Richard Feynman: Quantum Mechanical View of Reality 3
Vložit
- čas přidán 12. 07. 2016
- In this series of 4 lectures, Richard Feynman introduces the basic ideas of quantum mechanics. The main topics include: the basics, the Heisenberg’s uncertainty principle, Bell’s theorem and the Einstein-Podolsky-Rosen paradox.
- Věda a technologie
I love how in the start, he laughs about being recorded for all of time, and here we all are watching this decades later. Irony at it's best.
2.45 'What I'm saying must be so damned important, it must be recorded for all of time!'
You're up there, Prof Feynman.
I hope this video will be available for all of time. Thank you Richard Feynman, where ever you are...
Nice to see he was keeping up the tradition of physicist hair.
He gives off such a "regular guy" vibe that it makes the physics seem equally approachable.
He actually helped build the ivory tower rather than just live in it with tenure.
Please don’t put ads in this. It’s amazing and I understand very little of what he is talking about. What a man.
Brilliant! The professor that I never had in University. On the flip side quite intersting to hear audience's questions on elementary matters such as (random examples although are many) adding vectors and abstract thinking - which is physics 10
And yes Professor Feynman - you were indeed recording for posterity
If you aren't familiar with him, the diagram Feynman draws at 1:20:00 is his greatest contribution to physics. That idea took complex calculations that were almost impossible at the time and made them relatively simple, allowing for tremendous work to be advanced in quantum electrodynamics.
Pretty sure he invented them before completing his master's degree. Guy was still a student
All that due to his intention of simplification of complex phenomena with pictorial thinking before going for mathematical aid.
I studied the philosophy of physics in college. Feynman's work shown here is widely underappreciated by philosophers. Essentially, he established the premise that everything that possibly happened, given the most complete possible understanding of the world, actually did happen. That means that if the present exists, that established the past. On a classical view, this isn't obvious. If you have a leaky bucket that has emptied, it is impossible to reconstruct when it finished emptying. Now you could look at a deterministic world and presume that with sufficiently complete knowledge, you could. But quantum mechanics throws out determinism. Enter Feynman: if there is any uncertainty, any quantum fuzziness about what could be the past given the present, all of those possibilities happened in superposition, summing over the consistent histories to make a single unique past.
Most focus on the quantum implications for the future, but it is very underappreciated how well Feynman solved the quantum implications for the past. That's a point I made in my thesis many years ago.
iconoclast vituperations Obviously I'm using imprecise language in a CZcams comment in a way I would not in a thesis. I included quite a bit of the determinism in quantum mechanics debate in my thesis and these is still quite a bit left. My comment just briefly stated where I fall in that debate. I don't mean to have the debate here. I will say though that the relevant definition of "determinism" for philosophical purposes is the one espoused by Bohm and Einstein and not the one that Hawking more recently discussed in his popular science book "The Universe in a Nutshell." Hawking's version is undoubtedly correct, but also irrelevant.
The physics in my thesis was checked by highly qualified professional physicists. I was doing original philosophy and I talked to physics professors to make sure the physics premises I used in my philosophy were being used correctly. That required highly precise language that just isn't what I aim for in a comment like this.
iconoclast vituperations Sure. The two concepts of determinism are related but several steps removed. There is a great deal of debate in philosophy, indeed I would say the majority of the debate over free will, consists of to what extent the existence or lack there of of "hard determinism" (The technical term for the kind that I'm talking about) implies that free will does or does not exist. Personaly, I agree with Dennet's view on free will but I differ with Dennet in that I think that the lack of hard determinism is an important part of why everyone, even those inclined against views of his sort (known as conpatibilist views) should accept his view and believe in determinism.
But all of that is highly controversial and many smart people disagree quite reasonably. The lack of hard determinism is much more agreed upon in physics, though unfortunately philosophers are almost always shocked to hear that.
By Hard Determinism I mean that for all statements about the future, they are either true or false at all times. The temporal nature of a statement does not preclude it having a truth value nor does the truth value of a statement change over time (as long as all times in it are explicit and not relative). So fir example, if I say Donald Trump will be President on January 20th, 2017 (really not making any political statement here, though obviously I could), a hard determinist says that statement is true now, will be true in 20 years, was true 100 years ago.
Physics experiments of the sort proposed by Bell have all but completely ruled out hard determinism. Though you have to go beyond Bell's inequalities to get there, in my opinion the only way a hard determinism could be saved is by making essentially a Cartesian Evil Deceiver model of the universe. With Kochen-Specker and other modern arguments, including some experiments recently performed, you would need every possible way of generating psuedorandom numbers, like digits of pi, computer clock cycles, human choices, etc. to be perfectly correlated with the predictions of quantum mechanics with no plausible reason. To me, that's good enough to say hard determinism is dead.
