The sign of a great mind: he does not reject any of the stupid questions asked. Instead, he adjusts or augments them, first to validate the questioners and then to create meaningful answers from which he can continue and develop his arguments. UA-cam gives us the opportunity to learn from the best teachers of all ‘recorded’ time. It’s great!
Funny reading your reply verbatim .. At least in the context hindsight of the Challenger inquiry. Obviously I never knew him .. but I always liked to presume him a humble and approachable man. I still do. Though you can't help but belly laugh .. you just know he was setting them up as if an evil chess master with a giant fly swatter with that freakin' bit of o-ring and glass of water - not that they didn't entirely deserve it.. best reality .. actual reality .. TV moment ever!
It's 4:00am and I just finished the first lecture and now I'm starting the second one. God I'm glad I'm retired. I'm gonna wake up around 1:30 today...and look for more.
deltavee2 You can watch PBS Spacetime’s video called “The speed of light is not about the speed of light” It pretty much says that the speed of light isn’t about light but causality. And causality has a maximum speed limit which happens to be what we call the speed of light. I do need to do more digging though since this idea doesn’t sit well with me.
It's wonderful how he continually resists explaining what nature actually is. Our work can describe what will happen in some situation, but it won't tell us actual truth. He was able to live with uncertainty, how very rare.
Physicists don't live with uncertainty as much as they live with ambiguity. That's a much more interesting concept. You have to allow for multiple, sometimes equally good, explanations of the same phenomenon.
Anyone who can explain the laws of quantum mechanics by using terms like "adding arrows" instead of the 10th grade math term "vector" is truly brilliant.
I like how he is humble enough to say that this way of doing it is the one that works with every experiment man has come up with to date (when he answers the student at the 1hr mark). He does not arrogantly say that this is the only way of understanding the concept but rather leaves himself open to the possibility of something else being discovered in the future that could disprove this.
HI!! I AM so thankful... and so I make this message for You, mrtp:) ThankYou for propagating this beautiful lecture series! Im not a scientist, but a mere layperson whom is stricken with gratitude & curiosity towards "Reality", whatEver IT IS!! Years ago, before I'd even known of Mr. Feynman, I had a profound dream. In the dream I saw a written language that was based upon combinations of hexahedron shapes that were interlocked together in a way that I instinctually knew to be some kind of magnificent intelligence! The reason I'm saying all of this is because when I discovered Richard Feynmans diagrams, for whatever reason, they INSTANTLY referred me to the memory of this dream, and also to the inherent beauty of the dream and intelligence involved for this experience of being.
Richard has the patience of a saint. I would have taken that guy who thought he knew everything and kept interrupting and kicked his butt out into the hallway.
Little knowledge is dangerous. That attention-seeking guy was blocking himself from learning. RF was extremely patient and didn't let the focus to be lost.
Dr. Feynman's capacity for intelligence, explanation of the abstract into concrete examples, his humility, his patience, and his Renaissance variety of interests probably made him the greatest Science teacher of the 2nd half of the 20th Century. Feynman's lectures will be remembered for Centuries in the future while his well deserved Nobel Prize will be a historical blip..
Interesting how some of the student(s) are in more need of the attention and control of the teachers acknowledgement than others in the group. Feynman, had the patience of a god.
In that question where you are asked who you would sit with and talk with from the past if it was possible mine would be Feynman. If I was allowed a second it would be Bertrand Russell
Another sign: he recreates the context and thence the questions as great scientists like Newton would have asked them. It might all seem obvious because we have the answers Newton and others gave us. But what if some answers were wrong? Then we live with those mistakes until Feynman types come along, spot them and develop the corrected answers. And these Feynman types are lucid and simple in their delivery of arguments. They’ll tell you that if they can’t do that, then something is probably wrong with their arguments. From this basis, they are able to build up theories of great complexity that can always be deconstructed as long as you , knowing at all times where they were and where they’re going) no matter how complex they become. They never lose sight of those ‘dippy rules’ he refers to.
It didn't take Feynman to point out problems with Einstein's messed up model of light quanta. That had happened much earlier. One can argue that by 1928/1929 the worst cracks had been filled by smart people like Dirac (who was Feynman's advisor, I believe) and Mott. Feynman basically just screwed the lid on Einstein's quantum coffin in 1948. As you can see from the timeline, though, the major insights had been available way before him.
44:40 the guy in the audience says 'like a big bean' for Venus and quick as flash Feynman says "maybe you'll figure out it's a big arrow'. This works on multiple levels and took me like a minute to think through and Feynman took like 1 second. The man was a genius
I am desperate to find a copy of the audio version (90minutes ) of these 1983 workshops .SoundPhotoSynthesis apparently has gone out of business and I don't know who else would have a copy .
It's similar, except that he is talking about the quantum mechanical version. Since the result of the quantum mechanical calculation and the classical calculation are identical for this case, there is little that one can learn from his approach.
How exactly is it quantum mechanical about his approach? What is the subtle difference that I’m missing out here? Say if he didn’t mention that it’s quantum mechanical, would anyone be able to tell the difference?
