Feynman answered this question himself.
The quote is taken from his blackboard at the time of his death. Right underneath, it says, "Know how to solve every problem that has been solved."
When Feynman said "create", he did not literally mean that in order to understand particle physics, he had to go Tony Stark on us and build his own accelerator. Instead, he meant that, starting with a blank piece of paper and the knowledge already in his mind, he could take any theoretical result and re-derive it. ("Any" is probably an exaggeration, but he could likely derive whatever he was interested in.
Feynman answered this question himself.
The quote is taken from his blackboard at the time of his death. Right underneath, it says, "Know how to solve every problem that has been solved."
When Feynman said "create", he did not literally mean that in order to understand particle physics, he had to go Tony Stark on us and build his own accelerator. Instead, he meant that, starting with a blank piece of paper and the knowledge already in his mind, he could take any theoretical result and re-derive it. ("Any" is probably an exaggeration, but he could likely derive whatever he was interested in.)
Feynman thought that ability was the true marker of understanding something because the only way to be able to work something out yourself is to have a firm understanding of each step of the reasoning involved. Further, if you try this, even with relatively simple concepts you think you understand well already, you'll find that you frequently come away from the process with a much deeper appreciation for the problem.
An even more extreme position from Feynman was[1]
Once, I [David Goodstein] said to him, "Dick, explain to me, so that I can understand it, why spin one-half particles obey Fermi-Dirac statistics." Sizing up his audience perfectly, Feynman said, "I'll prepare a freshman lecture on it." But he came back a few days later to say, "I couldn't do it. I couldn't reduce it to the freshman level. That means we don't really understand it."
Feynman meant here that understanding something is not just about working through advanced mathematics. One must also have a notion that is intuitive enough to explain to an audience that cannot follow the detailed derivation.
I've seen a few more sources that spell out Feynman's position on this in detail.
The spinning plate story describes how Feynman felt that curiosity about simple things, and working them out for himself, helped him retain an attitude of play towards his professional work that got him out of a slump: http://books.google.com/books?id=7papZR4oVssC&lpg=PP1&dq=surely%20you're%20joking%20mr.%20feynman&pg=PA173#v=onepage&q=plate&f=false
Feynman's Tips on Physics, an extension to the Feynman lectures, has a chapter about how to learn physics, emphasizing that memorizing formulas is hopeless in the long run, and that by knowing a few key things and understanding the principles, you can work out whatever details you need. I can't find this chapter online, though.
Finally, Feynman's Lost Lecture is a fantastic example of precisely what Feynman meant. In it, he describes his own elementary proof that the inverse square law for gravity leads to elliptical orbits.
Great question, from what I’ve read of Feynman (Mostly his lectures, but also autobiography) this quote really gets to the core of him as a person, amazingly it’s also a valuable takeaway from his works.
Do you really know much?
You can ask most Highschool physics students ‘What is light?’ and they’ll reply “photons of course!”. They’ve got a fancy word to tag on to their experience, but if you dig a little deeper:
“So, what’s that, a photon?”
“uhm…Uh…A ball of energy? Maybe, Or a wave?…It’s packets of energy, that’s it!”
Then you can keep going, what’s a packet of energy? Is it a little rectangula
Great question, from what I’ve read of Feynman (Mostly his lectures, but also autobiography) this quote really gets to the core of him as a person, amazingly it’s also a valuable takeaway from his works.
Do you really know much?
You can ask most Highschool physics students ‘What is light?’ and they’ll reply “photons of course!”. They’ve got a fancy word to tag on to their experience, but if you dig a little deeper:
“So, what’s that, a photon?”
“uhm…Uh…A ball of energy? Maybe, Or a wave?…It’s packets of energy, that’s it!”
Then you can keep going, what’s a packet of energy? Is it a little rectangular mars bar shape? How big? How is a ball of energy reflected? How is it made?
And so on. The definition of ‘photon is a packet of energy’ isn’t sufficient to recreate the behavior of photons. It’s actually not sufficient for much other than making noise. Feynman realised on a deep level that knowledge is revealed when a person can recreate real world phenomona by applying their knowledge, or working within the model they have in their mind. Unless that model offers interesting insights into the deeper aspects of a thing it is likely little more than a label..
This goes for even the most elementary parts of mathematics and physics. Ask a bookish, high performing math student “What’s Pythagoras’ Theorem” and a hand will shoot up, with a proud recitation of a squared plus b squared yada yada. But that same student will almost always be baffled as to where that rule comes from, even college students are. The formula which is a prerequisite for everything they’ve studied for four years, and yet they can’t prove it!
So do these people, with nice shiny GPAs, really understand Pythagoras theorem? Probably not, they don’t see the workings behind the curtain. Which is fine for solving problems, but if you want some understanding of the real causes of things in physics you need to see the invisible connections behind the screen. And the only way to see those wispy, intangible things in many cases is to understand the origins of what you use in mathematics.
It’s a remarkable feat to realise just how little one understands a concept, and how insufficient knowledge without creation is. You’ll imbibe this to an extent if you work through Feynman’s lecture courses.
I think Feynman would be very averse to the wild statements people produce today concerning science, for example:
‘All our behaviour is just chemical reactions, the human mind is a product of chemistry and electrical impulses!’
