To say this is beyond my field of expertise would be an understatement, but it's great that this is freely available for everyone to watch. Sometimes the internet isn't so bad.
This course is beyond my current knowledge, but something was said during the very helpful intro. Hong talked about the importance of doing all problem sets to gain intuition of the subject, and that intuition will help learn and understand as the course progresses. In my current classes, I've been trying to read, take notes, and look at other sources for explanations on topics. But what he said made me realize that I am not doing the most important actions that will help me learn and master the subjects and courses I'm taking. So I thank him for that
This was my mistake as an undergrad taking upper div physics… I was just doing the assigned problem sets along with many explainers and such… later, after doing terrible in electrodynamics and scraping by with a acceptable grade for into quantum… I realized that doing ALL the problem sets introduced as you read section (for griffiths for both) is the best way to get through the class and would’ve been less stressful… they introduce subtle things you need to know throughout all the problems… so just doing to problem sets always had me unable to start the problem becuase I was skipping material that gradually made the other ones easier to figure out… these classes aren’t like the physics classes most people take where the problems are pretty much repetitive without much mathematical critical thinking… I’m going over my intro quantum book again but this time I don’t have time restraints and stress keeping from skipping problems… I feel much more satisfied with my learning… this brings up a gripe I have with college… the short time you get to gain intuition for a new mathematical landscape with the stress of tests and other classes really hindered my learning and my satisfaction for it… it didn’t feel like it was about learning… it felt like it was just about getting through it all without being give enough time to unpack the mathematical subtleties I’ve never encountered before.
“Anything is not difficult if you learned it in the right way”. “Whenever you think it’s too hard, the reason might be that you have to change your perspective”. Such openness and optimism can drastically alter the rate and thoroughness of learning. It’s great that the lecture is presented by someone who has confidence in the ability of others to comprehend the subject matter. We often overcome challenges in learning when we step back and attempt a different approach. To learn is to change the form of our minds and perceive things in a novel manner. It’s great to have this content for everyone here to view.
I want to say that Hong’s explanation is quite soulful. it is detailed, also helpful to understand. He delivers not only that knowledge but the way to understand it. God bless MIT and Dr. Hong Liu.
MIT OCW has become an invaluable tool for students and educators alike, offering access to a wide range of subjects. In response to the growing demand from physics and mathematics students, we strongly encourage the addition of a course on Mathematical Methods for Physics. Such a course would greatly benefit those seeking to deepen their understanding of the mathematical techniques essential for tackling complex problems in physics. We sincerely appreciate MIT OCW's commitment to open education and eagerly anticipate the inclusion of this course in their already impressive catalog. Thank you
Most excellent recap I have seen on these concepts! It is a long time since my classes at U. Also followed prof. Zweibach QM courses on MIT OCW some years ago, I highly recommend those as well. MIT OCW is a great resource! Will follow the rest of this series.
@@cycklist I was talking about second and third courses in this series, QFT 2 and QFT 3 , their lecture notes and problem sets are on OCW but not lectures yet
That's why we tell kids to stay away from light drugs - they inevitably lead to heavy ones. First, you try weed, and then you do not notice how you went into the quantum field theory.
The point is that we don't think of x as being the concrete position of some particle, say, which varies with time. x as a label is not a function of time, it is merely an index which tells us which point of the field we're looking at.
He is pointing out that the problem occurred in classical physics and it has nothing to do with quantum field theory. In classical physics we can make repetitive measurements on the same classical body at spacetime points (t0, x0), (t1, x1) etc.. The theory then translates that into a dynamical path variable x(t), even though that is NOT what we are actually observing. In modern physics we have to let go of the x(t) path completely. It simply doesn't exist.
Post Covid people came to realized about true powers of open source, actually people knew it way earlier but people have now started to harness the powers of true open source, open source is not just idea, or concept, it is the real soul of development.
oh, thank you, so much, for wonderful lectures, dear Professor. what i'm thinking recently is i'm going through an era in which i have to rethink if everything's correct or not, on my side...hope everyone is well...🥰
I'm excited to learn from this series and Dr. Hong Liu. I think you can use quantum field theory to understand human behavior and dynamics too. Any system which exhibits quantum behaviors, traits and interactions.