@@jadongao2880 What you are missing here is the proper mathematical expression for the path integral, which is an infinite number of nested integrals. One could look at the Huygens-Fresnel principle as an early precursor of Feynman's path integral, except that it does not contain the complex exponential of the classical action, yet, so it's not a proper quantization procedure. Other than that the basic ideas are similar. And like I said, for non-selfinteracting bosons the classical theory and the quantum mechanical theory are very, very similar, which makes light a very poor system to learn QM on.
I guess that's a bit of a shallow explanation, but one way to think about it is that intensity is the energy that permeates a surface over time. Now, light wave amplitude tells you about the energy content of the electric and magnetic fields. The square of the amplitude, multiplied by a proportionality constant gives you the intensity of the light. If you think about what intensity means for a stream of particles that travel with wave like properties, then you can imagine the places on an absorbing surface that have the most particles hitting is the place of the greatest probability of finding a particle. I hope this helps, I'm a materials scientist, not a physicist so I might have some things wrong.
The part at 25mn (reflection on glass depends on its thickness) and especially 28mn (an even surface would reflect some value between 0 and 16%, but in usual every lives the surface is not exactly the same thickness everywhere and we get the expected 8% overall) makes me thing about Hubble and James Webb telescopes: Do they purposely so uneven surfaces to not fall into the trap of maybe having a lower reflection? or on the contrary aim for the double reflection value? (probably can't aim for it as several different incoming wavelengths will need to meet different thickness to be reflected at the maximum value...)
22:55 Why would a proton get reflected from the "back surface"? I feel like the "back surface" wouldn't be a surface of glass to a photon that reaches it from *inside* the glass. Wouldn't that be the surface of the *air* below the glass. Otherwise, I feel this would mean that the glass in a window has four surfaces: two outside surfaces and two inside surfaces? Or billions of surfaces - one at every single point in (or layer of) the glass?
The surface is an illusion. It has no thickness, it's just a point in space between two materials. The light particles simply bounce on the irregularities between the two materials at that point.
Proton backscattering occurs when a high-energy proton encounters a surface, such as a solid material, and interacts with the atomic nuclei in the material. The probability of proton backscattering depends on various factors, including the energy of the incoming proton, the angle of incidence, the type of material the proton interacts with, and the atomic composition of the material. This phenomenon is essential in fields such as nuclear physics, materials science, and particle interactions, where the behavior of high-energy particles like protons is studied in detail.
The environment was uber inquisitive but in my opinion in a very positive way. "We never free a mind once it's reached a certain age. It's dangerous, the mind has trouble letting go." -Morpheus (in The Matrix, who knows whether it was positive definite or not...)
The next time you go to a bank look through the extra thick glass/acrylic panels between the tellers and the lobby, this will make plane the change in photon trajectories that thicker reflective surfaces can have.
what if the material was the composite, fiber optic i believe, that is made in space to prevent this very thing from happening? its made in space to reduce the "drag" on the light. you may want to look into this material. also, it could possibly be that its lined up exactly and the crystaline structure is responsible for the electron bouncing back? maybe i will think further and more thoroughly about this.
Time seems to be a factor in reflection of light. Hear me out. Is it possible that if time is in fact a factor, could it be that the atoms in the material do something a x time that causes collision and thus "reflection"? Photons have no charge AND they have no mass, however when they slam into your skin you can feel the transfer of energy that happens on this collision. Is it possible that the jiggling of the atom stops or harmonizes for a billionith of a second and when this occurs the photon slams into the atom and is either rebound OR obsorbed and a new photon is created and shoots of in the direction of the source of the first photon..
So is Feynman's ''grating'' a polarizing lens? And are gratings used in night vision goggles to isolate a single wavelength of light for greater reflection?
2:13 "We really don't understand it very well..." This was Feynman being charmingly self-deprecating to an audience he assumed was generally well-educated and take the understanding of classical physics as assumed. This recording played for a generally ignorant audience will have the unintended effect of giving them the idea that reality isn't well understood. This is generally false. Or rather, our profound ignorance kicks in well below the threshold of our senses, and at the extreme boundaries of our instruments - at the scale of individual atoms, and smaller. So when Feynman speaks with humility here, he's not speaking in general about physics, he's speaking specifically of the tiniest scales we can do experiments with.
Basically the same response Teller had to an Einstein lecture. Einstein, seeing Teller upset after, asked him why. Teller felt stupid, and told this to Einstein. Einstein told Teller: Stupidity is the human condition. (Edwin Teller went on to become a giant among giants)
1:07:08 ......."these are irrelevancies" and "if you try to make the model too correct, it isn't gonna be right for some other question". and that's why it's a theory with strong competitors. but the competing theories don't have 90 years of the world's smartest people having worked on them.
If we as spectator physicists like us have spent so much time considering alternative theories and interpretations, how much time must the world's smartest people, who devoted their entire lives to physics, have spent puzzling over them, especially knowing that with their clout and mathematical backgrounds, they could piece together something worthy of a Nobel? The marginalized theories haven't been ignored, they've just consistently refused to bear more fruit than standard QM, QED, and QCD.
He should have had the troll ejected! Obviously this guy was interfering with an elementary discussion to make himself seem more "intuitive" than he really is. I am unsure what he thought he would accomplish? Impress this man? Lmao
Although he was definitely interfering, maybe he was just being curious? Why assume his motive was a need to impress? Before ejecting someone for asking questions, maybe kindly ask to continue the lesson and end the tangent as Feynman actually did? Rme
Stupids ask if this and that. They think that,s smart, but its stupid. At the end of the lexture they talked so much rubbish, that they didnt learn anything. Wise men hold their mouth and learned someting.
