Lecture 1 | The Theoretical Minimum

(January 9, 2012) Leonard Susskind provides an introduction to quantum mechanics.
Stanford University:
www.stanford.edu/
Stanford Continuing Studies:
continuingstudies.stanford.edu/
Stanford University Channel on KZbin:
/ stanford

[@yannmaxpoirier]

I have no diplomas, --> bad student and lack of maturity when I was a teen. Yet I found a thirst for knowledge in my 20s, decided to start from scratch all the science and math. Two years ago I finally reached the confidence to start learning about quantum physics. I bought the book, did the math on paper It's been my only book for two years I never skipped a page until I was fully able to play and understand the mechanics involved. I watched the lectures many Times. And I come here just to say thank you. Unfortunately I'll never work in physics, I am too old and still without a diploma, I have managed to make a great career in IA and machine learning. To each his own path eh? Living in this era of knowledge, where you can learn from home, find communities to help you improve, is the greatest gift we have. Stanford and Leonard Susskind I thank you again for making this class available and henceforth contributing to what is the best about the world we live in. I felt, even though this video is old, that a heartfelt comment here was needed. Thank you again. (a friendly Swiss fellow)

[@feuzzionarts8129]

That’s…fascinating..!!}

[@vincenzopanella2705]

Complete an high school diploma at least

[@fra2025]

Wow!

[@lucasmcguire1554]

Hey that's really interesting! Do you have some sort of contact details? I'd love to see how you are progressing

[@user-tw2du9yz2c]

I've wanna praise your efforts to get more richer knowledges despite any obstacles You've have been through. Good Job! man!

[@smajidy]

Lecture 1 0:00:00 to 0:11:35 - Transition from classical to quantum mechanics 0:11:35 to 0:20:00 - The state of a system in classical mechanics 0:20:00 to 1:01:21 - The results of measurements on a qubit 1:01:22 to 1:15:10 - Vector space 1:15:11 to 1:24:12 - Dual of the vector space 1:24:13 to 1:46:31 - Inner products

[@Haheat]

50:00 cookie break

[@pushanpore8365]

great

[@ricardo_boutique]

@@Haheat thank you for that pearl

[@NazriB]

Lies again? Take Meds

[@adammac.1342]

Thank you 😊

[@RalphDratman]

I'm surprised and pleased that this is online. I bought the Kindle book a few months ago, without knowing there is a set of free online lectures by the author. Thank you to Stanford and Leonard Susskind for making these lectures available.

[@christopherplessinger4664]

Yeah, but this is quantum mechanics minimum. The book covered classical mechanics.

[@OlliWilkman]

My path with the Theoretical Minimum is a bit random: I bought the quantum mechanics book at a whim in a bookstore, but then I first watched the classical mechanics video series, ordered the two other books online, then read the classical mechanics book, then started reading the special relativity book, but after a few chapters switched quantum mechanics book and having read the first third I now started watching this video series… On the other hand, I studied all this stuff at university, so it's familiar, but it was over ten years ago and I've forgotten a lot.

[@speedcuber103]

Christopher Plessinger there is a book for quantum mechanics too

[@paddymcdoogle6753]

Santa is that you?

[@RalphDratman]

@@paddymcdoogle6753 Of course, my child, it is me.

[@Dom2k16]

I have no clue what any of this means but for some reason I’m fascinated by hearing him talk so I’ve nearly finished the whole thing

[@razza9647]

Same here

[@cryptic6969]

Keep trying to hear and you shall hear. For your effort i say, “ Good Job.”

[@victorvaca7429]

At least you stayed

[@majensen2007]

Why no share button?

[@jimc.goodfellas226]

Dom great channel my friend, keep listening that's where I started and now I am learning more science/physics than I ever did in school

[@MichaelHarrisIreland]

Tks Stanford, what a privilege to listen to this. And Susskind is an amazing teacher. I'm blown away by getting a glimpse into the theoretical minimum which I knew little or nothing about.

