Hi friends! Thank you so much for your support :) I've just made a video discussing the general concept of spin in a bit more detail (rather than focussing on the spin of an electron) - check it out here: ruclips.net/video/DCrvanB2UWA/видео.html
For everyone wondering why physicists named the state spin-up or spin-down: I read about an experiment called the Stern-Gerlach experiment, in which electrons passing through a magnetic field were deflected either up or down. The weird thing is that there was no difference in the amount of up or down the particles were deflected. It is either all the way up to the top of the limit, or all the way down. Every time. This experiment was pivotal in demonstrating the existence of a quantized spin angular momentum state for subatomic particles. That's why they say spin-up or spin-down. This up/right stuff is about calculating the probability of the particle's spin angular momentum being one way or the other. Not the actual direction the particle will travel or spin. Edit: added "I read about" to the beginning because I'm just a student and not an expert, and I feel it is disingenuous to portray myself as such, and I changed "atoms" to "electrons". I just now noticed that mistake...
@@MrJdcirbohey Can someone clear my doubt, If |a> and |b> are two basis states and the prob of both the states is 50% then we denote the total state of the e- as either 1/√2(|a> + |b>) and 1/√2(|a> - |b>). My doubt is, that the e- can also be in 1/√2( - |a> + |b>) and 1/√2(- |a> - |b>). Then why do we ignore these two states.
@@ruchi9917 when we measure probability we have to square the probability amplitude so in both cases you will get the same result. So we can take any one....
Really good explanations - thank you. Maybe, if you have time, you could ponder over how a wave of energy propagates through a wire, without radiating, (a transmission line) then how the wire ceases to be a transmission line and becomes a radiating antenna, then how the radiation leaves the antenna and launches into free space. [for instance you could ponder whether the 'electrons' are given a short ''jerk' (causing nature to wobble space) from the energy of the wave (or not)- [[is this combo electricity??]] Then, ponder how a distant antenna can 'pick-up' a wave (maybe concentrate on the magnetic and electric fields separately - and the respective geometry of each type of antenna?) and direct that wave back down a transmission line and into a detector (a good ol' radioset!). This would be a neat practical application of Maxwell in the real world. Maybe you could even do a series of practicals (unless of course you a theorist ;-). Thanks again.
Hey thanks for the video. I think "spin up" and "spin down" came from the Stern-Gerlach experiment where the electron from the silver atom either went up or down after the non-uniform magnetic field.Actually,even "spin" is a misnomer as an electon cannot spin on its own axis.It was suprising because the electron is supposed to be in the s-orbital for which orbital angular momentum is zero. Hence,it should not exhibit any magnetic moment and hence should not be affected by the non-uniform field. Instead, they found statistically the electrons exhibiting a quantized magnetic moment of two states. One set of electrons went up and the other went down depending on their spins and deflected by the magnetic field. Hence, S & G concluded that in there is another magnetic moment associated with the electron other than orbital angular momentum. This became a fundamental characteristic of particles like charge and mass.
It is because when an electron jumps from a higher energy state to a lower energy state, electromagnetic radiation is emitted. Now, if the shells were not discrete, we would get a smooth spectrum of the frequencies of radiation. However, we see that we do not get that smooth spectrum. Instead, we get discrete lines. Hope that helps :)
Excellent work on these videos, I shall be sure to recommend you to my students. However a very slightly unfortunate choice on the direction of spins you label 'spin up' and 'spin down' in the classical case as, as a result of editing perhaps, they are the opposite of the usual convention (a right hand rule one). I doubt that this will matter to most, and your point is still well taken. I look forward to your presentation on spin itself as that's a notoriously difficult one to present in a clear way (I bet you can though!).
Is the vector you are talking about a spinor.and is that the reason for inversion of sign of spinor as the real vector is rotated through an angle of 360 degrees.( because of orthogonal states)
Great question! Spin states are only "orthogonal" in a mathematical sense. We start with the fact that there are 2 possible results to our measurement (which in this case is the spin of an electron) and THEN we realise that quantum states behave kind of like vectors that are at right angles to each other. If we took another measurement that had 3 possible results then we definitely would have 3 perpendicular vectors, i.e. in 3D. Equally if there were 10 measurement results of another measurement, then we would have to imagine a 10-dimensional space with all vectors orthogonal to each other. The abstract vector space is something we construct for mathematical convenience, not the other way round!
In this context, the spin states refer to the amount of spin. An electron has only two amounts of spin, always the same magnitude but can be clockwise or anticlockwise (up or down). So, a total of two spin states. Some particles have more. A photon, for example, has three spin states: 0, +1 and -1. The vector space in which these spin states are represented is not directly related to ordinary 3D space.
Kind of! It's a really close parallel, but you're definitely on the right track! A better 'Rule' for thinking about the Angular Momentum and the resultant Spin of an electron is the right hand Grip rule. If you haven't heard of it, take your right hand, point your thumb up, and curl your other fingers inwards towards your palm (Like you're halfway to a thumbs up). Now imagine that the direction your fingers are curling is the direction that the electron is 'Spinning'. Your thumb points Upwards while you're doing this- Spin Up! If you want to imagine an electron spinning the other way, turn your hand upsidedown so your thumb is pointing to the floor. That's Spin Down, and if you imagine the way your fingers are curling is the direction of the spin, it's in the opposite way! The right hand grip rule is just another way to think about Orthogonality (Like the right hand rule!), but it's a bit more intuitive than trying to imagine spin with three fingers pointing in different directions. Hope that helps!
Hey Parth, I love the hand-drawn text (procreate?). I don’t think your lighting is correct (I’m no expert) - the right Side of your face is dark. Regardless, I appreciate you and this channel!! Keep it up
You are amazing and you explain it in a easier way to understand so please put a video about s matrix theory please please please please please please please please
Well, I always thought that the spin "up" and "down" convention came from the observation of energetic states of electrons on their "orbits" round nucleus. When electron shows a little higher energy, it would be linked to its spin up and if it has a little less energy (seems to be closer to the nucleus) it would denote its spin "down". Both are just clasic side effects of the spin, which were simply visible in detailed spectral lines of Balmer (and other) series. Was I wrong?
