Lecture 1 | String Theory and M-Theory

Help us caption and translate this video on Amara.org: www.amara.org/en/v/BAtM/
(September 20, 2010) Leonard Susskind gives a lecture on the string theory and particle physics. He is a world renown theoretical physicist and uses graphs to help demonstrate the theories he is presenting.
String theory (with its close relative, M-theory) is the basis for the most ambitious theories of the physical world. It has profoundly influenced our understanding of gravity, cosmology, and particle physics. In this course we will develop the basic theoretical and mathematical ideas, including the string-theoretic origin of gravity, the theory of extra dimensions of space, the connection between strings and black holes, the "landscape" of string theory, and the holographic principle.
This course was originally presented in Stanford's Continuing Studies program.
Stanford University:
www.stanford.edu/
Stanford Continuing Studies Program:
csp.stanford.edu/
Stanford University Channel on KZbin:
/ stanford

[@shikharamar1647]

Father of string theory teaching string theory for free for all the world. Imagine if Einstein taught GR or Newton Classical mechanics, we are living in golden era.

[@slyy4096]

But, i'm not good at humans, but i see, he teaches something he wanted to understand but got old before that.

[@ezbo1883]

I watched 3 full lecture series on entirely different branches of science that i think even the actual Stanford students couldn't have attended to at the university :) The technology of ages has been here for a while and it's truly remarkable when institutions as significant as Stanford use it to share their value with the world, seemingly free of monetary shackles and deceit. I can't imagine a scientist just sharing their knowledge and findings globally and free of charge in the monetary society we live in, currently it's only institutions that would do it.

[@rbr1170]

Newton's personality and pride will probably not let him do that. Einstein will happily do this. However, Newton will probably release a cryptic diss track against Leibniz.

[@justbeconfidentbro1286]

He's hardly the father of string theory.

[@saskoilersfan]

Newton's law applied to hollow earth proves the sun is earth's heated core...

[@vecter]

This is surprisingly accessible for anyone with a basic understanding of calculus and introductory physics. Susskind is an expert expositor.

[@connorarmstrong9998]

At 1:11:00 he gets really proud of himself for discovering the connection between classical and relativistic energy of a particle that made me happy lol

[@TheTrocek]

And the brave student puts him a little down in just the same sentence ... with q like - there should be some c2 on the board ... :D that just might show what's more important to those guys - person vs knowledge at the moment :D

[@TheTrocek]

​@Isomorphic :) You almost got my point - didn't you ;)

[@danielli9304]

@@TheTrocek hhhhhhhhh

[@emersonrocky8724]

I know im asking randomly but does someone know of a tool to log back into an instagram account?? I somehow lost the password. I love any tips you can offer me

[@thaddeusabram5855]

@Emerson Rocky Instablaster =)

[@entropyman2]

I have had dreams of sitting in a University class room learning Astrophysics and Quantum Mechanics/String Theory from one of the Masters! Watching these videos are the next best thing possible for now. This is like a free education for us poor citizens that missed out on the chance to experience and be part of something bigger than oneself. Thanks for the video classes ... I love this stuff, ... it's in my blood!

[@bbsonjohn]

70 year old. Healthy, clear-minded. I wish I will be as him when I get old.

[@whirled_peas]

Can't believe people need to be told this but, stay the fuck away from weed, THC is proven to cause early onset dementia.

[@biblebot3947]

@@whirled_peas what?

[@kekuleonitro]

Indeed

[@jzeerod]

IF not when

[@fyr3st0rm65]

I dunno, he seems to be mixing up his P's and F's today. :P

[@PatrickEngSU]

Hilarious: there are loads of comments complaining about math or downplaying math in favor of conceptual and intuitive understanding. None of these people have ever taken a real quantum mechanics class where absolutely nothing works the way you'd expect it to and math is the only thing you have- or if you're like me, the only thing you'll ever have to interpret and understand the quantum world.

[@morganjo2002]

Alex Scholtes I agree and might add as an example of this syndrome that a lot of people think the probability thing is the outcome of something like a billiard ball table belonging to or manipulated by hidden beings - so-called substrate theories to explain away the fact that non-deterministic ( or seemingly random ) outcomes of an experiment is all there is , it's not like a bell curve of class marks or student birthdays that are a function of cause-and-effect of macroscopic objects including people and the latter , or some of them , don't understand that probability is all you get and there is no further consideration for a lot of quantum physics , the probability of an outcome such as where the photon is going to land on the screen before coffee break is all you get . . . I am not much of a mathematician but find it frustrating to try to explain this to the people around me .