Brilliant? Richard feynman is considered one of the greatest physicist ever in the history of science.he was a genius,problem solver.!! He is the icon most of the theoretical physicist today.!!
also photons, are absorbed by atoms and then emitted with the same energy. rather its the electron field that does it. and they emit the energy at the opposite direction of that which it the received the photon. which is amazing due to seeing things from angular direction..
Usually, in the classical wave optics, the reflection happens when there is a change of refraction index, that happens on a so called "separation surface" between two different materials. The problem can also become more complicated if the refraction index of the material is not constant, but changes with position in a "continuous" manner.
Wave-particle: if you differentiate the wave function to determine real-time rate of change, then there's the self-defining measuring system of relative sync-duration in terms of AM-FM Communication. "Make up your mind", space-ing is coordination-identification to/of "empty" point positioning, ie Singularity, and that is why a "Particle" is the functional measure of point positioning Timing-spacing-> sync connection containment states, aka Quantum-fields Mechanism of AM-FM In-form-ation. ?! And the circumstances that lead to "One Electron Theory" or hyper-hypo Superspin-spiral thesis, in which Eternity-now is Functional Unity, AM-FM Universal standing wave-packaging (ancient Greece believed was a kind of temporal jello), elemental connection continuity.., "and so on". RF Imaginary Thought Experimentalist's practical Intuition=> "space" is continuously created in temporal superposition, of/by spin-spiral logarithmic shaping timing. The i-reflection universe of QM Mirror, through, back, and eternally contained with "any name we want" in logarithmic spin-spiral condensation modulation interference coordination positioning:- Lewis Carroll and Richard Feynman.., requiring Fine Tuning , "thinking for your actual self". Or, Temporal Superposition-point Quantum Operator, => no-size one Electron, one photon-phonon universally continuous zero-infinity axial-tangential e-Pi-i sync-duration modulation information-> Singularity-point positioning, NOW. "I like to use the word Amplitude", because it's analog line-of-sight "Arrow of Time" superposition identification density-intensity, real-numberness in e-Pi-i sync-duration connectivity.., probability resonance-wave functions of re-circulation/evolution.. too. If we move the dots to fit the curve, this demonstrates how projection-drawing methodology is a Theoretical Calculus, "it's always NOW" least timing incidence and not how in an Experimentalist's practical recognition of Actuality Conception, this is a reversible process of Observation. (Don't do that?) As demonstrated, the sum-of-all-histories temporal, here-now-forever Arrow-> amplitude, is time difference rates of i-reflection orthogonality, continuously creating the sync-duration probability resonance cavity space/bubble-modes at "flat" ground state, zero-infinity difference->singularity NOW. QM general logarithmic quantization, instantaneous logical observation, "Nature works that way", in re-view, re-cognize, and re-evolution.., This Time.
Problem with today's scientist is that they can seem to understand the laws of quantum physics are that nothing possible is possible and the possible is impossible
Most thought of internal reflections occurs to most people, but the best way to explain something complex is still one step at a time, especially when it's something so counter to the macroscopic scale of our everyday experiences and intuition.
This video basically illustrates Feynman's approach to doing quantum mechanics. I think he comes across as arrogant when he claims hiis approach "explains everything". Many other physicists reject his approach to doing quantum field theory; indeed some critics disparage the entire Feynman diagram methodology because it "covers up" problems involving infinity and non-convergence. See Paul Dirac's reaction and Freeman Dyson's own despair about this theoretical attack for doing physics.
A single photon reflects with a chance determined by the added amplitude arrows of each surface it encounters. I'd still like to know how that is determined if the photon is already on its way back before it would reach the last surface.
Like Michael Faraday, Feynman preferred drawings for the symbols rather than the usual symbols used by most people to represent the relationships involved in science?
Not necessarily. There is a maximum allowable percentage. If you get his book 'QED' (Quantum Electro-Dynamics) it's very readable and easy to follow and It's all in there. And it's full of surprises too!
i love the man........ Some of his Physics lectures are poor. His priorities are poor, and he gets bogged down on lots of tangents. One of my favorite people........ overall a letdown.
Can anyone answer this question for me? Take the experiment set up 0:00-1:00:00. He has described how to calculate the probability of reflecting. I am curious if I can make a further deduction during the experiment, taking advantage of the time it takes for a photon to travel a specified distance. Suppose I exaggerate the set up and push the second detector (on the other side of the source of light) further down enough so that it would take a noticeable amount of time (say 1 second) for the photon to reach the second detector. I keep the first detector (on the same side as the source) relatively close to the surfaces so that the amount of time it would take (if it were to be reflected) is negligible (say 0 second). Suppose I emit a photon from the source and waited 0.5 second and noticed the first detector did not receive the photon. Can I conclude that in the next 0.5 second, I must receive the photon in my second detector?
Or do I still have a chance of receiving the photon in the first detector during the later half of the second? if so, depending on the time it took for the first detector to receive the photon, can I deduce a range of possible paths the photon could have traveled between the source and the detector?