Maybe, but until you can concoct a set of chemical reactions and capacitors that create a human from scratch, you don’t really have the right to say that. This kind of shallow, superlative thinking is very popular today, cough*Sapiens* cough, but I don’t think much passes the Feynman test, which sets requirements on the concepts we put forward beyond ‘ah, that kinda sounds cool and seems like it may be right, in a vague kind of way’. It’s a wonderful way of seeing just how staunch ones own concepts are, or even the concepts you come across in books.
This was what Feynman called the Babylonian approach to science. It’s closer to engineering. To a Babylonian scientist, “Does it work?” “Does the bridge stand?” are better questions than, “Is it elegant?” “Does it explain the mind of God?”
Feynman divided all scientists as Athenians or Babylonians. He was of the second group. But Athenians wanted to know the essence of the problem. They, like Plato, thought of the perfect form. A chair had a form or an essence that was more elegant than the thing in your dining room that had splinters and wobbled. The form was more important to Athenian philoso
This was what Feynman called the Babylonian approach to science. It’s closer to engineering. To a Babylonian scientist, “Does it work?” “Does the bridge stand?” are better questions than, “Is it elegant?” “Does it explain the mind of God?”
Feynman divided all scientists as Athenians or Babylonians. He was of the second group. But Athenians wanted to know the essence of the problem. They, like Plato, thought of the perfect form. A chair had a form or an essence that was more elegant than the thing in your dining room that had splinters and wobbled. The form was more important to Athenian philosophy, than the thing itself.
Feynman pointed out that the Babylonians used mathematics with base 60 because it allowed for more factoring. So we still have a circle with 360 degrees, 60 minutes and 60 seconds of arc. It was practical. Feynman’s rival, Murray Gell-Mann was an Athenian in how he approached theoretical physics. These two brilliant physicists couldn’t agree on anything. It is ironic that Gell-Mann and Feynman shared a secretary. She must have had an interesting job.
In direct answer to your question, a Babylonian or an engineer stands by that which stands.
Feynman's words are now seared into the DNA code of the world's first man made living thing. Yes Craig Venter's built-from-scratch synthetic bacteria has Feynman's words "I cannot understand what I cannot build", converted from the original ASCII, in its trailing DNA codon base pairs. (So do all of its offspring of course.) I had the privilege of discussing with Craig his exploits over dinner. He pointed out to me that Feynman was from the start his inspiration in creating synthetic life!
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Note added 9/5/2015: As Malcolm Sargeant comment illustrates we need precision in describing what e
Feynman's words are now seared into the DNA code of the world's first man made living thing. Yes Craig Venter's built-from-scratch synthetic bacteria has Feynman's words "I cannot understand what I cannot build", converted from the original ASCII, in its trailing DNA codon base pairs. (So do all of its offspring of course.) I had the privilege of discussing with Craig his exploits over dinner. He pointed out to me that Feynman was from the start his inspiration in creating synthetic life!
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Note added 9/5/2015: As Malcolm Sargeant comment illustrates we need precision in describing what exactly Feynman did, least confusion is created. In his book "Life at the speed of Life", which I highly recommend, Craig is careful to explain what he did and did not do. See Allan Steinhardt's answer to Can science create life? If not, what stands as a barrier? for details.
Richard Feynman’s aphorism “What I cannot create, I do not understand” captures a scientific and pedagogical principle: deep understanding is demonstrated by the ability to construct or reproduce a system from first principles. The line appears on his blackboard and in popular accounts as a distillation of how he approached problems in physics, teaching, and engineering. Key meanings and implications:
- Constructive criterion for understanding
- To “create” means to build a working model, derive dynamics, or produce phenomena from the assumed ingredients and rules.
- If you can construct something your
Richard Feynman’s aphorism “What I cannot create, I do not understand” captures a scientific and pedagogical principle: deep understanding is demonstrated by the ability to construct or reproduce a system from first principles. The line appears on his blackboard and in popular accounts as a distillation of how he approached problems in physics, teaching, and engineering. Key meanings and implications:
- Constructive criterion for understanding
- To “create” means to build a working model, derive dynamics, or produce phenomena from the assumed ingredients and rules.
- If you can construct something yourself, you’ve identified the essential mechanisms and can predict behavior beyond mere description.
- Modeling and reduction
- Understanding involves reducing phenomena to a set of components and relations that, when assembled, reproduce observations.
- This is why theorists write models and experimentalists build apparatus: both test whether the assumed parts suffice.
- Contrast with descriptive or instrumental knowledge
- Describing how something behaves or having equations that fit data is weaker than producing the thing from those descriptions.
- The statement criticizes purely phenomenological or black-box knowledge that lacks generative explanation.
- Practical scientific practice implied
- Encourages building: thought experiments, toy models, simulations, laboratory reconstructions, or engineering prototypes.
- Encourages checking assumptions: if a construction fails, some element of the understanding is missing or wrong.
- Epistemic humility and iterative learning
- Admits that apparent comprehension can be superficial; attempting creation reveals hidden complexities.
- Creation is an iterative test: failed attempts refine hypotheses until the model works.