I clicked on this randomly because why not… this is AWESOME. I guess I just became a beginner in quantum stuff… Thank you YT algorithm! Can’t wait to get to shroddinger (really have no idea how that maths out…) Honestly I’m shocked by the amount of free classes you can take… what’s the point of going to MIT now?
\partial^\mu (superscript \mu) is standard notation for the contraction of the spacetime derivatives \partial_ u with the inverse g^{\mu u} of the spacetime metric. In more words: \partial_ u (subscript u) are just the derivatives with respect to the (usually 4) spacetime coordinates, i.e. \frac{\partial}{\partial x^ u}. Concretely, \partial_0 is the time derivative, \partial_1, _2, _3 are the spatial derivatives. To get the upper index, you need to contract with the inverse of the metric: \partial^\mu = g^{\mu u} \partial_ u. As QFT is usually done in the context of special relativity in flat spacetime, the metric (and its inverse) are just diagonal matrices with either (−1, +1, +1, +1) or (+1, −1, −1, −1) on the diagonal, depending on the conventions you use. So in the end \partial^\mu is just +/− \partial_\mu, where it depends on the conventions whether the time-derivative or the spatial-derivatives get the minus sign.
Because the numerical values of dimensionful constants like c and h-bar depend on the units of measurement you choose. Since units of measurement are arbitrary conventions, anyway, you simply pick your units of measurement such that c = 1 (and usually also h-bar = 1) in those units. This way you get much simpler formulae.
Simply the Lagrangian and Hamiltonian mechanics my friend. I think you should first catch up on classical mechanics and then quantum mechanics before taking this class.
Mental notes: - Formulate every difficulty in terms of quantum mechanics (for example heisenberg picture) - Any formalism in physics, no matter how abstract it is, it was always designed to solve some concrete physical problems and physical questions, very concrete physical questions. And if you understand what kind of concrete physical questions quantum field theory was designed to solve, then that can give you a very good perspective. -So when you do your Pset, when you look at the examples in the class, you should always ask yourself afterwards, say, after you have done your Pset problems, always look back at that problem. Say, what did I learn from this problem, OK? And just think through it again. Think through what you learned from that problem again. And that is a very good way to help
Locality implies continuity as subjectively experienced on the surface of the earth at 12 noon in the Astrodome on a Spring morning. General Relativity is a local theory of surfaces (a black hole is a perfect, non-radiating sphere, where all radii of curvature meet at from opposite points at the center. But vectors do not have a common origin by Fermat's Last Principle for n=2 c = a + b c^n = (a+b)^n = a^n + b^n+ f(a,b,n) c^n = a^n + b^n iff f(a,b,n) = 0 f(a,b,n) 0 c^n a^n + b^n QED (This was actually proved by a math "C" student within two weeks after Fermat's expression was published, but then the men in white coats took him away,m never to be heard from again) Note that for n=2, Pythagorean theorem is wrong (and thus, vectors, which are affine - have no common origin - i.e., are in principle not local) Each vector has its own coordinate system ( which is why the trace of the relativistic field tensor is zero, meaning nothing exists, as in the Pauli matrices - the foundation of SU(2). Note that SU(2) is a group that only has one operator - mutiplication, but that two elements must exist (by addition) in order for multiplication to take place at all (Russell's Paradox means 1^2 1). There is much, much more to this story, but I don't have the space-time to write it here. I've been kicked off most of the classical websites, but I am on physics.org with links to pdf's. "There is Me and Thee, but I'm not altogether certain about Thee...." and, finally, "Just because you're schizophrenic doesn't mean that the Universe isn't a figment of your imagination" Equations to follow only if you send beer and pizza. "Drink your Beer and Eat your Pizza" - Zen Koan from south Chicago....