I think of it like that too!!! Somehow quantum mechanics isn't that straight forward though, me and you are extremely logical thinkers. Tbh I don't know if we are right or wrong, but all I know is that spinning (according to this video) is because of constant angular momentum which we don't know how it started.
The more I watch this video, the less happy I'm with it, sorry. Could you just explain which are the actual physical properties of spin as measured in labs? AFAIK electrons behave in two ways, as if having intrinsical magnetic polarity, when subject to a very specific experiment (Gerlach-something?) and they are also required to have opposite spin in order to circunvent the Pauli exclusion principle, maybe we could begin there, then explain how does that manifest in the probability wavefunction of the electron (or photon or whatever else, I'm particularly intrigued about quarks but guess it's the same).
Hii Parth... I need your help in personal. I planned to pursue my masters in quantum computing in Waterloo,canada.. Which can i choose Ms math computer science -quantum information or Ms physics -quantum information. Im a computer science engineering graduate, working in an MNC in R&D dept... Pls do help me to choose the scope full studies.
How to thank you enough! I was reading chemistry actually and the whole idea of 'spin' messed up my mind. I googled a lot still was like-Huh?It's so confusing. Then I quickly searched your name and see-Ahha,finally he made a video! Anyway-You'd look nice if you wear a pink eye shadow!
If it’s not actually spinning, why call it spin? Can you describe it without using the word spin? Everybody knows what it is to spin. Can you describe what you mean by spin without actually using the word “spin?”
Great video Parth. I'm currently doing my A levels and this concept of spin is regularly skirted over in chemistry and physics A levels, but you explained this great clarity :) A quick request, could you please include more depth in terms of mathematical reasoning in your future videos. Thanks.
Great stuff. Suggestions: #1) Don't make references to videos and point somewhere when you don't put the links on the video itself. Best thing is to put your links in the description which is displayed below the video. Easy for you to edit etc. #2) if possible move your monitor to a 45degree angle to your face (but keep the camera head on). This means that you won't get direct reflection in your glasses (Snells law!). Maybe you have already tried this. At least have a play and see what looks good. Otherwise your videos are great and it seems that you have the backlighting and focus things sorted out. Great job!!
Parth, friend: The electron has two spin states, up and down. But for a particle which has a spin of 3/2, and four spin states, are those particles considered spin "up, down, left, right?" Or...?
Why z components are anti parallel? In some books they are represented as spin up and spin down. Can you please suggest a book or anything that I can find mathematical calculation of angle between spin up and spin down is 90 degree?
I thought that angular momentum direction can be determined by right hand rule. But you have it by left hand rule here ... I suppose you just did not care, you just wanted to explain the concept. Am I right?
I have come to enjoy your videos, but as an advice, you need to take some steps to improve their quality. You got rid of the straight on facing lights that were reflecting off your glasses, kudos, but there also some pinkish-red lights to your right coloring your eyes through the glasses. You have also dealt with the autofocus, great! Now it's time to reduce your involuntary clapping I think :) Thanks for a very nice video by the way!
6:09 My right hand rule!... Seriously, though, even though they do use that kind of representation in Descriptive Geometry, it makes it much harder to do vector calculus if you don't keep your directions consistent. Like in quaternions and octonions.
You should have mentioned that this occurs in complex vector space. The overall reason for these facts is that the state space of a particle of spin s is a (complex) vector space of dimension d=2s+1. In such a vector space, one can only ever find up to d vectors which are orthogonal to each other; two general vectors are, of course, not orthogonal. Therefore orthogonality can not be visualized in our simple 3D world.
Basically because of convention it has to be opposite up/own left/right in/out but what I didn’t know was why they don’t name it clockwise and counter clockwise. And that’s because it’s not really spinning in that simple way. But rather has properties of the underlying chirality describing all reality.
How can you measure the angular momentum of an electron? Aren't they probabilistic wave functions? By the time its collapsed, you know its location, but not how much energy it has.
how you decide the line of axis of electron spin ? It is infinely arbitary. to begin with an assumption that an electron has a configuration of a sphere is wrong!! since Bohr's atomic model with electron assumed as a spherical particle, everyone got stucked to that dogmatic idea. Actually electron is a cuboid with 4 corner dots. each dot is like a point of origin with 3 lines in x, y, z or -x, -y, -z direction. There are 6 pairs of parallel lines connecting all the dots...and there are six surfaces or 3 pairs opposite surfaces of a cuboid of equal areas. Any one diagonal connecting any two corner dots would be the axis of a spin, either clockwise or anti-clockwise along the diagonal axis. if the cuboid is made to stand vertically on any of the corners and activated to a spinning motion by a force(photon) in a magnetic field, the cuboid electron will continue to spin in the presence of magnetic field due to magnetic induction. infact all sub atomic particles including quarks, protons and neutrons are cuboids not sphere!!!
What if we can relate the spin of electron with that of right hand thumb rule? In Vector cross product, A×B we found the direction from right hand thumb rule. Also If the body is rotated in antclockwise direction then body produces linear motion in upward and similarly downwards in clockwise direction.e.g. If you roll the cap of the bottle in anticlockwise it will come up but if you roll clockwise it will come down. Similarly if the electron spins clockwise Angular momentum will be in downward direction and if anticlockwise it will be in upward direction.
i like parth g because he stix to proven facts. no nonsense math. unlike that other science channels that dabbles in philiosophy and speculation nonsense like string theory ...😡 and multiverse.
One question!! The representation of spin as orthogonal vectors.. Is it same as we represent potential difff across various elements in the LCR circuits..???
