What a pleasure it is to listen to this man (audio problems notwithstanding). He doesn’t flinch from explaining the issues honestly and clearly. Compare to many other videos online on the same topic where the explanations are frustratingly unclear or incomplete.
He makes learning fun. And that's not a common feature as expertise rises. There are plenty of people who know how to make basic learning fun. But by the time you get to the level of understanding that Feynman has, you lose a lot of those. Not all of them, or there wouldn't be any. But they are rare. And Feynman is one of the rare ones.
exactly.. these geniuses are lecturing about big science thing and could not even shoot the video in color let alone HD. 😂😂😂. also using the black board and chalk😂😂😂
Thank you for mentioning the DVD! OK I will search and buy the DVDs because I have problems understanding the words (the sounds) when he arrives to explaining how we use analogy to make a formula for light particles. Also there seem to be many wrong subtitles, which further confuses me. However, the way he explains things which otherwise are so hard to comprehend is wonderful. We had a lecture about the double slit in High School (Frederiksberg Gymnasium 1965, K.Kobberø was teacher, lektor). The duality of light was mentioned, but I don't remember how it was described. The point was that photons behaved like they were coming through both slits at the same time. There are many variation of the double slit experiment. A variation involves using a diffraction grating, which is essentially a plate engraved with numerous fine lines. These gratings act similar to multiple slits, dissecting incoming light into its component wavelengths and producing detailed interference patterns. This adaptation underscores the wave-like behaviors of light in a vividly observable way. Every setup tweak, including the grating, deepens our understanding of the fundamental principles.
@@donaldaxel Thank you for your extensive reply. I understand the technical stuff (as much as I can). I was only concerned with the audio, and we know from various human factors videos, knowing what previously unintelligible audio says, makes subsequent hearings intelligible. If you cannot find the boxed set, try to find me and I will gladly do you a dvd rip. I am in the UK Respect.
@@ClaymateDesigner :: Thank you so much. I can see that the box set is available. I hope the sound quality there is much better. But then again, it is only this special lecture which has fascinated me here and now, and I understand very well the background on which he is talking - I also think his audience are well versed with both the "common folk version of the double slit experiment" and the more intricate interpretations of those. I will listen again and I hope I will get more of the words. Even if wrong the subtitles help a little. If I am lost in the forest of unintelligible words, then I would like to return to your offer! 👍
This is the experiment that makes quantum physics interesting to the lay person! Einstein and Bell are eternal but this is the picture we will remember.
It would be greatly helpful if the video's English subtitles were proofread. At 03:00, the subtitles incorrectly state 'these particles are called proton now,' but I am quite sure Feynman actually says 'are called photons now.' The errors, of course, stem from the video's age and low quality. Still, Feynman was a remarkable popularizer of science, and even if the entire lecture were re-recorded with an actor, it would still be valuable to any physics beginner. Why so valuable? Because Feynman excels at explaining major conundrums, such as one from 'Special Relativity,' in just one sentence: 'That two things occur at the same time is just a subjective opinion.' From the perspective of a daily newspaper, nothing could seem more incorrect! However, Feynman uses this paradox to highlight a fundamental aspect of physics: the necessity to consider the minutely infinitesimal scales of atoms and photons.
this may be Feynman's finest gift to us... it is applicable to all systems that are governed by random events... like economics.. or other human behavior... think about it... please 🙏
it seems counter intuitive.. it's not... we have grown up with the idea that the more we can control a process the better the results are... in the case of a machine, that's true... in the case of random systems.. it's not true. because ==>> duration in a random system is brought about by positive reinforcement... negative reinforcement cancels out... if I try to measure a positive input.. value= 1 it looses energy and becomes some decimal value between 1 and zero ... and not always the same amount.. so there's no reinforcement.. it brings destructive interference... fractals occur on the border between order and chaos.. our lovely Universe is fractal it works best when we don't try to control it ✌️
Yes. Light is scattered by the electrons. I am not a physicist, but as a biologist that is a phenomenon that is used in biology to study the structure of biomolecules.
oh.. I heard of 'Compton scattering' en.wikipedia.org/wiki/Compton_scattering but that where the photon dislodges electrons in an atom.... but for the double slit, the electron is free, and if the electron-photo scatters at one of the slit, and the electron's path may have alter and possibly not even passes through that particular slit that gives of a 'blink of light'.... hmmm...
@@andywong2135 You have Raman light scattering, you have X-ray scattering (X-ray diffraction is considered a case of scattering in systems that have special characteristics, e.g. crystals)
Here, he is teaching a class. A good teacher will have, and will refer to, their notes, even if only to assure they haven't misused terminology, left out details, made a mistake, or forgotten to mention something they intended to mention.