[@jibran8410]

@@hawkeye2958 Hes not saying that , what hes trying to refer to is that if you dont know the mathematics hes using to Express the ideas you most likely will not understand anything. At such level observation becomes moot and mathematics is all we have to observe reality and extend it to something beyond what we can imagine

[@TheCorrectionist1984]

So true. Quantum mechanics is almost pointless to try and understand without playing with the equations. And that's why it's so abused by the Deepak Chopras of the world.

[@barrykendrick3146]

+@@TheCorrectionist1984 Einstein did believe that eventually a meaningful model would be found.

[@xvxvvv8924]

@@morganjo2002 I need your help.

[@Talleyhoooo]

Wow, Susskind is such a great lecturer, I'm surprised I was even able to follow! He's excellent at explaining the material.

[@gilian2587]

He's a fantastic writer, as well. Some physics authors try to impress you with their brilliance by making their books as formal, and obscurantist as possible. Texts written by authors like this are nearly worthless to teach yourself a subject with. Susskind's books are different; he wins you over with humor and suggests not to perceive the equations like mystifying cuneiform; but just as simple notation that anyone can learn and understand who cares enough to do so.

[@gilles466]

*SUSS*

[@jn3750]

He's one of the main guys inventing this theory!

[@SpaceMilk07]

I am glad they have these free lectures on youtube, was very informing.

[@kathyyoung1774]

Space Milk No kidding. I think nearly everything I learned in college is now available on KZbin. Awesome.

[@BradWatsonMiami]

Superstring theory: 6 dimensions hyperspace + 4 common dimensions = 10 dimensions spacetime or Supergravity theory & M-theory: 7D hs + 4D = 11D st Unified Strings 21 or 19 Dimensions & Aspects of Spacetime - Physics’ Theory of Everything: Superstring & M-theory + time analysis providing a very simple symmetry breaking 3 dimensions regular space + 7 dimensions hyperspace + 7 aspects regular time + 4 aspects hypertime = 21 dimensions & aspects of spacetime or 3D rs + 6D hs + 6A rt + 4A ht = 19D&A st (engineerable, e.g. Planet Nestor) 12 Dimensional Aspects of Time Eternal (DATE): 6 or 7 aspects of regular time: beginning, end, past, present, future, void?, a constant - speed-of-light 4 aspects of hypertime: fast-forward, reverse, pause/stop, before beginning & after end of Universe 12. imaginary time. Unified Strings 21 or 19 falls under the umbrella of GOD=7_4 or FOD=6_4 (on Planet Nestor); FIG=6|7 Bible & Buddha Code - Design Worlds Theory - The BIG TOE! See GOD704.fandom.com . These are Seals #2 & 3 of the "7 Seals" revealed as 'Beyond Einstein Theories'; see 7seals.blogspot.com . This has triggered The Apocalypse/ Revelation which is NOT the 'end of the world' - it's the return of the Christ/Albert Einstein reincarnated.

[@nuttshellman]

@@kathyyoung1774 y666676y77766yt7yy6yy7677y766766766y667yy6t6766y7y7y67yy666y66yy66y6y6yy6yyyyy667yy6yy6y6y76y6yy6y66yyyyyyyyyy6yyyyyyyyyyyyy6yyyyyy6yy66yyyyy

[@nuttshellman]

XOXO zzuuuuzxxzxzuu

[@nuttshellman]

Zzy

[@joabrosenberg2961]

Universal Regge slope; Meson-Meson scattering 11:00; World sheets 31:30; Relativity and strings 35:30; Light cone frame 43:00; Physics of strings 1:00:00; String tension 1:20:00; Fluxoid 1:33:00

[@thisistoomucheffort]

MVP

[@petergreen5337]

❤thank you

[@keaqan]

Power move: study using youtube first, then go to college and make an A because you already took the class

[@fernandovalner]

i think the inverse works better

[@keaqan]

Fernando Valner imagine how much easier you calculus class would be if u already knew calculus

[@AbirInsights]

@@Brad-qw1te I hope you were joking, nothing can replace college

[@ParanormalInception]

@@fernandovalner how so lol. if he fail;s its a waste of money.