- Broader applications (education, programming, design)
- In teaching, asking students to produce derivations, proofs, or implementations demonstrates mastery.
- In software and engineering, being able to implement an algorithm or design a device shows one truly grasps its workings.
- Limits and nuances
- “Create” need not mean literal fabrication of a macroscopic object; it includes constructing mathematical models, simulations, or experimentally reproducible behaviors.
- Some complex systems are presently beyond human ability to recreate in full (e.g., consciousness, climate down to all microstates); the maxim functions as an ideal guiding investigation rather than an absolute test.
Examples that illustrate the dictum
- Physics: Deriving planetary motion from Newton’s laws (creation of predictive model) shows deeper grasp than empirical tabulation of orbits.
- Biology: Synthesizing a functional gene circuit in the lab demonstrates mechanistic understanding of regulatory interactions beyond observing gene expression patterns.
- Software: Rewriting a cryptographic protocol from its specification affirms comprehension more than merely using an implementation.
Summary
Feynman’s statement is a compact epistemological standard: true understanding is shown by the ability to generate or reproduce a phenomenon from its principles. It promotes constructive modeling, critical testing of assumptions, and learning-by-building as the route to reliable, deep knowledge.
He really meant that one must be able to build up an idea from the ground up and explain it in such a way that anyone with sufficient intelligence could follow it and understand what it means.
And he really followed this. One time, I asked him how Hilbert Spaces were useful in physics, and he was stumped about how to explain it to a freshman. He was quite disappointed and said that meant he probably didn't really understand it himself.
Which on the surface is ridiculous. But he was an amazing and unique guy in a lot of ways... he managed to blend humility and arrogance so far that you genuinel
He really meant that one must be able to build up an idea from the ground up and explain it in such a way that anyone with sufficient intelligence could follow it and understand what it means.
And he really followed this. One time, I asked him how Hilbert Spaces were useful in physics, and he was stumped about how to explain it to a freshman. He was quite disappointed and said that meant he probably didn't really understand it himself.
Which on the surface is ridiculous. But he was an amazing and unique guy in a lot of ways... he managed to blend humility and arrogance so far that you genuinely couldn't tell the difference between them.
He meant, simply, if you don’t understand something well enough to create it from basic components or axiomatic elements, then you don’t understand it thoroughly enough. As an autodidact, Feynman was great at basing his knowledge confidence on how thoroughly he could recreate something from basic principles - which is how it should be. Nothing should be assumed or rote.
Feynman once advised those who want to learn quantum mechanics that self-study is the best way. Only if you go through the process of deriving it yourself will you really understand it. If you study it formally you will spend a lot of time studying the mathematical tricks that make calculations easier, but that could be at the expense of true understanding.
Of course Feynman himself was not really self-taught, but he worked hard to re-derive results that others discovered. One method he used was to read only the introduction of a research paper, and then try to figure out the complete result on
Feynman once advised those who want to learn quantum mechanics that self-study is the best way. Only if you go through the process of deriving it yourself will you really understand it. If you study it formally you will spend a lot of time studying the mathematical tricks that make calculations easier, but that could be at the expense of true understanding.
Of course Feynman himself was not really self-taught, but he worked hard to re-derive results that others discovered. One method he used was to read only the introduction of a research paper, and then try to figure out the complete result on his own.
I’m not sure where these guys got their answers from, I was born exactly nine months after Feynman died. The oddest thing was, when I first heard him speak, I thought I was listening to myself. I can tell you what he meant by this. He meant that if he cannot construct it as a system in his mind, then he could not understand it, he needed to visualize what was happening to truly comprehend it in its intricacies and motions, no matter the system or concept. I am exactly that same way. Take it with a grain of salt if you wish, that is how I interpret it, which certainly is not any less valid than
I’m not sure where these guys got their answers from, I was born exactly nine months after Feynman died. The oddest thing was, when I first heard him speak, I thought I was listening to myself. I can tell you what he meant by this. He meant that if he cannot construct it as a system in his mind, then he could not understand it, he needed to visualize what was happening to truly comprehend it in its intricacies and motions, no matter the system or concept. I am exactly that same way. Take it with a grain of salt if you wish, that is how I interpret it, which certainly is not any less valid than any other way, when dealing with ambiguity and subjective viewpoints.
I think Mark Eichenlaub's description is the best and most thorough, but as a fan of science fiction literature, I can sum it up with one word: Grok (http://en.wikipedia.org/wiki/Grok), though the term has more meaning in its original context.
"In an ideological context, a grokked concept becomes part of the person who contributes to its evolution by improving the doctrine, perpetuating the myth, espousing the belief, adding detail to the social plan, refining the idea or proving the theory."
He is answering the epistemological question of what it means to understand. Indeed, I take his quote as an attack on the current state of education, where we ask student to repeat and recite instead of teaching them to create and explore.
He simply meant: if he doesn’t understand something — some process or mechanism well enough that he could, himself, create it if he wanted to, then he cannot really claim to “understand” it.
It’s got nothing to do with theoretical physics. I am not a theoretical physicist; yet I immediately feel I understand what Mr. Feynman was getting at.