The confusion comes from people not being able to decouple the two spaces - one is a spacial representation of the spin (which was irrelevant for the previous video) and the other (the one you actually used the orthogonal basis vectors for) where we represent the probabilities of finding the electron in one state or the other. So no, you can't call it spin up and spin right. As a matter of fact, the basis vectors selection is arbitrary, for all practical purposes we use orthogonal basis vectors, but actually we can choose any set of vectors that are not linearly dependent, i.e. non parallel.
What happens if you can stop the spinning or the movement of an electron? My guess is that it reverts to EMF waves. If we can stop an EMF wave, it may revert to nothingness or just energy.
So what happens when you actually give electron some actual spin so the angular momentum created is opposite to electrons natural spin and thus they would cancel out. Would electron have 0 angular momentum? And is this used to measure the "spins" magnitude?
So do Spin Up & Spin Down electrons have the same energy in the absence of a magnetic field? From what I understand there is an energy delta between the two states in a magnetic field.
Please I know its quite some time but there is a doubt in an atom during emissions spectra there are doublets and triplets emissions lines that are explained on the basis of atomic spin now since these two lines have different wavelengths they must have resulted from different energy transition by Plancks hypothesis but electrons in same orbital wid different spin must have same energy so how is that possible.
You said spin comes into picture if think in conjunction with special relativity but what idea of special relativity results in consideration of spin ?
Thumbs up from me. The word "orthogonal" is what threw me. You said that spin up and down were orthogonal yet up and down are not orthogonal. Very good videos. Thanks.
John Pawlicki mathematically the dot product of the bra and ket are 0 and thus are orthogonal, and thus when representing spin up and spin down as vectors, since they are orthogonal mathematically as vectors, then they must be represented as 90 degrees. I think this is right but don’t quote me haha this was my interpretation.
Isn’t it spin up and down since the stern gerlach experiment was designed an irregular magnetic field oriented so that a spin up electron deflected upwards and spin down deflected downwards
is mass and energy is same thing?? i know mass can be converted into energy and energy into mass but... but my question is, that, is they are same thing are diffrenent???????
E=mc^2 . Mass is that property of matter which interacts with gravity. Matter is made up of atoms which in turn are also made up of protons, neutrons and electrons. To maintain their stable configuration they hold certain potential energy. So, mass and energy are equivalent. They are like 2 sides of a coin. Same thing in a certain sense and not, in another. I maybe wrong.
In elementary chemistry we are taught that two electrons can occupy the same orbital if their spins are "opposite," i.e. one up, one down. This concept is further extended to explain the magnetic properties of atoms and molecules---that, for example, oxygen is paramagnetic because (according to molecular orbital models), it has unpaired electrons in separate molecular orbitals, whereas diamagnetic molecules have mostly paired electrons (everything being fundamentally diamagnetic). The beginning student is further encouraged to think of the "spinning" electron as a magnet. Opposite spins are then like two magnets with their N and S poles opposite to each other, and as with two real bar magnets placed together in that manner, the magnetic field is confined within the pair and does not affect space outside of the magnets. (As you might surmise, I've taught first-year chemistry.) Now this explanation of "spin up" and "spin down" in terms of imaginary magnets seems to work really well. Can you comment on how the orthogonal spin model relates to magnetism? How do these orthogonal angular momenta interact with each other so as to repel magnetic fields? Or am I speaking gibberish, reflecting the fact that I never had a really decent physics class?
That's the explanation for why this property was called spin in the first place. The spin produces a magnetic dipole moment analagous to a spinning charged sphere. And that's how it was detected: the unpaired outer electron of silver was used in the Stern-Gerlach experiment which demonstrated the quantisation of electron spin. Electron spin does not work fundamentally like a classical charged sphere. The quantisation is fundamentally not classical. Now, the Fermi exclusion principle means that two electrons in the same orbital must have opposite spins, hence their magnetic dipole moments cancel. A similar things happens with an electrons orbital angular momentum. For each orbital there is an equivalent orbital where the electron has the opposite orbital angular momentum. So, electrons tend to pair off to cancel the magnetic dipole moment from that. This leaves unpaired electrons generally as the source of any residual magnetic phenomena. If you want answers to these sort of questions, you could try www.physicsforums.com, for example.
Orthogonal means that there is nothing "uppish" about down and there is nothing "downish" about up. So when we say *up* and *down* are "orthogonal", we are trying to say that they are as different from each other as any pair of states can be, with absolutely no overlap. Think of an orchard that produces apples and pears. A given fruit is either an apple or a pear -- it can't be "a bit of each". Now think of a graph lableled "apples" on the X axis and "pears" on the Y axis. The graph can show a cloud of points, and each point could represent how many apples and pairs were produced in some year. So apples and pears are "orthogonal" in the sense that we can plot them on perpendicular axes that capture distinct things --- but there is no physical sense of up, down, right or left. Now imagine that all the apples are produced in a place called the "North Orchard" and all the pears are produced in "South Orchard". We can still make the same graph, but with the X axis labeled "North" and the Y axis labled "South". Well, North and South are still orthogonal to each other in this graph, because a given fruit can't be produced partly in North and partly in South! This makes perfect sense in the context of this graph -- although you would be surprised if you saw a *map* with North pointing right and South pointing upwards!
As far as I understood, electrons (and other quantum particles) would only have angular momentum on one axis and the spin up or down only describes in which direction it would spin, right? How would you know which axis it is in a 3D space and is it common across particles (or at least entangled particles)????