[@ionuttoma3782]

Fimeri

[@Aman-tf8bt]

He is such a patient person ,he is calm and cheerful to teach with same patience and enthusiasm whether it's classical mechanics or string theory . Thanks a lot sir for your valuable lectures which will surely motivate more of us to physics and understand nature. I don't have words to describe your remarkable role as a very good physics teacher☺️☺️

[@12magicKid12]

It's incredible that such an intellectual powerhouse is contained in such a seemingly approachable person.

[@LovingLightFromCeci]

Thank you to all of you dear folks at Stanford University who have made these lovely lectures available to us all! Wonderful! Expressing thoughts on our collectively perceived reality in mathematical language offers all of us a fresh way of experiencing & enjoying life. Thank you so very much. I will enjoy this entire series! Bright blessings & warmest regards...Ceci

[@brownah]

This nigga been putting me to sleep on restless nights for a decade now. Thank you.

[@bradhayes8294]

I'm not sure why it was necessary to use the "n" word here?

[@panagiotiskotsaris1627]

its 3am and im watching a lecture on string theory

[@ultrahapoel99]

trust me you are not the only one and not the last who done that.

[@Mr.Nichan]

It's 4:00 am and I'm watching a lecture on string theory.

[@callumalexander6409]

same

[@yasserbibi8095]

me rn

[@zheqingzhang6136]

good luck with tomorrow final

[@NothingMaster]

Let's just hope those students realize how incredibly privileged & lucky they are to have Leonard Susskind--not just one of the pioneers of String Theory, but also one of the most gifted Physics expositors/professors of all time--treating them to this exquisitely brilliant retrospective on the subject. It's truly amazing to bear witness to Susskind's natural ability to take a tough/nontrivial subject like String Theory & tenderize it to the point that even a physics infant can easily digest it!

[@californiacajun4535]

Bruh r u mad whipped o something darn bro take it easy

[@vishwaskulkarni9211]

They are not privileged they have earned it

[@neonblack211]

Agreed

[@ImranKhan-ls4fe]

I am from Pakistan. I belong to a village remotely located and cut from alot of things happening in the world. I graduated from a college in a little town beside. In this college Experiments are never even thought of and theories that are taught are only famous ones likes of Newton's and Einstine but Student just dont know about the string theory, Parallel universes and other amazing works in Physics nowadays. I learned alot from Susskind, Michio Kaku, Hawking and other professors. Thanks to all

[@thelichking1242]

Leonard Susskind is a genius pure and simple and an amazing man to work with too I may like to add

[@07gingerkid]

Leonard Susskind you are a true genius and you are a great lecturer as well. Thanks for your work!

[@anthony64924]

This makes me want to go to college, I don’t have a clue what is going on but would love to learn with someone as passionate as this man!

[@davidcase1762]

I am so grateful to receive these marvellous lectures - thank you

[@ArchYeomans]

Professor Leonard is a treasure.

[@andreizimin443]

So you knew all the time. Thanks for letting me find it out on my own! I'm truly grateful.

[@yusufsalem809]

Lol this started playing in the background while I was transitioning into sleep with headphones in my ears...i had no idea what was going on but every time Susskind would start asking ‘so what is so and so...’ followed by some mathematical jargon my mind translated that to me sitting in a green open field with two students sitting also but far apart and i felt immense pressure to answer his questions...one of the most helpless experiences I’ve ever felt 😂😂😂😂😂

[@garymcallister4228]

1/2 million views for a lecture on String theory!

[@nmarbletoe8210]

+Gary McAllister Everyone who likes youtube cats by extension likes string :?>

[@25aces]

It gives me hope in society.

[@tommasotiberi5666]

+Gary McAllister Apart from this particular lecture being about String theory, i'm quite happy to know that so many people are interested in "fundamental" physics!

[@Fransamsterdam]

How many of them would have noticed that it's about string theory if that was not mentioned in the title?

[@tommasotiberi5666]

well, that's a hard question lol does susskind in this video actually say that? i'd need to check i don't remember

[@KevinECahill]

Leonard Susskind is one of the greatest physicists of our time. Also one of the best lecturers and writers.

[@crazygenx2539]

Love this. Great physicists look for meaning in the terms of equations, and this guy does that.