[@peterkay7458]

He really is and it takes one to know one. I totally disagreed with the final outcome of the black hole wars so I had to eat a lot of crow when i finally understood it. Totally worth it to have an insight into string theory.

[@sherlockholmeslives.1605]

He is actually quite a knowledgeable man, Leonard Susskind. I can grasp Plato's 'Wax Tablet Hypothesis', Aristotle's 'Theory of Everything' and Goethe's 'Theory of Colours' but these lectures are beyond me. Cheers - Mike.

[@ErnestYAlumni]

I really enjoy Susskind's lecture because even as a practitioner and expert, I like how he gets to the heart of the physical idea and it is wonderful that he is taking the time and effort to educate in this venue for continuing education.

[@DenisDmitriev]

Special thanks goes to camera operator, who predicts all the movements not even causing a real headache.

[@akash_goel]

yeah, i would love to see the setup that was done to record this!

[@yomamafatoshi]

and to the sound person too!

[@hishamhittini5069]

I think it is a system guided camera called lecture tracker camera, equipped with sound systems that activate or deactivate mics across the room

[@jlowe8059]

I agree, this was really well filmed.

[@itchyandscratchy7350]

Pretty sure it’s an AI.

[@TEKim-lk6op]

I'm so happy this is online. He is a great teacher - simplifying as much as possible. Visuals help immensely.

[@Goldslate73]

I can't say Thank You enough. It's been a year since I started with this course and now I am learning to apply all of this in my Quantum Computing course. To whomever this concerns: the explanations and tricks (not really) that you're gonna learn here will stay with you your whole life. Its THAT clear. Thank You Professor Susskind and Stanford University for this. ALWAYS and FOREVER.

[@DavidTJames-yq9dr]

@5:14 what an awesome sermon. I am loving these lectures. I am pissed that, in my far reaches of the world, this exposure and influence has been denied me via my class, cast, socio-econ, and generational & physical demographic. More knowledge. more brains. I am hungry to intuitively know more. I love Educaton X Generation :D Thank you Stanford and Prof+Team

[@ashkansnake]

NOTES: Systems have states A set of states can include subsets Inclusive (union) and exclusive (intersection) propositions can be made The space of the states of a system in QM doesn't follow the set logic It's a vector space An apparatus detects the status of Q-bit that like a coin (with H and T) could be in two states , 1 for pointing up or -1 for down, only one of them at any given time Both the apparatus and the Q-bit have a sense of direction of their own The directions of the apparatus and Q-bit in relation to one another, determines and changes the probability of the results Observing the system once prepares the result and will give you the same answer until the detector has been turned off and on again, If the internal vector of the apparatus lies in the same axis as the Q-bits we get the same answer over and over again, which is its component, meaning if we rotate the apparatus 180 deg, we get -1 in which the negative sign indicates the opposite direction Also even when we start with the apparatus on it's side (internal vector and Q-bit are in different axes) results are the same as long as the system is not disturbed. However 90 deg rotation of the apparatus around any axis makes the results random with probability of 50% for each, averaging at 0 Results of an angled apparatus are also random but they average in the component of the initial axis along the rotated internal vector (Cos of the angle apparatus makes with its initial axis) Mathematical vector space contains objects that aren't ordinary Vector space is a collection of mathematical objects In the vector space numbers are one dimensional and complex numbers are two dimensional Vector a is written as: |a> You can add vectors: |a>+|b>=|c> Vectors could be multiplied with complex numbers in the complex vector space: z|a> = |a'> Vector's components are represented in the form of columns in brackets Addition: n'th row of one column adds to the n'th of the other Multiplication: the number is multiplied with all of the rows in the column Complex conjugate vector that has a one to one correspondence with its elements Complex conjugate vectors lies in complex conjugate vector space Duel of a vector sum is the sum of their individual duels Duel of a vector |a> multiplied with a complex number z is ) = = α1. β1* + α2. β2* = = α1*. β1 + α2*. β2 Using postulate (1) must be true that: = * which means it's always real (its imaginary component is zero so the conjugate doesn't change it) and always positive (the real part is being multiplied by itself), resulting in the square of the vector's length (using Pythagorean theorem) T = * = α1.α1* + α2. α2* The orthogonality causes the inner product to be zero (because: cos 90 deg=0) Maximum number of mutually perpendicular non-zero vectors in a space determines the dimension of it