The problem here is that you're not going to detect every photon your source sends out. And those that it does send out have random intervals between them. Therefore, if you detect nothing in detector 1, you can't know if there is a photon "on the way", either to your detector or to somewhere else (without detector) or not.
If you make the two observations that 1) A photon was emitted, 2) A photon was not detected at the first detector, then supposedly the probability is very high that after 0.5 seconds you will observe a photon detected by detector 2. I guess the only strange thing is that at the photon doesn't ever "actually" go through or reflect. So you'd be incorrect to calculate a probability of the photon going through, but instead you can only talk about the probability of the final observation - a detector going off, during some certain time interval which will be relevant when the distance is large.
@@Franciscasieri That there is no wave function collapse is not an insight by Everett. It's a trivial consequence of the definition of wave functions... which Everett did not understand, by the way. You can find this expressed very clearly in his own thesis. The second sentence of that document is completely false, already, and his entire argument fails because he never corrects his mistake.
The Speed of Light was made a Constant Speed not too long ago. Around the 1920s the speed of light was found to change by a very small margin when it's speed was measured, approx 20 to 26 miles per second. This change would not fit in with calculations etc. So to fix the problem the Speed of Light was made a Constant Speed.
Well here's a sign of the times .. Richard Feynman: 277K views. Flat earth muppets, contrails, and run your SUV on water and cat pee - four or five million. If Fermi had foreseen "social media" .. let's just say it (the paradox) would have all made sense.
they need to not allow yell out rude people in class. I g2g they killed the lecture and if I was in class would say raise your hand and shut the hell up! Trust me I would. Because I have.
It is you who don't know what really is going on. You even don't know how your computer work, yet you thing you know something that scientists don't know;)
The sign of a great mind: he does not reject any of the stupid questions asked. Instead, he adjusts or augments them, first to validate the questioners and then to create meaningful answers from which he can continue and develop his arguments. UA-cam gives us the opportunity to learn from the best teachers of all ‘recorded’ time. It’s great!
Sign of a great mind is a great big pocket protector…
The only stupid question is the question that isn't asked.
The best question is the question yet to be asked.
@@roadracer1584 there are stupid questions, if you do zero background reading heading into a lecture
Funny reading your reply verbatim .. At least in the context hindsight of the Challenger inquiry. Obviously I never knew him .. but I always liked to presume him a humble and approachable man. I still do. Though you can't help but belly laugh .. you just know he was setting them up as if an evil chess master with a giant fly swatter with that freakin' bit of o-ring and glass of water - not that they didn't entirely deserve it.. best reality .. actual reality .. TV moment ever!
I just enjoy the fact that you can hear in his voice how much passion he has not only for the science, but how much he enjoys teaching.
I don't understand anything he says but I go to sleep listening hoping someday I'll absorb it!
It's 4:00am and I just finished the first lecture and now I'm starting the second one. God I'm glad I'm retired. I'm gonna wake up around 1:30 today...and look for more.
gOD I AM RETARDED , LOOKING FOR more today , photons are big but no one is more surprising than intensity of light
I’m doing this also but due to quarantine!
rovidius2006
What the fuck are you saying?
Just came across a statement a few days ago that *there is no speed of light.* It just *is.* More digging required.
deltavee2
You can watch PBS Spacetime’s video called “The speed of light is not about the speed of light”
It pretty much says that the speed of light isn’t about light but causality. And causality has a maximum speed limit which happens to be what we call the speed of light. I do need to do more digging though since this idea doesn’t sit well with me.
It's wonderful how he continually resists explaining what nature actually is. Our work can describe what will happen in some situation, but it won't tell us actual truth. He was able to live with uncertainty, how very rare.
Physicists don't live with uncertainty as much as they live with ambiguity. That's a much more interesting concept. You have to allow for multiple, sometimes equally good, explanations of the same phenomenon.
Feynman was a great scientist and greater teacher !! I learned a lot here. And I am going to finish all of his videos on UA-cam .
You tube is a goldmine of knowledge,history and science podcast etc. happy to be around this amazing concept!.
Anyone who can explain the laws of quantum mechanics by using terms like "adding arrows" instead of the 10th grade math term "vector" is truly brilliant.
I am immensely grateful for these brilliant lectures from the greatest of minds.
Even though I,m a high school drop out, and don,t understand much what he says, I get a basic idea and like listening.
You are never incapable of learning more. Never hold back on learning just because you don’t have the same credentials as others.
I like how he is humble enough to say that this way of doing it is the one that works with every experiment man has come up with to date (when he answers the student at the 1hr mark). He does not arrogantly say that this is the only way of understanding the concept but rather leaves himself open to the possibility of something else being discovered in the future that could disprove this.
bf
Not like a real polly, that knows it's right now and forever - bsqawk - bsqawk - bsqawk ...
@@fwqkaw are you ok btch?
HI!! I AM so thankful... and so I make this message for You, mrtp:)
ThankYou for propagating this beautiful lecture series! Im not a scientist, but a mere layperson whom is stricken with gratitude & curiosity towards "Reality", whatEver IT IS!!
