Lecture 2: Experimental Facts of Life

[@TheKingBeyondEverything]

It's so good we're living in this age where information is so easily accessible and MIT like Universities are enough generous to provide such valuable lessons for free .

[@beagle989]

we'd be a lot further along as a society if the internet was invented a thousand years ago

[@TheKingBeyondEverything]

@@beagle989 well, yeah😅.

[@kidkique]

Society doesnt value the knowledge, it only values the degree - which certainly is not availble for free

[@TheKingBeyondEverything]

@@kidkique Well, degree is able to give you instant/short-term benefits but knowledge is eternally beneficial.

[@andreaszweili8593]

Absolutely, instead of watching a stupid television show, I can relax to a physics lesson from the other side of the world.

[@mitocw]

Fair Use credit updated for the music, video quality upgraded to 1080p.

[@untwerf]

Nice! 1080p HYPE!!!

[@untwerf]

Nice! 1080p HYPE!!!

[@pob-4810]

I just want to really say thank you for the open lectures. I'm just really bored and learning about this is very fun

[@antoniolewis1016]

Whoo yah!

[@apburner1]

What was the resolution of the original recording? If you are claiming that you can increase resolution I am not sending my kid to MIT.

[@debadiptobiswas5611]

What I like about his teaching is that he not only teaches physics but also the history and the drama that revolves around it.

[@maxhagenauer24]

Why is the history and drama important?

[@austinbrown7183]

These are the facts, you're going to eat it and you're going to like it! I like a little bit of history, drama, and humor to lighten the load a bit. If I wanted a monotone boring guy I'd just read a textbook...

[@maxgeorge1463]

@@maxhagenauer24 its exceedingly difficult to focus on foreign, theoretical material for an hour and a half straight. Tossing in arbitrary historical facts lightens the mood and refocuses the mind.

[@A1.SoMoSa]

fr , bros kinda funny as well , i do computer science and maths , completely wrong field but his teaching makes thiis topic alot more interesting

[@ishaanghosh732]

@@maxhagenauer24it’s interesting

[@d.v.faller9251]

Wonderful lectures by Prof. Adams. Same topics as when I took 8.04, but delivered with such enthusiasm and with memorable analogies. I admire the way in which he defers using the actual names of certain quantum properties, calling them instead hardness, color, smooth and chunky. This gives the students a way to grasp the concepts, without even mentioning confusing terms such as quanta and spin. Greatly enjoyed his quick allusion to the original Star Trek and red shirts in Lecture 1. We all appreciate MIT's generosity and sense of public service in providing these lectures to the world. Years ago some of us paid tuition for them. Now everyone can appreciate the excellent teaching.

[@RobbyAndrews-j5k]

Is there someone that I can talk to. . This is bullshit... Really HEY, LITTLE BOYS AND GIRLS. I CAN DO A BETTER JOB . WILL YOU HELP ME HELP YOU. THIS GUY. YOU BETTER HAVE THAT ON MY DESK BY 8AM. NO KIDDING. IM JUST WONDERING IF THIS DIPSHIT COULD FIGURE OUT A 9X9 SQ BY 123 IN LESS THEN 7 MINUTES. YOU ARE BRING FKT.. JUST BE GLAD THAT IM NOT THERE. WE COULD LEARN SOME REAL PHYSICS. 😊

[@AAscension]

Could you explain me why this course is called 8.04?

[@JoeTomasone]

As someone whose school days are long behind him but who has a late passing interest in quantum mechanics, I'm not only grateful for this being online but so badly wish that I had attended MIT and had this gentleman as my professor. He is effortlessly going beyond the basics yet not losing me in the math - which heretofore has been a significant challenge in my self-study journey.

[@Feliz_BroDad]

Don’t place limits and caps on what you can do or achieve… not too late to go enroll in this mans class, awkward, maybe but impossible, no…

[@antikoerper256]

Thank God that the Internet exist and the fact that such knowledge is freely accessible through it.

[@aaronkonstantine2794]

💯

[@tayday424]

quantum mechanics, electromagnetism, classical mechanics: these lectures are intimidating if you go in expecting to understand the first time you watch. Its much more enjoyable to watch them several times, taking in more meaning with each viewing. Just as interesting as the best shows on netflix. Has more staying power than most good novels.

[@nicostadi]

He should have a hand held mic so he can drop it at the end of all lectures...

