This guy is a genius teacher. As a teacher I can tell you this is the result of great intelligence, experience, and mastery of the subject.
@adrienrandall94833 жыл бұрын
i realize I'm kinda randomly asking but does anybody know a good website to stream new series online?
@jimhalpert98982 жыл бұрын
yes I do
@thehellfromthemountaint3 ай бұрын
@@adrienrandall9483 idk if it helps. But in Russia we pirate everything and it usually have original in English with subtitles, you can try kinogo, zetflix, seasonvar Oh fck you asked this 3 years ago my bad
@joesmith82884 жыл бұрын
I like how much time he spends on clarifying the superposition principle and measurement.
@isatousarr704428 күн бұрын
In quantum mechanics, the concept of superposition is fundamental, particularly when discussing the state of photons and the intrinsic spin of particles. Superposition refers to the ability of a quantum system to exist in multiple states simultaneously until a measurement is made. For photons, superposition commonly manifests in their polarization states. A photon can be in a superposition of horizontal and vertical polarization states, represented mathematically as |ψ⟩ = α|H⟩ + β|V⟩, where |H⟩ and |V⟩ denote the horizontal and vertical states, respectively, and α and β are complex coefficients that determine the probabilities of measuring each state. Similarly, spin states in particles like electrons also exhibit superposition. An electron's spin-½ state can be expressed as |ψ⟩ = a|↑⟩ + b|↓⟩, where |↑⟩ and |↓⟩ represent the "up" and "down" spin states. The coefficients a and b correspond to the likelihood of measuring the electron to be in either spin state upon observation. The fascinating aspect of superposition lies in its implications for quantum entanglement, interference, and the behavior of systems at the quantum level, fundamentally challenging our classical intuitions about the nature of reality. As a result, superposition not only plays a crucial role in the theoretical framework of quantum mechanics but also underpins many emerging technologies, including quantum computing and quantum cryptography.
@thisisFaye15 жыл бұрын
he got a hair cut
@MrDroenix4 жыл бұрын
Haha that was my first thought too
@endogenic69134 жыл бұрын
@@MrDroenix same
@uncountableuk Жыл бұрын
:) my first observation too
@ldanielfch Жыл бұрын
Yes
@eightysevenf Жыл бұрын
Lolol thanks i was like.. something’s different i’m confused 😅
@drdd3336 ай бұрын
I thoroughly enjoy this gentle teacher. Brilliant.
@nst10584 жыл бұрын
Awesome mathod of explaining the theory, respect from India🙏
@zhaoxingdeng52642 ай бұрын
Amazing quantum mechanics! Amazing professor!
@zheyuchong94772 ай бұрын
The way he explained this was very efficient.
@kaushaljain59994 жыл бұрын
4:41 to 4:57 in previous lecture L1.4 you have said that after polarization state becomes either or . There is no significance of cosAlpha or sinAlpha coefficient which is in front of them. So after polarization there should be no or One real parameter which is no. "1". Another Query_If there is one parameter then before polarization there should be three real parameter (one from real no 1 and two from complex no beta by alpha)
@brainstormingsharing13094 жыл бұрын
Absolutely well done and definitely keep it up!!! 👍👍👍👍👍
@sayedahmed74654 жыл бұрын
Excellent way of teaching , absolutely fascinating !
@FirstAmendmentAudits4 ай бұрын
❤ come back to 7:07
@kaushaljain59994 жыл бұрын
2:04 to 2:09 _ how will we get state minus A or iota A by superposition of A by itself. Since to get state 2 A is obvious by superimpose one A by another A.
@andressalvadorsartarelli63932 жыл бұрын
Muy buen docente. Explica con mucha claridad
@georgesbegon42524 жыл бұрын
Données claires excellent professeur l écriture est très lisible ce qui est déjà révélateur le tableau est bien filmé quant à la validité des théories je reste très modeste pour ma part vu que l on a constaté tant de remise en question depuis Newton ..