That's a fantastic question, holy crap! In QM, you know a question's good when the answer to it is very, very weird. The reason why Parth said that electrons (and other fundamental particles) *don't* actually spin/turn around (but have an angular momentum) is that imagining a partical spinning on one axis implies there's only one direction its angular momentum can be represented (So you're right!). If a particle did only spin on one axis at a time, it'd be very hard to look at in 3D space. You'd have to align all the electrons on the same axis to have an 'up/down' Spin when comparing them, and that's a mess! But they don't! Elementry particles *don't* have a single axis of spin. They don't spin in any particular direction- They don't spin at *all*. In fact, no matter /what/ direction you look at an electron from, it will always have an angular momentum of ħ/2 or -ħ/2. Hard to wrap your head around, I know. The reason why Quantumn Mechanics is separate to Classical Mechanics is because of ideas like this. Because of questions (like yours) that we can ask and get MUCH different answers to what we expect. If this was classical mechanics, an object spinning can only have one direction of rotation and, hence, one axis that represents its angular momentum. But in Quantumn Mechanics a particle doesn't really 'spin' at all, it just has a discreet angular momentum that's the same (or opposite) whatever direction you look at it. First time explaining something like this, so if it isn't quite enough, blame me not yourself!
Oh! And no, some particles have different values of Spin! All Fermions have what's called 'Half Spin' (1/2), and all Bosons but the Higgs have a 'Full Spin' (1).
@@kingfooddude8803 Wow, let see if I (kinda of) understood what you are trying to say: Spin is not axis or direction dependant, so let's say that a particle would have an inherent angular momentum (despite not actually rotating) that is uniform on all directions, meaning that it would have for example the same angular momentum on the x-positive and the x-negative axis, and spin up or down would actually refer whereas that angular momentum is outwards or inwards????? Some thing like L (phi, theta) is actually a constant (or a super position of 2 opposing constants until its observed) hahaha. I probably got it wrong, but only that act of trying to warp my head arround it is entertaining xD
@@in3kro274 Super close! Your first statement's correct; the Angular Momentum you observe in an electron (From ANY angle or axis- It won't change), will always be the same, and will always either be (Not inwards or outwards) *positive* or *negative*- That is, either *towards* or *away from* the direction of the observer.
The video explains part of the story of electron spin, but of course there is more. The electron has a fixed total spin. If you measure its spin about any axis you get exactly 1/3 of the total spin. The direction of that spin can be clockwise or anticlockwise (up or down). If you then measure spin about another axis, again you always get 1/3 of the total spin, and again either clockwise or anticlockwise. This is very different from the Earth, say. If you measure the spin about the Earth's axis, you find ALL its spin. The electron spin is really what quantum is all about: you get fixed, quantised values for certain measurements. No matter how you measure an electron you always get a fixed amount of spin in the chosen direction. The only degree of freedom is whether the spin is clockwise or anticlockwise.
This one was unclear for me. You're saying the directions must be opposite to each other (for reasons you explained), but why are they represented as right angles?
That's all explained in my previous video about the Language of Quantum Physics! Check it out here if you have a minute (or 15 lol) ruclips.net/video/payp7simhBM/видео.html
Stern Gerlach Experiment.... This single word , can explain the full video with much deeper understanding...Hi Parth , I am naveen from India..... I like to say... The perspective of explanation can be more of why and from which experiment people calling the spin of electron .
Good explanation. For anyone still struggling: It is important to understand that spin up and spin down is represented with two orthogonal vectors becouse once you measure some random Electron and it turns our to be spin up IT CAN'T BE spin down. This is how the word "orthogonal" translates into the abstract space. Orthogonal means that getting spin up is mutually exclusive with getting spin down. Just like two arrows forming 90 degree in the common R3 space are linearly independent.
A topic i would like to request: 1. Electron flow at temperatures near 0 deg K. For a given material, is there a certain temperature, below which, super conductance happens? or is it a gradual decrease in conductivity?
Hi friends! Thank you so much for your support :) I've just made a video discussing the general concept of spin in a bit more detail (rather than focussing on the spin of an electron) - check it out here: ruclips.net/video/DCrvanB2UWA/видео.html
For everyone wondering why physicists named the state spin-up or spin-down: I read about an experiment called the Stern-Gerlach experiment, in which electrons passing through a magnetic field were deflected either up or down. The weird thing is that there was no difference in the amount of up or down the particles were deflected. It is either all the way up to the top of the limit, or all the way down. Every time. This experiment was pivotal in demonstrating the existence of a quantized spin angular momentum state for subatomic particles. That's why they say spin-up or spin-down. This up/right stuff is about calculating the probability of the particle's spin angular momentum being one way or the other. Not the actual direction the particle will travel or spin.
Edit: added "I read about" to the beginning because I'm just a student and not an expert, and I feel it is disingenuous to portray myself as such, and I changed "atoms" to "electrons". I just now noticed that mistake...
really?;
Nice piece of information, thank you sir.
@@jeewansingh4060 that's my understanding of the origin. BTW, I meant to say "electrons" passing through magnetic field. Not "atoms". My bad
@@MrJdcirbohey Can someone clear my doubt,
If |a> and |b> are two basis states and the prob of both the states is 50% then we denote the total state of the e- as either 1/√2(|a> + |b>) and 1/√2(|a> - |b>). My doubt is, that the e- can also be in 1/√2( - |a> + |b>) and 1/√2(- |a> - |b>). Then why do we ignore these two states.
@@ruchi9917 when we measure probability we have to square the probability amplitude so in both cases you will get the same result. So we can take any one....
In the Stern-Gerlach experiment, what happens if the polarity of the magnetic field is reversed? Do the electrons that used to go Up now go down?
Really good explanations - thank you. Maybe, if you have time, you could ponder over how a wave of energy propagates through a wire, without radiating, (a transmission line) then how the wire ceases to be a transmission line and becomes a radiating antenna, then how the radiation leaves the antenna and launches into free space. [for instance you could ponder whether the 'electrons' are given a short ''jerk' (causing nature to wobble space) from the energy of the wave (or not)- [[is this combo electricity??]] Then, ponder how a distant antenna can 'pick-up' a wave (maybe concentrate on the magnetic and electric fields separately - and the respective geometry of each type of antenna?) and direct that wave back down a transmission line and into a detector (a good ol' radioset!). This would be a neat practical application of Maxwell in the real world. Maybe you could even do a series of practicals (unless of course you a theorist ;-). Thanks again.