Many people say “I understand <this> or <that>.” But all they usually mean is that they are relatively familiar with <whatever> sufficient that staring at <whatever> doesn’t freak them out and that they can usually, more-or-less predict what <whatever> is goi
He simply meant: if he doesn’t understand something — some process or mechanism well enough that he could, himself, create it if he wanted to, then he cannot really claim to “understand” it.
It’s got nothing to do with theoretical physics. I am not a theoretical physicist; yet I immediately feel I understand what Mr. Feynman was getting at.
Many people say “I understand <this> or <that>.” But all they usually mean is that they are relatively familiar with <whatever> sufficient that staring at <whatever> doesn’t freak them out and that they can usually, more-or-less predict what <whatever> is going to do based on direct observation of <whatever>.
Richard Feynman meant something else with the word “understand” as used in the quoted sentence. Richard Feynman meant grok. But not the water drinking part, the other kind.
But that kind of deep-through-the-bones understanding feels as good as drinking water when you’re really thirsty.
Five tons of flax.
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Furry cows moo and decompress.
After going through all the answers and revisiting your question, I think the basic aim of your question was to analyse how a theoretical physicist can 'create' anything when he/she is not practically 'making' any experimental setups for his/her theory.
Well, one needs to understand that 'create' doesn't only mean to 'make' something visible to the human eye. One can also create intuitive ideas.
A mathematical physicist (or theoretical physicist) creates new variables which represent real-life physical quantities to prove the physically existing laws of nature. Thus, creation is not only lim
After going through all the answers and revisiting your question, I think the basic aim of your question was to analyse how a theoretical physicist can 'create' anything when he/she is not practically 'making' any experimental setups for his/her theory.
Well, one needs to understand that 'create' doesn't only mean to 'make' something visible to the human eye. One can also create intuitive ideas.
A mathematical physicist (or theoretical physicist) creates new variables which represent real-life physical quantities to prove the physically existing laws of nature. Thus, creation is not only limited to the practical world but also to the theoretical world of numbers and variables.
The statement basically means to own the variables/numbers/physical quantities and derive the equations yourself (as if you're the creator of that equation) which shall further lead to a better conceptual understanding.
Thanks for the question! :)
Note- Not a factual answer. Would only like to share this small little interesting piece of information.
When young Richard Feynman met the great physicist Neils Bohr aka Nicholas Baker for the first time.
It so happened that Richard Feynman and his team at Los Alamos were working on an atomic bomb project. Neils Bohr and his son Aage Bohr (real name is Jim Baker) came from Denmark to check on to the problems regarding the bomb. The first meeting was quite formal and also involving the big guns of the then time and young Feynman was sitting at the back of the table most of the time.
The next day,
Note- Not a factual answer. Would only like to share this small little interesting piece of information.
When young Richard Feynman met the great physicist Neils Bohr aka Nicholas Baker for the first time.
It so happened that Richard Feynman and his team at Los Alamos were working on an atomic bomb project. Neils Bohr and his son Aage Bohr (real name is Jim Baker) came from Denmark to check on to the problems regarding the bomb. The first meeting was quite formal and also involving the big guns of the then time and young Feynman was sitting at the back of the table most of the time.
The next day, his son called Feynman to meet Neils Bohr and to discuss on how to increase the efficiency of the bomb.
They both went nuts discussing these whole trivial facts and ideas regarding the bomb. Young little Feynman would bluntly disagree with the ideas of Neils Bohr even though he was quite a young scientist back then. He had this very trait of passionately discussing scientific ideas.
And after they had done discussing all the ideas, this is what Neils Bohr said to his son the next day, "Remember the name of that little fellow in the back over there? He’s the only guy who’s not afraid of me and will say when I’ve got a crazy idea. So next time when we want to discuss ideas, we’re not going to be able to do it with these guys who say everything is yes, yes, Dr. Bohr. Get that guy and we’ll talk with him first.”
Isn't that a remarkable statement!
(Reference - Surely you're Joking Mr Feynman)
While some of the other replies present interesting ideas, none seem to express one simple answer. Feynman was in the business of discovering the laws of nature. He understood how to derive various equations and statements out of other equations and principles. He understood the mathematical relations between various fields, bodies and processes.
However, having discovered the laws of nature, one has not gained an understanding of them but only a formulation of what they are. Where do they come from? Why aren't the laws different from what they are? Why are there laws at all? Understanding the
While some of the other replies present interesting ideas, none seem to express one simple answer. Feynman was in the business of discovering the laws of nature. He understood how to derive various equations and statements out of other equations and principles. He understood the mathematical relations between various fields, bodies and processes.
However, having discovered the laws of nature, one has not gained an understanding of them but only a formulation of what they are. Where do they come from? Why aren't the laws different from what they are? Why are there laws at all? Understanding the laws of nature implies having definitive answers to such questions, as one might who created them. Feynman never pretended to have such answers. "...the world is very mysterious and wonderful," he said in an interview, "There are many profound questions that leave me awestruck and confused."
You asked a great question, but there seems to be no conflict in his statement.
I always meter my own understanding in a way to ask: if I was sent back in time, without the peers or existing results I have today, could I prove/invent X. I think this is what Feynman is saying: to understand something is to be able to come up with it individually.