@mona827 жыл бұрын
Thanks MIT
@nimeshdwivedidwivedi15302 жыл бұрын
Wonderful session sir proper understand thats superposition sir
@kaushaljain59994 жыл бұрын
1:47 to 1:52 Why is it physical assumption? Because i think it seems obvious.
@FirstAmendmentAudits4 ай бұрын
6:35 Come back to 6:44 6:44 6:44 6:45 6:45 6:45
@magnfiyerlmoro33017 жыл бұрын
i dont understand when he says, for 2 complex parameters there is 4 real parameters, thanks for explaining!!
@fcwong15 жыл бұрын
alpha = a + bi beta = c + di. a, b, c, and d are the 4 real parameters.
@eshankvaishnavi38214 жыл бұрын
fcwong1 thanks
@brandomiranda67034 жыл бұрын
how did he resolve Einstein's paradox (e.g. how do we know if half were down already before the measurement rather than this superposition)?
@akindeleoduwole10946 жыл бұрын
Quite enlightening and helpful. Thanks. From Nigeria
@zack_120 Жыл бұрын
These Superposition lectures did not explain the mechanism how a particle can be in both positions at the same time but only talked about what it is which is already known. It looks really weird, even hard to teach by experts. By comparison, the entanglement topic is taught clearer in a simple but convincing eq.
@lepidoptera93373 ай бұрын
The language of non-relativistic quantum mechanics is, unfortunately, very misleading. There are no particles here. What we have are systems that are exchanging energy, momentum, angular momentum and charges. When he talks about "spin up", then he means that the detecting system has received a small amount of angular momentum that has a (classical) angular momentum vector that is pointing up in the coordinate system of the detector. A quantum measurement is a histogram of a series of individual spin measurements, i.e. in that histogram roughly half the spins will point up, half will point down. Therefor the histogram is in superposition, NOT the individual measurement. The individual measurement is quantized and can only have one realized states of two possible states. That is no different from throwing dice. The probability distribution of fair dice is 1/6 for all six possible outcomes, but an individual dice throw can only be one of the possible values of 1, 2, 3, 4, 5 and 6.
@jorfoas2 жыл бұрын
I would really appreciate if the teacher labeled axes properly. For example, in minute 7:23, I am assuming that both X and Y axis represent electric fields, but that should be clarified.
@furkanunsal58144 жыл бұрын
11:07 Up allons y and down allons y
@p.s.design43387 жыл бұрын
Really great lectures.
@saskiavanhoutert6081 Жыл бұрын
Very clear explanation, thank you very much Einstein was right, your explanation also, kind regards, Saskia van Houtert engineer/office-manager graduaded at the Graphic Lyceum, the Netherlands 29 june 1995 as a Graphic Technical Engineer. And graduaded at 19 july 1997 as a office-manager. at the Economical Administration Education ECABO-BOVA at Breda. So I have 2 profession possibilities; engineer/office-manager.
@SaeKan-x1h5 ай бұрын
This is a great lecture. However, I didn't understand the last explanations. Why we get all the particles spinning up in x-direction after measurment in a superposition? I'm sorry if I misunderstanding it.
@lepidoptera93373 ай бұрын
If you are preparing an ensemble of spins all up in x-direction and then you make a measurement of that ensemble in y-direction, then on average 50% will be up and 50% will be down. The mix depends on the angle between the preparation and the measurement.
@joseluisrodriguez2605 Жыл бұрын
Exelente mi profe saludos desde la fiee lima peru especialidad ing electronica de potencia
@ryanrizzo38667 жыл бұрын
Excellent Lectures! Very helpful.
@silberlinie5 жыл бұрын
0:49 best. How he stands there, how the many contradictions expressed by others to what has been said here in his thoughts rush past. And he then stomping his foot inwardly and he defiantly arrives at an SO.
@afifakimih88233 жыл бұрын
He is just not a good Professor,and an excellent teacher,he is one of the leading string theorist as well !!