[@aqwiz]

Thus, the information contained in these lectures is an eye-opener if you truly understand any of it to begin with, and opens new avenues of thought to pursue.

[@santeri-leinonen]

I just love the fact that I can learn about String and M-Theory from top professors online while still going to a perfectly normal high-school in Finland. Well there are bits of the maths that I don't fully grasp, but that might be due the fact that it's 3am... Hope to gain more motivation to study the basic physics even better to one day gain this level of understanding in particle physics. And hope this will boost the enjoyment of my possible upcoming field trip to CERN next spring!

[@mandiraghosh7227]

Have u been to CERN?

[@wojak6793]

@@mandiraghosh7227 Not Swiss but I’ve been to Fermilab many times (my high school was actually founded by a Fermilab director so we have tons of connections with them) but I’d like to have a trip to CERN lol

[@Evan2718281828]

1:15:00 the value of dX in dX/d_sigma is the length of the string stretched out uniformly because it's at rest when it's stretched out, as opposed to vibrating with energy.

[@Yasinaktimur]

Thank you stanford. Nobody can talk about string theory with math on internet, only this source is findable also its best resource too. Also thanks to teacher for clean explanation.

[@RickIsShalom]

Many years ago I bought a set of Feynman lectures, which made no sense to me -- I have a neuroscience / psych background. Now the lectures came to life, and the diagrams have meaning. This is wonderful lecture, even if much of it is beyond my capability. Thanks to Stanford for being so generous with resources.

[@JamesEIvoryIII]

👍 Those “many years ago”, below the threshold of your conscious awareness, there was some information sorting taking place. Now affording you a better sense of correlating these complex and nuanced concepts together with what I think can be partly attributed to neuroplasticity. The mind, I don't have to tell you, is as amazing as it is mysterious. 💡

[@alberteinstein3078]

Mike before breaking bad lol

[@sammarks9146]

Turns out both he and Walter were science teachers!

[@marcux83]

I'm the one who teaches!

[@eliash.6142]

Looks more like john malkovich tbh.

[@davidrich27]

Fring Theory is the next lecture.

[@truncatecar3429]

I don't think Mike was Jewish.

[@bobcrunch]

This guy is fantastic. His lectures on general relativity are superb. He can take the most complex science and math and make it understandable, even to n00bs, and yet are of substantial benefit to those with advanced mathematical knowledge. I can now read all the Wikipedia articles on general relativity and understand them pretty well.

[@dr.ambiguous4913]

Some of this is surprisingly more intuitive than i thought it would be.

[@jotagalvan]

I LOVE STANFORD.

[@GulGeeOfficial]

I was sleeping while listening songs and after I awake KZbin is playing this theory on my phone😂 wtf

[@AlessioQ]

I really love those kind of lecture on KZbin!!!! This was really instructive

[@MrGiuse72]

I watched it today and it was marvelous ! THANK YOU MIT THANK YOU PROF. SUSSKIND

[@crazygenx2539]

I did my undergraduate where Susskind got his Ph.D. I'm having geek flashbacks.

[@mexicanwootwoot]

Where is that?

[@sagniksarkar1503]

@@mexicanwootwoot Cornell University .

[@KoLecnac]

I love these! Could we get a prerequisites list, please? I'm pausing every few seconds to look up mesons, gluons, pions, etc.

[@mastershooter64]

prerequisites for string theory is GR and QFT

[@yteicosf1103]

now plz don't tell us that you have to look up GR and QFT.

[@davidpalmer9802]

Prerequisites include intro to physics

[@lukamtc9188]

this is the 2nd guy at Stanford blessing me with knowledge way out of my league

[@FullMoongrn]

well said. This touches me too, cause many people didn't have the chance to get education do to different reasons. When we watch this, the only thing that cames to my mind is wishing going back in time and have the opportunity to go to school again.

[@hoogmonster]

I think this lecture has really helped me... I can now tie my shoelaces.

[@andrea.dibiagio]

This is priceless. Keep posting courses!

[@oudezhong9820]

it really is something to learn string theory from someone who helped coming up with it... there's nothing like it thx for the vid

[@smilinjack11]

For those interested in Dr Susskind's lectures, I found it easier to go to the list at the end of the Wikipedia article on Dr. Susskind. You will get a better sense of the whole series. These lectures were open to inerested non-students and the "class" included many older people. I would advise those interested to look at the listing I mentioned and go thru them in order, starting with Susskind's lecture on "Classical Mechanics" Ain't the internets great??