Too much audio distortion, scientific honesty , requires that I can't dispute words I didn't hear , and thus , not being falsifiable , nothing is proven either. But clearly he does indicate that it's not observation which disturbs the pattern development, but the means by which one might observe does. He here does not prove the unpredictability of quantum events either , nor that individual photons interfere with themselves. Potentially, temporally spaced photons may . I've not heard that crossed beams of light interfere making the sum illumination not equal to the sum of emitted light. Frankly , it is the understanding of what constitutes Any wave which I doubt is properly conceptualized , And discreteness , likewise. But I'm no physicist. It's nice to hear him expound the attitudes towards scientific pursuit though. Wrong or right about facts , such men had integrity, class , sincerity , nice to see. 👍
To briefly address this From what experiments (and the math, but that's complicated) indicate, it isn't the means by which these phenomena are measured, but the fact a measurement was made at all, that causes the differences we see. The double slit experiment is a good demonstration, but doesn't address that particular concern in and of itself. One example that does, however, and actually demonstrates far more than just this, is the bell test. The technicalities are a lot to go over, but the basic gist is that two entangled photons are fired in opposite directions, and on either end of their paths they are subjected to a few sets of polarization filters. If they pass, they're detected by one detector, if they don't, there's another detector they hit instead. To make a lot of technical stuff simpler, the idea is that if the particles actually have a defined state at the moment of their creation (when they were entangled) and you measure each one with a filter chosen at random, the amount of times a set amount of such entangled particles will pass through the filters on both sides is something you can calculate on a statistical level. The exact number depends on the particular filters you choose to use and their relative overlap, but you can figure out that for example with some set of 3 filters, you should be getting x/y agreements in the data set. Obviously for any one experiment there will be variation, but through repetition and large sample sizes, you can even those out. What has been found experimentally, however, is that the statistics do not match the data. Consistently, the results deviate from the statistical predictions, and line up with what is expected by quantum mechanic's hypothesis (and now, as of 2022, conclusively proven theory) that until you measure one of the two entangled particles, neither has a definitive state, and once it is measured, BOTH decide instantly. Of course, in physics, "instantly" is a dirty word. That's not a real thing, relativity tells us, both because the information of any given to events take time to travel and as such appear to happen at different times based on something like the observer's location relative to the two, and because time itself is subject to dilation, notably in gravitational fields but also from acceleration. Any amount of acceleration dilates time, though the effects are imperceptible at the ranges any of us ever experience. But, this is where we have to reference back to the beginning. These photons are traveling in opposite directions. Nothing you do to one *can* affect the other, because the information from whatever you did to photon A will never reach photon B, not under the laws of relativity anyway. Whatever it is you did to the photon, whether you just let it hit a wall, passed it through a filter, or whatever else, any and all information you can get from it will be identical on the other end. This despite concrete proof neither has a state until that moment (because the data from earlier would line up with statistical models presupposing a pre-defined state, and it doesn't) TL;DR the method of measurement is of absolutely no consequence or relevance, tests have been done showing in no uncertain terms that 1. Photons (quantum particles more generally) do not have a defined state prior to the measurement 2. Whatever measurement it is you do on an entangled particle affects its entangled partner instantaneously (though in fairness it is technically possible there is some speed limit on this, despite all the current, successful models indicating otherwise, just because we aren't technically capable of doing these experiments over arbitrarily long distances, leaving the possibility that at some immense distance, there is a slight "time delay" open) As for individual photons interfering themselves, that's shown by the double slit experiment itself, as you can fire individual particles at the slits and get the interference pattern. Though, a more interesting demonstration in my opinion is the quantum eraser. The QE works in much the same way as the double slit experiment, except directly after the slits, the photons are split into two entangled photons (of half the energy each, though this is mere trivia) and while one continue to go towards the screen as normal, another is sent to the socalled quantum eraser. Conceptually it's simple, the quantum eraser is just a set of beamsplitters that either let through or reflect light with a 50/50 chance, arranged so that whichever slit the photon actually passed through, it either ends up at detector A or detector B, though it's not possible to tell which slit it came from. The photons that hit the screen, if you just look at all of them, just paint a clump of light, as one would expect if there were no slits. Interesting in its difference from the regular double slit experiment, but easily handwaved by "well, when it hit the crystal, it 'reset' so of course this is what happened" (ultimately not correct, but sounds reasonable enough) What's interesting, however, is our two detectors. They're nothing fancy, they just detect whether a photon hit at all. However, we were smart, we made sure to timestamp each time a photon hit the screen, and each time a photon hit one of our detectors. This basically means for every hit on the screen, we know which detector its entangled partner hit. So, we look at only the photons on the screen which partner hit detector A. Interference pattern. We do the same with detector B's photons. Interference pattern (though the gaps are where the bands are for detector A's pattern) "Alright," we say, "I see how it is. I'm going to trick you." We set up another two beam splitters along the two paths leading to the eraser, which direct to detector C or detector D, depending on which slit it went through. We run the experiment again, and now we check C and D against the photons on the screen. No pattern whatsoever, it's just two blobs now, though ever so slightly offset to the left and right of each other (barely perceptible, but statistically significant) A and B's respective screen-photons still show the same interference patterns as before, though of course now only at 50% intensity as we removed 50% of the incoming photons (we directed half to C and D after all) It's important to note here, and many explanations of the quantum eraser fuck up this part, the screen itself never shows any pattern