[@suvarnadhiraj]

absolutely :)

[@TheKingBeyondEverything]

Correct 😂

[@jonidwyer7174]

Mic drop

[@the3rdking747]

GHAYYY

[@davidloter5391]

I'd like this comment but it's already at 420.

[@DaytakTV]

Professor Adams is a phenomenal lecturer!

[@CaptainCalculus]

hear hear!! a brilliant lecturer

[@nimagaousmane2702]

What is he drinking? You guys un the u.s... such a mystery about this drink

[@katekane6697]

Yes. He is smart.

[@Peddayana]

Yet not comparable to Sir Walter Lewin

[@samuelallan7452]

sundar ram Levin was amazing. And I believe he got totally framed

[@mabdinur85]

I like how he dropped such an insight with respect to Bell's inequality not working in Quantum Mechanics and just say's "see you next Tuesday". That's like dropping the mic and walking off the set in a very funny stand up comedy routine ... you know you have to watch the next episode to be satisfied after that bombshell.

[@ciel1083]

Wonder what his lectures are gonna be like after they proved bell right last year.

[@sadakoprochichi]

This teacher is incredible! The enthusiasm is so contagious. I wish I could take this class :(

[@firstatheist]

you can; all the HW, assignments, notes, and lectures are online

[@Cipher71]

DUDE! THANK YOU! I had wondered at one point yesterday if they had the HW's, etc accessible online, but hadn't remembered to check on that. Thank you for reminding me. I'm studying physics at Georgia Tech, and they are TERRIBLE at teaching Quantum 1 and 2 here. I love professor Adams' lectures. He's so much better at both explaining everything *and* making it seem interesting. Plus, his recommendation for that book that approaches QM from a philosophical standpoint is exactly what I've been looking for. I wish we had professors like him here.

[@xipuli2264]

Which website particularly? I’m interested in quantum mechanics, I want to practice more so that I can understand those concepts more deeply. Thank you!

[@zagyex]

you just took it.

[@meowrkerd4rker_]

@clay miller: what book is it?

[@michaeldebellis4202]

This guy reminds me of Gilbert Strang, also from MIT, who has online recording of his lectures on Linear Algebra, another topic (like quantum mechanics) I never thought I would get but after the first lectures, Strang made so much sense compared to the other books and materials I tried to understand that I really understood it and to my surprise I stuck with the lectures to the end including doing homework problems from one of Strang’s books. We’ll see how long I make it in this one, this is harder than Linear Algebra, but after the intro lectures I already feel like I understand some of these concepts in a way that many pop science books and videos never achieved.

[@e4rohan]

That is one really passionate human being

[@meetghelani5222]

I'm an undergrad in my final year of my Bachelor of Science, i've almost completed my taste of the Quantum Mechanics i'm gonna get but i love how this guy teaches and will be here until the end!

[@jonchicoine]

I don’t remember my professors having anywhere near this level of enthusiasm… love this guy. (Once the math kicks in, in the next video, I’m in over my head)

[@brucelarsen6650]

I have the same reaction to the math. My Mother said it was because she was seriously frightened by a mechanical adding machine when she was pregnant with me, but I think THAT is some kind of "Quantum Leap".

[@alexolah805]

This dude is a awesome lecturer, I failed math twice in highschool but the way he explains things makes it so easy to grasp

[@KingOfTheDerp]

He's a super dope lecturer who goes at a great pace, explains nuisances very well, and is very entertaining to watch. Thanks for uploading these!

[@arizonacolour8793]

So you watch to be entertained or to learn??

[@KingOfTheDerp]

Both :D@@arizonacolour8793

[@citizen240]

nuances instead of nuisances?

[@stuartofblyth]

What Rutherford *actually* said (4:40) was "It was quite the most incredible event that has ever happened to me in my life. It was almost as incredible as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you". As a Kiwi living and working in England he would have had little interest in 10-pin bowling. He also said "All science is either physics or stamp collecting", with which I heartily concur. Two other favourites: "An alleged scientific discovery has no merit unless it can be explained to a barmaid", and "If your experiment needs statistics, you ought to have done a better experiment".

[@oliverandm]

Allan Adams encapsulates what a good teacher is! The enthusiasm, the ease of communication, the humor, and that fucking outfit! Love him!