[@BennettAustin7]

good stuff, the ones I took are similar as well

[@AniSepherd972]

you are legend

[@NoActuallyGo-KCUF-Yourself]

I love that Lenny is so old-school that no matter how white the white board is, he still calls it a "blackboard."

[@wafikiri_]

The 'black' in blackboard does not mean the black colour any longer. A blackboard, whatever its colour, always is a blackboard. Or do you think an atz has to be made of stone just because, since millenia ago, atz means stone?

[@heath8358]

@@wafikiri_ That may be true but a white board is still called a white board and not a black board

[@abbyh5158]

He doesn't see color 😉

[@liberteen22]

its not a blackboard, it is a quantum object that your evolutionary structure cannot conceive, so you label it a blackboard, it is both a blackboard and a white board at the same time, it depends on the observer to determine which. 50% of people believe it to be a white board and 50% a blackboard. Although if it is rotated too exactly 45 degrees, the number suddenly spikes to 85% of people bellowing it is one of these but then returns to 50/50 outside that angle.

[@johnnyboy4ever]

Lenny? I thought his name was Mike... :)

[@tylerx8848]

I'm in college rightnow to learn about business, but I'm just doing this in order to become financially independent so that I may afford to learn about quantum physics, and get to solve our greatest mysteries and problems. Science is what I am truly fasinated about! I'm so exstatic to know that I live in an age where I can learn this information from the small technology in my hand. Thank you for posting this lecture!

[@amritkumarpatel5717]

Sir Leonard suskind wait for me for some years. I will definitely meet you in Stanford. I am currently at 7th. :)

[@tymekbraciszewski447]

Good luck!

[@ImUpsetThatYouStoleMyUsername]

So happy that person in the audience mentioned the collapsing of a wave function, because that was the moment all of this made sense to me

[@Akshaygupta13]

Thank you Stanford for this guy's lectures ❤️❤️❤️

[@jjarvis007]

the thing I love about these lectures is that he starts with the fundamental concepts, then illustrates how the theories differ, at that fundamental level. IMO, Feynmann didn't really do that...

[@arthurmee]

I agree ErnestYAlumni. I also enjoyProf. Susskind's dry humour like the bit where he says in answer to a question at about 54:50 "They might have got the Qbits from a Qbit store!" . . . humour helps the process of learning. ;-)

[@TmyLV]

Leonard Susskind is A living Legend, you know as students we call "legends" the great or greatest teachers...

[@schmetterling4477]

Well, he is 81 years of age now... so don't expect too much teaching from him. I take that back! Surprise... he is still teaching "PHYSICS 361: Cosmology and Extragalactic Astrophysics". Cool!

[@ajitharidas9496]

Thank you, Stanford and Susskind

[@capitanmission]

Thnks Stanford and Mr Susskind, his teaching is gold, i guess he learned a lot from mr Feynmann :P

[@agrajyadav2951]

One of the greatest men alive. Without a fringe of doubt!

[@THEGREATONE420]

this guy is a legend.

[@francescos7361]

Thanks so much prof. Susskind as a student and undegraduate in architecture I appreciate . Thanks.

[@EduJin100]

I read the book, Quantum Mechanics(The Theoretical Min). Your book was specular parts, matrix math.... Thank you... Republic of Korea

[@tpmbe]

Thank You, it is helping me to understand logic principles and abstract thought

[@sconeofark]

Both upper and lower case are valid depending on the frame of reference of the observer.

