peace-ey5hn
    @Peace-ey5hn 6 ปีที่แล้ว

    IMO, a "quantum vibrational wave/ripple" is set off at the point where the electron is fired. A quantum aerodynamics of sorts. The wave precedes the electron. It is this wave that is responsible for the distribution pattern as each electron, even though fired 1 at a time, is carried on it. It explains the "probability" of where each would land.
    When you try to measure the electron, it is not the "conscious" act of doing it that causes the electrons to behave as particles, but it's because you break the wave. Thus, as there is no wave for the electron to ride on, it will come through the slit as an independent particle.

  • @fredsolo730
    @fredsolo730 3 ปีที่แล้ว

    30:50 The stupid one is not a function but a relation by definition as a function can't be multiple valued Is that the reason why it can't be a wave function?

  • @JoeyFknD
    @JoeyFknD 3 ปีที่แล้ว

    Ugh as someone with a math degree, I have paaaain imagining the problem he just casually tossed out: show why the wave function must be continuous. THANK GOD it's just in one dimension as well.

  • @psharmacgk
    @psharmacgk 9 ปีที่แล้ว +101

    Welp that settles it, I definitely wanna be a physics major

    • @davidnovosardian6848
      @davidnovosardian6848 9 ปีที่แล้ว

      No Name Sharma Really?

    • @psharmacgk
      @psharmacgk 9 ปีที่แล้ว +3

      Yes! This was so cool :-)

    • @joseph9589
      @joseph9589 9 ปีที่แล้ว +15

      +dubhad Physics major here - actually, there is a 1% unemployment amongst physics majors, unlike the 49% among business majors.

    • @ahadicow
      @ahadicow 9 ปีที่แล้ว +11

      +Joseph Godoy that's probably because 99% of physics majors don't want a job.

    • @joseph9589
      @joseph9589 9 ปีที่แล้ว +10

      +ahadicow No, quite the opposite. The 99% do have jobs, either in mathematics, physics, or sometimes on wall street or in business.

  • @samposyreeni
    @samposyreeni 3 ปีที่แล้ว +1

    Question: what's the physical interpretation of doing something like a Hilbert transform on a wave function? I mean, if a complex function is normalized and analytic, it'll stay that way after the transform, so it ought to represent *something*. At the same time, I have difficulty seeing what the resulting wavefunction really then *does* represent.
    I ask because I come at this from a linear algebraic, LTI, DSP, and maybe even radio modulation (there mostly linear, but no longer time-invariant) viewpoint. Within those disciplines, such operations on complex signals (real, complex, distribution valued, whatever) are common, and their mutual connections are well settled as mathematical fact. So is the Fourier analysis side of things. So it'd be interesting and I think useful to see what the canonical signal processing operations/symmetries, which are known to preserve wavefunction-likeness, do to the physical interpretation.
    Do they just lead to unlikely physical systems, or do they map to something intuitive?

    • @schmetterling4477
      @schmetterling4477 3 ปีที่แล้ว

      The Hilbert transform is not a physical transformation as far as I know. One can only implement physical approximations of it. I am not a theorist, but I think I know enough to warn in general against understanding mathematical transformations as fundamental to physics. They are useful tools in theory, but that doesn't mean that they have to have an interpretation in terms of physical observables. Specifically the Hilbert space approach to non-relativistic quantum mechanics suggests that one can perform nearly arbitrary transformations on systems. This is only so because covariance is not a requirement of the theory. In relativistic field theory the more common case seems to be that many desired formal operations on quantum field representations break covariance in a fundamental way, thus introducing non-physical states (ghosts) in the process. If anything it seems to me that the state-space approach is actually an artificial way of dealing with quantum fields. We borrowed it from classical theory where it works because we are working on averages of complex distributions but as soon are higher order (actually infinite order) correlations have to be dealt with, the math breaks down pretty quickly and has to be tweaked constantly to produce the desired results. Like I said, I am not a theorist, it still seems to me that many of the problems of quantum field theory are the result of a poor choice of representation rather than a fundamental property of the theory.

    • @samposyreeni
      @samposyreeni 3 ปีที่แล้ว

      I didn't ask whether it was a physical transform. Because it *is* a valid transformation from one wavefunction to another. The transformation itself does not *need* to represent anything physical, even if its end result does.
      So what *is* the end result? In various experiments?

    • @schmetterling4477
      @schmetterling4477 3 ปีที่แล้ว

      ​@@samposyreeni On paper you can transform whatever you want. The four dimensional harmonic oscillator, for instance, can be transformed into the three dimensional Kepler problem. On paper. Can you do that in reality? Not so much. A Fourier transform, on the other hand, can be approximated in an optical setup with a lens. To me that's a physically implementable transformation. Many others are not. I don't know how else to understand your question. Math is math and physics is physics. The two have next to nothing in common except for the language. Physics is far more restrictive than mathematics.

  • @jandejongh
    @jandejongh 3 ปีที่แล้ว +8

    Thanks Prof. Adams; absolutely brilliant intro into QM (not that I would know, I'm EE :-)). But just in case viewers need a perhaps equally well-taught lecture series on Fourier: There's an excellent treatment on this topic by Brad Osgood from Stanford available on YT. Highly recommendend!

  • @Anomander888
    @Anomander888 3 ปีที่แล้ว

    This man is so funny .
    Creativity is intelligence having fun in motion right here .

