The beauty of Schrodinger's equation is that the principal quantum numbers emerges naturally out of the equation and not from any presumption. That's why the Schrodinger equation stands tall as one of the greatest achievements of human understanding of the natural world. Some of the others are Maxwell's 4 consolidated equations (you will see them embossed in brass in one the aisles at the MIT building) completely describing the Electromagnetic force, Einstein's field equations, Special Relativity opening the gates to the Nuclear power/weapon etc).
Schroedinger's equation is a non-relativistic approximation. It's more or less the endpoint of physics to a chemist, but to physicists it's mostly an irrelevant blip that was obsolete after a mere two or three years. Conceived in 1926, it was replaced by the physically far more important Dirac equation in 1928 as the center of attention. Schroedinger's equation is like Newton's definition of force, deceptively simple and completely false.
@@schmetterling4477 I think you could say that about all of physics (as known, understood, and decided by humans)... "deceptively simple and completely false" 😁 Also, most chemists who actually need to use equations definitely learn the Dirac equation. Schroedinger's is just a fun and rather consistent way to reason molecular orbital theory as used by many chemists that don't do so much math. It's still a pretty equation that models nature quite well
@@mississippijohnfahey7175 Yes, and as a physicist I do. All of physics is an approximation. It's not absolute truth. We teach that in university level physics either in the first or at the beginning of the second year. Truthfully, we should be teaching it in high school. Not having absolutes is the strength of the scientific method. Being able to work with errors and handicaps is incredibly useful in the real world. Being able to question old lore is absolutely necessary. That's the difference between science and religion. Science adapts to new facts, religion piles up wood to burn the critics. What would you do with the Dirac equation in chemistry???? None of your systems are relativistic. All you really need are the spin rules for fermions. You never try to calculate the energy shift caused by inner orbitals from fist principles, either. As far as I know not even x-ray scattering calculations are done at that level. Schroedinger doesn't even conserve energy, momentum and angular momentum. It's a toy model. The only reason why we use it is because the real theory is absolutely unwieldly.
@@schmetterling4477 you kinda answered your own question, lol. It has flaws, so the more correct equation is preferable when those flaws become a nuisance. But really the Dirac equation is mostly a stepping stone to QFT and thus QED, which is useful to a lot of chemists. If it weren't for relativistic effects, gold would look like silver--or at least if it weren't for relativistic corrections, we wouldn't be able to explain gold's absorption of blue-ish wavelengths
@@mississippijohnfahey7175 Or "deceptively simple and… not very useful in practice", because as soon as you try something more complex than single-electron ions (like multi-electron atoms, molecules, bonds, resonance structures, crystalline grids etc.), you immediately discover how ridiculously complex the equations get, and pretty much unsolvable in exact terms with our current methods of solution, and even numerical calculations might be very complex unless you make some serious simplifications and settle for some mere approximations of the real phenomenon :q
"You can share answers before clicking in. It's not cheating. It's teamwork." I really REALLY like Catherine as a teacher, I wish a had a teacher like her in my chemistry course at university, she is really motivating and, for example, I think that this "teamwork" approach should be the standard way of thinking in academia, because ultimately that's the way you do research, and as a student it allows you to learn a lot more because you can a lot of different points of view.
wow, I've been looking for some quality lectures. I wish I would have stumbled upon these two months ago. Catherine, if you see this... I appreciate you.
I'm interested in quantum physics but I have never taken any courses. This teachers explanations are so clear to be understood by self-learning people like me. Thanks a lot
E = hc/lamba we can simplify the calculation by using formula E = hc/lambda = 12400/lambda energy obtained here is in electron volt and lambda used in angstrom Short formula to solve the energy
I always get that chance to abuse my male teachers. I m not student anymore. I m like Dynamo magician. Although youtube gives better lectures than class room.
Really enjoying these. I had freshman chemistry, and freshman and sophomore physics, and the professors were okay, but this instructor really puts things together in a way that's really helpful. Plus, I've had 32 years to think about it all, since then. Thanks, this is a real treat.