If all you're introducing is the derivative, then nothing exists. (An element can't change if there is no element) The traces of the relativistic Field Tensor and the Pauli matrices are all zero, which means nothing exists locally. There are no negative numbers: -c = a-b, b>a iff a = b-c, a+0 = a, a-a = 0 If there are no negative numbers, there are no imaginary numbers. del X B = 0, means the coordinate change dB from B = 0 to B = B means that B = 0 for any coordinate system.
The original state prior to existence forming is the state known as 'Being'. Logically, it simply has to 'Be' in order for everything else to then 'Be Able To Come Into Being'. But, who's 'Being' is it? That is the intelligent question. And the answer to that question is, 'It Is My Being'. The 'Being' part of the 'Human Being' now reading these words. You know, the 'Being' part of every 'Human Being' that coincidentally always gets ignored. Our 'One Common Ground'. Best wishes.
@@NowisEvollovetion The Original existence that has no beginning and no end. The necessary existence that all contingent existences depend upon to exist in the first place. That necessary existence is Allah(The God). The Creator, the designer, The sustainer of all existences. None has the right to be worshipped besides this necessary existence Allah SWT. Allah is the only One ☝️ with the right to legislate for Allah’s creation. Allahu Akbar!!!
@@sovereigncitizen3633 And yet. In that state prior to existence forming there is 'No Existence'. There is 'Absolutely Nothing' the 'Source Of Everything'. Best wishes.
Some professors were teaching with overhead projectors even 50 years ago. It didn't make the lectures any better. What is important is what you teach, not how.
To say this is beyond my field of expertise would be an understatement, but it's great that this is freely available for everyone to watch. Sometimes the internet isn't so bad.
Hoped in my country this was more of a thing
I am a psychology student but I find myself watching this vids so much
This course is beyond my current knowledge, but something was said during the very helpful intro. Hong talked about the importance of doing all problem sets to gain intuition of the subject, and that intuition will help learn and understand as the course progresses. In my current classes, I've been trying to read, take notes, and look at other sources for explanations on topics. But what he said made me realize that I am not doing the most important actions that will help me learn and master the subjects and courses I'm taking. So I thank him for that
Thanks for highlighting this.
This was my mistake as an undergrad taking upper div physics… I was just doing the assigned problem sets along with many explainers and such… later, after doing terrible in electrodynamics and scraping by with a acceptable grade for into quantum… I realized that doing ALL the problem sets introduced as you read section (for griffiths for both) is the best way to get through the class and would’ve been less stressful… they introduce subtle things you need to know throughout all the problems… so just doing to problem sets always had me unable to start the problem becuase I was skipping material that gradually made the other ones easier to figure out… these classes aren’t like the physics classes most people take where the problems are pretty much repetitive without much mathematical critical thinking… I’m going over my intro quantum book again but this time I don’t have time restraints and stress keeping from skipping problems… I feel much more satisfied with my learning… this brings up a gripe I have with college… the short time you get to gain intuition for a new mathematical landscape with the stress of tests and other classes really hindered my learning and my satisfaction for it… it didn’t feel like it was about learning… it felt like it was just about getting through it all without being give enough time to unpack the mathematical subtleties I’ve never encountered before.
“Anything is not difficult if you learned it in the right way”. “Whenever you think it’s too hard, the reason might be that you have to change your perspective”.
Such openness and optimism can drastically alter the rate and thoroughness of learning. It’s great that the lecture is presented by someone who has confidence in the ability of others to comprehend the subject matter. We often overcome challenges in learning when we step back and attempt a different approach. To learn is to change the form of our minds and perceive things in a novel manner. It’s great to have this content for everyone here to view.
I remember last year I missed lectures of quantum field theory and here it is now !
Thnx MIT !
I want to say that Hong’s explanation is quite soulful. it is detailed, also helpful to understand. He delivers not only that knowledge but the way to understand it. God bless MIT and Dr. Hong Liu.