Of course the leg up I would have over Newton is not in ingenuity, but knowing the right questions to ask.
In "Surely You're Joking Mr. Feynman" he talks about a conference he attended in Rochester and how Lee had tried to explain something to him and he felt it was too complicated for him to understand so he didn't even try to read the paper Lee had given him. He was staying at his sister's house and he said to her "I can't understand these things that Less and Yang are saying. It's all so complicated." His sister said to him "No what you mean is not that you can't understand it, but that you didn't invent it. You didn't figure it out your own way, from hearing the clue." Feynman was also fon
In "Surely You're Joking Mr. Feynman" he talks about a conference he attended in Rochester and how Lee had tried to explain something to him and he felt it was too complicated for him to understand so he didn't even try to read the paper Lee had given him. He was staying at his sister's house and he said to her "I can't understand these things that Less and Yang are saying. It's all so complicated." His sister said to him "No what you mean is not that you can't understand it, but that you didn't invent it. You didn't figure it out your own way, from hearing the clue." Feynman was also fond of puzzles. He said that one time while at a party that some guys girlfriend tried to fool him with stories, and since he had heard a lot of stories in his time, she wasn't able to fool him because he'd heard them all before. She said "a mother and her daughter are travelling in Europe..." and Feynman interrupts her by saying "the daughter had the bubonic plague." The girl didn't bother him with more riddles after that. He also said that while he was in high school someone would come to him at the beginning of the day and would ask him to solve a problem. It might take him 20 minutes to do but he'd get it worked out. Later in the day more people would ask him to solve the same problem and he do it faster because he'd already solved it so to the next 5 guys he looked like a genius.
Historically, early engineering schools were content to graduate students who successfully memorized the formulas. Richard Feynman was astonished to fine this to be the case in many foreign universities. When one can derive an equation, presumably they know something about it. Otherwise, the level of knowledge is unsatisfactory and incomplete.
Is it fair to say then, that no one understands gravity, inertia, or charge? Maybe so.
In Feynman lectures in Physics, Vol.1, at one place, Feynman talks about a japanese temple where two rocks have identical sculpturing, except for one. He points out, people believe, it has been done intentionally so that Gods won't envy the accuracy with which humans can create it again and again. I think he believed, If you have really mastered the art of something you can create it again identically, if not you haven't understood the craft.
The "create" in the sentence should mean replicate the idea. He perhaps used this word, because Japanese Temple's Rock Sculptures had a great influence on
In Feynman lectures in Physics, Vol.1, at one place, Feynman talks about a japanese temple where two rocks have identical sculpturing, except for one. He points out, people believe, it has been done intentionally so that Gods won't envy the accuracy with which humans can create it again and again. I think he believed, If you have really mastered the art of something you can create it again identically, if not you haven't understood the craft.
The "create" in the sentence should mean replicate the idea. He perhaps used this word, because Japanese Temple's Rock Sculptures had a great influence on him.
Sadly the educational system rewards you for whether or not
you can reproduce what the Instructor has taught far more than
if examining whether you actually understand what you have been taught.
I used to offer my students the option of a five minute oral exam
or a three hour final exam. Those that really understood the material
were happy to take the five minute exam. Those that did not and
failed the Oral Exam, could then take the Final for a best possible grade
of a “B”.
What you truly understand (top to bottom), you can create. If you can’t create it, then you don’t yet fully understand it.
Example:
Car: An engineer can create a car and its parts
Atom: Humans can’t manifest matter into existence
There are all these interesting answers below: My personal opinion, having read much about him and his own writings, is that he knew his days were numbered - so he wrote that to mess with peoples' minds for one last time with this cryptic statement. For eternity!
Physicists interpret this as "If I can't derive this result from first principles, I don't understand it."
Engineers interpret this as "If I can't build something out of it, I don't understand it."
Random folks see this and say "Whoa! Feynman was so smart!" - (likely the response he wanted! ;)
However you interpret it, take it with a gra
There are all these interesting answers below: My personal opinion, having read much about him and his own writings, is that he knew his days were numbered - so he wrote that to mess with peoples' minds for one last time with this cryptic statement. For eternity!
Physicists interpret this as "If I can't derive this result from first principles, I don't understand it."
Engineers interpret this as "If I can't build something out of it, I don't understand it."
Random folks see this and say "Whoa! Feynman was so smart!" - (likely the response he wanted! ;)
However you interpret it, take it with a grain of salt. It was Dick Feynman in his element.
That's why I agree with the saying, "if you can't do it, teach it". This is usually said in a derogatory way but having been a teacher for over 35 years, I have found it's the best way to fully understand something.
Theoretical physics is about creating mathematics to understand nature.
If there is a phenomenon in nature that you cannot create mathematics for you haven't understood it.
Probably that he lacked the capacity to understand anything that he is not able to create sometimes people just mean what they say
Being a physicist, he might have found the
idea of anything that could not be defined in terms of some basic measurable dimensions, discomforting and a limitation of our senses.
Pretty much the same thing that Albert Einstein had meant when he said:
“If you can’t explain it simply, you don’t understand it well enough.”
Basically they both mean that just because you can derrive mathimatical models in order to produce results that match experimental evidence doesn’t mean that you understand something.