Vvvv:vvvvScientists think the largest solar storm ever witnessed during contemporary history was the 1859 Carrington Event, which released roughly the same energy as 10 billion 1-megaton atomic bombs. After slamming into Earth, the powerful stream of solar particles fried telegraph systems all over the world and caused auroras brighter than the light of the full Moon to appear as far south as the Caribbean.Scientists think the largest solar storm ever witnessed during contemporary history was the 1859 Carrington Event, which released roughly the same energy as 10 billion 1-mega:ggton atomic bombs. After slamming into Earth, the powerful stream of solar particles & :v:v:vv systems all over the world and caused auroras brighter than the light of the full Moon to appear as far south as the Caribbean.
These are the best lectures on this topic. She makes learning such an easy process and I love that that the profs at mit always have such great experiments to supplement their lectures
@@michaelrislingnb306 There is no wave-particle duality. That's a 90 year old boondoggle at this point. She also doesn't know what the Schroedinger equation is. Look, people who are stuck at the level of non-relativistic quantum mechanics rarely take the time to research the actual theory. You are basically given a time-slice of physics here that was obsolete by the mid-1930s. Now, if this was a class on the history of physics, then you would learn something. It's not. You are listening to a class for chemists and even chemists should be taught the modern facts.
I believe it has been shown experimentally that with very high light intensities, it is possible to see a second-order photoelectric effect whereby an electron can be ejected by simultaneously absorbing two photons which each have less than the normal threshold energy.
@@schmetterling4477 Why be rude? The person is just expressing their appreciation. If you know of better, then why not just suggest it, and help others?
She's a great lecturer, but as a physicist I have to say she's saying a lot of wrong stuff about the particle nature of light. For example, she says in 19:30 that from the photoelectric effect we understood light has momentum. This is not true, as early as 1865 when Maxwell understood that light is an electromagnetic wave, it was shown that it has momentum, and the relation was p=E/c. Einstein just said "well, if a basic energy unit of light is E=hv, then there is also a basic momentum, p=h/lambda. She has other mistakes talking about photons, but if you ignore this specific thing which is more physics than chemistry, she's really a great teacher!
Feynman’s comment about the equation came from Schrodinger’s mind was mainly to stress the fact that, like F=ma is not derivable, the Schrodinger’s equation is a new First Principle, which is in principle, also not derivable. There are actual a number of ways to “derive” the Schrodinger’s equation, based on the wave function proposed by de Blogie. One however needs to be reminded that those are really not actual derivation. The Schrodinger’s equation is the first principle, which is not derivable and would naturally yield Newton’s second law F=ma with macroscopic approximation.
F=ma is derivable from other, deeper principles of mechanics and in a good textbook on theoretical classical mechanics it will be derived. The problem with Schroedinger is fundamentally different. Unlike the equations of Newton's theory it is not a physical equation and can not be made into one. It works well for a handful of cases, which is why we still teach it, but it does not give us a hint about what is really going in. That's why physicists abandoned it almost as soon as it was published.
I'm not an expert at all, just a fanatic who loves re-observing the Schrodinger Equation. But, every time I look at the Schrodinger Equation, and I see the following equation from the Schodinger Equation: Kinetic Energy + Potential Energy = Total Energy I just wonder if Erwin Schrodinger thought the following: "Okay, particles have wave-like properties... so let's add in a wave-function, Psi(r,t)... Alright... how do we even solve this equation?" **Looks at a bunch of different experimental Results** "Okay... the potential energy is mostly spatially dependent... but the kinetic energy is "wave-like" in nature... well... how do I limit the spatial and temporal components to include the wave-like nature of kinetic energy and solve for the wave-function?... there must be an e^{i*r} to include the wave-like nature... but momentum must be wave-like... How do I solve the Kinetic Energy given the wave-like nature of momentum of a particle?... Well... 'i' is cyclical by nature so that must play a role... (p_hat=-i*h_bar*Del)..." I am definitely unsure how Erwin Schrodinger came up with this solution still, unfortunately... But I am guessing a little bit...
i had this all balanced out and forgot it from lack of use over time working to pay off my student loans now am 58 now i have quantum memory flash back neither off or on functions are the same active memory or latent atrophy
I am surprised how as opposed to the kilometer the mile as a unit of distance is mentioned in college technical courses in the US. Here we have miles being used to in the same breath with meters.
A negative exponent scientific number, 1.0 x 10EXPONENT-2 = 1/100 = 0.01, may undermine your solution, since a negative and hence positive for meaning concatenated aspatio-temporal unique number, breaks the law of non-contradidiction : nothing is it's opposite.