Lecture begins at 14:58
Thx🎉
MIT OCW has become an invaluable tool for students and educators alike, offering access to a wide range of subjects. In response to the growing demand from physics and mathematics students, we strongly encourage the addition of a course on Mathematical Methods for Physics. Such a course would greatly benefit those seeking to deepen their understanding of the mathematical techniques essential for tackling complex problems in physics. We sincerely appreciate MIT OCW's commitment to open education and eagerly anticipate the inclusion of this course in their already impressive catalog.
Thank you
Thoroughly enjoyed this. Dr. Liu clearly has empathy for his students as well as an intimate grasp on this difficult yet beautiful subject.
Most excellent recap I have seen on these concepts! It is a long time since my classes at U. Also followed prof. Zweibach QM courses on MIT OCW some years ago, I highly recommend those as well. MIT OCW is a great resource!
Will follow the rest of this series.
Incredible first lecture. Can't wait to watch the entire course!
Finally !!! I hope we also get the second and third part in a few months. OCW is the best
The whole course is available now.
@@cycklist I was talking about second and third courses in this series, QFT 2 and QFT 3 , their lecture notes and problem sets are on OCW but not lectures yet
@@dw96969Relativistic Quantum Field Theory 3 is available.
@@kw7807 where ? also videos ?
Could you share the link please ?
MIT is so goated for making this free
yes this is probably the most difficult course in the world for free
Please also upload QFT II and QFT III in the next semesters
Thank you for sharing your expertise.
starts @14:40, you' re welcome
sorry clicked by mistake while being high, this is dope
Haram
That's why we tell kids to stay away from light drugs - they inevitably lead to heavy ones. First, you try weed, and then you do not notice how you went into the quantum field theory.
Please also record the lectures of the course on QFT II as well.
As an aspiring quantum field theorist in a masters program, thank you so much!
Looks very promising: So far one can actually read what he writes on the blackboard. That's a good sign.
43:33 can someone please elucidate the difference between labels and dynamical variable.
The point is that we don't think of x as being the concrete position of some particle, say, which varies with time. x as a label is not a function of time, it is merely an index which tells us which point of the field we're looking at.
He is pointing out that the problem occurred in classical physics and it has nothing to do with quantum field theory. In classical physics we can make repetitive measurements on the same classical body at spacetime points (t0, x0), (t1, x1) etc.. The theory then translates that into a dynamical path variable x(t), even though that is NOT what we are actually observing. In modern physics we have to let go of the x(t) path completely. It simply doesn't exist.
Post Covid people came to realized about true powers of open source, actually people knew it way earlier but people have now started to harness the powers of true open source, open source is not just idea, or concept, it is the real soul of development.
When the Phi looks like a marshmellow on a stick, you are in the realms of physics.
MIT, thank you for this refreshing lecture.
Perfect lecture set!
oh, thank you, so much, for wonderful lectures, dear Professor.
what i'm thinking recently is i'm going through an era in which i have to rethink if everything's correct or not, on my side...hope everyone is well...🥰
It seems that Professor Sunil Mukhi is also developing something about field theory. The language he used was quite similar to Professor Hong Liu.
Great lecture. Thanks.
Holy shit. Thank you so much!
oi, wish this was available literally 5 years ago lol.
I'm excited to learn from this series and Dr. Hong Liu. I think you can use quantum field theory to understand human behavior and dynamics too. Any system which exhibits quantum behaviors, traits and interactions.
Finally it’s time for relativistic qft!!
Mit lectures are treat to watch
Very helpful, thank you
I clicked on this randomly because why not… this is AWESOME. I guess I just became a beginner in quantum stuff… Thank you YT algorithm! Can’t wait to get to shroddinger (really have no idea how that maths out…) Honestly I’m shocked by the amount of free classes you can take… what’s the point of going to MIT now?
My man Hong went from walking pace to warp in less than a Planck unit of time.
i waited so long for this , thanks MIT ❤ god bless you
Thank you so much
This is beyond my comprehension but beautiful nonetheless. Really cool to be able to see lectures from the World’s great Universities.
thanks for the videos!
any chance at getting a quantum field theory 2 and 3 uploaded?