[@lindadee2053]

This lecture is great. The professor is obviously starting from baby steps to demonstrate the foundation of quantum mechanical statistics, but some of his students are either bored or want to show off their "advanced" knowledge. Actually, this is very similar, if not identical, to Dirac's experiment and treatise on a 45 degree polarizer sandwiched between two polarizers oriented at 90 degrees to each other. Very beautifully prepared lecture.

[@12388696]

Stanford's reputation is reproved by you!

[@albertodecaro]

What a beautiful series of lectures!! Actually I bought the book before discovering the lectures were on line on KZbin!! As a mathematician, my objective was to get in touch with the Quantum Mechanics and to have a higher level understanding of the underneath models. And I really loved Susskind's way to be so clear and consistent without turning into a 100% formal and axiomatic lecture. BTW, are you aware of any online discussion group or forum about those lectures?

[@aaronvan9999]

Right, I purchased it. I think it's the best calculus intro I've ever read.

[@arnauddion1204]

Thank you Pr. Susskind, Stanford ! As crazy French say: "Chapeau bas, M. Susskind" !!

[@mohamedalshamari9156]

stanford,thank you very much for this free knowledge

[@sconeofark]

I can visualize five dimensional space time.., but don't you Dare ask me what I was doing when I saw it.

[@brendawilliams8062]

✅

[@mohananandanavanam2654]

Every second of this lecture reminds me how important Feynman's learning technique is.

[@matusfrisik3887]

What cookies does he use to eat? I want them.

[@schokoladenjunge1]

Somebody asking the right questions.

[@MrGOTAMA420]

chocholate chip

[@nihadtp539]

Its actually scone. He told that in one of his previous lectures of Classical Mechanics

[@Ninjahat]

SUSSKIND = LEGEND!

[@schelsullivan]

Okay I'm halfway through the lecture and I want to raise my hand and asked a question, what a classical analogous system be as follows, imagine a coin flipping experiment in which any time the coin flipper was fasting in the East-West Direction he would get a random 50/50 coin toss. But if he was facing in the north Direction he might always get heads and if facing south always tails?

[@gaemer3967]

Bought the book and felt it was a bit too rushed, I wanted to expand more on the maths behind it so I went online to search for further explanations and turns out his lectures are all available on youtube! Thanks for providing these videos to the internet.

[@pradyumnak641]

Do you think the book adds any more value over these lecture? I'm contemplating buying the book but if it's just a transcript of these lectures, it may be a waste

[@NoWitnessesNoRegrets]

I don't know what he is saying sometimes, but I love his voice.

[@Abihef]

This explanation finally Made me understand what and how a sin/cos really is😂 It's been years since I graduated and always have been using them but I always used to get into arguments about what it really was with my teachers as they only kept saying its an division which never satisfied me into abstractly grasping the concept. This is way easier and better than math Well at least the part that never clicked in my head. Been using it for years but I never had an analogy for goniometrie like how I have a basic understanding of how to simplify and use other stuff. Everything made sense except for this til just now. Awesome Also always got into fights about dividing by zero and never truly understood math til I studied complex numbers in my final year. Schools should really start with this and complex numbers and build from there, at least these things make sense when you look at the world around you and when trying things and applying things to calculate, design and make things or theories and analogies. Anyway, would've saved me a lot of fights with teachers who would just state things instead of teach you what it is and how it works and give you concepts so you can apply it to everything in life.

[@valtih1978]

Finally, they started to treat vectors as functions. Functions are vectors because then can be added together and scaled. But, functions are also vectors of single variable. The argument is called "index" or "coordinate" in the vector space. Vector a=[a0,a1,a2] is a map a(0)=>a0, a(a)=>a1 and a(x)=>a_x in general. This is a function of single variable. Vectors are just discrete functions in the narrow view.

[@sudharsank5780]

That's a good explanation! Thanks!

[@sparks.speaks]

What a great professor. Literally feeling this rn. I detect that kid is a brat! I'll leave it at that. So grateful for these free lessons!