There are softer forms of determinism though. Hawking proposed that, putting it in more philosophical terms than he did, every possible state of the universe is set in advance. What is random is which state the speaker of this sentence happens to find themselves. But that doesn't really change the randomness of outcomes, rather it is a statement of which outcomes could occur. Indeed, not EVERYTHING is possible, but it is also true that not everything is predetermined.
There is a LOT I glossed over in there, but hopefully it is enough for you to do some googling.
Peter AI Yes. Again, my language is not that careful in a CZcams comment. If I were writing a professional paper, I would have been more explicit about that. But thank you for clarifying.
Do you happen to have a copy of your thesis you could share?
"The physics in my thesis was checked by highly qualified professional physicists. I was doing original philosophy and I talked to physics professors to make sure the physics premises I used in my philosophy were being used correctly. That required highly precise language that just isn't what I aim for in a comment like this."
So, your only purpose here could have possibly been self-aggrandizement. All this amounts to is naked appeals to academic authority (yours and others) which hasn't been as weak as it is today since the days of ancient greek sophistry. Any work produced by the academy is only as valuable as what it produces of consequence. This is a problem for 21st century physics and an even bigger problem for philosophy going-on over a century now. This takes pretentious to whole new level, and encapsulates the overarching problem with the Western intellectual class. You follow behind materialist physics without producing anything novel beyond endless "-isms" (symbols) for you and other scholars to write papers about, but no amount of peer review matters when nothing you say makes a difference to civilization, and any engagement with such symbols requires exponentially more unproductive time in the form of reading alone, let alone participation in social institutions. You all have to appeal to authority in the end, because even your value is merely theoretical. Your knowledge is impotent without tenure, state funding, and tax-exempt endowments.
Philosophy actually generated wealth once upon a time. Now, it merely generates poorly-worded comments in a digital bathroom stall.
The lecture by a man who understands Quantum Mechanics most on this planet.
Richard Feynman was one of the most brilliant minds around, if he only had the technology of plasma conductors he would have figured it all out. All of it.
To my own layman’s perspective- Feynman is breaking it down to basic algebra. I would be so interested into hearing him speak advanced mathematics. I almost feel cheated, because he’s made it so simple that even I can understand.
So many quantum physics videos I love listening to go so above my head, the math makes no sense..: the fact this makes sense to me is almost as confusing…. Does that make sense?
Ha!
According to page 418 of Einstein: His Life and Times (1972) by Ronald W. Clark:
"It should be possible to explain the laws of physics to a barmaid." - Rutherford
"All physical theories, their mathematical expressions apart ought to lend themselves to so simple a description 'that even a child could understand them.' " - Einstein
Attributed to Richard Feynman, by two of his colleagues at Caltech in 1989 (after his death):
Feynman was once asked by a Caltech faculty member to explain why spin 1/2 particles obey Fermi-Dirac statistics. He gauged his audience perfectly and said, "I’ll prepare a freshman lecture on it." But a few days later he returned and said, "You know, I couldn’t do it. I couldn’t reduce it to the freshman level. That means we really don’t understand it."
"what im about to say must be so damned important it must be recorded for the rest of time". yes exactly hahaha
I have seen all that's on CZcams of Feinman's talks. It's unfortunate that more footage either wasn't created or wasn't kept of him. He's clearly a name that Physics will not soon forget.
gotta love feynman
"What I'm saying must be so damned mportant that it has to be recorded for all time." TGF that.
51:18 Classic Feynman: "...boy that was fast...it was also right !"
love you SIR!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
37:11 anyone cares to elaborate a bit more on this? can't understand why "these circles are tighter, when we change the angles quicker, so that the bumps get smaller""
OMG he said there were two kinds of polarized light... was this really before they figured out Elliptical polarization?
Elliptical and linear, that makes two.
you can always have a super position of linearly polarized light with a phase difference and construct any exact elliptical polarization. What he means is no matter what basis you choose (linear or circular) you always need two components (up,down or clockwise, anticlockwise) to fully and accurately describe light.
he already made the detector with sensitivity for two different energies with the gradings hehe he just needed to add another multiplier.
15:40 is explaining echo of light
I need to talk like him
51:26 yyyyyyy wow...
'just a moment please.. Just a moment... Aah.. Just a moment....'
can't stand that guy
I cant stop laughing every time he makes humor
I See Photons ! Therefore I AM !!!