  • @sameertomar5099
    @sameertomar5099 3 ปีที่แล้ว

    One of the best Professors

  • @WondererWandering
    @WondererWandering 2 ปีที่แล้ว +1

    amazing lecture

  • @squeevey
    @squeevey 2 ปีที่แล้ว +1

    Did professor just make a strong bad reference at 40:02? (The system -is down)

  • @ปาริชาติแซ่ย่าง-ค4ฝ
    @ปาริชาติแซ่ย่าง-ค4ฝ 3 หลายเดือนก่อน

    Great thanks for letting us know that lectures

  • @JoeDeglman
    @JoeDeglman 5 ปีที่แล้ว

    So basically what we learn here is that all charged particles create a transverse electrical wave in the ether medium defined by the COS function, and the particles also create a magnetic wave in the ether that is orthogonal, and 90 out of phase, and lagging the electric transverse wave. The magnetic field is defined by the SIN function.
    The probability of find the particle inside the wave it creates in the ether medium is defined by COS^2 + SIN^2 of the electrical and magnetic fields (or a superposition of feilds) it creates as it travels through the fluid ether or magnetic field. Also we learn that quantum works only when the fields we superpose are caused by individual particles and not just waves, because there have to be individual momentum associated with each wave. So we can get a general wave caused by the different particles and superpose them, but the momentum of each wave doesn't not superpose well.
    We also learn the polarizers are just radiators of the light signals they receive and when we put a polarizer at 45 degree angle to two quarter wave polarizers they can retransmit a light signal back into the original direction of travel of the light. The ether medium creates a double layer around all prisms from which we can extract a evanescent wave, with another prism or polarizer. So the polarizer at 45 degrees doesn't transmit all of the signal orthogonal to the original direction of travel and the next polarizer can pick up that signal and transmit it through as light. th-cam.com/video/9BkfFjr9Tyw/w-d-xo.html

  • @seeker313
    @seeker313 7 ปีที่แล้ว

    What does it mean that the wave associated with a particle is the interference of many different waves? I mean what is the significance of each wave?
    I think it means that the particle's wave can have any wavelength among those many waves with different probabilities. So it's nothing but the Uncertainty Principle.

  • @breaker4312
    @breaker4312 8 ปีที่แล้ว +130

    I followed the first episode 100%. Then I plummeted :(

    • @JimBob1937
      @JimBob1937 6 ปีที่แล้ว +9

      Yeah, the first lecture is covering an intuitive understanding and developing a platform before introducing the mathematics. However, you can only progress so far before introducing that portion is required. However, MIT OCW has the prereqs on their site I'm sure.

    • @ankeunruh7364
      @ankeunruh7364 6 ปีที่แล้ว +7

      @Eric R, try the second lesson again! We, who are watching here on youtube, aren't MIT students. I can sware, that mathematics (esp. calculus) has been taught to us for centuries as it was an enemy. We need to fight for better teaching!! Those Professors must work on this!! They must try their very best, and I think most of them will fail (as I can see in regular schools) - but, this is not an excuse for giving up this demand to the Universities!!! Let's continue asking for what we need. Giving up is not an option.

    • @mykofreder1682
      @mykofreder1682 6 ปีที่แล้ว +1

      Assuming you understand calculus I used WolframAlpha for my PC, I have it because I knew it was a good math package and it was real cheap in Windows store, it relies on a backend server though and I crashed it entering a complex addition of several waves. Then enter the equations he blows over like (e^0.2it) or (e^2it) and see the results real and imaginary and the sin/cos breakdown. You can also enter the normal and normal square to see that |e^2it| or |e^2it|^2. His lecture would be helped if he had a math package on his PC and ran samples of the equations he wrote up there through a math package, shown on the overhead projector. The days of memorizing heavy or even light math are over, using the same math through a package long enough the memorization will occur eventually.

    • @ankeunruh7364
      @ankeunruh7364 6 ปีที่แล้ว

      @@mykofreder1682 I do not believe something like 'understanding calculus', still trying to learn Lagrange formalism. I think, this is something to 'go through' - which means "shut up, follow, and calculate!". But: your advice "WolframAlpha" was a surprise, although it's not hidden (and never was)... In a school, we have to do more than I can oversee. Will try to get closer. Reflections welcome! :)

    • @Andrewtmcb
      @Andrewtmcb 5 ปีที่แล้ว

      @@JaredBryan calc and linear algebrah strongly recommended

  • @manavnaik1607
    @manavnaik1607 6 ปีที่แล้ว +1

    Everytime I think to myself 'wow there's no way he has anymore room to write anything,' he pulls out another fucking blackboard out of nowhere

  • @nomad9518
    @nomad9518 ปีที่แล้ว

    Wow, they applauded for the guy. Well deserved.

  • @yugantarbhasin3752
    @yugantarbhasin3752 5 ปีที่แล้ว +1

    What does psi tell because it also has a dimension

  • @grindingthegearsofalltides4504
    @grindingthegearsofalltides4504 9 หลายเดือนก่อน

    the watch time Distribution of this video looks like the superposition of the first two wave functions haha. It has 2 spikes at x_1= 6:30min and x_2=36:37min

  • @cinema2748
    @cinema2748 4 ปีที่แล้ว

    Why the wave function is complex ? Where does the imaginary part comes into the picture from ? How did Schrodinger get the idea of the wave function and its representation? Help.

  • @prn718
    @prn718 3 ปีที่แล้ว

    8.04.1 = Look at me, I'm watching an MIT quantum physics class and I *get this*
    8.04.3 = *head exploding*

  • @wafikiri_
    @wafikiri_ 3 ปีที่แล้ว

    To pronounce Broglie more accurately, just make the last syllable more acute in tone. Almost any polysyllabic French word is the same (some are not because the last syllable is mute).

  • @usptact
    @usptact 4 ปีที่แล้ว +3

    Quantum physicist pickup line: your wave function is so beautiful.

    • @rajns8643
      @rajns8643 3 ปีที่แล้ว

      Really amazing