[@ZaphodBeeblebrox]

My last math class was about 20 years ago. Understood all of lecture one, now I boldly go to lecture two :D

[@ScreamingatWhispers]

To infinity and beyond 🎉

[@daniellanes813]

What a great fucking gift to humanity. Thank you Stanford and Mr. Susskind.

[@gasser5001]

these students....he spent so much time trying to get 2 simple ideas across to them...holy hell. this lecture couldve been 1/3 as long and i wouldve got just as much! sheesh! i cant get enough of these! (the lectures, not the students)

[@dangiscongrataway2365]

It's much easier to understand stuff behind a screen than irl at least for me

[@abhishekcherath2323]

way easier to get stuff when you can pause mate.

[@timqian3919]

1:35:12 inner product of the vector with itself is the square of its length. It is a Real number and positive

[@MrAlfred1995]

You know shit's getting serious when Paul Dirac comes back from beyond the grave to set things straight.

[@LaureanoLuna]

@ganeshie8 No. Once you get a value for some orientation of the apparatus, you will consistently get the same value while measuring the same system with the same orientation. You have just collapsed its wave function. Until a measurement has collapsed the wave function, the actual orientation of the system doesn't make much sense in QM. You just have the probabilities for each result for the different orientation angles (that's the wave function or the state vector). That's all there is to it.

[@harshadjeffthomlinson7305]

Hello friends- My daughter, in 2nd year of university, gave me The Theoretical Minimum for Christmas, as she knows I appreciate the thought experiments around physics, and can hang in there during a discussion. However, when reading this text, and watching these inspiring videos, I am lost. I can kinda follow, but feel there are some foundations I am missing (I am 62, and I believe I was stoned during an essential class in high school, double entendre). What do you suggest I study/watch/practice to get up to some semblance of understanding to continue this text and lecture? I am willing to put in some time.

[@helencardrick1048]

I was so spooked when the guy asked a question at 30:00

[@jorgepeterbarton]

was slightly patronising response given he gave away what heads come tails could represent half a minute later haha... Quantum spin States, or any other state really, that could be bound by uncertainty principle but he was introducing the abstract logic with a familiar concept

[@energysage9774]

Hey, sorry for the late reply. The reason you don't hear much about fractals in a class about quantum mechanics is because the quantization of matter prevents true fractals from existing. Approximate fractals appear on cosmological scales through microscopic scales, but eventually there's a fundamental limit, so for example a coastline is not actually infinite. A better place to look for fractal theory would be a course on complex variables or chaos theory, graphics design or fracture mechanics.

[@omarmaswadeh5434]

You are just a legend!

[@VinceMounts]

@Abdullah Naeem, The answer is no it doesn't take it out of the quantum world. Or rather, you are only out of the quantum world about that specific axis. If you know the spin around one axis you have maximal uncertainty (i.e. a 50-50 chance of either result) about its spin around an orthogonal axis. That's quantum mechanics. It should become more clear as the lectures go on and he covers more of the mathematics describing this weird situation.

[@ReadingRambo152]

This is what the internet is meant for

[@jayeshmahajan4891]

Thanks for great lecture 🙏

[@thatsamoreeel4505]

Thank you Leonard Susskind. You are a new hero if mine. I am reintroduced the awe that I felt studying physics in university. I absolutely love having these lectures available. Are there lecture notes available anywhere? I often listen while doing other things, and I'd like to be able to review the notation before moving in.

[@sparkymist8650]

I think he has a book he wrote with all the lecture summaries written in it :)

[@nickosborne5822]

Great teaching - thanks!

[@timqian3919]

Definition: What is the dimension of a vector space? The max number of orthogonal vectors you can find in the space 1:38:21

[@wordprocessbrian4497]

a flipped coin is a process that is in motion or not. It is on the edge when in motion and on either side when not. The universe is organized in sets of three gravity medium dimension sets with an observer in the middle. The set of three straddles a force set of four. Both form a process of 12 parts every three cycles. The minimum value of each, is a non event and can only exist within the other as an opposite value, in the opposite direction.