Years ago, before I'd even known of Mr. Feynman, I had a profound dream. In the dream I saw a written language that was based upon combinations of hexahedron shapes that were interlocked together in a way that I instinctually knew to be some kind of magnificent intelligence! The reason I'm saying all of this is because when I discovered Richard Feynmans diagrams, for whatever reason, they INSTANTLY referred me to the memory of this dream, and also to the inherent beauty of the dream and intelligence involved for this experience of being.
Ah! If only you’d had that dream earlier!!
…we’d be calling them Karlerik diagrams now.
Richard has the patience of a saint. I would have taken that guy who thought he knew everything and kept interrupting and kicked his butt out into the hallway.
Little knowledge is dangerous. That attention-seeking guy was blocking himself from learning. RF was extremely patient and didn't let the focus to be lost.
I could hear myself saying, "shut the f up" or "take him out of here"... what a patient man!
Lol. That's why you aren't Richard Feynman.
you could try. but, students pay to go to classes and students can complain.
Dr. Feynman's capacity for intelligence, explanation of the abstract into concrete examples, his humility, his patience, and his Renaissance variety of interests probably made him the greatest Science teacher of the 2nd half of the 20th Century. Feynman's lectures will be remembered for Centuries in the future while his well deserved Nobel Prize will be a historical blip..
Interesting how some of the student(s) are in more need of the attention and control of the teachers acknowledgement than others in the group. Feynman, had the patience of a god.
yeh, that guy was a tool
Irving Kurlinski h
He's a passionnate
every class has them.
He was a great guy
I definitely learned something new today
tell me what you learned!
Incredibly informative! Thank You.
Holy hell, he is an excellent teacher.
Several times he says 'I should have explained' when he actually has, taking the blame, just to ease his audience. A bit like Columbo.
Are you talking about physics ?
Koen Th you have a rare insight, don't lose that my friend.
lol so true
This man is nothing like the fictional detective. Columbo was not a conman.
@@Chicken_Little_Syndrome are you a flat earther? Why do you say one of the 21st century's most brilliant minds is a con artist?
Take A Moment
This must be The Best episode
Thanks from
Calgary Alberta
Untruedaux Land
My physics professor's teaching style is very similar to fynman. He is a fan ofcourse
In that question where you are asked who you would sit with and talk with from the past if it was possible mine would be Feynman. If I was allowed a second it would be Bertrand Russell
Another sign: he recreates the context and thence the questions as great scientists like Newton would have asked them. It might all seem obvious because we have the answers Newton and others gave us. But what if some answers were wrong? Then we live with those mistakes until Feynman types come along, spot them and develop the corrected answers. And these Feynman types are lucid and simple in their delivery of arguments. They’ll tell you that if they can’t do that, then something is probably wrong with their arguments. From this basis, they are able to build up theories of great complexity that can always be deconstructed as long as you , knowing at all times where they were and where they’re going) no matter how complex they become. They never lose sight of those ‘dippy rules’ he refers to.
It didn't take Feynman to point out problems with Einstein's messed up model of light quanta. That had happened much earlier. One can argue that by 1928/1929 the worst cracks had been filled by smart people like Dirac (who was Feynman's advisor, I believe) and Mott. Feynman basically just screwed the lid on Einstein's quantum coffin in 1948. As you can see from the timeline, though, the major insights had been available way before him.
Feynman's advisor was the great John Wheeler. Not Paul dirac.
44:40 the guy in the audience says 'like a big bean' for Venus and quick as flash Feynman says "maybe you'll figure out it's a big arrow'. This works on multiple levels and took me like a minute to think through and Feynman took like 1 second. The man was a genius
I don't get it.
No mistaking it, the man was definitely from New Yawk.
Raised in Far Rockaway, Queens. Ya can't get more than that.
@@deltavee2 a great safecracker
@@badmintongo4832 A very intelligent man of many talents. Personally, I hold him above Einstein because quantum physics.
He was one of our best, yes.
the last part he explained seemed very doable. is there any videos on youtube about it?
Fantastic lecture and endlessly funny to watch him struggle with the mic ;D ;D
just... WOW!
I am desperate to find a copy of the audio version (90minutes ) of these 1983 workshops .SoundPhotoSynthesis apparently has gone out of business and I don't know who else would have a copy .
13:30, 27:28, 30:22, 33:12, 42:28, 1:14:55, 1:29:58, 1:45:23, 1:54:07, 1:54:54, 1:55:30, 1:55:57, 1:57:54
Correcting: ‘that can always be deconstructed by knowing at all times where you were and where you’re going’ etc.
Man I’m damm sure Feynman is my bestestest chance at understanding this👍🤔😂🙏
For the arrows explaining the glass reflection, isn’t it equivalent to the wave explanation?
It's similar, except that he is talking about the quantum mechanical version. Since the result of the quantum mechanical calculation and the classical calculation are identical for this case, there is little that one can learn from his approach.
How exactly is it quantum mechanical about his approach? What is the subtle difference that I’m missing out here? Say if he didn’t mention that it’s quantum mechanical, would anyone be able to tell the difference?
@@jadongao2880 What you are missing here is the proper mathematical expression for the path integral, which is an infinite number of nested integrals. One could look at the Huygens-Fresnel principle as an early precursor of Feynman's path integral, except that it does not contain the complex exponential of the classical action, yet, so it's not a proper quantization procedure. Other than that the basic ideas are similar. And like I said, for non-selfinteracting bosons the classical theory and the quantum mechanical theory are very, very similar, which makes light a very poor system to learn QM on.