[@ayanluthor6203]

9 years but still helping, thanks mate :) hope u r doing well

[@Shingjanjie]

It's like I've been accepted :')

[@dariamashanova3739]

+Grace 夢幻專家 Same

[@legendarylightyagamiimmanu1821]

Did you get accepted ? By who or for what?

[@ols47]

@@legendarylightyagamiimmanu1821 to stanford

[@atallguynh]

Yeah, and then kicked out in short order when I couldn't keep up. 😉

[@jaxonfreeze7882]

aTallGuyNH, Hey me too!

[@sasukesuite1]

This really helps a lot with my DP Extended Essay topic. Very informative.

[@SaurabhSaket61234]

I slept halfway during the lecture. In dream the same professor was teaching me same topic with Bill Gates overlooking from other bench. Freaky and yet it was the best lecture I ever had and I now understand a bit of string theory. Thank you professor.

[@gbiota1]

I'm not trying to sound greedy, but the chances are good this video and others like it will wind up educating a lot more people than the 80 or so that might be in a given class room. I think that it could go even further if Susskind or a graduate student at Stanford would append a few questions to the end of each lecture to make sure the core ideas were absorbed. I have my own calculus books, I have my own mechanics books, but the chances are even if I had my own string theory book, it wouldn't contain any questions.

80 ? christ how big is your classes ?

[@afx935]

My Modern Physics class was 110. Largest was a history class with 150.

[@34_atharvamujumale57]

gbiota1 I

[@gilian2587]

I had a quantum mechanics class with 2 students (myself included). Not private education... just a *VERY* small physics department.

[@carloscastanheiro2933]

This is so cool. Im getting lessons from Stanford all the way in Portugal, gotta love technology lol. Wish I won a scholarship to study in the USA.

[@buckryan1173]

Oi, Bom Dia! (I'm learning to speak Portuguese, as a second language)

[@carloscastanheiro2933]

Cool, it's hard though, especially all the verbs, it's like French.

[@caiduncan7633]

Great lecture.. Leonard Susskind is really one of the greatest minds in this generation.

[@ZoeTheCat]

In general, you will need some Group Theory, Lie Algebra, differential Geometry (Tensors & vector bundle concepts), K-Theory, Algebraic Topology & Non-commutative geometries, gauge theories, ads/CFT correspondence and much more. It is a daunting journey. While tackling these topics, you may find that you need further sub-tools. I'd recommend mastering SR, GR, QED, QCD, Standard Model. These topics which are well documented give further intuitions.

[@Constantinesis]

Mathematics are so interesting when you don`t need to actually memorize 100 formulas each semester

[@SickMetalAddict]

Constantin Eugen Cozma This is the problem with schools. When you actually become a physicist, you could literally put all of the formulas as a cheat sheet, and just be able to know which one to use in which situation, then use it. Eventually as you use it often, you memorize the ones that are the most commonly used, but there is nothing wrong with not memorizing them.

[@mariorpg11]

SickMetalAddict Fortunately schools (at least in Germany) are changing more towards not memorizing formulas. We got a collection of formulas to use in our tests.

[@razzmaster02]

SickMetalAddict People don't realize that solving problems gets easier when you don't concentrate on memorizing formulas and plugging in numbers, because often times the difficulty of the problem increases drastically as well...you have to have a full grasp of all the formulas and methods you use in the process of solving a problem, and for the most part if this is accomplished you will have very nearly memorized the equation, or know how to reproduce it. Especially in intro level physics classes. In higher level classes, most upper level teachers (at least at the undergraduate level) allow cheat sheets, but of course this is the least of your problems in an advanced electrodynamics course...

[@benwaful]

Constantin Eugen Cozma the thing is that once you start understanding physics you realize that all these equations can be derived from a handful. And with experience, more and more of those derivations become standard and straightforward. From now on, it is better for schools to forbid cheat sheets as most of those "100 formulas" can be found back easily. Example: trigonometry: just by drawing a circle and using exp(i a)=cos(a)+i sin(a), you can derive all the trigonometric equations most students in school will ever need. The whole point of forcinng students to "memorize" those "formulas", is to challenge them into realising that there is always another way in math/physics. Math/Phys is not history or geography people!