[@jodo6329]

"What does heads and tails have to do with it? What's the purpose of using heads or tails?" Interruptions of this nature make my blood boil.

[@archyology]

+Jo Do It's a continuation on the previous lecture series where they talked about it as an example for laws of Physics.

[@capitanmission]

+Jo Do hahaha people are actually answering your question.

[@ThePurestOnes]

Jo Do dude I don't get how someone that would ask such a question got into Stanford university

[@mistadopeyy]

Jo Do mr. perfection

[@abhishekcherath2323]

They aren't students of Stanford. Well, for the most part.

[@iExamineLife]

thanks!! you are the man!!

[@esorse]

Non-quantitative-number-numeral symbol hyphen, - , concatenated with quantiative-number-numeral one, 1, doesn't result in something from either category and therefore, is excluded from a vector : something with magnitude and direction, space by definition.

[@DerPeterIsh]

is this correct: ? when i measure the spin to be 1 at 0° and then measure the spin at 90° to be whatever and then measure again at 0° the probability to get a 1 at the third measurement is 50% ? this is using the same quark in all three measurements. BUT when i measure the spin to be 1 at 0° and then measure the spin at 1° to be whatever and then measure again at 0° the probability to get a 1 at the third measurement is very high ? this is using the same quark in all three measurements. thx!

[@michalchik]

I strongly agree with his assertion that the abstract intuitions and math are extremely powerful and important to develop. I disagree that that higher dimensional visualization (or lower) are impossible or useless. He is right that most people don't correctly visualize what two or 1 dimension are like though they think they are. The story of flat land is a good place to start.

[@chriscowman]

You've just made my day!! :)

[@edtronic]

This is such much fun!!

[@JASONQUANTUM1]

Let's imagine the grid structure of Planck pixels (plixels) and how they interact with vectors representing the changing states of hawking radiation over Planck time. We can explore how these vectors, characterized by the cosine of the angle (θ), relate to the speed of light and describe acceleration, which in turn corresponds to gravity. In QIH, the grid structure of plixels represents the fundamental fabric of spacetime at the Planck scale. Each plixel acts as a discrete unit, contributing to the overall information processing and entanglement within the holographic framework. Now, let's consider the vectors that represent the changing states of hawking radiation over Planck time. These vectors describe the properties of the emitted radiation, such as its energy, momentum, and direction. The cosine of the angle (θ) associated with these vectors represents the percentage of the speed of light contained within the hawking radiation. As the angle (θ) changes over successive moments, new hawking radiation is emitted, reflecting the evolving quantum state of the system. This changing angle and the subsequent emission of radiation correspond to acceleration within the QIH framework. Acceleration can be seen as a manifestation of the altering quantum states and entanglement patterns between the plixels and the emitted hawking radiation. In the context of the equivalence between acceleration and gravity, this changing angle and the resulting emission of hawking radiation can be understood as gravitational effects within the QIH framework. The modulation of quantum states and the interaction between the plixels and the emitted radiation encode the gravitational behavior, thereby linking acceleration, hawking radiation, and gravity. Through the lens of QIH, this perspective allows us to explore how the grid structure of plixels, the changing angles of hawking radiation, and their associated acceleration can provide insights into the interplay between quantum information, spacetime, and the gravitational phenomena. It offers a framework for understanding how gravity emerges from the quantum information processing occurring within the holographic structure of spacetime.

[@ucanihl]

How do we know that the outcome is random? Is it simply a way of saying that we couldn't find any pattern in it no matter how hard we tried or is there some way to prove that there can be no deterministic algorithm that could be generating the sequence of ups and downs?