[@frqgrenade]

38:54 the book is "Einstein in Berlin" by Thomas Levenson

[@ElectromecanicaIndustrial]

Thanks

[@rubyredfort2843]

Thanks

[@Constyish]

Incredible stuff! Thanks MIT for putting it online, thanks prof Adams for these great, passionate and so well put lectures!!

[@portlyoldman]

Exhausted but exhilarated by the entire lecture series so far. Wonderful series, fantastic lecturer wishing I was eighteen and could take the course!!

[@kosmos-sky]

На тайминге 49:42 играет песня 5’nizza "Солдат". Это - эпично! At 49:42 the 5’nizza song “Soldier” is playing. This is epic!

[@Supalayzee]

No ads, no nothing, just pure lesson, I haven't even studied these kinds of lessons yet but I somehow understand every single word that the lecturer says

[@sirmongoose]

Professor Gordon Freeman teaches me Quantum Physics. I always knew I needed this. Thank you MIT.

[@UnchainedEruption]

Lol He does look like Gordon Freeman. I can't unsee that now!

[@samuel77112]

Makes sense considering Gordon Freeman canonically graduated from MIT

[@EnchantedGardenGnome]

He's AWESOME!!!! Oh my God, I am so thankful for this existing. This is the best explanation of this subject I've found yet in a way that's easy to understand and SUPER engaging. Yay!!!

[@thedeadpoet_33]

I've never taken a QP class in my life but Im fascinated by this. Whats even more fascinating is that I can actually understand most of it. 👏 to this chaps enthusiasm - goes a lomg way. Saved some for larer viewing.

[@richard_ags]

I am not familiar with Quantum Mechanics as I am just learning that to be ready for the next era of Quantum Systems apps in our future. Even as a Software Developer I can understand all classes easily and not getting bored due to his enthusiasm and his teaching approach, enjoying and loving his own job. Thank you Prof. Adams. I won’t forget how I started into Quantum Mechanics field and how it changed my life migrating from coding classic apps to quantum apps/systems.

[@erwinmulders]

good luck you young guys, I wish I didn't make that many wrong choices when I was young, cause I always loved learning, I just didn't like schools, now I am older, I even was a teacher for a while before I got ill, that was the best time of my life, good to see you have such great teachers like this man, you are really lucky with this guy, he has passion in teaching, not every teacher has that ability, just drag yourself through cause it will pay of in the end, way to go folks and thank you for this video and all the others

[@postmangibbons]

The awesomeness of this lecture is greater than or equal to the sum of the awesomeness of all other lectures.

[@sanatanmeaning]

Sir Allen Adams can make really good students because of his wonderful *PERSONALITY* and *TEACHING* THANKS MIT OCW

[@zuesbenz]

yes i know, indian professors are assholes in general and many do not know the material clearly enough in their head to teach properly.

[@binxuwang4960]

Maybe he is a theorist but he has such a great great understanding of classical experiments and can expose the core core idea of it and discard the technical details as gossip news is so inspiring~ His lecture may be on par with Feynmann s

[@berkeleycodingacademy7015]

Love the way Professor Adams ends lectures with a flourish!

[@ArnabBose]

1:18:15 - didn't we establish in lecture 1 though that we assign two properties simultaneously to an electron.

[@ramko685]

professor Adam is dope at explaining and being enthusiastic

[@CAshishRaj]

27:28 I think varying intensity does not change the stopping potential , but varying frequency does this. Correct me if I'm wrong.

[@you2tooyou2too]

Yes. Since the speed is constant, the intensity is a function of the number of particles, the particle 'momentum' is a function of the frequency (energy density of each particle).

[@dixithanoop]

This is one hell of a lecture! Particularly, the Bell Inequality part. I still can't believe the real world is so different.

[@Dipayan21485]

Thank you sir for this amazing lecture and also thanks MIT for providing such amazing lectures for free

[@tehwubbles]

When the students laugh at 14:30, it really shows that those are people that truly want to be there. I'm just trying to imagine telling the same story in the same way to lowerclassmen undergrads at my university and the crickets I'd get

[@mr195lion1]

i didn't get it why is it funny?

[@Timpjsh]

Am I getting this right about 1:00:44: -This is explaining the famous phenomenon in the double slit experiment where adding an observer changes the result from one corresponding to wavelike behaviour to particle like behaviour? i.e. it is not the presence of an observer, that collapses the probability wave. It is an electromagnetic wave, of high enough frequency to be able to use for measurement/observation, that counteracts the interference pattern?