whatsoever. Under no circumstance will there be any pattern other than a blob of light on the screen in a quantum eraser setup. The patterns only become apparent when you selectively look at the photons with a partner that hit detector B, or those with a partner that hit detector A. What's happening, very, very basically, is that at the final beamsplitter, where a photon ultimately goes to either A or B, the two possible paths (slit 1 or 2) the photon could have taken to get there interfere with one another, the relative phases either cancel out or amplify each other, and essentially a decision is made, and they go to A or B based on the result. Of course, if it first hits the screen, the screen's photon makes that decision, manifesting on its end as you may have guessed as its position on the screen (something not made clear enough in my opinion with explanations of the double slit experiment is that we are dealing with extremely small equipment. The screen isn't a bedsheet or something of that nature, it's on the scale of 20 millimeters across, meaning the phase of the light at the moment of impact determines its position) As for two beams interfering to result in a different level of illumination than the two separate beams, I can't entirely say I know what this is referring to. If you're referring to the resulting interference pattern, it's a simple misunderstanding. The light measured is the exact same as the light fed into the system, there's no less and no more light measured than fed in, it's just distributed with a higher probability (thus more light as the end result) where there's constructive interference, and a lower probability (thus less light as the end result) where there's destructive interference. The interference doesn't affect how much light you get, you get exactly 1 photon per 1 photon fired (well, excluding the ones that didn't even make it past the slits because they hit the wall) they're just distributed according to the interference, much like you'll measure the water level to be higher where the waves from two ripples in a pool of water intersect (because the water from the two waves add to each other) than you do where there's no waves. Though the analogy to waves in water breaks down because you'd expect the rest of the water to make it resulting in a uniform spread, whereas with quantum waves, it's more akin to one measurement of where the water level is highest at a given moment, many, many times in succession. If you somehow did that, randomly selecting when you take the measurement of that moment, and looked at your data afterwards, you'd see something very similar to the slit experiment's pattern. A series of bands where the water level was highest very frequently, and gaps between those bands where the water level was practically never the highest.
Turn song on radio, and check under hood for sound vibrations through the chassis check the next pickup on the radio stations until you can hear the radio
The noise reduction seems to have spoiled the sound so much, listening through normal speakers, I couldn;t listen to more than about 20 seconds .. I jumped ahead hoping it would improve. Having dead silence when he's not speaking makes it sound unnatural .. perhaps there's a slightly less intrusive setting ... I didn't realise there was a noise problem on the feynman lectures anyway - I've listened to them many times before without issue, but perhaps this one sounds even worse without NR. Sorry, just saying - it kinda hurts my ears a bit - a bit harsh
Indeed, noise reduction does strange things to the audio, makes it sound unnatural and repels us from it. It's a classic bug where the engineering team fails to weigh in the nuance features that makes it human (the breathing in the voice in text to speech on ios for example)
It s quite odd to see that a scientist like Feynman still needs notes for this kind of,elementary,lecture.I once saw Walter Lewin explain how much he studied when he prepared for a two hour basic lecture about Newtonian laws of motion.My education went bust because I thought if I couldn t get straight A`s without studying was too untalented to learn anything.Then I saw a mathematician say in a public lecture that maths is 90% hard work and 10% talent/gift.Man was I bummed to learn how stupid I had been.I had straight A`s in "junior high" without studying for tests but in high school it didn t work anymore and I totally lost interest in studying.I could still get A`s in languages like English,German and Swedish but Advanced maths and physics not.I could get by with very little study but not as well as I was used to.Nan o man was I naive and just super dumb!!
Nice lecture, too bad that is just old, and really does not hold water anymore. In an stochastic universe/world, science can very well defined as not necessary same input will yield same results. Also, the electron should be considered just as a disturbance of a field , then this experiment makes more sense (human sense),i.e., the disturbance occurs everywhere there, kind of 'An Electron travels all possible paths , a single electron'", . I attended some of his lectures when I was very young, it was delightful
The universe maybe like grid points and field force open like zooming by magnifying so we see light hidden beneath and that why our thinking all sharing equally except those are toothed or cursed by sound
The noise reduction was overdone. Back off the parameters a little, and you might get it right. You don’t want to eliminate ALL noise, because it destroys too much of the signal. There’s a balance you can achieve where it’s still very understandable, and less noisy, but not dead silence and digitally distorted signal.
He is pretty amazing. Describes such a complex, intricate and weird phenomenon and experiment in a way anyone can understand. I love watching lectures like this, and I'm very sad that a lot of geniuses lived before audio and video could be recorded.
That and really if you set an experiment up with a hypothetical extremely precise timer that measures extremely small fractions of milliseconds, you'd find that most things apearing to happen simultaneously are actually not truly perfectly in sync and the probability for 2 things to occur at the same time is extremely low.
Your title is NOT helping the number of views. While, I hate "click bait titles" you'd be better served to name this video "Nobel Winner David Feynman and his Brilliant Electron Slit Experiment, with Enhanced Audio"" Do this and quadruple your view rate....
Minute 25, "You never get two clicks at the same time." I show how that is wrong and what they did wrong to make them think they were right. Find me and my website.
you have an audio freely available to you from one of the greatest minds of the 20th century, which somebody managed to preserve and augment to make the sound distinguisable, so your far less advanced brain gets a change to grasp a most intriguing feature of nature, and you complain
So 'comes in lumps' is just another way of saying they're 'discrete'. I guess he wouldn't be Feynman if he just said they were discrete, and been done with it. Perhaps he believed that it'll be remembered better if he says it like that, rather than using the word 'discrete'. Both Feynman and Krauss were sexually predatory. Not a good look for the profession.