@samybouzida79563 жыл бұрын
Your comment could be misunderstood. Let me help you out here: ´´He is not just a good Professor, and an excellent teacher, he is also one of the leading string theorist as well !!`` The location of the word ´´just´´ in your sentence could lead to understand that you actually didn´t like the guy. We all know what you meant. Hope you won´t find me snob or anything. I 100% agree with you, this guy is beyond brilliant.
@bobbwc70112 жыл бұрын
But string "theory" is scientific trash and should have been abandoned decades ago.
@Mizraab29124 жыл бұрын
But you have to look in another direction-Such a nice line to convey that perspective matters
@joedarkmatter50513 жыл бұрын
1:05 After he said "strange" , i see Dr Strange in him. Or is it just me =)
@theconstellation__4 жыл бұрын
If a photon is polarized in x direction by a polariser ,then what will happen when it passes through another identical polariser, as on Photon level it's not predictable, so do all the photons come out or ,they again come out in some probability
@kaushaljain59994 жыл бұрын
4:04 meaning of QM state
@jessstuart74952 жыл бұрын
My gut tells me using the two measured outcome states (spin-up and spin-down) to describe the particle's state before measurement (superposition) might not be the best approach.
@mareksozolins63475 жыл бұрын
Good old days at school i have getting sleep to listen to teacher -)
@nickknight53734 жыл бұрын
He seems to be talking at a similar tempo whatever the playback speed.
@redberries80393 жыл бұрын
6:50 beta/alpha .... '2 real parameters' or gamma 'one complex parameter' ...How are we getting the complex from a division of the reals? ...and I thought the alpha beta has to be complex anyhow?
@ryanjbuchanan2 жыл бұрын
How beautiful the internet is. If only Einstein and Newton had such tech.
@phononify7 жыл бұрын
Would the argument hold also for the Hydrogen atom (assuming a nuclear spin of zero): Would the state of the bound electron would be also N*(|up>+|down>), or is the ensemble of that H atoms a mixture of up and down electron spin variants ? :) How could somebody distinguish these two cases experimentally ? Could you ? Thanks for your opinions.
@cakeathon99837 жыл бұрын
I'm not sure what you mean by "N*(|up>+|down>)", the electron of each atom will have spin up or down with 50% probability. The experiments for spin are done on the 47th electron of silver atoms, the same thing should apply for all atoms. That being said, I don't think it can be done experimentally, it is just assumed that what is true for silver atoms is true for all atoms. The problem is that orbitals cause an angular momentum which dwarfs the angular momentum of electron spin, so you need large atoms for which the angular momentum due to orbitals cancels itself out enough to detect electron spin.
@elsayed1114 жыл бұрын
Dear Sir, in case of super position u tl about polaristion in two diretion where in the previous lec. u told that only one direction is the valid and other vanished, THEN HOW COULD YOY TAL ABOUTH SUPERPOSITION OF BOTH OF THEM THANS
@tangye82436 жыл бұрын
Mind-blowing!
@brandomiranda67037 жыл бұрын
Also I wasnt super convinced about his argument of how we really know they are in a superposition rather than apriori being 50-50 split, does he explain it better latter or did someone catch that better than me?
@mohamedakrout97426 жыл бұрын
This lecture kzbin.info/www/bejne/oouWk4OLgNRosMU of the same course (taught during another semester) explains exactly how and more importantly why there should be a superposition.
@rai21343 жыл бұрын
How can we design a superposition state of spin with probabilitis of 40% and 60%?
@schmetterling44772 жыл бұрын
We change the strength of the magnetic field.
@kaushaljain59994 жыл бұрын
8:04 why have you given thanks at this time?
@abdurrauf75252 жыл бұрын
Respected Sir, which books you used for these letters?
@jessstuart74952 жыл бұрын
Zwiebach recently published a textbook _Mastering Quantum Mechanics: Essentials, Theory and Applications_ , MIT Press, 2022
@abdurrauf75252 жыл бұрын
@@jessstuart7495 thanks
@stormtrooper94044 жыл бұрын
May someone explain what is IA> ? And how possibly IA> ~ 2IA> ~ -IA> ~ iIA> How can one "state" be equal to that same state x2?