[@schmetterling4477]

There is no collapse of the wave function. That's just intellectual nonsense that is completely useless in physics.

[@shrodikan]

Thank you MIT and Professor Adams! This series has enriched my life and helped me understand phenomena I hadn't before.

[@matroxman11]

Beautiful explanations, prof Adams is excellent at breaking down complex topics and making them seem very simple and intuitive. I wish I had access to the problem sheets.

[@mikefullermikefuller4711]

A Higgs-boson particle goes into a church. The vicar says "We don't want your sort in here!" The Higgs-boson particle says "But you can't have mass without me!"

[@dangerouslydubiousdoubleda9821]

its the interaction with the higgs field that gives particles mass so sorry to ruin your joke:(

[@kdmdlo]

And as a follow-up, Mass is said by a Catholic Priest ... not Vicars (Vicars is more of an Anglican term). But that, in itself doesn't negatively impact the joke.

[@Zzz-ghostyyy]

Dangerously Dubious Double Davidson higgs boson is the outcome of the interaction with the Higgs field. Like any other fundamental particle

[@earendilthebright5402]

Seems a bit forced

[@Yetipfote]

badummtss

[@adi29raj]

How is this not a tv series ...I am getting hooked at the end of every episode

[@KasenB100]

49:38 music: Комбат - я солдат

[@klavesin]

Kassen Boyaubai Yup, by 5Nizza

[@adiletbeishenov5731]

пятница я солдат if being more accurate

[@Mlvcollege6682]

thanks

[@Spewwow]

50:22 didnt expect 5"nizza's "Ya soldat" to be played at the MIT lecture, what a treat

[@noahhysi8622]

Claps at the end of a lecture, amazing

[@tiberiusgracchus4222]

Great professor! I'm just as excited by how many people in the comments express enthusiasm for QM. I think it's dangerous that in our daily life we utilize technology derived from the concepts discovered by QM but so few people know anything about it and are not interested anyway. To many people our cell phones might as well be magic. We should all be curious about how the universe actually works at both large scales and the smallest scales and how that intersects with our daily lives.

[@michaelblankenau6598]

I agree . But most of these concepts are too difficult to understand for the vast majority of people . Especially when taking into consideration the mathematics that underpins all of it .

[@augustinasskirsgilas2603]

Anyone knows where to find Heisenberg's lecture from 1930, that was mentioned in the video?

[@kevinw.6342]

you probably found it already, but here you go www.nobelprize.org/nobel_prizes/physics/laureates/1932/heisenberg-lecture.html ;) if you just want to read the part hes talking about, page 297.

[@fn0rd-f5o]

what really fascinates me is how we've gotten so good at harnessing the power of the electron.

[@Tim-Kaa]

Fantastic course. I'm in accounting and I watched first 1 lectures in one go. Will be looking forward to download lectures, materials and actually watching through the whole course.

[@Occular_systems]

31:09 light is continuous from source to the observer. Light cannot exist in waveform without a single c Source of kenetic wave. Electromagnetic energy exist from beginning to observer at the same time. Frequency beam is the closest to accurately describing how light travels continuously with chunks and gaps. Light is a beam that can be rode on or Traveled faster than.

[@angry4rtichoke646]

I wish I could go to those office hours, this is awesome!

[@Kyle-sz2xq]

I'm in 8th grade, in high school physics, and even I understood this clearly. I am astonished how good of a teacher he is.

[@schmetterling4477]

Then you can surely tell me what a quantum is. ;-)

[@Kyle-sz2xq]

The smallest subatomic partical, non duplicable, and relative in energy.

[@schmetterling4477]

@@Kyle-sz2xq There are no particles. There are only people who aren't paying attention in school when the concept of a quantum is being explained to them. You need to stop guessing and learn the definitions. ;-)

[@Kyle-sz2xq]

OK, OK, you got me there, it is the middle of the school year. Studying for midterms are a thing. So, sorry for not learning the definitions to a point but more concepts. And also I have trigonometry, and other ap courses to study for. And maybe stop arguing with 13 year olds who are just trying to give a unseen complement to the professor. And hears one for you, what is the purpose of the ATP-binding cassette sub family B member 1, in cancer cells. Just something to chew on.