What do you suggest ? I'm still trying to figure out what's so special about this experiment. Isn't observing particles the same thing as interacting with them, hence the change of their behavior ?
@@nabilbensafi This is the system. They push probability on you as if it was a law of physics. And you either take it or you fail the course. Basic electrostatics tells you every particle has an electric field. The field passes through both slits, causing the particle to deflect accordingly. But they make it sound like some miraculous thing. But in reality is just Maxwell's work.
@@walterbrownstone8017 Always some idiot on the internet pretending to be smart. First of all, the Feynman Double Slit Experiment has actually been done and has been proven correct. So your assertion that it's garbage is already wrong. Then you claim that "every particle has an electric field." Are you really that stupid? I suppose neutrons don't exist and have never existed. But, to further my point, I was able to find a paper where they did a double slit experiment with neutrons and lo and behold it's still probabilistic. You're just wrong. Probably someone who failed quantum and is salty they failed. Paper in question: D.M. Greenberger and A. Yasin, "Simultaneous wave and particle knowledge in a neutron interferometer" The paper does give some interesting insight into how much we can know about a particles path but it is *still* inherently probabilistic. Shocker. Some rando who failed quantum isn't smarter than one of the most influential scientists of the 20th century
@@walterbrownstone8017 You're just wrong. Firstly, neutrons are electrically neutral. That's why they're called neutrons. Secondly, you are implying that this experiment would not work with neutrons. This is also completely false. Here's a nice little paper you can read, although given it is obvious you failed quantum I don't know how much you'll understand. This is basic electrostatics. D.M. Greenberger and A. Yasin, "Simultaneous wave and particle knowledge in a neutron interferometer" Shocker. One of the most influential physicists of the 20th century is smarter than a some rando in the youtube comments who is salty about failing quantum.
@@JohnSmith-if2qv Firstly neutrons are emergent particles that are made from charged particles. Meaning they always have a presence in the field density of is local space. All particles with spin are emergent. Spin can only emerge from two charged particle fields interacting in the only why they know how, by spinning.
😊 you're right as a spectator there is a lot of laughs and a lot of jokes outside the train tracks probably as you attend the parade It's not so funny to the security inside the train perhaps the president is inside ...😮 It's a little more serious for the security And he takes his job very seriously .. but I guess if you were holding over 200 tons of gold ...😊 Everything would be serious ..... Now you can hear the jokes from the people because of microphones .... And the insensibility ..... But yes some straight references may continue As the laughs and jokes could only get themselves an ice cream or go home 😊 Job gets f***** up around here It's not cool 😊 Because nobody likes the bleaching ... Nobody nothing licks to be bleached
What a pleasure it is to listen to this man (audio problems notwithstanding). He doesn’t flinch from explaining the issues honestly and clearly. Compare to many other videos online on the same topic where the explanations are frustratingly unclear or incomplete.
He makes learning fun. And that's not a common feature as expertise rises. There are plenty of people who know how to make basic learning fun. But by the time you get to the level of understanding that Feynman has, you lose a lot of those. Not all of them, or there wouldn't be any. But they are rare. And Feynman is one of the rare ones.
you're comparing someone like him to some passionate average youtuber?
A criminally under-viewed video. Thanks for this incredible upload
What should the penalty be since you say it’s criminally under- viewed ? And what statutes are you referring to ?
If you think you know Quantum Machanics you don't know QM! Lol best line ever?
exactly.. these geniuses are lecturing about big science thing and could not even shoot the video in color let alone HD. 😂😂😂.
also using the black board and chalk😂😂😂
@@LeeGee If only your comment made some sense . But it doesn’t.
Thank you for your stupid brainless comment.
The world is emptier because of it.
“It is necessary for the very existence of science, that the same conditions always produce the same results”
“Well, they don’t…”
Am I the only one that saw the title of this video and wondered why "noise" was affecting the double slit experiment ?
No…I wondered that too 😂
I believe the audio was processed... that's what it's referring to.
@@scowell yes…. Yes.. that is what it was referring to. Thank you for the enlightenment.
I think they are speaking of visual not audible noise.
Oh! I realized what's going on only after reading your comment. I was also waiting, when Feynman starts talking about the noise :)
I could listen to him forever.., play this at my funeral… man.. I desire to understand what is.. what we are.. to comprehend 🙏🙏🙏🙏🙏🌹
I have the DVDs's of these lectures.
The audio and video quality is so much better than presented here.
Thank you for mentioning the DVD! OK I will search and buy the DVDs because I have problems understanding the words (the sounds) when he arrives to explaining how we use analogy to make a formula for light particles. Also there seem to be many wrong subtitles, which further confuses me.
However, the way he explains things which otherwise are so hard to comprehend is wonderful. We had a lecture about the double slit in High School (Frederiksberg Gymnasium 1965, K.Kobberø was teacher, lektor). The duality of light was mentioned, but I don't remember how it was described. The point was that photons behaved like they were coming through both slits at the same time.