Good. Thank for your video from korea
language of the gods
Thanks! ❤
Thank you so much for this
"Education is only way of live a peaceful life"
-anonymous
cope
Thank you.
Bless you 1:04:35
I have trouble balancing my check book but I will listen to this course (and not understand anything :)
Good profesor thanks from egypt
Sorry I didn't get that, can you start again slowly.
*0.25x speed youtubers enter the chat*
Thank s. Need more cours
1:05:06 What does the \partial ^ \mu mean?
\partial^\mu (superscript \mu) is standard notation for the contraction of the spacetime derivatives \partial_
u with the inverse g^{\mu
u} of the spacetime metric. In more words: \partial_
u (subscript
u) are just the derivatives with respect to the (usually 4) spacetime coordinates, i.e. \frac{\partial}{\partial x^
u}. Concretely, \partial_0 is the time derivative, \partial_1, _2, _3 are the spatial derivatives. To get the upper index, you need to contract with the inverse of the metric: \partial^\mu = g^{\mu
u} \partial_
u. As QFT is usually done in the context of special relativity in flat spacetime, the metric (and its inverse) are just diagonal matrices with either (−1, +1, +1, +1) or (+1, −1, −1, −1) on the diagonal, depending on the conventions you use. So in the end \partial^\mu is just +/− \partial_\mu, where it depends on the conventions whether the time-derivative or the spatial-derivatives get the minus sign.
@@EdwinSteiner Thank you very much!
Does anybody know if prof. Liu teaches the second course on QFT?, and if so, are there plans to publish that second course on youtube?
Here's what we have by Prof. Liu: ocw.mit.edu/search/?q=Prof.+Hong+Liu. Best wishes on your studies!
@@mitocw Thank you very much MIT
So if I add MSG, I can theoretically taste it later if I lick the space within its propagation window? I think I am pick'n up what you are put'n down.
magnificent❤
I can't believe man hong liu the god is here🎉
La ilaha ilallah (There is no God, but the One ☝️ God).
Nice joke@@sovereigncitizen3633
True bro
Why c equal to one?
Because the numerical values of dimensionful constants like c and h-bar depend on the units of measurement you choose. Since units of measurement are arbitrary conventions, anyway, you simply pick your units of measurement such that c = 1 (and usually also h-bar = 1) in those units. This way you get much simpler formulae.
Hi MIT please upload undegrad physics core ❤
watch at 3x speed
大家認為微積分的符號以及意義有瑕疵嗎?
Is this the thing about the cat in the box?
No! it's the theoretical physicist sitting in a box and thinking
No, it's the thing about infinitely many cats in infinitely many boxes.
What happened to
L = T - V
H = T + V
??????
Simply the Lagrangian and Hamiltonian mechanics my friend. I think you should first catch up on classical mechanics and then quantum mechanics before taking this class.
In general, L and H do not follow the form you provided
That was simple 😅!
Only here to see how he wrote on the top of the board
Mental notes:
- Formulate every difficulty in terms of quantum mechanics (for example heisenberg picture)
- Any formalism in physics, no matter how abstract it is, it was always designed to solve some concrete physical problems
and physical questions, very concrete physical questions. And if you understand what kind of concrete physical questions
quantum field theory was designed to solve, then that can give you a very good perspective.
-So when you do your Pset, when you look at the examples in the class, you should always ask yourself afterwards, say, after you have done your Pset problems, always look back at that problem. Say, what did I learn from this problem, OK? And just think through it again. Think through what you learned from that problem again. And that is a very good way to help
👏👏👏💯🔝
Locality implies continuity as subjectively experienced on the surface of the earth at 12 noon in the Astrodome on a Spring morning.