[@hawkeye2958]

You don't have to memorize formulas to be good at it. But that ability does help.

[@salvadorfawkes4141]

Does that mean E^2=potential energy x c^4 ?

[@Oners82]

A free university level course on String Theory and some people genuinely give it the thumbs down?! Idiots, this is great stuff!

[@TheLycanStrain]

I love Leonard Susskind. The Cosmic Landscape was a very interesting book. I really did like his explanation of the Holographic Principle (using the Library of Alexandria if I remember correctly). I think that by using things we can imagine in our mind, he can better explain it to non-technical types. "The information content in a given box is equal to the amount of information that can fit on the box's walls." That just blows my mind. A new way to look at the Universe.

[@Moronvideos1940]

I downloaded this Thank you professor Leonard ......

[@buckeyeguy81able]

Thank you for posting this. I never went to school and I regret it. So I soak up as much as possible

[@FidelAngelOrozco]

I have enjoyed the class. My congratulations to Stanford University for this good idea and to mr L Susskind for this string theory point of view. I will look for further Susskind's videos. §tring Theory is a fascinating subject. Thanks a lot.

[@garywpearson1955]

A great public service! Thank you professor (and CalTech) for making these lectures readily available to the public. (There's only so far the Brian Green type explanation, in which none of the actual background on String Theory is presented, will get you.)

[@jefferytoledo2505]

It's Stanford, not Caltech :p

[@garywpearson1955]

Hah! Of course, I knew that. ;-)

[@jefferytoledo2505]

@@garywpearson1955 If so, 10/10 for the subtle troll :p

[@garywpearson1955]

What do billy goats taste like, anyway? :-D

[@GoldSlidePark]

Does anyone else use videos like these to fall asleep?

[@osemudiame123]

yeah occasionally. get educated and get a good night sleep while having math related dreams.

[@nexuspcsolution6242]

yes a fool like you do such things who can use technology but doesnt have the talent to understand where all the science that we use today as technology comes from

[@Ari-jm6xx]

Yes! Oddly relaxing.

[@sjorsheefer7327]

Haha I thought I was the only one!

[@nerdio1]

every night

[@fulmarmusic1413]

I feel like a dog listening to classical music. I like it when "But, then something amazing!".

[@itsiwhatitsi]

It seems he understand so good things that for him is all so simple.. all the symbols and formulas are natural and clear like water

[@GamerTheTurtle]

this whole lecture is one huge humble brag

[@joaopedroaguiarformigamato3557]

Im struggling on mechanics and studying string theory 1010 would recommend

[@Rob3P]

Is there another series of String Theory lectures done with white chalk on a blackboard?

[@rodrigosalasolivares9921]

ted talk, much simpler btw

[@Reav3rz]

Thank you so much for uploading all of those :D Very imfomative , and Leonard kicks ass as always.

[@AngeBleudeLou]

Wow. After googling quite a few basic terms of what he was talking about, (I never took a college level physics course) I am hooked. I wish now that I had, but thanks to poster, and Google, I find that it wasn't necessary. I'm looking forward to the next videos! Thank you for opting!

[@thegrandmuftiofwakanda]

I love the internet.

[@JackCodeKid]

Instead of college

[@stilekropfilms6610]

billiepipersteeth I love your name

[@thegrandmuftiofwakanda]

Nhật Tuấn I went to college, but in terms of the raw theory I don't see the point anymore. The texts and other information are widely available, and free.

[@jaxonfreeze7882]

Same, you can find anything

[@Dorkus89Malorkus]

Hell yeah I'm transferring to Stanford this summer, see you soon Leo!

[@ohillnam4714]

Hey how is your life after 9 years? Have you got married to your girlfriend or got separated! And what is changed in your life after those 9 years... Please answer???

[@tim57243]

I correctly recognized Susskind from the back of his head in the thumbnail. I really like these lectures he publishes.

[@notsonap5981]

@ 02:56 the linear progression of the mass of the particles makes it seem as if the progression of particles are Octaves of the preceding particle created by the addition of a radian of angular momentum which would "Square the mass".

[@roommyneri5390]

Thankyou, this really helped my insomnia

[@arunavachakraborty4565]

🤣🤣🤣🤣🤣so funny I love you

[@griffinfitzpatrick]

12:35 he’s saying Pi-mesons, is it the same Hadron as Pions?