[@jorgepeterbarton]

I don't think we can but we pick such an interpretation as we are at a limit of being able to observe further. If not random then a pseudo random state that is very perfect in its distribution. We can't really find a way into slicing a particle up to see what its thinking then its for all intents and purposes random. The interpretation is the non empirical philosophy, some metaphysics that allows us to proceed. Like Copenhagen interpretation, and most of them. Although others like bohmian mechanics speculated otherwise, it was other elements that sent it out of favour. We can say its non local as experimental data shows it is illogical to infer local causes. But asking about randomness is ontology, its not really a question that can be answered empirically, no less than asking if free will exists or if god controlled the randomness, its just what would seem to look random and we know we can't look further in detail due to limits of observation. So its a unfalsifiable and beyond asking a physicist the answer to that. It just gives random distributions from many repeated experiments and that is considered elementary state of things.

[@timqian3919]

1:03:51 quantum system space is vector space: a collection of vectors

[@lostinthoughts13]

When the apparatus is upside down, does the -1 mean that it's pointing opposite to the direction of the apparatus ? Which means it's pointing up.

[@rapbigze]

Downloading it all.

[@a5h1n8r]

Yes, the q-bit doesn't have to "reset" at a specific angle to come up with the same ratios... I feel like he keeps it that way because it will uphold the integrity of the experiments being "wiped clean" with every new q-bit.

[@kamrannasir3871]

this course on quantum mechanics is good but I found the previous series entitled "Modern Physics- Quantum Mechanics" more helpful, these are not bad though..

[@friendlystonepeople]

When you take the second deterctor, you have perturbed the system...so you will get the randomness again....

[@onlinekids7907]

May God bless you sir

[@bladehaze]

Say you have the experiment at 51:29, so you have a tilted detector at about 30 degree, then you have cos(30) probability of getting a 1, then you take another detector at about 60 degree and measure the same thing, you have the probability of cos(30)*cos(30) for the final result to be 1, this is different from take a detector with tilted degree of 60 degree, it is higher than that, is it true that you can tilt any vectors to any degree with probability 1?

[@DerPeterIsh]

or in other words: the degree by which i rotated the aparatus after a measurement defines the likelyhood to get the same measurement at the second measurement of the same quark? so at the third measurement, the outcome of the first measurement has no impact on the result whatsoever anymore? but the outcome of the second measurement has a decisive impact on the probability? this is soo cool!

[@orp0piru]

At 1:19:30 could the right side be written as Z*

[@badlydrawnturtle8484]

The student at 57:28 asked a question that I don't think Professor Susskind quite understood. To put the question another way, if we assumed the system could be any orientation, not just up or down, we would still get the same results because the detector is only capable of giving a binary answer: The binary nature of the system's states is assumed rather than demonstrated; so what's the justification for the assumption? Edit: At 59:52, another student asks the same question and he misunderstands it again. Sigh.

[@raulclinchpoop7864]

If a function is a vector of infinite dimension, can the components be thought of as the terms in a Fourier or Taylor series expansion of that function? If memory serves, the terms of a Fourier series are orthogonal in the sense that the product of any two of them, integrated over one period is zero.

[@valtih1978]

Have you seen the Susskind's lecture? Why you cannot visualize dimensions other than 3? Which tools have you developed to be not able to do that?

[@en3857]

If you have a set of "up" qubits prepared... and then turn the messauring device an angle for a random distribution based on the degree. It means you can DECIDE the outcome depending on the angle, if you turn it up you get more +1 and turn it down get more -1, right? And your choice determines the outcome. Makes you wonder if you can "alter" the reality outcome by how you meassure things. "positive thinking gives positive results" sort of speaking... ?

[@halilibrahimcetin9448]

I love the way Lenny explains the physical phenomena as if he explains to a man in the street.

[@jamesanthony5681]

Lenny? Do you know him?

[@halilibrahimcetin9448]

@@jamesanthony5681 I know him as much as you don't know me.

[@jamesanthony5681]

@@halilibrahimcetin9448 Because you called him by his first name I thought you knew him.

[@Nox.INkRecords]

Good stuff. Well played, KZbin.