General Relativity is a local theory of surfaces (a black hole is a perfect, non-radiating sphere, where all radii of curvature meet at from opposite points at the center. But vectors do not have a common origin by Fermat's Last Principle for n=2
c = a + b
c^n = (a+b)^n = a^n + b^n+ f(a,b,n)
c^n = a^n + b^n iff f(a,b,n) = 0
f(a,b,n) 0
c^n a^n + b^n QED
(This was actually proved by a math "C" student within two weeks after Fermat's expression was published, but then the men in white coats took him away,m never to be heard from again)
Note that for n=2, Pythagorean theorem is wrong (and thus, vectors, which are affine - have no common origin - i.e., are in principle not local) Each vector has its own coordinate system ( which is why the trace of the relativistic field tensor is zero, meaning nothing exists, as in the Pauli matrices - the foundation of SU(2). Note that SU(2) is a group that only has one operator - mutiplication, but that two elements must exist (by addition) in order for multiplication to take place at all (Russell's Paradox means 1^2 1).
There is much, much more to this story, but I don't have the space-time to write it here. I've been kicked off most of the classical websites, but I am on physics.org with links to pdf's.
"There is Me and Thee, but I'm not altogether certain about Thee...."
and, finally,
"Just because you're schizophrenic doesn't mean that the Universe isn't a figment of your imagination"
Equations to follow only if you send beer and pizza. "Drink your Beer and Eat your Pizza" - Zen Koan from south Chicago....
Elon I know your lurking here good day to you sir.
Nah, he's too busy X-crementing.
A lecture like this is why I gave up on Physics after one semester at University
10:09
One day I’m going to be able to use all this stuff I learn 😂 either that or I’ll end up begging for money “will practice theoretical physics for food”
How to invest Real Estate: Location... Term, Condition, Price ? Bacccarat Strategy...
Niiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiice
❤
but lagrangian and Hamiltonians are in economics
0:10
Square viewless..rate..🤔
General thought view..not check..
Hong seemed to only read from his notes. 😢
😂but am sure it you're asked to read the same 😂😂😂😂you may get stuck
Very beautiful sweet sir ❤❤❤❤❤
中央量子場小組需要台端
If all you're introducing is the derivative, then nothing exists. (An element can't change if there is no element)
The traces of the relativistic Field Tensor and the Pauli matrices are all zero, which means nothing exists locally.
There are no negative numbers: -c = a-b, b>a iff a = b-c, a+0 = a, a-a = 0
If there are no negative numbers, there are no imaginary numbers.
del X B = 0, means the coordinate change dB from
B = 0 to B = B means that B = 0 for any coordinate system.
The original state prior to existence forming is the state known as 'Being'. Logically, it simply has to 'Be' in order for everything else to then 'Be Able To Come Into Being'. But, who's 'Being' is it? That is the intelligent question. And the answer to that question is, 'It Is My Being'. The 'Being' part of the 'Human Being' now reading these words. You know, the 'Being' part of every 'Human Being' that coincidentally always gets ignored. Our 'One Common Ground'. Best wishes.
Allahu Akbar!
@@sovereigncitizen3633 Yes. That original 'Unmoving State' that some call 'God'. Best wishes 🙏
@@NowisEvollovetion The Original existence that has no beginning and no end. The necessary existence that all contingent existences depend upon to exist in the first place.
That necessary existence is Allah(The God). The Creator, the designer, The sustainer of all existences.
None has the right to be worshipped besides this necessary existence Allah SWT. Allah is the only One ☝️ with the right to legislate for Allah’s creation.
Allahu Akbar!!!
@@sovereigncitizen3633 And yet. In that state prior to existence forming there is 'No Existence'. There is 'Absolutely Nothing' the 'Source Of Everything'. Best wishes.
@@NowisEvollovetion How can something come from nothing? How can existence come from non-existence?
I graduated from MIT but I have to admit I cheated. A lot.
ehh I'll just stick to pure math
this is probably thwe most difficult class in the world
Ngl i thought he Said he was Hung xD😅😂
Teacher can not write without paper😂😂😂
So instructors are still using chalkboards today, and not powerpoints!? Or at least interactive whiteboards?
Some professors were teaching with overhead projectors even 50 years ago. It didn't make the lectures any better. What is important is what you teach, not how.
sad to say but, US top universities especially in stem sector, are dominated by chinese and indian, immigrant or not
He mumbles a lot