Thank you, I'm taking a quantum mechanics class at UC Berkeley, and this video was much more helpful than lecture, office hours, and the textbook. Now it's time to see if I can solve problems!
To what extent did you have "no previous context"? I mean, it is reasonable to doubt you have fully understood the subject if one takes those words literally.
you are the only one in the world, i wish to meet you one day Doctor! By the time i started following your videos, i immediately quit read books.... i am addicted to yours videos Doctor!!!!!!!. Please don't stop producing them we are await them for 24hrs.
I think that the spin of photon is equal to 2 rather than to 1 without using the renormalization of the spin vector along the z axis. This is because the speed of light as the escape velocity from the cosmic field is : c = (G × M × r^-1)^(1/2) with a = c × H, which also means that the gravitational spin of photon is equal to 2 according to the principle that the gravitational capture occurs in 2 : 1 spin - orbit resonance. We suggest that the spin-2 of photon results from the interaction between the mass of photon (as the dual Newtonian potential) and the mass of cosmos (as the Newtonian and the dual Newtonian potentials).
These are outstanding lectures. But I sure wish you would say something about the representation of these Lie algebras and how that manifests itself physically.
Welcome to SimpleScience! Our very new Educational UA-cam Channel. On here you will get to cover all sorts of science topics ranging from Biology, to Chemistry and to Physics in SIMPLE and SHORT and EXTREMELY INFORMATIVE videos from our experts! Please come and watch our channel!
I'm getting pissed off with spin! The fact that the Stern Gerlach experiment showed that particles have some property called spin which is discrete and either one of two states, we call them up or down if you like. Then why give them components like Sz,sx and Sy, surely like charge, we don't say charge in the z direction, charge in the y direction. It's just plus or minus, why do we do this for spin then?
On measurement it is only up and down. But if you could produce identical spinned electrons, they could give from 100%up 0% down - to- 0% up 100% down, including 80%-20%, 79%-21%, etc.... So we could produce a bunch of electrons with exactly the same spin, and they could give for example 50% up and 50% down. And this is because they have other properties, which gives them a quality between up and down. So you can find its different only based on statistics, but if you measure it, it can only give you one by one up OR down.
Angular momentum along x, y and z axis is a quantum puzzle and can be extended to any number of dimensions (all you need is a larger matrix ), mathematically conforming to the superposition of qubits of a quantum computer, representing multidimensional reality of QM. No wonder that the universe is a quantum computer (Maldecena), operating in an infinite dimensional space.
It begins like this: there is a relation between orbital angular momentum operators and commutation. From here, L = r by p. Then we can assign L its components. There exists noncommutativity of the rectangular components of angular momentum. This means that a complete set of states cannot be defined for which each component of the angular momentum vector has a precise and definite value, just like in Quantum Physics.
A level mathematics in the United Kingdom, higher-school, is sufficient for giving the beginning student what it takes to follow these videos. In the United States it is New Media Charter, for example, that has Vectors for Elementary Theoretical Physics in high school and the course beautifully gives these American students nearly everything needed to understand and follow the derivations here in. At university level Physics, before the student even attempts to verify vector commutation relation for the totality of system's angular momentum, the student must be able to prove that L is Hermitian. This particular video is the Bomb! Follow it.
I learned before that the commutator [X, Px]=i(h-bar) so then [Pz, Z]= (-i)(h-bar) so why is YPx[Pz, Z] still equal to (-i)(h-bar)? I think there is something I'm missing and failing to understand, so it would be helpful if I could get an answer, thanks.
@4:55 you represent an increase in angular momentum by tilting a vector. It was my understanding that the magnitude and not the direction of an axial vector represented the amount of angular moment. So shouldn't the vector be made longer and direction kept the same?
In the first 90 seconds, his definition of the angular velocity vector is the OPPOSITE of 'the right-hand rule' method of determining direction. - If you orient your right hand such that it will curl around the axis as it follows the spin, the direction your right hand's thumb points corresponds to the direction of the angular velocity vector. Therefore, unless I'm perceiving a mirror image of what he's sketched, the clockwise motion he has shown would result in the arrow pointing down, not up.
I agree, although from a presentation standpoint, following a convention is better. Also, when performing an operation such as a cross product, in order for the sign (+ - ) of the result to match convention, the defined orientation for what is the positive direction for BOTH axes must break from convention. (i.e. rotation in the X Y plane from positive X to positive Y yields a cross product term in the positive Z direction)
Yes I noticed that, his first drawing is a bit ambiguous. If you listen to what he's saying in his second drawing you realize that it's just the right hand rule and you're looking at his first drawing wrong.