@compilationsmania4514 жыл бұрын
1) i is a complex number equal to square root of -1. The teacher explains that in the previous lectures. You should start from there if you haven't seen them. 2) In a superposition equation, the states refer to the possible results and their coefficients squared are proportional to the probability of getting that state. So, the coefficient just refers to the probability, not an actual physical quantity. So, if you have a single possible state, then it doesn't matter what coefficient you add in front of it, physically it doesn't make a difference. To give you an example, if you take a bag with any number of red balls in it, if you choose any random ball from the bag, the probability of that ball being red is 1 irrespective of how many balls are in the bag, because there are only red balls in the bag.
@PrivateSi4 жыл бұрын
I don't get it, he starts by saying two photons in superposition don't add or substract from each other, yet we know they constructively or destructively interfere.
@kaushaljain59994 жыл бұрын
Explain 3:19 to 3:29
@sauravmittal5387 жыл бұрын
how cn i build a new quantum state by superposition of spin of two electrons
@GrandGobboBarb6 жыл бұрын
11:19
@brandomiranda67037 жыл бұрын
Does he ever explain what "physical equivalence" really means? Is the rescaling valid due to quantum probability measures adding to one?
@vwcanter4 жыл бұрын
Yeah, it’s just a consequence of the same linearity he spoke of. If A and B are solutions, then A+ B is a solution. Therefore, A + A is also a solution. So 2A or 3A or iA or -A are also solutions. I think you could think of it as a result of probabilities adding to one, because he describes it as “normalization”. But someone else can perhaps explain that better.
@guitarttimman Жыл бұрын
Look up schrodinger's equation.
@duf.l62683 ай бұрын
What is the professor's name?
@jamalelqars31892 ай бұрын
Sir Barton Zwibach
@not_amanullah3 ай бұрын
Thanks ❤️🤍
@brandomiranda67034 жыл бұрын
why does scale affect the physics?
@anonymous.youtuber3 жыл бұрын
When you do an experiment in classical physics you act on trillions and trillions of atoms at the same time and you only measure some average result that is the sum of many individual results. The atoms don’t scale, there are just many of trillions of them. You can’t grow an atom the size of a football and experiment on it.
@not_amanullah3 ай бұрын
This is helpful ❤️🤍
@mishalkiranreddy12144 жыл бұрын
Sir what exactly a state is?
@surendrakverma5552 жыл бұрын
Very good 🙏🙏🙏🙏🙏🙏
@jamesfullwood77884 жыл бұрын
It's amazing how long a physicist can go on talking about something without even defining it (i.e., the wave function). If I was one of the students in the class I'd be like "Ok great, but what IS |A> ?"
@flygonfiasco97514 жыл бұрын
This is a continuation of other lectures, not the first day of class.
@jamesfullwood77884 жыл бұрын
@@flygonfiasco9751 I watched all the lectures leading up to this one....
@flygonfiasco97514 жыл бұрын
James Fullwood Rewatch L1.4. In the latter part of the video, he goes into depth about Dirac notation describing quantum states using a photon as an example.
@jamesfullwood77884 жыл бұрын
@@flygonfiasco9751 He still doesn't give a precise definition of the wave function. In mathematics, a function is a relation between two sets, one called the domain (the set of inputs)and the second called the codomain (the set of outputs). It's obvious that the codomain of the wave function is the complex numbers, but he never defines the domain.
@m.s.64494 жыл бұрын
Defining something before you know anything about it is impossible. First you learn of the existence of some new object, investigate its properties and only then, based on acquired knowledge, you can invent a definition for it.
@haiekmohammed65487 жыл бұрын
Thankx professor from morroco
@themasstermwahahahah4 жыл бұрын
he looks a lot more whimsical with the longer hair
@kaushaljain59994 жыл бұрын
9:27 Explain
@mp3lwgm4 жыл бұрын
The title is misleading. You do not discuss the spin states of the photon. Instead you Segway from the polarization of the photon to the spin states of the electron; awkward !