[@schmetterling4477]

@@Kyle-sz2xq I don't do biology. I only do physics. That's because it is something I actually know. Advice for your future self: don't try to be a smartass about things that you don't understand, yet. ;-) And no, you can't learn quantum theory from this professor, either. He is slightly better than some of the others, but he still makes the same fundamental mistakes when he is trying to explain it as everybody else. The status of QM 101 courses is almost equally abysmal all over this planet (I know because I looked at quite a few of them). You would have to visit some university at least a few parsecs away to see a really good class. ;-)

[@harrysharma1]

The way sir connected the first lecture to this is outstanding, The moment 55:01 I realised this

[@Stolen__spirit]

Sir was like proving Bell's inequality... And convence us that it's correct........ And when we are convenced to it.... He says it wrong 😶😶😶...... True legend 👏

[@R3SHABH7]

Yeah

[@vinaykushwaha5223]

Thanks MIT for this precious study material.

[@battlewing221]

This is not study material lol

[@masonroberts3461]

@@battlewing221 it is it’s information, you can study information end of.

[@satishkumar-fd5jm]

You know you are amazing when you can teach quantum physics to a pharmacy graduate like me. Great lecture.

[@coolman7663]

satish kumar bro I’m in grade 10 and he can teach to me. He really is amazing

[@manuelvazquezacosta9845]

I have a question regarding the last point about the Bell's Inequality. In the formula, the term N(H, not B) was actually established as meaningless in the first lesson: You can't say anything about the color of 'hard' electrons. So, something happened that we now can do an experiment with hard and not black (white) electrons.

[@paulmuindiwilliam2945]

Last time, he said see you on Thursday, its Sunday morning here. I'm rewatching these lectures from Kenya... Africa. This is what the internet was made for.

[@reizkianyesaya8727]

That closing statement literally gives me a goosebumps

[@liamdurkin7327]

This is the best teacher I’ve ever seen

Bell's Inequality!!! That was awesome

[@MC-br1gk]

I wonder if the stuff in quantum mechanics, the sort of building blocks of "everything", is sort of like the stem cells in the biological world, or vice versa?

[@Ryndae-l]

Marc Castro Well, stem cells are not building blocks in the same sense. They are cells that did not yet become a specific type of cells, but your body is not made of stem cells. It is made of differenciated (non stem) cells, with *maybe* a tiny reserve of stem. Matter is made of quantum stuff. All of it.

[@user-gw8ch8nw2d]

@refresh It's a pretty inaccurate analogy, but if it helps I guess...

[@aaroroka106]

Vo must be dependant on frequency and not on intensity .. Photocurrent is dependent on intensity.. Love the lecture btw...

[@stuartdearaujo6245]

Question: When describing Bell's Inequality, Professor Adams talked about an electron in two known states. (ie hardness and color). I thought in the previous lecture, we concluded that you couldn't know both the color and softness simultaneously. One of the characteristics must be in a state of superposition. Have I missed something?

[@rajshreegupta4416]

I have the same question

[@giantmiller1136]

What is the difference between 'the electron is not going through both slits' and 'having gone through the top and the bottom (superposition)' See 56:11

[@armida1976]

Thank you for uploading this great lecture. I am not a physicist, I am a biologist but the lecturers are so well explained that even I can understand it and be intrigued by it. I am just a bit confused with the duality of light and electrons that are actually quanta of energy or single electrons respectively but when they interact with each other they behave as a wave (or at least exhibit some wave like properties). For some reason this duality is presented as counter intuitive but to my mind , and I may be completely wrong, but to my mind what we call a classical wave is a distortion of matter, molecules and zooming in atoms moving in a specific way through space passing energy from one to another. The wave is a movement of matter so it has all the properties mentioned is not localized and it exhibits interference. However a wave needs a material to travel through (again I may be wrong that is what I remember from my physics class) So if wave is a movement or distortion of matter it doesn't have an existence as a photon for example has or as a water molecule, but the molecules for example of the water forming the wave on a pond are distinct molecules of water so in a way every wave can have that duality because the matter through which it moves is made of distinct molecules and atoms but when then move together they create the wave. Pretty much as a human cell is distinct and occupies a single spot in the human body but the multi cellular organism still acts as one distinct organism. Although that would mean that if gravitational waves exist and they distort space time that would mean that space time itself is made of chunks that are distinct but when they interfere with each other they create the space time, much like atoms create molecules and molecules create elements etc. I may have it wrong. I would appreciate any suggestions.