There are many variation of the double slit experiment. A variation involves using a diffraction grating, which is essentially a plate engraved with numerous fine lines. These gratings act similar to multiple slits, dissecting incoming light into its component wavelengths and producing detailed interference patterns. This adaptation underscores the wave-like behaviors of light in a vividly observable way. Every setup tweak, including the grating, deepens our understanding of the fundamental principles.
@@donaldaxel Thank you for your extensive reply.
I understand the technical stuff (as much as I can). I was only concerned with the audio, and we know from various human factors videos, knowing what previously unintelligible audio says, makes subsequent hearings intelligible.
If you cannot find the boxed set, try to find me and I will gladly do you a dvd rip.
I am in the UK
Respect.
@@ClaymateDesigner :: Thank you so much. I can see that the box set is available. I hope the sound quality there is much better.
But then again, it is only this special lecture which has fascinated me here and now, and I understand very well the background on which he is talking - I also think his audience are well versed with both the "common folk version of the double slit experiment" and the more intricate interpretations of those.
I will listen again and I hope I will get more of the words. Even if wrong the subtitles help a little.
If I am lost in the forest of unintelligible words, then I would like to return to your offer! 👍
two sheets and a lamp, and universe seems broken
This is the experiment that makes quantum physics interesting to the lay person! Einstein and Bell are eternal but this is the picture we will remember.
It would be greatly helpful if the video's English subtitles were proofread. At 03:00, the subtitles incorrectly state 'these particles are called proton now,' but I am quite sure Feynman actually says 'are called photons now.' The errors, of course, stem from the video's age and low quality. Still, Feynman was a remarkable popularizer of science, and even if the entire lecture were re-recorded with an actor, it would still be valuable to any physics beginner.
Why so valuable? Because Feynman excels at explaining major conundrums, such as one from 'Special Relativity,' in just one sentence: 'That two things occur at the same time is just a subjective opinion.' From the perspective of a daily newspaper, nothing could seem more incorrect! However, Feynman uses this paradox to highlight a fundamental aspect of physics: the necessity to consider the minutely infinitesimal scales of atoms and photons.
this may be Feynman's finest gift to us... it is applicable to all systems that are governed by random events... like economics.. or other human behavior...
think about it... please 🙏
it seems counter intuitive.. it's not... we have grown up with the idea that the more we can control a process the better the results are... in the case of a machine, that's true... in the case of random systems.. it's not true.
because ==>> duration in a random system is brought about by positive reinforcement... negative reinforcement cancels out...
if I try to measure a positive input.. value= 1
it looses energy and becomes some decimal value between 1 and zero ... and not always the same amount.. so there's no reinforcement.. it brings destructive interference...
fractals occur on the border between order and chaos.. our lovely Universe is fractal
it works best when we don't try to control it ✌️
What year is this?
The University of Aukland Feynman videos have much better audio and video. Well worth a look
The original and most perfect mic drop.
@32:58 "...Light is scattered by electrons..." really ? I've never studied this, would anyone help elaborate that ?
Yes. Light is scattered by the electrons. I am not a physicist, but as a biologist that is a phenomenon that is used in biology to study the structure of biomolecules.
oh.. I heard of 'Compton scattering' en.wikipedia.org/wiki/Compton_scattering but that where the photon dislodges electrons in an atom.... but for the double slit, the electron is free, and if the electron-photo scatters at one of the slit, and the electron's path may have alter and possibly not even passes through that particular slit that gives of a 'blink of light'.... hmmm...
@@andywong2135 You have Raman light scattering, you have X-ray scattering (X-ray diffraction is considered a case of scattering in systems that have special characteristics, e.g. crystals)
It's interesting to see him mildly nervious, and using notes during his presentation. Typically unusual for him, at least later in life 🙃
Here, he is teaching a class. A good teacher will have, and will refer to, their notes, even if only to assure they haven't misused terminology, left out details, made a mistake, or forgotten to mention something they intended to mention.
Hard to get through this; just keep seeing/hearing Ed Norton from Honeymooners…
he's the real ed norton
This must be very rare. Hopefully you have an entire vault of these. If so. What would it take to get them all published?
These are Feynman's Cornell Messenger Lectures of 1964. A series of seven lectures. You will find them if you Google for them. They are each unique.
When Feynman says: h₁₂=h₁+h₂, and a₁₂=a₁+a₂; is he referring to the term of sequence?
Timestamp? But prob. No, he’s summing (coherently) over amplitude from slits 1 and 2
Yep I know. @@DrDeuteron
Beautiful task
When and where was this originally recorded?
I believe this was recorded as part of his Messenger Lectures at Cornell, later published as "The Character of Physical Law."
Chad Feynman dropping the H-bomb near the end of the lecture, basically mid cold war
Brilliant 👏
Too much audio distortion, scientific honesty , requires that I can't dispute words I didn't hear , and thus , not being falsifiable , nothing is proven either.
But clearly he does indicate that it's not observation which disturbs the pattern development, but the means by which one might observe does.
He here does not prove the unpredictability of quantum events either , nor that individual photons interfere with themselves.
Potentially, temporally spaced photons may . I've not heard that crossed beams of light interfere making the sum illumination not equal to the sum of emitted light.
Frankly , it is the understanding of what constitutes Any wave which I doubt is properly conceptualized ,
And discreteness , likewise.