If you watched more than 90 seconds of the video, you would have realized that you, indeed, did perceive a mirror image of what he sketched. Later he explains that the angular velocity is clockwise, and that the vector is pointing into the page.
Hello Hello So I am very new to the field and you make it seems easy however i know it is not so thanks for the great explanation sending my greats from egypt
Dear DrPhysics can you please teach us calculus the way you teach us physics. I love your teaching style. I wish I had math teachers like you, when I was growing up. Or maybe I did and did not pay attention. But I love to believe it is not to late to learn calculus. I also know you can not learn science without it.
At 32:58 written L^2= 'L-L+'+ ' Lz' + 'Lz^2 is not follow unit's...so, how can you written here like this? Sorry, but I'm confused here because of I have very poor knowledge about quantum mechanics and particle physics
Lz is written without multiplying with h-bar just follow that part of explanation and You will see that he told that he set h-bar to number 1 without any unit.In fact h-bar is in units of J×s and multiplying with Lz You eventually get J^2×s^2 which is in unit relation with L^2 and other elements of the equation.....
Hello Sir, You are very firm with basics for the math.-theoretical QC, QED, und that stuff - like. Show us some experiments with the formulars to call it physics^? ... you know Sir that the function by casical convention match only less 10^8 cm (M. Planck). That's of cause an meme/ideom fact for spectrum-technic even by 'visible light' overmore. Let me say: Physics will make to all that 'nature-science from ...' theoretical physic experiments an calculation for to show and use. It's a very computation to measure that high-energy physics. It's very clear that the classic mechanical physics not match the Quantum-Theory for Western ideal, and anyhow the distinct is'nt an chemical reason resp. reason of Chemistry. A.Einsteins "g(nm)'s" - factors for tensor abstractive to the that times theory definitions are well known. Unfortunately no one understand the resp. or more rightious physics for that scientific problems. E.g. no one will define Wigner-Matrix by Spin-Groups reasons by that formular equations. All die Schwarzschild-Radius are computabel by material estimation. From that the relativistic Radius of Earth is 0.01 m. ... there is nothing from, especial overmore (Feynmann, Heisenberg, et al), know and include for operation. Is this an difference to Cartesian vs Leibniz?
I still can not get the angular momentum quantification. Why is that your measurement quantize and not the "original" angular momentum value? If, let us suppose, angular momentum quantize, i.e. is aligned in a vector space to a fixed grid, then your measurement quanta must depend on the angle we look at the grid from. you may say i am poisoned with mechanical analogies, but so far, it seems to me, i only use pure geometry.
Where is my Pi value. Pi squared 9.86 to size tenth in class. I am a Doctor of Physics. And where is the gravity Pumpkin? It is a three dimensional Pump maintaining its existence to the infinity.
Thank-you for these amazing videos Dr. Eagle, what a wonderful set of videos they are.
This is such a clear and no - nonsense treatment of the subject, thank you!
Finally I DISCOVERED MY REAL PROFESSOR.
Thanks man, just keep working on making people know what really is physics. U're more than just Awesome..
I am extremely sorry to say but he does not upload videos on youtube for the last 6 or 7 years.
I watched so many lectures and books and This is the video where it all ends.
Thanks, man. Why did you stop.
This lecture is awesome. This guy is a legend
Boring
Fuck off
Wow! Such an interesting and fast explanation. You are really a good teacher Sir.
Thank you, I'm taking a quantum mechanics class at UC Berkeley, and this video was much more helpful than lecture, office hours, and the textbook. Now it's time to see if I can solve problems!
What a simple way to make people to understand complex topics !!
Sir .... Excellent !!
You just explained to me what an undergraduate textbook and two professors couldn't do in a week.
Same for me.
Wow. That was excellent. I had no previous context yet somehow I understood it all. Fantastic lecture
To what extent did you have "no previous context"? I mean, it is reasonable to doubt you have fully understood the subject if one takes those words literally.
Dayummm! nice stuff man , keep up the good work
You are the best Physics channel. Where are you dude?
Aww man this is awesome got to come back to this with paper and pencil
you are the only one in the world, i wish to meet you one day Doctor!
By the time i started following your videos, i immediately quit read books.... i am addicted to yours videos Doctor!!!!!!!. Please don't stop producing them we are await them for 24hrs.
I think that the spin of photon is equal to 2 rather than to 1 without using the renormalization of the spin vector along the z axis. This is because the speed of light as the escape velocity from the cosmic field is : c = (G × M × r^-1)^(1/2) with a = c × H, which also means that the gravitational spin of photon is equal to 2 according to the principle that the gravitational capture occurs in 2 : 1 spin - orbit resonance. We suggest that the spin-2 of photon results from the interaction between the mass of photon (as the dual Newtonian potential) and the mass of cosmos (as the Newtonian and the dual Newtonian potentials).