Why add a decimal point to whole numbers and why represent frequency with the archaic v rather than the much clearer f? And for God's sake pronounce de Broglie correctly.
@@schmetterling4477 Frequency is frequency no matter what letter you use to represent it. Instead of just memorizing symbols and conventions (which are arbitrary and irrelevant to the phenomenon anyway), it's better to understand the formulas and what these symbol represent.
@@schmetterling4477 I'm not sure how did you get that PhD (assuming that you really have one) without the ability to read and understand simple text. I can go with whatever notation is used, and that's what my previous comment was about: that notation doesn't matter, it's the ideas behind it that matter. And I could bet my tail that I understand physics better than you with your PhD, considering that I study it for decades.
@@bonbonpony I got that PhD by doing my homework, whereas you don't even know what the word "particle" means in physics. That's first year material. ;-)
I knew an experimenter who used half transition energy photons to excite helium. Helium was at high temperature (high thermal energy) anyway so doppler shift was a problem. Half his photons hit a mirror at the back of the cell so Helium would therefore occasionally be hit simultaneously with two photons from the laser, one redshifted, one blueshifted, and together they added up to the transition energy. Or do I remember it wrong?
Pour la démonstration de l’équation de Schrödinger je vous conseille le merveilleux cours de physique quantique d’Etienne Parizot sur You tube (notamment le cours 19).
If the speed of an object is close to zero, the wavelenght should be detectable then? Isn't it in contradiction with what we observe everyday? (stationary objects do not appear wavy...)
The wavelength is detectable, it just takes a bit of experimental technique because it is small. So, yes and no. Can we make it visible? Yes. Can you see this in your everyday life? No.
@@schmetterling4477 why would it be small? First, the speed depends on the observer (which already seems weird, cause it means the size of the wavelenght changes with the observer's speed, but fine). So we can make the wavelenght as big as we want. If I observe a car with 30km/h spped, I just have to go at 30km/h myself, the car would seem stationary to me, which means its speed is 0, which means its wavelenght is infinite! We don't even need to be exactly the same speed, just close enough and the wavelenght would be big.
Over simplified Generalization sometimes causes massive compton effect How the qantum dot made? if smaller medium leave the space then smaller dots are arranged. If larger medium leaves the space between ? guess what
The Schrodinger wave equation may have come from his mind as Richard Feynman said but the spark for that thought came from Prince de broglie's proof of wave particle duality. This I read somewhere about the history of quantum mechanics.
You don't have to believe all the bullshit that you read "somewhere". Schroedinger wrote a series of five papers which are convoluted as heck. If you want to know what he was thinking then you need to read those.
That lines up with what I read. A modern physics book I have said that Schrodinger's equation can't be derived from first principles. Rather, it's a fundamental equation (like F=ma) that has a basis in experiment and is thought to be universally true.
@@bonbonpony The Schroedinger equation is a non-relativistic quantization procedure. That's QM 101, usually a second year topic. ;-) And, no, most Schroedinger equations are not even physical, hence they are not "universally true". They are toy systems for children to play with who are not experienced enough to do quantum field theory. ;-)
@@schmetterling4477 I don't understand what your comment means but he basically did not like the implications of his own equation. That is why he came up with Schrodinger's cat to show the absurdity of a cat being alive and dead at the same time which does NOT happen. He is quoting as having said that "I wish I had nothing to do with this quantum mechanics!"
@@isonlynameleft Just what I said. Nature didn't give a hoot. Schroedinger's cat is just a folly. He basically failed to analyze the physical situation he proposed correctly. It came way too late, anyway. At that time people had long moved on to relativistic theory which has none of the inconsistencies of nonrelativistic quantum mechanics.
What if there are no electrons to eject but E is greater than Phi? Does the photon turn into kinetic energy (as heat) as if one were to shine IR light on the metal?
Photon have relativestic mass Using equation E^2=(mc^2)^2+(pc)^2 Photon have relativestic mass m=p/c. From de broglie relation momentum of photon is p=h/lambda
everything has mass nothing is massless in this universe its just that its mass is soo small that we pefer to neglect itand so it makes the momentum very small
13:06 was she assuming that a metal surface's threshold energy is lower than the laser pointer's energy of the photon? i'm confused, do such laser pointers exist whereby exhibiting such high energy photons? or what about very low threshold energy metal surfaces?