In order to truly understand something you need to have a logical model that can explain it.
Paul Ikeda's answer to What is the difference between logic and mathematics?
I don't have an answer!
In a video he was asked about the antigravity machine. In the response, he says he could not design it because he simply doesn't understand what is antigravity machine is. The best closest thing to antigravity machine is the floor underneath our feet. I think this explains pretty much the meaning of that statement.
Biologists have not yet fully understood the whole process of life emerging from non-life in every detail. If they have, then they would have already created life from non-life, and would have shown to the world that there is no mystery anywhere.
Not what most think…
There was another saying, in a separate box, below it. Are they connected?
I don’t think so, I believe they were 2 different things.
I believe what he meant was a statement having to do with scientific or mathematical discovery. For instance, he might need to develop different solutions before he could use them.
Thus his desire to know every solution to problems, but I think it goes much further.
THIS answer is NOT about the MEANING of the Feynman statement, but of a possible SOURCE or QUOTE behind his statement. He was citing Giambattista Vico (1668–1744) from Italy, with a twist of his own.
The Dutch educator, philosopher, theologian who was equally well versed in mathematics, Judaism, languages, (para)psychology Prof HENRI VAN PRAAG (1916–1988) used to quote the Italian scholar Giambattista VICO (1668–1744) with his epistemic principle ‘De mens kent, wat hij maakt’, which can be translated as ‘Man knows/understands, what he makes/builds/creates’. Henri van Praag is known to have corr
THIS answer is NOT about the MEANING of the Feynman statement, but of a possible SOURCE or QUOTE behind his statement. He was citing Giambattista Vico (1668–1744) from Italy, with a twist of his own.
The Dutch educator, philosopher, theologian who was equally well versed in mathematics, Judaism, languages, (para)psychology Prof HENRI VAN PRAAG (1916–1988) used to quote the Italian scholar Giambattista VICO (1668–1744) with his epistemic principle ‘De mens kent, wat hij maakt’, which can be translated as ‘Man knows/understands, what he makes/builds/creates’. Henri van Praag is known to have corresponded with Feynman about the problem of Cold Fusion, among other things, and probably also about Jewishness and religion.
Wikipedia quotes this epistemic principle as ‘VERUM est/ipsum FACTUM’ in Latin:
The principle of Verum factum[edit]
Vico is best known for his verum factum principle, first formulated in 1710 as part of his De antiquissima Italorum sapientia, ex linguae latinae originibus eruenda (1710) ("On the most ancient wisdom of the Italians, unearthed from the origins of the Latin language"). The principle states that truth is verified through creation or invention and not, as per Descartes, through observation: "The criterion and rule of the true is to have made it. Accordingly, our clear and distinct idea of the mind cannot be a criterion of the mind itself, still less of other truths. For while the mind perceives itself, it does not make itself." This criterion for truth would later shape the history of civilization in Vico's opus, the Scienza Nuova (The New Science, 1725), because he would argue that civil life—like mathematics—is wholly constructed…..’
So, Feynman wouldn’t be Feynman if he didn’t give it a twist of his own, and turned it into a negative: ’What i cannot create, i do not understand’
The moment i heard Feynman make this statement, i knew i heard the echo of Henri van Praag’s FAVORITE QUOTE. (Nobody else knows Giambattista Vico, unless you’re an historian or political philosopher)
Its an idiotic quote anyway… To suggest man cannot understand what he cannot create is a folly idea yet so indicative of our species frame of mind in recent times.
“Man can create nothing… In all his existence he has only manipulated the form of what has already been created.”
'What I cannot create, I do not understand' is illustrated wonderfully in 2 areas of education - at the kinder garden level the importance of child-centred learning (well established in the 1st world but struggling to be introduced into the 3rd world) and the 'Computer as Laboratory' the title of a project in the 70s at Surrey University based on the idea: 'an excellent way to understand a physics concept is to make the computer simulate it'
Great question. feynman always seemed interested in understanding the true nature of a thing, it's a process and its context in totality.
Feynman didn’t say “shut up and calculate.” That phrase was coined by David Mermin (who did not agree with that attitude, by the way).
But Feynman did say that “nobody understands [how to interpret] quantum mechanics.” Trying to interpret quantum mechanics, he warned, will “get you into a blind alley from which nobody has yet escaped.” But that’s not quite the same as “shut up and calculate.”
Feynman’s attitude was more akin to opening up to the mystery and wonder of nature, and accepting with humility that we don’t have any final theory or understanding of what nature “really” is.
I think it's m
Feynman didn’t say “shut up and calculate.” That phrase was coined by David Mermin (who did not agree with that attitude, by the way).
But Feynman did say that “nobody understands [how to interpret] quantum mechanics.” Trying to interpret quantum mechanics, he warned, will “get you into a blind alley from which nobody has yet escaped.” But that’s not quite the same as “shut up and calculate.”
Feynman’s attitude was more akin to opening up to the mystery and wonder of nature, and accepting with humility that we don’t have any final theory or understanding of what nature “really” is.