Why is the probability proportional to the square of the amplitude? and not just the amplitude itself?
I guess that's a bit of a shallow explanation, but one way to think about it is that intensity is the energy that permeates a surface over time. Now, light wave amplitude tells you about the energy content of the electric and magnetic fields. The square of the amplitude, multiplied by a proportionality constant gives you the intensity of the light. If you think about what intensity means for a stream of particles that travel with wave like properties, then you can imagine the places on an absorbing surface that have the most particles hitting is the place of the greatest probability of finding a particle. I hope this helps, I'm a materials scientist, not a physicist so I might have some things wrong.
The square of the possibility is the probability that the outcome will be that way!
The part at 25mn (reflection on glass depends on its thickness) and especially 28mn (an even surface would reflect some value between 0 and 16%, but in usual every lives the surface is not exactly the same thickness everywhere and we get the expected 8% overall) makes me thing about Hubble and James Webb telescopes: Do they purposely so uneven surfaces to not fall into the trap of maybe having a lower reflection? or on the contrary aim for the double reflection value? (probably can't aim for it as several different incoming wavelengths will need to meet different thickness to be reflected at the maximum value...)
No. :-)
22:55 Why would a proton get reflected from the "back surface"? I feel like the "back surface" wouldn't be a surface of glass to a photon that reaches it from *inside* the glass. Wouldn't that be the surface of the *air* below the glass. Otherwise, I feel this would mean that the glass in a window has four surfaces: two outside surfaces and two inside surfaces? Or billions of surfaces - one at every single point in (or layer of) the glass?
The surface is an illusion. It has no thickness, it's just a point in space between two materials. The light particles simply bounce on the irregularities between the two materials at that point.
Proton backscattering occurs when a high-energy proton encounters a surface, such as a solid material, and interacts with the atomic nuclei in the material. The probability of proton backscattering depends on various factors, including the energy of the incoming proton, the angle of incidence, the type of material the proton interacts with, and the atomic composition of the material. This phenomenon is essential in fields such as nuclear physics, materials science, and particle interactions, where the behavior of high-energy particles like protons is studied in detail.
The environment was uber inquisitive but in my opinion in a very positive way. "We never free a mind once it's reached a certain age. It's dangerous, the mind has trouble letting go." -Morpheus (in The Matrix, who knows whether it was positive definite or not...)
The next time you go to a bank look through the extra thick glass/acrylic panels between the tellers and the lobby, this will make plane the change in photon trajectories that thicker reflective surfaces can have.
i wonder if rappers take inspiration from this. his talk was so good he dropped the mic 10 times
When these lectures were recorded. Would be intersting to know. Somewhere in 80s probably..?
He passed away in 1988
Yes, same year as my mother. These vids are made some time before. He doesn 't seem sick at all.
@@sekoivu True he doesn't seem to be sick at all but you can't always tell if someone is ill! You can fight cancer for a long time!
I want him talking about bells theorem and epr
Watch the first video.
Commentors - please time stamp your examples to clarify. It's, well, a bit more "scientific" that way.
what if the material was the composite, fiber optic i believe, that is made in space to prevent this very thing from happening? its made in space to reduce the "drag" on the light. you may want to look into this material. also, it could possibly be that its lined up exactly and the crystaline structure is responsible for the electron bouncing back? maybe i will think further and more thoroughly about this.
Time seems to be a factor in reflection of light. Hear me out.
Is it possible that if time is in fact a factor, could it be that the atoms in the material do something a x time that causes collision and thus "reflection"?
Photons have no charge AND they have no mass, however when they slam into your skin you can feel the transfer of energy that happens on this collision.
Is it possible that the jiggling of the atom stops or harmonizes for a billionith of a second and when this occurs the photon slams into the atom and is either rebound OR obsorbed and a new photon is created and shoots of in the direction of the source of the first photon..
At 1:14 he says if we get there, unsaid if that guy shuts up.
So is Feynman's ''grating'' a polarizing lens? And are gratings used in night vision goggles to isolate a single wavelength of light for greater reflection?
that's classified
2:13 "We really don't understand it very well..." This was Feynman being charmingly self-deprecating to an audience he assumed was generally well-educated and take the understanding of classical physics as assumed. This recording played for a generally ignorant audience will have the unintended effect of giving them the idea that reality isn't well understood. This is generally false. Or rather, our profound ignorance kicks in well below the threshold of our senses, and at the extreme boundaries of our instruments - at the scale of individual atoms, and smaller. So when Feynman speaks with humility here, he's not speaking in general about physics, he's speaking specifically of the tiniest scales we can do experiments with.
It seems the chap who keeps interrupting would rather sound smart, than be smart.
Thank you for making me feel more stupid. Legend.
When you feel stupid it means that youve already taken your first step towards becoming smart :)
Basically the same response Teller had to an Einstein lecture.
Einstein, seeing Teller upset after, asked him why. Teller felt stupid, and told this to Einstein. Einstein told Teller: Stupidity is the human condition.