@timmy181354 жыл бұрын
11:10
@davidwilkie95515 жыл бұрын
Spin, the concept, is a particular identification of probability positioning states in the context interpreted Superspin Modulation, the Conception of the infinitesimal sync-timing, of zero difference synchronicity universally distributed by the mechanism suggested by Wheeler and Feynman applying to the "One Electron Theory", an infinite-closed loop equivalent to the meaning of a Black Hole Singularity Conception of inflation-collapse singularity = Eternity-now +/-.., the actual circumstances of time duration timing, QM-TIMESPACE. (Requires a pictorial observation technique/imagination) If QM-TIMESPACE e-Pi-i in-form-ation of Time Timing is a Holographic brane, an objective of resonance imaging that "floats on nothing" (Avagadro's? No, Archimedes principle is the same positioning here-now forever Principle as Superposition-Exclusion holographic image projection drawing. Multi-phase reciprocal-resonance-> "loop" between micro-macro vanishing point
@bobbwc70112 жыл бұрын
You need to stop taking drugs. Your comment is insane rubbish.
@andreeapopa96354 жыл бұрын
can he teach our online classes? he's a much better teacher than ours LOL. you should always focus on the explanation instead of reading your PDF @my prof. *cough cough*
@bustercam1994 ай бұрын
Seems like he is misquoting what Einstein said about Realism.
@lepidoptera93373 ай бұрын
He is talking a lot of nonsense in general here. This class won't help the average student to an understanding of quantum mechanics.
@brandomiranda67034 жыл бұрын
does he depend what physically equivalent means?
@elhaditalbi346 Жыл бұрын
🌎
@SfhjjFghjki7 ай бұрын
For sy contest sup calculate Never RE MINDED ,,QUESTION QUALITY WE HAVE ,WHERE A SUBJECT, 2()+ ing¿ Like similar EYES ARE GOING STAGE // «««««| NEW SWORDS ,IM XOING AND WHAT // Energy free ,quanta Est MYTH DES PROBS ,
@thehellfromthemountaint3 ай бұрын
Hold up, medic from tf2?
@bustercam1996 ай бұрын
No, this is incorrect.
@elosant2061 Жыл бұрын
when he says "superimpose" doesn't he mean "superpose"?
@scimad3 жыл бұрын
1.25x
@ken9165611 ай бұрын
It looks like a circular argument to me.
@ericreiter1 Жыл бұрын
I retract my comment. I just have experiments showing qm fails.
@jpzhang82905 жыл бұрын
Laudau-style teaching. I like it.
@ericreiter14 жыл бұрын
What a terrible professor.
@mubeendewan2287 Жыл бұрын
how so?
@xrfxlp4 жыл бұрын
Utter nonsense!
@mubeendewan2287 Жыл бұрын
how so?
@glenmenas94246 ай бұрын
Describing spin up or down along the z axis is so far from what is actually happening. You cannot describe the wave two dimensionally and then describe spin on a third dimensional axis, especially if we're talking about photons because of how the electric field interacts with the magnetic field in a light wave. If you're going to describe the wave function of the nature of light and photons specifically, you must start by describing the perpendicular electric and magnetic fields in three dimensions instead of two, which I have seen no one do ever. Stop thinking in terms of sign waves!
@lepidoptera93373 ай бұрын
There are no waves here. There are only quanta of energy, momentum and angular momentum. You are correct that up/down doesn't work for photons because of relativity and we have to talk about helicity, instead, but that's a technical detail that doesn't matter at this level.
@ericreiter1 Жыл бұрын
I retract my comment. I just have experiments showing qm fails.
@ericreiter1 Жыл бұрын
I retract my comment. I just have experiments showing qm fails.
@ericreiter1 Жыл бұрын
I retract my comment. I just have experiments showing qm fails.