I think it's much more interesting to live not knowing than to have answers which might be wrong. I have approximate answers and possible beliefs and different degrees of uncertainty about different things, but I am not absolutely sure of anything and there are many things I don't know anything about, such as whether it means anything to ask why we're here. I don't have to know an answer. I don't feel frightened not knowing things, by being lost in a mysterious universe without any purpose, which is the way it really is as far as I can tell. ~Richard P. Feynman
In my view, because he likely didn't settle for simple hand-me-down explanations himself, and searched for various explanations, from many angles, until he found a way to understand that made sense for him.
That might be the hand-me-down view, or might be one he created, or adapted himself.
In general, this is true not just of Feynman but almost anyone who has thought long and hard about an issue and acquired some level of perspective and clarity on the issue.
So when you listen to such people, or hear them, they come across as good at explaining.
In contrast, those who learn rote-like tend to be
In my view, because he likely didn't settle for simple hand-me-down explanations himself, and searched for various explanations, from many angles, until he found a way to understand that made sense for him.
That might be the hand-me-down view, or might be one he created, or adapted himself.
In general, this is true not just of Feynman but almost anyone who has thought long and hard about an issue and acquired some level of perspective and clarity on the issue.
So when you listen to such people, or hear them, they come across as good at explaining.
In contrast, those who learn rote-like tend to be not so good at explaining things.
It really is that simple. Except it obviously is not.
So Feynman simplified for others after all the great effort he put in to work things out for himself. Others do the same too. Not just Feynman.
But to really understand such people you have to come along on the journey a bit. You also have to know how not to approach a topic before you can understand viable approaches.
People like Feynman had thought of many approaches - including dead ends - and then shared the one they found the most useful.
In contrast, others who learned just the one approach, tend not to have a view of the overall terrain and know just the one approach. They tend not to be that good at explaining things. They are like a GPS instruction list telling you how to get from A to Z, but without knowledge of the terrain. Feynman in contrast might tell you why there are so many windings roads in the English countryside. He would tell you they meander because villages were set up around meandering streams and rivers, and natural paths followed those streams, eventually being developed into roads. He might then tell you about various ways to get from A to Z, including the GPS method, but you’d have learned far more from him than if you only heard the GPS version on its own.
See this is why you can get an A+ in a graduate level course but not really understand all that much. Because you only just learned the one hand-me-down approach - that GPS instruction list.
The quote comes from Feynman's book The Character of Physical Law, which is based on his Messenger Lectures at Cornell. If you look at the quote in context, it is very clear exactly what Feynman meant: He meant that quantum mechanical phenomena cannot be understood using concepts or models from our ordinary experience. They cannot be understood by analogy with anything familiar. But, of course, physicists do understand very well the mathematical formalism and how to apply it to physical systems and make predictions about the results of experiments.
Here is a video of Feynman's lecture where he
The quote comes from Feynman's book The Character of Physical Law, which is based on his Messenger Lectures at Cornell. If you look at the quote in context, it is very clear exactly what Feynman meant: He meant that quantum mechanical phenomena cannot be understood using concepts or models from our ordinary experience. They cannot be understood by analogy with anything familiar. But, of course, physicists do understand very well the mathematical formalism and how to apply it to physical systems and make predictions about the results of experiments.
Here is a video of Feynman's lecture where he makes this statement. The quote comes just after the 8 minute mark.
So, when Feynman says, “nobody understands quantum mechanics,” he means that nobody can interpret it in terms of our common sense notions of reality. That is why there are dozens of interpretations of quantum mechanics, none of which conforms to common sense, and no consensus on which one is correct. And this is perhaps why Feynman also said that trying to interpret quantum mechanics will “get you into a blind alley from which nobody has yet escaped.”
“Study hard what interests you the most in the most undisciplined, irreverent and original manner possible.” R.F.
He also used to say that he was a slow student, because he always thought about how to apply a new concept, where it could lead, how to prove it, what the consequences were. When I read that, it made me think of all the people who did great things with elementary math, and I never did, because I read a formula and my mind stopped there. For instance, anybody with very elementary math could have thought of calculating the radius of the earth like Erastosthenes, but most of us don’t t
“Study hard what interests you the most in the most undisciplined, irreverent and original manner possible.” R.F.
He also used to say that he was a slow student, because he always thought about how to apply a new concept, where it could lead, how to prove it, what the consequences were. When I read that, it made me think of all the people who did great things with elementary math, and I never did, because I read a formula and my mind stopped there. For instance, anybody with very elementary math could have thought of calculating the radius of the earth like Erastosthenes, but most of us don’t think like that (History of geodesy - Wikipedia). It is a shame, isn’t it, that practically everybody knows a little bit of math nowadays, and when we go home, we don’t think of using it!
Feynman is demonstrating how far you can go if you just play with the information you learn. Start playing on the Internet with every concept you learn. Take the simple example of the Pythagorean theorem:
- In history: Pythagoras: Everyone knows his famous theorem, but not who discovered it 1000 years before him. This is a great paper discussing also how many ways you can prove it. Why is it that we learn one proof in school and we think it is “the proof”?
- Did you ever think of the theorem in 3D? Using Pythagoras in 3D - Higher. See also Revolution in the Pythagoras theorem?
- Is it the same as the law of cosines? Pythagoras' contributions to modern astronomy.