(Edwin Teller went on to become a giant among giants)
@@jacobcastro1885 Okay then I'm in good company hahahahaha
45:25 - explanation start
1:07:08 ......."these are irrelevancies" and "if you try to make the model too correct, it isn't gonna be right for some other question". and that's why it's a theory with strong competitors. but the competing theories don't have 90 years of the world's smartest people having worked on them.
If we as spectator physicists like us have spent so much time considering alternative theories and interpretations, how much time must the world's smartest people, who devoted their entire lives to physics, have spent puzzling over them, especially knowing that with their clout and mathematical backgrounds, they could piece together something worthy of a Nobel? The marginalized theories haven't been ignored, they've just consistently refused to bear more fruit than standard QM, QED, and QCD.
Feynman was a fine man.
He should have had the troll ejected! Obviously this guy was interfering with an elementary discussion to make himself seem more "intuitive" than he really is. I am unsure what he thought he would accomplish? Impress this man? Lmao
Although he was definitely interfering, maybe he was just being curious? Why assume his motive was a need to impress? Before ejecting someone for asking questions, maybe kindly ask to continue the lesson and end the tangent as Feynman actually did? Rme
Stupids ask if this and that. They think that,s smart, but its stupid. At the end of the lexture they talked so much rubbish, that they didnt learn anything. Wise men hold their mouth and learned someting.
Art Rose shut up.
He was a brilliant man
Brilliant? Richard feynman is considered one of the greatest physicist ever in the history of science.he was a genius,problem solver.!! He is the icon most of the theoretical physicist today.!!
Why does light only bounce off of the SURFACE of glass? What property does the surface have that the rest of the substance doesn't?
reflectivity, that and the ability of our eyes to see reflective light, in a way that we can mentally picture as a reflection of another image
also photons, are absorbed by atoms and then emitted with the same energy. rather its the electron field that does it. and they emit the energy at the opposite direction of that which it the received the photon. which is amazing due to seeing things from angular direction..
Usually, in the classical wave optics, the reflection happens when there is a change of refraction index, that happens on a so called "separation surface" between two different materials. The problem can also become more complicated if the refraction index of the material is not constant, but changes with position in a "continuous" manner.
no
what do you mean, no?
Wave-particle: if you differentiate the wave function to determine real-time rate of change, then there's the self-defining measuring system of relative sync-duration in terms of AM-FM Communication.
"Make up your mind", space-ing is coordination-identification to/of "empty" point positioning, ie Singularity, and that is why a "Particle" is the functional measure of point positioning Timing-spacing-> sync connection containment states, aka Quantum-fields Mechanism of AM-FM In-form-ation.
?! And the circumstances that lead to "One Electron Theory" or hyper-hypo Superspin-spiral thesis, in which Eternity-now is Functional Unity, AM-FM Universal standing wave-packaging (ancient Greece believed was a kind of temporal jello), elemental connection continuity.., "and so on".
RF Imaginary Thought Experimentalist's practical Intuition=> "space" is continuously created in temporal superposition, of/by spin-spiral logarithmic shaping timing.
The i-reflection universe of QM Mirror, through, back, and eternally contained with "any name we want" in logarithmic spin-spiral condensation modulation interference coordination positioning:- Lewis Carroll and Richard Feynman.., requiring Fine Tuning , "thinking for your actual self".
Or, Temporal Superposition-point Quantum Operator, => no-size one Electron, one photon-phonon universally continuous zero-infinity axial-tangential e-Pi-i sync-duration modulation information-> Singularity-point positioning, NOW.
"I like to use the word Amplitude", because it's analog line-of-sight "Arrow of Time" superposition identification density-intensity, real-numberness in e-Pi-i sync-duration connectivity.., probability resonance-wave functions of re-circulation/evolution.. too.
If we move the dots to fit the curve, this demonstrates how projection-drawing methodology is a Theoretical Calculus, "it's always NOW" least timing incidence and not how in an Experimentalist's practical recognition of Actuality Conception, this is a reversible process of Observation. (Don't do that?)
As demonstrated, the sum-of-all-histories temporal, here-now-forever Arrow-> amplitude, is time difference rates of i-reflection orthogonality, continuously creating the sync-duration probability resonance cavity space/bubble-modes at "flat" ground state, zero-infinity difference->singularity NOW.
QM general logarithmic quantization, instantaneous logical observation, "Nature works that way", in re-view, re-cognize, and re-evolution.., This Time.
In the example around 1hr 38 min, why do we assume that light travels only in straight lines?
There's a case to be made for curves???
It doesn't. Ray optics is an approximation of wave optics, which is a limiting case of quantum optics.
outstanding-----thanks
Amazing!
What year was this?
1:57:17 WHAT DID HE SAY???
Problem with today's scientist is that they can seem to understand the laws of quantum physics are that nothing possible is possible and the possible is impossible
if it is possible could you add subtitle please. ps : i am not a native speaker.
Finally since the beginning i was bothered with this part 1:30:00 , how the hell Feynman disregarded the multiple reflections?
Most thought of internal reflections occurs to most people, but the best way to explain something complex is still one step at a time, especially when it's something so counter to the macroscopic scale of our everyday experiences and intuition.