Whatever is reflecting off of your glasses makes it look like you're wearing some hip
pinkish eye shadow
pink eyeliner... :0
I would look great wearing pink eyeshadow
😂😂😂
You've got the best RUclips channel about physics right now. Looking forward to your next videos!
Here is another great animation video channel. you would like it if you haven't seen his video yet.
ruclips.net/video/8F0gdO643Tc/видео.html
Can you suggest me few more?
Hey thanks for the video. I think "spin up" and "spin down" came from the Stern-Gerlach experiment where the electron from the silver atom either went up or down after the non-uniform magnetic field.Actually,even "spin" is a misnomer as an electon cannot spin on its own axis.It was suprising because the electron is supposed to be in the s-orbital for which orbital angular momentum is zero. Hence,it should not exhibit any magnetic moment and hence should not be affected by the non-uniform field. Instead, they found statistically the electrons exhibiting a quantized magnetic moment of two states. One set of electrons went up and the other went down depending on their spins and deflected by the magnetic field. Hence, S & G concluded that in there is another magnetic moment associated with the electron other than orbital angular momentum. This became a fundamental characteristic of particles like charge and mass.
Editing parth did well
I'm requesting for a topic .
" Bohr theroy and Energy levels of atom "
Why the enegry has to be discrete for a energy shell??
See about photoelectric effect
hi saddy
It is because when an electron jumps from a higher energy state to a lower energy state, electromagnetic radiation is emitted. Now, if the shells were not discrete, we would get a smooth spectrum of the frequencies of radiation. However, we see that we do not get that smooth spectrum. Instead, we get discrete lines. Hope that helps :)
Excellent work on these videos, I shall be sure to recommend you to my students. However a very slightly unfortunate choice on the direction of spins you label 'spin up' and 'spin down' in the classical case as, as a result of editing perhaps, they are the opposite of the usual convention (a right hand rule one). I doubt that this will matter to most, and your point is still well taken. I look forward to your presentation on spin itself as that's a notoriously difficult one to present in a clear way (I bet you can though!).
Is the vector you are talking about a spinor.and is that the reason for inversion of sign of spinor as the real vector is rotated through an angle of 360 degrees.( because of orthogonal states)
Looking forward to the in-depth spin video.
If spin states are orthogonal, why are there not 3 spin states?
Great question! Spin states are only "orthogonal" in a mathematical sense. We start with the fact that there are 2 possible results to our measurement (which in this case is the spin of an electron) and THEN we realise that quantum states behave kind of like vectors that are at right angles to each other.
If we took another measurement that had 3 possible results then we definitely would have 3 perpendicular vectors, i.e. in 3D. Equally if there were 10 measurement results of another measurement, then we would have to imagine a 10-dimensional space with all vectors orthogonal to each other. The abstract vector space is something we construct for mathematical convenience, not the other way round!
In this context, the spin states refer to the amount of spin. An electron has only two amounts of spin, always the same magnitude but can be clockwise or anticlockwise (up or down). So, a total of two spin states. Some particles have more. A photon, for example, has three spin states: 0, +1 and -1. The vector space in which these spin states are represented is not directly related to ordinary 3D space.
@@RAFAELSILVA-by6dy Esse nome é de brasileiro.. eita mundo pequeno
So is the representation of spin like the right hand thumb rule, used in vectors?
Kind of! It's a really close parallel, but you're definitely on the right track! A better 'Rule' for thinking about the Angular Momentum and the resultant Spin of an electron is the right hand Grip rule. If you haven't heard of it, take your right hand, point your thumb up, and curl your other fingers inwards towards your palm (Like you're halfway to a thumbs up). Now imagine that the direction your fingers are curling is the direction that the electron is 'Spinning'. Your thumb points Upwards while you're doing this- Spin Up!
If you want to imagine an electron spinning the other way, turn your hand upsidedown so your thumb is pointing to the floor. That's Spin Down, and if you imagine the way your fingers are curling is the direction of the spin, it's in the opposite way!
The right hand grip rule is just another way to think about Orthogonality (Like the right hand rule!), but it's a bit more intuitive than trying to imagine spin with three fingers pointing in different directions.
Hope that helps!
Hey Parth, I love the hand-drawn text (procreate?). I don’t think your lighting is correct (I’m no expert) - the right Side of your face is dark. Regardless, I appreciate you and this channel!! Keep it up
Its better
You are amazing and you explain it in a easier way to understand so please put a video about s matrix theory please please please please please please please please
Keep making these videos, please. Your enthusiasm for physics is a pleasure to watch
Well, I always thought that the spin "up" and "down" convention came from the observation of energetic states of electrons on their "orbits" round nucleus. When electron shows a little higher energy, it would be linked to its spin up and if it has a little less energy (seems to be closer to the nucleus) it would denote its spin "down". Both are just clasic side effects of the spin, which were simply visible in detailed spectral lines of Balmer (and other) series. Was I wrong?
I think of it like that too!!! Somehow quantum mechanics isn't that straight forward though, me and you are extremely logical thinkers. Tbh I don't know if we are right or wrong, but all I know is that spinning (according to this video) is because of constant angular momentum which we don't know how it started.
Thanks for making all these great videos. You've even better than my physics teacher
The more I watch this video, the less happy I'm with it, sorry. Could you just explain which are the actual physical properties of spin as measured in labs? AFAIK electrons behave in two ways, as if having intrinsical magnetic polarity, when subject to a very specific experiment (Gerlach-something?) and they are also required to have opposite spin in order to circunvent the Pauli exclusion principle, maybe we could begin there, then explain how does that manifest in the probability wavefunction of the electron (or photon or whatever else, I'm particularly intrigued about quarks but guess it's the same).