He really is a legend!
So why do moons/stars spin backwards creating an angular problem?
These are outstanding lectures. But I sure wish you would say something about the representation of these Lie algebras and how that manifests itself physically.
Welcome to SimpleScience! Our very new Educational UA-cam Channel. On here you will get to cover all sorts of science topics ranging from Biology, to Chemistry and to Physics in SIMPLE and SHORT and EXTREMELY INFORMATIVE videos from our experts! Please come and watch our channel!
I'm getting pissed off with spin! The fact that the Stern Gerlach experiment showed that particles have some property called spin which is discrete and either one of two states, we call them up or down if you like. Then why give them components like Sz,sx and Sy, surely like charge, we don't say charge in the z direction, charge in the y direction. It's just plus or minus, why do we do this for spin then?
On measurement it is only up and down. But if you could produce identical spinned electrons, they could give from 100%up 0% down - to- 0% up 100% down, including 80%-20%, 79%-21%, etc.... So we could produce a bunch of electrons with exactly the same spin, and they could give for example 50% up and 50% down. And this is because they have other properties, which gives them a quality between up and down. So you can find its different only based on statistics, but if you measure it, it can only give you one by one up OR down.
ua-cam.com/video/3k5IWlVdMbo/v-deo.html
Angular momentum along x, y and z axis is a quantum puzzle and can be extended to any number of dimensions (all you need is a larger matrix ), mathematically conforming to the superposition of qubits of a quantum computer, representing multidimensional reality of QM. No wonder that the universe is a quantum computer (Maldecena), operating in an infinite dimensional space.
Dear Dr.PhisicsA,may i translate your lectures in my own language,which is Bulgarian and upload?Is it possible?
It begins like this: there is a relation between orbital angular momentum operators and commutation. From here, L = r by p. Then we can assign L its components. There exists noncommutativity of the rectangular components of angular momentum. This means that a complete set of states cannot be defined for which each component of the angular momentum vector has a precise and definite value, just like in Quantum Physics.
A level mathematics in the United Kingdom, higher-school, is sufficient for giving the beginning student what it takes to follow these videos. In the United States it is New Media Charter, for example, that has Vectors for Elementary Theoretical Physics in high school and the course beautifully gives these American students nearly everything needed to understand and follow the derivations here in. At university level Physics, before the student even attempts to verify vector commutation relation for the totality of system's angular momentum, the student must be able to prove that L is Hermitian. This particular video is the Bomb! Follow it.
BRILLIANT!
I learned before that the commutator [X, Px]=i(h-bar) so then [Pz, Z]= (-i)(h-bar) so why is YPx[Pz, Z] still equal to (-i)(h-bar)? I think there is something I'm missing and failing to understand, so it would be helpful if I could get an answer, thanks.
@5:53 ..do electrons actually spin ? i thought "spin" was more to do with the small dipole moment the particle, say an electron ?
Have you done a vid on ISO spin ?
Is it iso-spin that has 4pi rotational symmetry ?
@4:55 you represent an increase in angular momentum by tilting a vector. It was my understanding that the magnitude and not the direction of an axial vector represented the amount of angular moment. So shouldn't the vector be made longer and direction kept the same?
why the spin quantum number has half values? can spin quantum number fitted in Schrodinger equation
I went from learning how the machine from Spider-Man 3 made sandman turn the way he did and somehow ended up here
15:00 Why am I able to rearrange the terms?
Awesome, Looking forward to the Higgs mechanism video (if its possible) :)
Sir, please explain to me why the quantum spin number is expressed as 1/2 and -1/2
hahah it's like you know what my course is. Did this last week. :D TY
In the first 90 seconds, his definition of the angular velocity vector is the OPPOSITE of 'the right-hand rule' method of determining direction. - If you orient your right hand such that it will curl around the axis as it follows the spin, the direction your right hand's thumb points corresponds to the direction of the angular velocity vector. Therefore, unless I'm perceiving a mirror image of what he's sketched, the clockwise motion he has shown would result in the arrow pointing down, not up.
I agree, although from a presentation standpoint, following a convention is better. Also, when performing an operation such as a cross product, in order for the sign (+ - ) of the result to match convention, the defined orientation for what is the positive direction for BOTH axes must break from convention.
(i.e. rotation in the X Y plane from positive X to positive Y yields a cross product term in the positive Z direction)
Depends if you think the arrow is going behind or in front of the axis
Yes I noticed that, his first drawing is a bit ambiguous. If you listen to what he's saying in his second drawing you realize that it's just the right hand rule and you're looking at his first drawing wrong.