What happen if it hits a sphere
This video basically illustrates Feynman's approach to doing quantum mechanics. I think he comes across as arrogant when he claims hiis approach "explains everything". Many other physicists reject his approach to doing quantum field theory; indeed some critics disparage the entire Feynman diagram methodology because it "covers up" problems involving infinity and non-convergence. See Paul Dirac's reaction and Freeman Dyson's own despair about this theoretical attack for doing physics.
I have no idea what the hell he is talking about. Is he talking about quantum mechanics in general or is he talking about his thesis work
He is hung up on photons from false assumption about how a PMT works. He explains the PMT with photons. Circular.
OMG Feynman has highlights in his hair.
So quantum mechanics is really just about mechanics 44:15
Was my man up there barefoot!? 57:23
His Microphone is attracted to the floor not his shirt, he should of explained that in his lecture
🙂
Quantum mechanics 2 but half the lecture is spent explaining vector addition...
A single photon reflects with a chance determined by the added amplitude arrows of each surface it encounters. I'd still like to know how that is determined if the photon is already on its way back before it would reach the last surface.
Richard was full of it.
Quantum mechanical view of reality
Where is the math?
Like Michael Faraday, Feynman preferred drawings for the symbols rather than the usual symbols used by most people to represent the relationships involved in science?
Is Feynman barefoot?
52:59 😅😅😅😊😊😅😅😊😊😊😊😊😊😊😊😊😊😊😊😊😊😊😊😊😅😅😅😊😊
no ppts back then lol... nice
Holes in mirror might increase intensity of mirrored light
Not necessarily. There is a maximum allowable percentage. If you get his book 'QED' (Quantum Electro-Dynamics) it's very readable and easy to follow and It's all in there. And it's full of surprises too!
Henadz Yermakavets
Davis Helen Martinez Robert Miller James
he was just guessing, he had no clue
Davis Elizabeth Lewis Brenda Brown Joseph
Why is he and some of the audience members barefoot?
Martinez Anna Rodriguez Gary Jackson Jason
i love the man........ Some of his Physics lectures are poor. His priorities are poor, and he gets bogged down on lots of tangents. One of my favorite people........ overall a letdown.
Wait Matthew started counting it sorry about that you're on your own
Can anyone answer this question for me? Take the experiment set up 0:00-1:00:00. He has described how to calculate the probability of reflecting. I am curious if I can make a further deduction during the experiment, taking advantage of the time it takes for a photon to travel a specified distance. Suppose I exaggerate the set up and push the second detector (on the other side of the source of light) further down enough so that it would take a noticeable amount of time (say 1 second) for the photon to reach the second detector. I keep the first detector (on the same side as the source) relatively close to the surfaces so that the amount of time it would take (if it were to be reflected) is negligible (say 0 second). Suppose I emit a photon from the source and waited 0.5 second and noticed the first detector did not receive the photon. Can I conclude that in the next 0.5 second, I must receive the photon in my second detector?
Or do I still have a chance of receiving the photon in the first detector during the later half of the second? if so, depending on the time it took for the first detector to receive the photon, can I deduce a range of possible paths the photon could have traveled between the source and the detector?
The problem here is that you're not going to detect every photon your source sends out. And those that it does send out have random intervals between them. Therefore, if you detect nothing in detector 1, you can't know if there is a photon "on the way", either to your detector or to somewhere else (without detector) or not.
If you make the two observations that 1) A photon was emitted, 2) A photon was not detected at the first detector, then supposedly the probability is very high that after 0.5 seconds you will observe a photon detected by detector 2.
I guess the only strange thing is that at the photon doesn't ever "actually" go through or reflect. So you'd be incorrect to calculate a probability of the photon going through, but instead you can only talk about the probability of the final observation - a detector going off, during some certain time interval which will be relevant when the distance is large.
You dont measure a photon, you measure a propability.
Trying to predict something you couldn't count.....
Uh oh another Matthew
Please delete the wave function of that big-head student interrupting all the time!
Hugh Everett would say this is impossible because the wave function never collapses
@@Franciscasieri That there is no wave function collapse is not an insight by Everett. It's a trivial consequence of the definition of wave functions... which Everett did not understand, by the way. You can find this expressed very clearly in his own thesis. The second sentence of that document is completely false, already, and his entire argument fails because he never corrects his mistake.
Young Steven Lewis Donald Thompson Elizabeth
Hall Mary Clark Shirley Martin Larry
Was it really necessary to add that obnoxious watermark on the entire video ?
The people interrupting and asking questions are narcissists.
The Speed of Light was made a Constant Speed not too long ago. Around the 1920s the speed of light was found to change by a very small margin when it's speed was measured, approx 20 to 26 miles per second. This change would not fit in with calculations etc. So to fix the problem the Speed of Light was made a Constant Speed.
80 people were the 4% of the photons..
Well here's a sign of the times .. Richard Feynman: 277K views. Flat earth muppets, contrails, and run your SUV on water and cat pee - four or five million. If Fermi had foreseen "social media" .. let's just say it (the paradox) would have all made sense.
58:37
💕💕❤❤💘💘
they need to not allow yell out rude people in class. I g2g they killed the lecture and if I was in class would say raise your hand and shut the hell up! Trust me I would. Because I have.
❤
Shut up and math seems to be ok with these scientists. What a loss to not want to know what really is going on.
It is you who don't know what really is going on. You even don't know how your computer work, yet you thing you know something that scientists don't know;)