31:57, 1:08:05, 1:26:50, 1:41:07, 1:49:55
❤❤❤
PROVER.
NEWTON.
EP.
the probability of a what?
7.
1.
So lowwww!!! Can't hear
DALAMI.
MONDAY.
BUDDHI.
PRIME.
I respect and love Feynman like hell.....but they are unbearable and boring to death.....😂😂😂😂😂😂😂
I think he doesn't know what he is talking about! :)
youcanfoolmeonce Not to put too fine a point on it, very nearly all the physicists in the world think Feynman did know what he was talking about. In fact, very nearly all the all the physicists in the world consider Feynman a hero, precisely because he found out the rules that he is explaining in these lectures. I am sure you can find some renegade who says bad things about Feynman or about quantum mechanics in general, but you will find that that renegade is in a very small minority. I realize that you might be joking. The problem is that there are people who say the same thing you wrote, who are not joking. I don't want to leave any confusion, not even as a joke. Pardon me if you think I am being too picky.
I am not joking either. Just because he was given the Nobel prize I don't have to accept BS! This"'lecture" is a total fake, incoherent! You can pretend that you understand this gibberish, but you are fooling yourself. It's a pity that seemingly educated people fall for humbuggery out of respect for authority. Pardon me if you think I hurt your feelings.
youcanfoolmeonce Like it or not, Feynman is describing, in this lecture, the way things really work. The hard fact is that the world of the very small is very different from the world of our everyday experience. I don't see why this difference is any harder to accept than other differences in our world. Nobody complains when we point out that crocodiles are very different from goats, or goldfish. Nobody complains when we point out that whales are clearly quadrupedal mammals that returned to and evolved for life if the sea. (Well, a lot of religious fanatics do complain, but I think we can agree they are wrong.) So, why complain when we tell you that the world of the very small behaves oddly?
+ Mark Holmes If Feynman is describing the way things really work for you in this "lecture" then you have a very peculiar understanding of things to put it mildly. But you are missing my point. Nobody has a problem understanding the difference between our everyday experience and the very small. We all know about the invisible atom (which is a tiny ball under the most powerful electron microscopes) and its components, the electrons, protons, neutrons, etc. The problem is when someone is trying to explain things that are not visible by any means, cannot be explained by observation, by scribbling useless lines on the board, making up things to confuse and getting confused and making useless statements and mathemagics with the power of authority. All this with great charisma of course, unmistakable hocus-pocus that only the "learned" can understand, never mind the uninitiated, the students and laymen.
My point is that there are things that we will never understand and at one point we need to acknowledge this. Examples are the beginning of the universe, (if there was one) life, the nature of the particles within the atom, their purpose, gravity, magnetism, etc. Feeble attempts to claim that we can understand all that by hubris, hypotheses and unprovable theories is a waste of time. There always will be charlatans who will be admired and rewarded for their "work". I am not saying that science must stop research. But it has to be reasonable.
+ Iconoclast Really? So you see the Emperor's clothes? By the way, I don't use "smart phones", dumbshit!
I studied the philosophy of physics in college. Feynman's work shown here is widely underappreciated by philosophers. Essentially, he established the premise that everything that possibly happened, given the most complete possible understanding of the world, actually did happen. That means that if the present exists, that established the past. On a classical view, this isn't obvious. If you have a leaky bucket that has emptied, it is impossible to reconstruct when it finished emptying. Now you could look at a deterministic world and presume that with sufficiently complete knowledge, you could. But quantum mechanics throws out determinism. Enter Feynman: if there is any uncertainty, any quantum fuzziness about what could be the past given the present, all of those possibilities happened in superposition, summing over the consistent histories to make a single unique past.
Most focus on the quantum implications for the future, but it is very underappreciated how well Feynman solved the quantum implications for the past. That's a point I made in my thesis many years ago.
I’m not sure if that’s the correct interpretation. Technically, the “possible” events that combine to form a superposition have not happened. They exist only as probabilities until a measurement is made. This is what makes the quantum world so strange - the math tells us that nothing exists until we look at it, at which point whatever we’re looking at manifests its state/properties at random.
@@dannykal That isn't what I'm talking about. I'm talking about quantum implications for the existence of the past, not the future. But as for the future, what you said is one possible interpretation. The math works equally well on the opposite view, that all possible futures equally exist. I tend to like the unfolding manifold view where the future doesn't exist until we get there, but quantum mechanics works equally well either way. Physicist Roland Omnes described the divide between these views as "the chasm" in his book Quantim Philosophy. That was a major point in my college thesis on this stuff.