But I'm no physicist.
It's nice to hear him expound the attitudes towards scientific pursuit though. Wrong or right about facts , such men had integrity, class , sincerity , nice to see. 👍
To briefly address this
From what experiments (and the math, but that's complicated) indicate, it isn't the means by which these phenomena are measured, but the fact a measurement was made at all, that causes the differences we see. The double slit experiment is a good demonstration, but doesn't address that particular concern in and of itself.
One example that does, however, and actually demonstrates far more than just this, is the bell test. The technicalities are a lot to go over, but the basic gist is that two entangled photons are fired in opposite directions, and on either end of their paths they are subjected to a few sets of polarization filters. If they pass, they're detected by one detector, if they don't, there's another detector they hit instead.
To make a lot of technical stuff simpler, the idea is that if the particles actually have a defined state at the moment of their creation (when they were entangled) and you measure each one with a filter chosen at random, the amount of times a set amount of such entangled particles will pass through the filters on both sides is something you can calculate on a statistical level. The exact number depends on the particular filters you choose to use and their relative overlap, but you can figure out that for example with some set of 3 filters, you should be getting x/y agreements in the data set. Obviously for any one experiment there will be variation, but through repetition and large sample sizes, you can even those out.
What has been found experimentally, however, is that the statistics do not match the data. Consistently, the results deviate from the statistical predictions, and line up with what is expected by quantum mechanic's hypothesis (and now, as of 2022, conclusively proven theory) that until you measure one of the two entangled particles, neither has a definitive state, and once it is measured, BOTH decide instantly. Of course, in physics, "instantly" is a dirty word. That's not a real thing, relativity tells us, both because the information of any given to events take time to travel and as such appear to happen at different times based on something like the observer's location relative to the two, and because time itself is subject to dilation, notably in gravitational fields but also from acceleration. Any amount of acceleration dilates time, though the effects are imperceptible at the ranges any of us ever experience.
But, this is where we have to reference back to the beginning. These photons are traveling in opposite directions. Nothing you do to one *can* affect the other, because the information from whatever you did to photon A will never reach photon B, not under the laws of relativity anyway. Whatever it is you did to the photon, whether you just let it hit a wall, passed it through a filter, or whatever else, any and all information you can get from it will be identical on the other end. This despite concrete proof neither has a state until that moment (because the data from earlier would line up with statistical models presupposing a pre-defined state, and it doesn't)
TL;DR the method of measurement is of absolutely no consequence or relevance, tests have been done showing in no uncertain terms that
1. Photons (quantum particles more generally) do not have a defined state prior to the measurement
2. Whatever measurement it is you do on an entangled particle affects its entangled partner instantaneously (though in fairness it is technically possible there is some speed limit on this, despite all the current, successful models indicating otherwise, just because we aren't technically capable of doing these experiments over arbitrarily long distances, leaving the possibility that at some immense distance, there is a slight "time delay" open)
As for individual photons interfering themselves, that's shown by the double slit experiment itself, as you can fire individual particles at the slits and get the interference pattern. Though, a more interesting demonstration in my opinion is the quantum eraser.
The QE works in much the same way as the double slit experiment, except directly after the slits, the photons are split into two entangled photons (of half the energy each, though this is mere trivia) and while one continue to go towards the screen as normal, another is sent to the socalled quantum eraser.
Conceptually it's simple, the quantum eraser is just a set of beamsplitters that either let through or reflect light with a 50/50 chance, arranged so that whichever slit the photon actually passed through, it either ends up at detector A or detector B, though it's not possible to tell which slit it came from.
The photons that hit the screen, if you just look at all of them, just paint a clump of light, as one would expect if there were no slits. Interesting in its difference from the regular double slit experiment, but easily handwaved by "well, when it hit the crystal, it 'reset' so of course this is what happened" (ultimately not correct, but sounds reasonable enough)
What's interesting, however, is our two detectors. They're nothing fancy, they just detect whether a photon hit at all.
However, we were smart, we made sure to timestamp each time a photon hit the screen, and each time a photon hit one of our detectors. This basically means for every hit on the screen, we know which detector its entangled partner hit.
So, we look at only the photons on the screen which partner hit detector A.
Interference pattern.
We do the same with detector B's photons.
Interference pattern (though the gaps are where the bands are for detector A's pattern)
"Alright," we say, "I see how it is. I'm going to trick you."
We set up another two beam splitters along the two paths leading to the eraser, which direct to detector C or detector D, depending on which slit it went through.
We run the experiment again, and now we check C and D against the photons on the screen.
No pattern whatsoever, it's just two blobs now, though ever so slightly offset to the left and right of each other (barely perceptible, but statistically significant)
A and B's respective screen-photons still show the same interference patterns as before, though of course now only at 50% intensity as we removed 50% of the incoming photons (we directed half to C and D after all)
It's important to note here, and many explanations of the quantum eraser fuck up this part, the screen itself never shows any pattern whatsoever. Under no circumstance will there be any pattern other than a blob of light on the screen in a quantum eraser setup. The patterns only become apparent when you selectively look at the photons with a partner that hit detector B, or those with a partner that hit detector A.