If you watched more than 90 seconds of the video, you would have realized that you, indeed, did perceive a mirror image of what he sketched. Later he explains that the angular velocity is clockwise, and that the vector is pointing into the page.
Hello Hello So I am very new to the field and you make it seems easy however i know it is not so thanks for the great explanation sending my greats from egypt
Very nice crystal clear.
Dear DrPhysics can you please teach us calculus the way you teach us physics. I love your teaching style. I wish I had math teachers like you, when I was growing up. Or maybe I did and did not pay attention. But I love to believe it is not to late to learn calculus. I also know you can not learn science without it.
dear dr. physics, please tell me what did you said @36:58 that the extra term in anguler momentum is... WHAT ???. I couldn,t hear that clearly.
+Pritam Roy residual angular momentum
It’s just hard not to imagine 10044.100526, 1007438 and 100526 not being considered.
MANY APPRECIATE FOR THE VIDEOS...
Measurement doesnt reveal a chacteristic,it creates it!
At 32:58 written L^2= 'L-L+'+ ' Lz' + 'Lz^2 is not follow unit's...so, how can you written here like this?
Sorry, but I'm confused here because of I have very poor knowledge about quantum mechanics and particle physics
Lz is written without multiplying with h-bar just follow that part of explanation and You will see that he told that he set h-bar to number 1 without any unit.In fact h-bar is in units of J×s and multiplying with Lz You eventually get J^2×s^2 which is in unit relation with L^2 and other elements of the equation.....
Can you recommend a book that explains quantum mechanics in depth? I like physics but I'm not studying it at uni
cal tech recommends Saxon text, as shows much detail
Why is the fact that the commutator of x and p is not 0 means that we can not measure them with arbitrary precision at the same time?
Learn hisenberg principles and triangular inequality derivation ans is clear
very very very .... good explanation
I like this one! Reminds me somebody ....
It’s good to see old friends coming back!
I'm really don't get it. At 54.36 minutes, how alpha = 1, beta = -i?
just substitute those values into the two equations for alpha and beta
Dr. Physics, Did you just say that angular momentum determines a masses directional momentum?
+James Lewis Is the Earth rolling around the sun on dark matter? Please help me. don't want to kill myself.
+James Lewis If we reverse the angular momentum of the earth would the sun run off and leave us?
Hello Sir,
You are very firm with basics for the math.-theoretical QC, QED, und that stuff - like.
Show us some experiments with the formulars to call it physics^? ... you know Sir that the function by casical convention match only less 10^8 cm (M. Planck). That's of cause an meme/ideom fact for spectrum-technic even by 'visible light' overmore.
Let me say: Physics will make to all that 'nature-science from ...' theoretical physic experiments an calculation for to show and use.
It's a very computation to measure that high-energy physics. It's very clear that the classic mechanical physics not match the Quantum-Theory for Western ideal, and anyhow the distinct is'nt an chemical reason resp. reason of Chemistry.
A.Einsteins "g(nm)'s" - factors for tensor abstractive to the that times theory definitions are well known. Unfortunately no one understand the resp. or more rightious physics for that scientific problems. E.g. no one will define Wigner-Matrix by Spin-Groups reasons by that formular equations. All die Schwarzschild-Radius are computabel by material estimation. From that the relativistic Radius of Earth is 0.01 m.
... there is nothing from, especial overmore (Feynmann, Heisenberg, et al), know and include for operation.
Is this an difference to Cartesian vs Leibniz?
Good explanation✌👍
29:26, 0 value comes bc y/x are orthogonal to z
Like explication so much
nvm, I see now that you were using it to represent an increase/decrease in the z component of angular momentum only.
Well explained
Griffiths?
very good lecture
but what is spin ._.?
salutations drphysics btw is angular momentum of the s shell =0
sry nt shell orbital
Thankyou.
I still can not get the angular momentum quantification.
Why is that your measurement quantize and not the "original" angular momentum value?
If, let us suppose, angular momentum quantize, i.e. is aligned in a vector space to a fixed grid, then your measurement quanta must depend on the angle we look at the grid from.
you may say i am poisoned with mechanical analogies, but so far, it seems to me, i only use pure geometry.
Interesting if you’re looking for the Higgs I guess
Where is my Pi value. Pi squared 9.86 to size tenth in class. I am a Doctor of Physics. And where is the gravity Pumpkin? It is a three dimensional Pump maintaining its existence to the infinity.
👍
Thanks Sir
Funny math for calculating spin with x,y,z vectors and angular momentum. lol.
This math is not for " Particle Physics" sorry
I am back again. Thx
just to say thks~!!!😀
great...maybe I've eaten the eden apple
I laughed pretty hard at 36:25.
BrAVO
Bhutto h