[@KK-fv5bs]

I would like to correct you over there. Waves, do not need a medium to travel. MECHANICAL Waves, do. Mechanical Waves appear as distortion of matter. Water waves are mechanical waves, in essence, that they have literal atoms or molecules executing an SHM motion so that the wave exists. However this is not the case with Light. Light, is an electromagnetic wave. It doesn't require a medium of matter. Now one may wonder what is, in fact, an Electromagnetic Wave? Well, I won't be restating Maxwell's Equations, but I will just say that it's the oscillating Electric Field and Magnetic Field at each point. At any point, the Magnitude and Direction of Electric and Magnetic Fields are such that plotting them against time, gives a sinusoidal wave on the graph, just like SHM of particles. So these "oscillating" electric and magnetic fields are analogous to oscillating water molecules in a water wave. So, if there is a wave travelling, it doesn't mean there needs to exist some particle or a chunk. Electrons, and in fact all matter have a wave property to them, which are called Matter Waves. As the professor explains too, the electron is not literally a wave, or a particle. it's in 'superposition' of both, in essence that it exhibits different kinds of properties in different phenomena. When you look at an atom, electrons behave like standing waves inside the atom, with a certain wavelength. When you look at electrons in a CRT, it displays particle phenomena. Visualising it is, almost impossible. It is the way it is, that is nature (as far as we have discovered).

[@michaelblankenau6598]

Good explanation .

[@scientific.Furqan]

MIT Physics Department is one of the best places in the world for research and education in physics.

[@ianzen]

I have a question about bell's inequality. During the first lecture he stated that with color and hardness boxes you can't simultaneously measure the color and hardness of an electron. But here with bell's inequality, the parameters each electron is satisfying is 2, isn't that contradictory to the conclusions of lecture one?

[@pablo_brianese]

I'm just guessing here, but I think you could make sense of it if N(A,B)≠N(B,A). We could declare that N(A,B) is the number of particles that had (for example) A=spin up in the x direction and B = spin up in the y direction where we measured their spin in the x direction first, and then we measured their spin in the y direction, and give a similar definition to N(B,A). I would love to be corrected if this is not the way to go about ir.

[@aniketsaha7455]

But Bells inequality does not hold in quantum realm...

[@qiangzhang8033]

Qiancheng Fu but you could always introduce time as a binary third parameter

[@medhasingh4428]

U can understand the statement once u have the knowledge of quantum operators.

[@harshulgupta4604]

Same problem 😂

[@alkistsironis4678]

This man has some powerful energy while teaching i watched some lectures by accident and even if its not my type of videos he kept me listening and i understood some of them pretty easily... Good job!! Teach our teachers how to teach us man ... PLEASE

[@scifactorial5802]

This is the part I don't understand: how can we talk about electrons having both spin up in the x axis and spin down in the y axis? Wont measuring one of the two make the other random like what he talked about in the first lesson?

[@aniketsaha7455]

That is why i guess the inequality does not hold

[@10-AMPM-01]

20:00 so that's the theory behind spectral analysis? Turn something into gas, energize it, and observe the frequencies?

[@schmetterling4477]

That's the experimental technique, yes. Has been since Wollaston and Frauenhofer in the early 19th century.

[@JohnVKaravitis]

If I am learning MIT-level Quantum Mechanics form KZbin, why do I have to pay ANY tuition at my podunk state college?

[@yourlordandsaviouryeesusbe2998]

To obtain a degree. No one knows that you've actually attained the required proficiency in the subject unless you appear for exams.

[@ahuramazda9442]

@MIT OpenCourseWare What if light is not a wave but a mechanical longitudinal pressure differential that travels thru a medium? (Like sound) When the longitudinal pressure differences go thru 2 slits, 2 pressure differences (fields) appear on the other side of the slit. On the other side they interfere with each other. Like sound can only be heard when it hits a interface (like your eardrum), light can only be observed if it hits an interface of a other medium. So, visible light is the transverse wave (the reaction of the longitudinal pressure difference hitting the surface of a other medium). The surface (interface) resonates. This mechanical movement of the surface can be observed and is what we call visible light. To really comprehend this theory you would have to comprehend anti-space (the opposite of space) The difference of sound and light is that: light travels thru anti-space and sound travels thru space. Space is inductive and anti-space is capacitive. Space couples thru “exo” outer space(magnetic). Anti-Space couples thru inner-space(dielectric, between the molecules). Where molecules are attracting because of equal spin direction (anti-space, like in a coil where you add spin direction because you wind the coil in the same direction) or repulsing because of opposite spin direction.