What's happening, very, very basically, is that at the final beamsplitter, where a photon ultimately goes to either A or B, the two possible paths (slit 1 or 2) the photon could have taken to get there interfere with one another, the relative phases either cancel out or amplify each other, and essentially a decision is made, and they go to A or B based on the result. Of course, if it first hits the screen, the screen's photon makes that decision, manifesting on its end as you may have guessed as its position on the screen (something not made clear enough in my opinion with explanations of the double slit experiment is that we are dealing with extremely small equipment. The screen isn't a bedsheet or something of that nature, it's on the scale of 20 millimeters across, meaning the phase of the light at the moment of impact determines its position)
As for two beams interfering to result in a different level of illumination than the two separate beams, I can't entirely say I know what this is referring to.
If you're referring to the resulting interference pattern, it's a simple misunderstanding. The light measured is the exact same as the light fed into the system, there's no less and no more light measured than fed in, it's just distributed with a higher probability (thus more light as the end result) where there's constructive interference, and a lower probability (thus less light as the end result) where there's destructive interference. The interference doesn't affect how much light you get, you get exactly 1 photon per 1 photon fired (well, excluding the ones that didn't even make it past the slits because they hit the wall) they're just distributed according to the interference, much like you'll measure the water level to be higher where the waves from two ripples in a pool of water intersect (because the water from the two waves add to each other) than you do where there's no waves. Though the analogy to waves in water breaks down because you'd expect the rest of the water to make it resulting in a uniform spread, whereas with quantum waves, it's more akin to one measurement of where the water level is highest at a given moment, many, many times in succession. If you somehow did that, randomly selecting when you take the measurement of that moment, and looked at your data afterwards, you'd see something very similar to the slit experiment's pattern. A series of bands where the water level was highest very frequently, and gaps between those bands where the water level was practically never the highest.
"After noise reduction"! How about the aspect ratio? Yes, it doesn't impinge on the physics, but - just - why not?
Very few colleges get the privilege of scholarly lectures like this.
I wonder if AI could clean-up the audio, better that other noise-reduction techniques.
I hope it could clean up the video too. Making it a lot more sharp.
How does the light from a candle move at the same speed as the light from the sun?
Light moves at maximum speed in a vacuum?
@@YourTripleScorpio Light has NO speed anywhere.
From 1:00 to 2:19 the most genius thing
LOL at everyone complaining about the audio and video. Kids.
A lot of famous quotes in the early parts
Ed Norton came a long way from the sewer said Ralphie boy.
Very interesting how his body language imitates a heavy man to add gravitas to his words.
Sounds make different waves of vibration.
Hi explanation of hidden variables at the end was not very good. He'd have benefited greatly from Bell's ideas.
Turn song on radio, and check under hood for sound vibrations through the chassis check the next pickup on the radio stations until you can hear the radio
The noise reduction seems to have spoiled the sound so much, listening through normal speakers, I couldn;t listen to more than about 20 seconds .. I jumped ahead hoping it would improve. Having dead silence when he's not speaking makes it sound unnatural .. perhaps there's a slightly less intrusive setting ... I didn't realise there was a noise problem on the feynman lectures anyway - I've listened to them many times before without issue, but perhaps this one sounds even worse without NR. Sorry, just saying - it kinda hurts my ears a bit - a bit harsh
Indeed, noise reduction does strange things to the audio, makes it sound unnatural and repels us from it. It's a classic bug where the engineering team fails to weigh in the nuance features that makes it human (the breathing in the voice in text to speech on ios for example)
i think its fins
It s quite odd to see that a scientist like Feynman still needs notes for this kind of,elementary,lecture.I once saw Walter Lewin explain how much he studied when he prepared for a two hour basic lecture about Newtonian laws of motion.My education went bust because I thought if I couldn t get straight A`s without studying was too untalented to learn anything.Then I saw a mathematician say in a public lecture that maths is 90% hard work and 10% talent/gift.Man was I bummed to learn how stupid I had been.I had straight A`s in "junior high" without studying for tests but in high school it didn t work anymore and I totally lost interest in studying.I could still get A`s in languages like English,German and Swedish but Advanced maths and physics not.I could get by with very little study but not as well as I was used to.Nan o man was I naive and just super dumb!!
I was hoping we'd see the cat?
Nice lecture, too bad that is just old, and really does not hold water anymore. In an stochastic universe/world, science can very well defined as not necessary same input will yield same results. Also, the electron should be considered just as a disturbance of a field , then this experiment makes more sense (human sense),i.e., the disturbance occurs everywhere there, kind of 'An Electron travels all possible paths , a single electron'", . I attended some of his lectures when I was very young, it was delightful
His centre of mass is in an unstable equilibrium.
The universe maybe like grid points and field force open like zooming by magnifying so we see light hidden beneath and that why our thinking all sharing equally except those are toothed or cursed by sound
10:21 The holes are not even leveled!
The noise reduction was overdone. Back off the parameters a little, and you might get it right. You don’t want to eliminate ALL noise, because it destroys too much of the signal. There’s a balance you can achieve where it’s still very understandable, and less noisy, but not dead silence and digitally distorted signal.
This is what genius looks like.