[@marcusrosales3344]

Yes, a Hadron is just a baryon or a meson. These are defined by their quark content: 3 or 2, respectively.

[@griffinfitzpatrick]

Marcus Rosales thank you sir

[@SonLe-mk4sq]

Finally.. FINALLY! The best ASMR video on KZbin!

[@insanidadeEspelhada]

Thank you for this lecture !

[@GregBernhardt]

This is the beginning of a series that gives an introduction to perturbative quantum field theory (pQFT) on Lorentzian spacetime backgrounds in its rigorous formulation as locally covariant perturbative algebraic quantum field theory. Reference www.physicsforums.com/insights/paqft-idea-references/

[@mohammadwasilliterate8037]

Do you even earn money in the real world or only at a university lecturing to people that need safe spaces?

[@ronjose51]

This is amazing. I wish I had a greater knowledge of this.

[@homerco213]

Does angular momentum imply literal spin of the particle; or merely an abstract quality that, "spin," is simply a term for?

[@jayceonetrick3101]

bro, i am up until 4;00 just to watch these lectures, i am 9 and i understand everything dude.... My brother teaches me everything before I even hear this lecture

[@WBradJazz]

I love Susskind

[@estamos_aqui_para_aprender]

So, marry him

[@meddelhed]

Cool Story, bro. I'm 3 and I've coded parts of the Battlefield 3-engine.

[@elisabethcuriel]

This is wonderful. Sir, I am your biggest fan. Thank you for the videos.

[@jameswestlake3525]

i find it hard to work in dimensions, your clear explanation is amazing.

[@harshprajapati9251]

Me: listening songs KZbin : here a lecture on string theory :x

[@phpART]

Mike?

[@CesarioRandazzo]

λ = 0 is the equation of the quantum deformation of the quantum particles and the conformal field strings. Correct?

[@nmarbletoe8210]

1. energy of string proportional to length; as you stretch, new 'string' field gets added. 2. what else acts like that? dark energy. 3. is our U inside a higher D string that is being stretched?

[@scienceforalll]

can anyone recommend a good string theory books

[@izaaktehdinosaur7043]

Joseph Polchinski has done a couple of good books on String Theory

[@nishit7147]

The Elegant Universe by Brian Greene.

[@redrocket1770]

Try working out Zwiebach's Basic concepts of String Theory, which is a good introductory book to read and lays down a strong foundation. Afterwards you can go on to read Polchinski/Green Schwarz Witten/Peter West/ Becker Becker Schwarz/ Blumenhagen Lust Thiesen/Kiritsis and many other books which are at a more technical level.

[@sananapee]

I wish I was smart enough to understand this. It's so intriguing!

[@craigfowler7098]

His ability to instantly answer complex questions by keen students at his age is breathtaking. Clearly a world leading expert whom developed this theory.

[@lotharschramm5000]

He’s 70, not 100.

[@brainstormingsharing1309]

Absolutely well done and definitely keep it up!!! 👍👍👍👍👍

[@sarcasticstartrek7719]

He's like the physics version of Mike Ermantraut.

[@rusurveillancetaskforce]

Have an updoot for this genius comment, fellow redditor!!!

[@79898325]

Leave Leonard alone

[@sarcasticstartrek7719]

@@79898325 It was a compliment.

[@corysteiner7353]

THANK YOU i’ve been thinking this for so long

[@BlueHawkPictures17]

there are two kinds of people: people who watch this, and people who watch the tv documentary

[@JadenZeCreator]

True. Yay to us.

[@ChuyReynosoHaro]

+BlueHawkPictures I watched both, am I in a third category? or in another dimension? xD

[@abhishekrengarajan1849]

String theory tells us there are >10^300

[@Yizak]

Juan \ I see what you did there, because relativistic energy was described in two dimensions :)

[@jamesmurray4030]

Juan N *Pulls out möbius strip.*

[@michaeltobia1274]

Why can we assume that momentum in the other directions is nonrelativistic compared to the Z direction? If we're allowed to arbitrarily accelerate particles in one direction why wouldn't they freely accelerate in the other directions? How fast do strings move? If the strings are motionless but experience vibration is that vibration not still motion even if its on the plank scale?

[@gergelyfazekas7285]

I love the way he explains things! He makes it easy to understand

[@thomasolson7447]

I opened my browser and this was on. It must have been going all night long. Maybe youtube is string theory.