Hey! It'd be cool if you make a video on the Netflix Dark series.
Hii Parth... I need your help in personal. I planned to pursue my masters in quantum computing in Waterloo,canada.. Which can i choose Ms math computer science -quantum information or Ms physics -quantum information. Im a computer science engineering graduate, working in an MNC in R&D dept... Pls do help me to choose the scope full studies.
How to thank you enough! I was reading chemistry actually and the whole idea of 'spin' messed up my mind. I googled a lot still was like-Huh?It's so confusing. Then I quickly searched your name and see-Ahha,finally he made a video!
Anyway-You'd look nice if you wear a pink eye shadow!
How does an electron have angular momentum without actually spinning? I do know that it is impossible for electrons to actually spin
If it’s not actually spinning, why call it spin? Can you describe it without using the word spin? Everybody knows what it is to spin. Can you describe what you mean by spin without actually using the word “spin?”
Great video Parth. I'm currently doing my A levels and this concept of spin is regularly skirted over in chemistry and physics A levels, but you explained this great clarity :) A quick request, could you please include more depth in terms of mathematical reasoning in your future videos. Thanks.
How did the Physicist find that Electrons don't spin though having Angular Momentum?
Great stuff. Suggestions: #1) Don't make references to videos and point somewhere when you don't put the links on the video itself. Best thing is to put your links in the description which is displayed below the video. Easy for you to edit etc. #2) if possible move your monitor to a 45degree angle to your face (but keep the camera head on). This means that you won't get direct reflection in your glasses (Snells law!). Maybe you have already tried this. At least have a play and see what looks good. Otherwise your videos are great and it seems that you have the backlighting and focus things sorted out. Great job!!
"it doesn't spin but it has angular momentum " Do we really know what it is ...?
Parth, friend:
The electron has two spin states, up and down. But for a particle which has a spin of 3/2, and four spin states, are those particles considered spin "up, down, left, right?" Or...?
Why z components are anti parallel?
In some books they are represented as spin up and spin down.
Can you please suggest a book or anything that I can find mathematical calculation of angle between spin up and spin down is 90 degree?
I thought that angular momentum direction can be determined by right hand rule. But you have it by left hand rule here ... I suppose you just did not care, you just wanted to explain the concept. Am I right?
I have come to enjoy your videos, but as an advice, you need to take some steps to improve their quality. You got rid of the straight on facing lights that were reflecting off your glasses, kudos, but there also some pinkish-red lights to your right coloring your eyes through the glasses. You have also dealt with the autofocus, great! Now it's time to reduce your involuntary clapping I think :) Thanks for a very nice video by the way!
6:09 My right hand rule!...
Seriously, though, even though they do use that kind of representation in Descriptive Geometry, it makes it much harder to do vector calculus if you don't keep your directions consistent. Like in quaternions and octonions.
You should have mentioned that this occurs in complex vector space. The overall reason for these facts is that the state space of a particle of spin s is a (complex) vector space of dimension d=2s+1. In such a vector space, one can only ever find up to d vectors which are orthogonal to each other; two general vectors are, of course, not orthogonal. Therefore orthogonality can not be visualized in our simple 3D world.
Basically because of convention it has to be opposite up/own left/right in/out but what I didn’t know was why they don’t name it clockwise and counter clockwise. And that’s because it’s not really spinning in that simple way. But rather has properties of the underlying chirality describing all reality.
How can you measure the angular momentum of an electron? Aren't they probabilistic wave functions? By the time its collapsed, you know its location, but not how much energy it has.
how you decide the line of axis of electron spin ? It
is infinely arbitary. to begin with an assumption that an electron has a configuration of a sphere is wrong!! since Bohr's atomic model with electron assumed as a spherical particle, everyone got stucked to that dogmatic idea.
Actually electron is a cuboid with 4 corner dots. each dot is like a point of origin with 3 lines in x, y, z or -x, -y, -z direction. There are 6 pairs of parallel lines connecting all the dots...and there are six surfaces or 3 pairs opposite surfaces of a cuboid of equal areas. Any one diagonal connecting any two corner dots would be the axis of a spin, either clockwise or anti-clockwise along the diagonal axis. if the cuboid is made to stand vertically on any of the corners and activated to a spinning motion by a force(photon) in a magnetic field, the cuboid electron will continue to spin in the presence of magnetic field due to magnetic induction.
infact all sub atomic particles including quarks, protons and neutrons are cuboids not sphere!!!
What if we can relate the spin of electron with that of right hand thumb rule? In Vector cross product, A×B we found the direction from right hand thumb rule. Also If the body is rotated in antclockwise direction then body produces linear motion in upward and similarly downwards in clockwise direction.e.g. If you roll the cap of the bottle in anticlockwise it will come up but if you roll clockwise it will come down. Similarly if the electron spins clockwise Angular momentum will be in downward direction and if anticlockwise it will be in upward direction.
Sir your Explanation is quite good.. But you're too fast in lecturing.. Some times we don't catch it..
i like parth g because he stix to proven facts. no nonsense math. unlike that other science channels that dabbles in philiosophy and speculation nonsense like string theory ...😡 and multiverse.
One question!! The representation of spin as orthogonal vectors..
Is it same as we represent potential difff across various elements in the LCR circuits..???
Why do electron spin around nucleus
The confusion comes from people not being able to decouple the two spaces - one is a spacial representation of the spin (which was irrelevant for the previous video) and the other (the one you actually used the orthogonal basis vectors for) where we represent the probabilities of finding the electron in one state or the other. So no, you can't call it spin up and spin right. As a matter of fact, the basis vectors selection is arbitrary, for all practical purposes we use orthogonal basis vectors, but actually we can choose any set of vectors that are not linearly dependent, i.e. non parallel.