He is pretty amazing. Describes such a complex, intricate and weird phenomenon and experiment in a way anyone can understand. I love watching lectures like this, and I'm very sad that a lot of geniuses lived before audio and video could be recorded.
Yes. It's one thing to know complex information. It's another thing entirely to communicate that knowledge effectively to others. He's a born teacher.
Feynman was a fool
@@KenTheoriaApophasis That's the single dumbest thing I've ever heard.
Lopez Anthony Gonzalez Karen Robinson Brian
Sat WHAT ??????
terrible audio
If thats what you have to say about it, i am happy you dont complain about it not having color.
Did he just explain that simultaneity doesn't objectively exist?
Well, it is an abstraction. Things do objectively happen simultaneously, but there is no real thing that is "simultaneity"
That and really if you set an experiment up with a hypothetical extremely precise timer that measures extremely small fractions of milliseconds, you'd find that most things apearing to happen simultaneously are actually not truly perfectly in sync and the probability for 2 things to occur at the same time is extremely low.
No, though a garden walking pretty in the gardens at night she shies like a nighten gail.
Martinez Margaret Jackson John Gonzalez Scott
Please stand still.....
Oh big deal
Your title is NOT helping the number of views. While, I hate "click bait titles" you'd be better served to name this video "Nobel Winner David Feynman and his Brilliant Electron Slit Experiment, with Enhanced Audio""
Do this and quadruple your view rate....
Uses the human as a tool for computing. AI with human intelligence.
never trust a theoretical physician too much, they leave out what dont fit into their calculation. (please dont get angry, is just a joke).
There's no theoretical physician though 😂😅
Minute 25, "You never get two clicks at the same time." I show how that is wrong and what they did wrong to make them think they were right. Find me and my website.
0:54 _see me after class_
You’re drunk
hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh
Audience cringe
you have an audio freely available to you from one of the greatest minds of the 20th century, which somebody managed to preserve and augment to make the sound distinguisable, so your far less advanced brain gets a change to grasp a most intriguing feature of nature, and you complain
So 'comes in lumps' is just another way of saying they're 'discrete'. I guess he wouldn't be Feynman if he just said they were discrete, and been done with it. Perhaps he believed that it'll be remembered better if he says it like that, rather than using the word 'discrete'.
Both Feynman and Krauss were sexually predatory. Not a good look for the profession.
literally nonsense 😊
Comparing bullets to charged particles is just plain wrong. And this is the basis of the double slit. Garbage theory.
What do you suggest ? I'm still trying to figure out what's so special about this experiment. Isn't observing particles the same thing as interacting with them, hence the change of their behavior ?
@@nabilbensafi This is the system. They push probability on you as if it was a law of physics. And you either take it or you fail the course. Basic electrostatics tells you every particle has an electric field. The field passes through both slits, causing the particle to deflect accordingly. But they make it sound like some miraculous thing. But in reality is just Maxwell's work.
@@walterbrownstone8017 Always some idiot on the internet pretending to be smart. First of all, the Feynman Double Slit Experiment has actually been done and has been proven correct. So your assertion that it's garbage is already wrong.
Then you claim that "every particle has an electric field." Are you really that stupid? I suppose neutrons don't exist and have never existed. But, to further my point, I was able to find a paper where they did a double slit experiment with neutrons and lo and behold it's still probabilistic. You're just wrong. Probably someone who failed quantum and is salty they failed.
Paper in question:
D.M. Greenberger and A. Yasin, "Simultaneous wave and particle knowledge in a neutron interferometer"
The paper does give some interesting insight into how much we can know about a particles path but it is *still* inherently probabilistic. Shocker. Some rando who failed quantum isn't smarter than one of the most influential scientists of the 20th century
@@walterbrownstone8017 You're just wrong. Firstly, neutrons are electrically neutral. That's why they're called neutrons. Secondly, you are implying that this experiment would not work with neutrons. This is also completely false. Here's a nice little paper you can read, although given it is obvious you failed quantum I don't know how much you'll understand. This is basic electrostatics.
D.M. Greenberger and A. Yasin, "Simultaneous wave and particle knowledge in a neutron interferometer"
Shocker. One of the most influential physicists of the 20th century is smarter than a some rando in the youtube comments who is salty about failing quantum.
@@JohnSmith-if2qv Firstly neutrons are emergent particles that are made from charged particles. Meaning they always have a presence in the field density of is local space. All particles with spin are emergent. Spin can only emerge from two charged particle fields interacting in the only why they know how, by spinning.
😊 you're right as a spectator there is a lot of laughs and a lot of jokes outside the train tracks probably as you attend the parade
It's not so funny to the security inside the train perhaps the president is inside
...😮 It's a little more serious for the security
And he takes his job very seriously
.. but I guess if you were holding over 200 tons of gold
...😊 Everything would be serious
..... Now you can hear the jokes from the people because of microphones
.... And the insensibility
..... But yes some straight references may continue
As the laughs and jokes could only get themselves an ice cream or go home
😊 Job gets f***** up around here
It's not cool
😊 Because nobody likes the bleaching
... Nobody nothing licks to be bleached
Thank you for the off-topic interlude.
Studied under Professor Feynman. Hard going.......But I youst like his talks...... Now I find irritating.