I wish I had a brain that could fully understand all this. I admire men like Bohr, Einstein, Shrodinger, Heisenberg and professors like her. Wasn't born with a brain that can think like this.
it’s not really about being born with a good brain any average person can understand this if they have the right prior knowledge, if you go into this lecture with zero understanding of physics or the basic structure of atoms of course it isn’t gonna make sense
You _do_ have a brain that can fully understand all this (and more). You just have to use it the right way. When I was in school, I was always bad at math and physics and I thought that there's something wrong with my brain too, and that I will never be able to understand it. Then, after my formal education ended, I started learning this stuff again on my own, because I needed it for my work and my hobbies, which quickly became my passion, and now I'm good at math, physics, chemistry, and more. I found better teachers, better sources of knowledge, better textbooks, than my schools could offer, and then I realized that there wasn't anything wrong about me - it was something wrong about my school teachers: they simply couldn't teach, because it wasn't their passion, and because they didn't understand well enough what they taught. From confusion you can only get more confusion. Someone who doesn't understand a subject well enough, cannot teach it well enough for other people to understand it either. So start from finding good teachers for yourself. As for the video lectures that you commented about: If you watch such a lecture and you feel that you don't understand much, it is probably a sign that either the teacher is teaching it poorly, or you don't have some important prerequisites for the material presented (i.e. there might have been some other lectures before this one that you missed where these things have been explained). But if you watch from lesson 1, and you still don't get it, start noting down every term that you don't understand. Then pause the video (either after the first unknown term that you encountered, or after collecting a bigger list of such terms), and start looking them up. You'll probably find loads of websites, videos and books that explain it, some of them might still be hard to understand, some of them might be easier, so start with those that you understand. And if you encounter another thing that you don't understand, then repeat this process again, recursively. Follow the trail of unknown terms, dig deeper, until you get to the roots that connect with what you already understand, and then trace back to the thing that you started with. It also helps to draw a map of these unknown terms and how they are connected, because then it will be easier for you to see what subjects you have to update your brain with.
The speed of a baseball can be chosen to be sufficiently low so that the De Broglie wavelength of the baseball is equal to the baseball diameter. (diameter = Wavelength = h/mv, v = h/md). The energy of that wave is very low as the speed is low so there are few quanta/sec. Have we observed that radiation? Probably we need to supercool and block all noise radiations....
The thing is, "sufficiently low" speed depends on the observer, so even if you don't supercool, for some observer, the wavelength of the baseball could be in the same order of magnitude of the baseball size.
Actually the photo electric effect is not a proof of photons. You can describe that phenomenon with a classical electromagnetic field and the Schrödinger equation. Lamb published a paper about this misconception: ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19680009569.pdf Btw Americans are so ignorant about pronouncing foreign names.
@@ZigSputnik I can try to give you the idea as a non-native speaker. The point is that you need quantum mechanics to describe this phenomenon (you don't have a chance to describe it classical) but you don't need a quantized electromagnetic field and photons is what you get if you quantize the electromagnetic field. To release electrons out of a metal you need a minimum energy W. This energy can be provided by an electromagnetic field. However, the observation is that the field needs to have a minimum frequency. If it is below this frequency you can't release electrons no matter how high the intensity is. What you can do is to calculate the transition probability that an electron in a metal with a classical electromagnetic field that acts on it will be released in a small time frame dt. This is where quantum mechanics come into play. By these calculations you figure out that these transition probabilities are almost zero if the frequency is smaller than W/h with h as the planck constant. Note that there is no need for a quantized version of the electromagnetic field in these calculations. I am not sure how to illustrate this without calculations. At least you need to have a deeper understanding of quantum states and how they change if you apply a field. I don't know your knowledge. If you understand a bit of quantum mechanic calculations you can take a look here. www.physikerboard.de/topic,52217,-faq---zur-interpretation-des-photoelektrischen-effektes.html It is German though but the equations are understandable internationally. Very important in this regard is Fermis golden rule en.wikipedia.org/wiki/Fermi%27s_golden_rule I am a software engineer who happened to study theoretical physics. Therefore I have a bit knowledge in this stuff.
great instructor but lousy explanation of the experiment. Was the E-meter neutralized, because electrons were ejected fron the zinc plate thus lowering the charge ?