What happens if you can stop the spinning or the movement of an electron? My guess is that it reverts to EMF waves. If we can stop an EMF wave, it may revert to nothingness or just energy.
We can understand spin of a photon by maxwells equation. Is there a similar possibility to understand the electrons spin?
6:11 Arrow should show downwards. Viewing from the top it is clockwise rotation and clockwise goes "into the plane"
So the charge/ magnetic moment of a charged particle is like gravitational waves because it makes flux in a field?
So what happens when you actually give electron some actual spin so the angular momentum created is opposite to electrons natural spin and thus they would cancel out. Would electron have 0 angular momentum? And is this used to measure the "spins" magnitude?
So do Spin Up & Spin Down electrons have the same energy in the absence of a magnetic field?
From what I understand there is an energy delta between the two states in a magnetic field.
When im high ur low,
When ur high im gone,
When im low, ur gone,
When ur low, ur high. Thats whats goin on. Dont think too much about it.
Sorry...someone said that the cause of all diseases is the wrong rotation of electrons or wrong spin direction. Is something like this even possible?
Great quality video as always Parth! :D
One video on explaining quantum states...
Please I know its quite some time but there is a doubt in an atom during emissions spectra there are doublets and triplets emissions lines that are explained on the basis of atomic spin now since these two lines have different wavelengths they must have resulted from different energy transition by Plancks hypothesis but electrons in same orbital wid different spin must have same energy so how is that possible.
You said spin comes into picture if think in conjunction with special relativity but what idea of special relativity results in consideration of spin ?
Demonstration is awesome, its beutifull sir.. Thank you soo much
I think you shouldn’t say I am not gonna talk about ... in this video. Try to explain as much as you can in the video
Thumbs up from me. The word "orthogonal" is what threw me. You said that spin up and down were orthogonal yet up and down are not orthogonal. Very good videos. Thanks.
John Pawlicki mathematically the dot product of the bra and ket are 0 and thus are orthogonal, and thus when representing spin up and spin down as vectors, since they are orthogonal mathematically as vectors, then they must be represented as 90 degrees. I think this is right but don’t quote me haha this was my interpretation.
Thanks for the great comment John! Glad I could clear it up :)
Interesting, How to get spin from relativistic quantum mechanics?
Just like how photons have an associated momentum, electron has its own angular momentum?
Isn’t it spin up and down since the stern gerlach experiment was designed an irregular magnetic field oriented so that a spin up electron deflected upwards and spin down deflected downwards
You said that there is a connection of spin to the special theory of relativity. Can you elaborate on it, or maybe give a reference...
How are dx2-y2 and dz2 designed and what does the minus sign as well as squared mean?
Does the earth actually spin on it's axis or is that angular momentum as well?
Maxwell's equations For The fuc*ing Win
How do you do your edit please , and thank for your videos really love them.
Why can't the angular momentum be spinning right or left?
Obtain spin up and spin down Spin wave functions for electron.
is mass and energy is same thing??
i know mass can be converted into energy and energy into mass
but...
but my question is, that, is they are same thing are diffrenent???????
E=mc^2 . Mass is that property of matter which interacts with gravity. Matter is made up of atoms which in turn are also made up of protons, neutrons and electrons. To maintain their stable configuration they hold certain potential energy. So, mass and energy are equivalent. They are like 2 sides of a coin. Same thing in a certain sense and not, in another. I maybe wrong.
Samir Patnaik What you have typed is pretty much correct, but I don't think it answers the essence of the question.
Is the spin of an electron (since its not actually spinning) stored or potential energy?
Next video. What is the difference between cold and flu.
How do you know that electrons are not actually spinning?
Can you do another video covering isospin?
In elementary chemistry we are taught that two electrons can occupy the same orbital if their spins are "opposite," i.e. one up, one down. This concept is further extended to explain the magnetic properties of atoms and molecules---that, for example, oxygen is paramagnetic because (according to molecular orbital models), it has unpaired electrons in separate molecular orbitals, whereas diamagnetic molecules have mostly paired electrons (everything being fundamentally diamagnetic). The beginning student is further encouraged to think of the "spinning" electron as a magnet. Opposite spins are then like two magnets with their N and S poles opposite to each other, and as with two real bar magnets placed together in that manner, the magnetic field is confined within the pair and does not affect space outside of the magnets. (As you might surmise, I've taught first-year chemistry.) Now this explanation of "spin up" and "spin down" in terms of imaginary magnets seems to work really well. Can you comment on how the orthogonal spin model relates to magnetism? How do these orthogonal angular momenta interact with each other so as to repel magnetic fields? Or am I speaking gibberish, reflecting the fact that I never had a really decent physics class?
That's the explanation for why this property was called spin in the first place. The spin produces a magnetic dipole moment analagous to a spinning charged sphere. And that's how it was detected: the unpaired outer electron of silver was used in the Stern-Gerlach experiment which demonstrated the quantisation of electron spin. Electron spin does not work fundamentally like a classical charged sphere. The quantisation is fundamentally not classical. Now, the Fermi exclusion principle means that two electrons in the same orbital must have opposite spins, hence their magnetic dipole moments cancel. A similar things happens with an electrons orbital angular momentum. For each orbital there is an equivalent orbital where the electron has the opposite orbital angular momentum. So, electrons tend to pair off to cancel the magnetic dipole moment from that. This leaves unpaired electrons generally as the source of any residual magnetic phenomena.
If you want answers to these sort of questions, you could try www.physicsforums.com, for example.
Orthogonal means that there is nothing "uppish" about down and there is nothing "downish" about up. So when we say *up* and *down* are "orthogonal", we are trying to say that they are as different from each other as any pair of states can be, with absolutely no overlap.