[@gerardomoscatelli8584]

I can't believe I wasted my time learning finance and not this !

[@hussainrazik1251]

I have always read about Bell’s Inequality.... this is the first time I understood it as it stands... thank you MIT and prof...

[@hasanxnv]

Amazing. Prof Allan makes it so much interesting. Thanks to both MIT and the professor

[@crazyfly5505]

@12:42 you said "fluctuating in and out of existence" . I would concede that there exists an "out of existence" but I believe that stating that something can go there and come back seems like an overreach. They become invisible, I'll buy that. They go to another dimension, another universe, something obstructs our view, they move through our barrier, there are 2 existing in the same space and time and one dies in our apparatus... Any of these, but we have to do better than "in and out of existence" .

[@helenslattery4356]

Hey; I am super new to physics and quantum. I have picked it all up pretty quickly, I love that it's the part that was always missing for me in classical physics taught in school. The beautiful degree of randomness is now explained so simply. In the last 6 months, I have bought and binge read range of books on physics, thermodynamics, statistical thermodynamics, information theory, graph theory, Bells to name a few, it's much more than my wallet is comfortable to admit. As it's all pretty self-taught on my part and has been more of a covid hobby than anything else. Does anyone have any great resources on the physics notation that could aid my learning process? It's my main weakness as I understand how and why to rearrange them, but yet the notation/symbols I am still pretty slow on. Thank you, Helen

[@you2tooyou2too]

Good adventures for you! It is to be expected, since most such symbols are randomly attributed, like H, C, & W. Also, many such symbols are context dependent, & ambiguous out of context.

[@rahulgupta021]

checkout courses on physics on NPTEL youtube channel.

[@rationalthinker9612]

If you actually want to know what's truly going on, check out Bohmian mechanics and pilot wave theory

[@thezhybercafe]

"See you on next tuesday". Talk about suspense. This is so much better than netflix.

[@balasujithpotineni8184]

50:32 just blew my mind.

[@seditt5146]

The fact he got a classroom to clap for double slit experiment blew my mind lol

[@BlueMacGyver]

Could not the wave/baseball example be modified by reducing the distance behind the barrier when using it for light? How do we know what the distance behind the second barrier should be when dealing with light? Like wise if you increase the distance behind the baseball example second barrier then, couldn't the baseballs wander like light does? I would just like to see a chart showing the distribution of baseballs, water waves, light and other energies as the distance behind the second barrier is changed. As you saw in the water wave example he says the waves are given enough distance to straighten out, so then why would we not expect to hear something about the distance behind the second barrier and it's affects on results, thus giving some correlation of patterns maybe between all double slit experiments?

[@bhabeshgoswami3897]

Great Professor Adams as always you have kept my mouth wide open.............

[@doll7186]

Fell asleep and woke up watching MIT… how did I get here…

[@RajPatel-di2qw]

thank you MIT

[@jurotn]

How does a claim come at 1:02:04 that gravitational waves must come in chunks? If a gravitational wave is (presumably) a high frequency wave with low energy (low amplitude) giving little energy to the electron, i.e. the electron increases a little the frequency and we would see the expected pattern. The gravitational wave did not come in chunk, but in a low amplitude continuous energy.

[@schmetterling4477]

A gravitational wave is a classical phenomenon. We don't know how gravity behaves at the quantum level but the general belief is that it should be quantized. That general belief might be wrong. It doesn't matter because there are no consequences in either case. ;-)

[@champalitieu]

everything in life seems related and meaningful, from law of attraction, twin flame, to everything, thanks OCW, looking forward to learn more

[@NergusFlame]

Everything you listed has no basis in reality.

[@seditt5146]

You're a good teacher dude don't forget that. You got a class to clap and cheer for the fucking double slit experiment. Never underestimate the full impact of that.

[@cyberbum4835]

BUT THE REAL SAD THING IS THAT THERE ARE ONLY 69351 VIEWS OF THIS VIDEO!!!!!