You need to understand that this isn't a complete chemistry course, it is more or less an introduction to it and she has to stick to her syllabus lmao xD. So I am gonna say what my Chemistry teacher told me, If you want specific details, please research and share the details with me too xD
You can always tell a good scientist from a bad scientist by turning off their smartphone :) Just watch as they forget half of their important knowledge and are no longer able to calculate anything without their Internet access ;) (while the good ones can still re-derive all the equations and recall the constants that they need)
Neither light or matter are particles. She does not actually understand the topic she is teaching, but then, she is teaching physics to chemists. That's a lost cause, anyway.
She is a full professor at MIT. Her specialty is to “visualize” molecular processes by obtaining snapshots of enzymes in action. chemistry.mit.edu/profile/catherine-l-drennan-2/
16:15 so is there a particular metal, if not the metal in the detector used in the demonstration, that is suitable for shooting lasers at that would cause effects like motion?
I just did my grade 11 physics class and barley passed with a 62% so I am not very smart. But this is not very complicated, like I would fail if I went in right now but if I do my grade 12 corse too I could probably understand and pass a class like this.
Mike Fuller In no way the supposed intelligence of the students inhibits the comparative simplicity of the course. Also, it's too presumptuous to call - if indirectly - people stupid just because they barely scraped by high school physics - that's stuff is too often bland, and monotonous, and tiring.
@@vincent-of-the-bog Lack of knowledge doesn't make people stupid. But lack of willingness to learn that knowledge and being proud of it definitely does. Stupidity is always a choice, and not a very virtuous one, for that matter. Unfortunately, a very popular choice these days, especially in some parts of the world :q
JEE aspirants after seeing this video: pathetic (we have this topic in our 11th and students are made to solve 100s of questions on this topic and remember all conversions) sry if it was offensive
That is Indian education, You won't be provided with anything where as EVEN in M.I.T you have conversions provided. Tbh for JEE, this is a good series to understand the concepts but by no means is enough xD it just makes reading books easier
1.How on earth the plate will be negatively charged, if it is ejecting electrons? 2. You've said it is about Zn, but then this guy talks about Aluminium plate. Why?
If they can't tell what an electroscope is, why do you expect that they'll be able to distinguish zinc from aluminium? :q They were measuring results for a totally different phenomenon than the one for which they made calculations, so they got answers to a totally different question than they originally asked. But who ares - the "detector of some kind" goes brrr! SCYENS! As for your first question though: They electrify the metal plate with that plastic rod that the dude in the red shirt had previously rubbed. This transfers additional negative charges (electrons) onto the metal plate, and since the plate is connected with the electroscope, it makes its needle deflect by repulsion. Once the UV light shines upon the plate, it gives those extra electrons more energy and they can escape from the plate, discharging it (making it less negative, as the extra electrons, negatively charged, escape from the plate), and the electroscope's needle is no longer repelled and goes back to its normal position.
MethÅ it just the space/time in EPR bridge court in time like a photo. that was discovered by a plumber. some history they put all the real knowledge in plumbing as they do not know how to use it…. lol. Good luck in finding what you’re looking for
@@abdirahmanali8939 There are no stupid questions, but there are definitely stupid answers. And if cheating is OK, soon everyone cheats instead of learning, and we get people who see an electroscope and cannot name it ("a detector of some kind"), and who cannot distinguish zinc from aluminum, and aren't even aware that they're looking for answers to a totally different question (threshold energy for a totally different metal than the one for which they made the calculations).
How does she dare to mispronounced “Schroedinger”, never heard anyone pronouncing the “g” as j !! Ok, chemists, how do you even dare? It’s like you heard about him the day before
@@bonbonpony Well I'd have to watch it through again and it was a year ago that I watched it. What were the other (or just a couple of the other) mistakes?
@@ZigSputnik I pointed out some of them in other comments under these videos, but to be frank, if I had to correct them all, I would have to write an entire article several pages long, and I don't think that RU-vid's comment section is well suited for such lengthy texts. And even if I did take my time to do that, there's a strong likelihood that my comment would just get deleted by people who run the channel, because that's what usually happened to such analyses I did in the past on other popular educational channels.