[@dewaldo]

I can't get over how much this professor looks like Mike from Breaking Bad.

[@stephendavey4406]

I wish this lecture had existed when I was studying physics.

[@AniSepherd972]

same man,

[@shanchuanxing1929]

I didn't know lord Tywin was a Physics professor.

[@ameyajatinshah458]

He is like a fusion of tywin and mike from breaking bad

[@andrewcriscione]

I was thinking John Malkovich.

[@RogerWazup007]

It might be obvious that I'm not a physics student, but in the universe, are there any truly closed systems given the affect of things like gravity?

[@1WaySafe]

there seems to me to be a rotational direction bias in this first explanation. the orientation of the :Detector : is making an inference that is the case.

[@johnfraser8116]

One thing which confuses me is that the ket vector, |a>, is written before the bra vector, |a>, giving, "ketbra" and not, "braket". I'm guessing that in some other circumstance the bra actually comes first but for now the use of, "braket" feels backwards.

[@markszivs7114]

Guys, advice needed. I am slightly familiar with the topic, and i want to watch all of the LS lectures starting from quantum mechanics. Should i start with this one (theoretical minimum) or from 2008 Lecture 1 Quantum mechanics? Thanks

[@tomaszdzied]

+Marks Zivs Start with this one (if you're familiar with classical mechanics). The other ones are just older versions of the same thing - with worse audio and video.

[@timqian3919]

11:10 you can not visualize quantum machines, our neural network is trained only for the 3d world we experience. But we can try to use mathematics to describe quantum machines (for nano world

[@mmechrizma]

Zero = orthaginal? Orthaginality doesn't matter what order? I'll have to chew on that one. So would a 4th dimension mean 4 orthoginal vectors max?

[@Tetrodioxide]

Susskind's a hoot!

[@marcosimone4320]

Does anyone have the notes he talks about in these videos? I can't find them on the internet

[@jeffwilken7241]

Jesus, people - they aren’t Stanford students (nor even physics students, to boot). Prof. Susskind gave these lectures to members of the community who wanted to learn more about the subject. Same is true for just about all of his Stanford-sponsored lectures on YT, to my knowledge.

[@BosqueMagno]

why would Grandi's series give 1/2 but running this experiment give an average of 0? Is there in correlation between the manipulation of groupings in Grandi's series with the fact that the detector itself is also part of the quantum equation?

[@redsix5165]

From the course website: January 9, 2012 Professor Susskind opens the course by describing the non-intuitive nature of quantum mechanics. With the discovery of quantum mechanics, the fundamental laws of physics moved into a realm that defies human intuition or visualization. Quantum mechanics can only be understood deeply by studying the abstract mathematics that describe it. Professor Susskind then moves on to describe how the space of states for quantum mechanics, and the rules for updating those states, are fundamentally different from those of classical mechanics. For quantum mechanics, the space of states is a vector space versus a set of states for classical mechanics. He then then describes the basic mathematics of vector spaces. Topics: The non-intuitive logic of quantum mechanics Vector spaces Rules for updating states Quantum preparation and measurement are the same operation Mathematics of abstract vector spaces References Quantum mechanics Vector space

[@schmetterling4477]

You don't have to believe every bullshit they put out at Stanford. Quantum mechanics is actually quite easy to understand if you aren't falling into the usual traps. Unfortunately for you, the way Susskind teaches the topic, you will.

[@redsix5165]

@@schmetterling4477 who teaches it better? What are the usual traps?

[@schmetterling4477]

@@redsix5165 The usual traps are mistaking quanta for particles and the single system for the quantum mechanical ensemble. Not knowing that non-relativistic quantum mechanics is not a self-consistent theory. It's not even physical. Not having a background in atomic physics, not knowing enough (or anything at all) about special relativity. That kind of stuff. Some teach better than others. The best I have seen is Alan Adams from MIT, but even he misses the mark on many of these topics.

[@Typho0n86]

5:00 when to update? how do you mesure how long its been?