[@skipsassy1]

sex and gambling are the norm Sir. How do you think the internet is paid for? Not Jewish and Asians professors - though the former invented it at Stanford Cisco Systems founded in 1988.

[@benhongh]

We gotta pump those numbers up. Those are rookie numbers.

[@tj_h3005]

Now it's up to 375k!

[@flumpyhumpy]

Sadder is that 80 people disliked it.

[@timbeaton5045]

420,649 views• as of 10 May 2016. maybe these views are cumulatively going to give an interference pattern, even though they are all at different times?

[@boboshermusurmonov978]

Excuse me, isn't the last inequality at 1:18:11 the other way around?

[@ankushjain35]

Greate lecture. Thanks a lot! I have a question on Bell's inequality. Could someone please explain to me how could anyone get the number of electrons which are hard and black (as shown during 1:17:28 ) or the number of electrons which are hard and not black, etc? In the first lecture, it was shown that there is no such thing as an electron which is hard and black simultaneously. How was this experiment done to calculate the N(H,~B), N(B,~W), and N(H,~W)?

[@peersvensson9253]

He was playing a bit fast and loose at the end. The inequality actually is a statement about two electrons, so N(H,~B) should be interpreted as one electron is hard and the other one is not black. There is another subtlety though, which is that hardness, color and whimsyness would not actually lead to a violation of the inequality (which is why he started writing angles at the end). You have to be a bit more clever in how you pick which properties of the electron you want to work with.

[@honestabe_9207]

6:55 When your professor is lecturing about Quantum Physics, and decides to pick up his bottled drink only to: 1) not take a sip & 2) do a minimal amount of work by wasting energy walking around the table and set it a small distance away from where it originally was… 🤣

[@MrFryfish]

The final statement was stately as a conclusion! WOW!

[@albadarqamar7380]

Is there a mistake at 1:18:20 cuz the sign flipped

[@KyleDB150]

what year in ug physics is this aimed toward?

[@asa_1896]

Normally 4th but 3rd sometimes depending on the school or possible concentration

[@manassharma8781]

Kyle Brown thats actually funny bcz in my country its taught in final year of high school (class 12)

[@KyleDB150]

the photoelectric effect and basics of quantisation of light were in mine, are you sure your school went into the full quantum mechanics? what country was that in?

[@manassharma8781]

Kyle Brown actually i just this year finished high school and will be joining college. btw i am from India, what about you

[@KyleDB150]

new zealand, my school cared more about sport than anything but I did stuff a year ahead and did a first uni physics paper, but that went through all the classical physics topics and didnt go past the two slit experiment in quantum mechanics. I'm 4th year mechanical engineering atm which obviously doesnt cover qm or relativity

[@Dipayan21485]

Happy new year MIT

[@mitocw]

Happy New Year! 🥳

[@cyberbum4835]

The 6 people who didn't like this video have either miss-clicked or they are the kind of idiots which are the reason we have not yet explored and exploited the rest of the galaxy and inhabitable planets.

[@timewalker6654]

No, there could be other possible reasons like, they want something more,some confusion in their mind which the professor didn't try to touch.

[@ArnoldSommerfeld]

The lecturer is evidence of lowered academic standards. There is in fact more than one school of thought on physics and truth, but you would never know this from this lecturer. Yes, some think physics is just models with predictions (a somewhat Heisenbergish view), but others believe there is an underlying reality (a physical reality) that physics should in fact be capable of describing. And which view you hold, if you are a theoretician, can determine which questions you are inclined to investigate.

[@Blacattacsquadron]

I'm intrigued by your comment. Been a subscriber here for since 2008 and looking for dialogue with someone. Would you elaborate or give some insight on your view?

[@schmetterling4477]

Why are you telling us that you failed in high school science? We didn't ask and we don't need to know. ;-)

[@florianleis6793]

I liked the Band joke :) love from germany

[@life42theuniverse]

32:58 Rather than being strictly a straight line. Since the quanta of light are also quantized in energy. The graph would be a staircase of energy states?

[@QueenGlory13]

I believe that's the graph of the amount of energy in each quanta as you increase the frequency of the wave that contains that quanta, so it can be any amount (or it might be a staircase of each smallest possible increase in frequency haha). I'm not entirely sure about that though, so someone please correct me if I'm wrong