Think of an orchard that produces apples and pears. A given fruit is either an apple or a pear -- it can't be "a bit of each". Now think of a graph lableled "apples" on the X axis and "pears" on the Y axis. The graph can show a cloud of points, and each point could represent how many apples and pairs were produced in some year. So apples and pears are "orthogonal" in the sense that we can plot them on perpendicular axes that capture distinct things --- but there is no physical sense of up, down, right or left.
Now imagine that all the apples are produced in a place called the "North Orchard" and all the pears are produced in "South Orchard". We can still make the same graph, but with the X axis labeled "North" and the Y axis labled "South". Well, North and South are still orthogonal to each other in this graph, because a given fruit can't be produced partly in North and partly in South! This makes perfect sense in the context of this graph -- although you would be surprised if you saw a *map* with North pointing right and South pointing upwards!
Praveen b I hope your explanation is correct, because it sorta made sense to me
how spin is related with specail or general relativity?
Do a physics meme review 🤣🤣
Love your videos Parth! Hope you get better soon
As far as I understood, electrons (and other quantum particles) would only have angular momentum on one axis and the spin up or down only describes in which direction it would spin, right?
How would you know which axis it is in a 3D space and is it common across particles (or at least entangled particles)????
That's a fantastic question, holy crap! In QM, you know a question's good when the answer to it is very, very weird.
The reason why Parth said that electrons (and other fundamental particles) *don't* actually spin/turn around (but have an angular momentum) is that imagining a partical spinning on one axis implies there's only one direction its angular momentum can be represented (So you're right!). If a particle did only spin on one axis at a time, it'd be very hard to look at in 3D space. You'd have to align all the electrons on the same axis to have an 'up/down' Spin when comparing them, and that's a mess!
But they don't! Elementry particles *don't* have a single axis of spin. They don't spin in any particular direction- They don't spin at *all*. In fact, no matter /what/ direction you look at an electron from, it will always have an angular momentum of ħ/2 or -ħ/2.
Hard to wrap your head around, I know.
The reason why Quantumn Mechanics is separate to Classical Mechanics is because of ideas like this. Because of questions (like yours) that we can ask and get MUCH different answers to what we expect. If this was classical mechanics, an object spinning can only have one direction of rotation and, hence, one axis that represents its angular momentum.
But in Quantumn Mechanics a particle doesn't really 'spin' at all, it just has a discreet angular momentum that's the same (or opposite) whatever direction you look at it.
First time explaining something like this, so if it isn't quite enough, blame me not yourself!
Oh! And no, some particles have different values of Spin! All Fermions have what's called 'Half Spin' (1/2), and all Bosons but the Higgs have a 'Full Spin' (1).
@@kingfooddude8803 Wow, let see if I (kinda of) understood what you are trying to say:
Spin is not axis or direction dependant, so let's say that a particle would have an inherent angular momentum (despite not actually rotating) that is uniform on all directions, meaning that it would have for example the same angular momentum on the x-positive and the x-negative axis, and spin up or down would actually refer whereas that angular momentum is outwards or inwards?????
Some thing like L (phi, theta) is actually a constant (or a super position of 2 opposing constants until its observed) hahaha.
I probably got it wrong, but only that act of trying to warp my head arround it is entertaining xD
@@in3kro274 Super close! Your first statement's correct; the Angular Momentum you observe in an electron (From ANY angle or axis- It won't change), will always be the same, and will always either be (Not inwards or outwards) *positive* or *negative*- That is, either *towards* or *away from* the direction of the observer.
The video explains part of the story of electron spin, but of course there is more. The electron has a fixed total spin. If you measure its spin about any axis you get exactly 1/3 of the total spin. The direction of that spin can be clockwise or anticlockwise (up or down). If you then measure spin about another axis, again you always get 1/3 of the total spin, and again either clockwise or anticlockwise. This is very different from the Earth, say. If you measure the spin about the Earth's axis, you find ALL its spin. The electron spin is really what quantum is all about: you get fixed, quantised values for certain measurements. No matter how you measure an electron you always get a fixed amount of spin in the chosen direction. The only degree of freedom is whether the spin is clockwise or anticlockwise.
how is spin a consequence of special relativity
Sir,, I did not understand it properly
This one was unclear for me. You're saying the directions must be opposite to each other (for reasons you explained), but why are they represented as right angles?
That's all explained in my previous video about the Language of Quantum Physics! Check it out here if you have a minute (or 15 lol) ruclips.net/video/payp7simhBM/видео.html
How many spin state Cu+ and Cu2+ have?
Can you explain Special Relativity in a clear way?
Sounds good, Maybe you could add that regardless of the axis being measured there are only two possible outcomes. spin up or down.
Sir can you make playlist on spin please?😅 It's really confusing to find videos on spin...
I really want to know the answer...
What happens to the atom if the spin of the electron is 1 ?
Stern Gerlach Experiment.... This single word , can explain the full video with much deeper understanding...Hi Parth , I am naveen from India..... I like to say... The perspective of explanation can be more of why and from which experiment people calling the spin of electron .
lorentz transformation and the inverse of it
Why does light have a speed limit? Why not 2xC....3xC...4x
Not exactly a question humanity can answer right now, if ever
Good explanation. For anyone still struggling: It is important to understand that spin up and spin down is represented with two orthogonal vectors becouse once you measure some random Electron and it turns our to be spin up IT CAN'T BE spin down. This is how the word "orthogonal" translates into the abstract space. Orthogonal means that getting spin up is mutually exclusive with getting spin down. Just like two arrows forming 90 degree in the common R3 space are linearly independent.
How spin is connected to relativity
Make a video about Noethers theorems.
Will a static electron have intrinsic spin?
Clockwise and anticlockwise!
What's the tune at the end of the video?
In retrospect it was probably covid-19, as it now turns out it was circulating globally in December.
A topic i would like to request:
1. Electron flow at temperatures near 0 deg K. For a given material, is there a certain temperature, below which, super conductance happens? or is it a gradual decrease in conductivity?
Was waiting for this for long time
Finally got it...