- It is even fun to think in what kind of jobs one uses the theorem! Jobs That Use the Pythagorean Theorem. Think about it and check if you missed one!
Another Feynman quote: ““I don't know anything, but I do know that everything is interesting if you go into it deeply enough.”
Everyone will have a different favorite reason. For me it was his magical ability to explain almost anything in terms that almost anyone could understand. It was once said that if they gave Nobel prizes for teaching, he would have won them all. I don't know about that; there's a lot more to teaching than just explaining things so that people can understand. But if they gave Nobel prizes for lectures, he'd surely have retired that prize.
In fact, being too easy to understand can actually hamper learning -- many people had the experience of listening to Feynman explain something that had pr
Everyone will have a different favorite reason. For me it was his magical ability to explain almost anything in terms that almost anyone could understand. It was once said that if they gave Nobel prizes for teaching, he would have won them all. I don't know about that; there's a lot more to teaching than just explaining things so that people can understand. But if they gave Nobel prizes for lectures, he'd surely have retired that prize.
In fact, being too easy to understand can actually hamper learning -- many people had the experience of listening to Feynman explain something that had previously seemed unfathomable, and understanding it perfectly with almost no effort; but ten minutes after they left the lecture theater, their easily-won understanding faded. To "own" understanding, you have to suffer through working it out yourself. Sorry.
But, again, Feynman showed everyone that is was possible to understand, and that empowered us to go learn it ourselves.
Thank you, Richard!
He meant precisely what he said.
The quote comes from this letter:
http://www.diigo.com/item/image/7fr9/rhi7
I don't find it difficult to reconcile "studying hard" with doing so in an irreverent or original manner; this just means "don't take other people's word for something, think for yourself." What's difficult to understand, for me at least, is how one can study hard yet study in an undisciplined way. Usually hard study, and hard work, are very disciplined.
Most textbooks and teachers will lead you through a linearly prescribed set of topics, regardless of your personal interest, in order to cover a subject completely. Tha
The quote comes from this letter:
http://www.diigo.com/item/image/7fr9/rhi7
I don't find it difficult to reconcile "studying hard" with doing so in an irreverent or original manner; this just means "don't take other people's word for something, think for yourself." What's difficult to understand, for me at least, is how one can study hard yet study in an undisciplined way. Usually hard study, and hard work, are very disciplined.
Most textbooks and teachers will lead you through a linearly prescribed set of topics, regardless of your personal interest, in order to cover a subject completely. That is the "disciplined" approach. Feynman suggests that instead, the most effective way to learn something in an original way is to follow what intrigues you about a subject--not to follow the pre-set structure for learning the subject.
If you do this relentlessly--digging deeply into each new intriguing challenge as it arises in your studies, and then really mastering each challenge, then eventually you will "succeed" in understanding that subject in an original and deeply insightful way.
is a limit of for large n. So if , tends to . The same idea works, under suitable restrictions, even if A is a differential operator.
For nice enough , , so .
Bringing H inside the integral, it acts on the exponential converting H into its “symbol”, which is just the classical Hamiltonian function. Multiplying it by , and then replacing it by the exponential function of it creates a W with . But that’s just Schroedinger’s equation, which is thus sol
is a limit of for large n. So if , tends to . The same idea works, under suitable restrictions, even if A is a differential operator.
For nice enough , , so .
Bringing H inside the integral, it acts on the exponential converting H into its “symbol”, which is just the classical Hamiltonian function. Multiplying it by , and then replacing it by the exponential function of it creates a W with . But that’s just Schroedinger’s equation, which is thus solved (ignoring convergence questions), by .
That’s just an n fold iterated Fourier integral, and the exponentials all combine to a single exponential of a sum of terms of the form p dx - H dt, a discrete approximation to the integral of the Lagrangian. This can be interpreted as the action over a piecewise linear path having n segments, while the integration becomes a collation over all such paths. But every continuous path can be uniformly approximated to an arbitrary degree of precision by such piecewise linear paths. That’s how it ``actually works’’.
What does it mean? That’s harder to say. It might be just a mathematical trick. Or it could be a profound statement about how nature works. The same approach works for rather arbitrary quantum fields.
But here’s one way of thinking about it.
A given action along a path shifts phases. Let be the amount of that phase shift. Then is a complex number of modulus 1, that is taking values in U(1). Moreover, . In other words, is a unitary continuous character on the vector space of actions, so there is a linear form for which
The total phase shift between events is a collation over all paths of where a is the action along that path.
If we define h so that , then
My best guess would be that he saw physical reality as governed by a small set of rules (symmetries), no matter how complex and subtle the world we see. I would guess that he was thinking as a teacher… make everything as simple as possible, and no simpler.
Because he understood them first. He had a very curious mind. I mean, do you know any other Nobel prize winners in physics who could spend one day locked in a bathroom observing how ants moved and marking their trajectories?
A lot of people, many teachers included, don’t really understand what they teach. Sure, they can recite definitions and use inference to proof things, they can juggle equations around, but they do not understand. And school education with its mindless memorization of definitions?
Feynman used to do this trick - he asked some fellow scientist about certain principle, he’d hap
Because he understood them first. He had a very curious mind. I mean, do you know any other Nobel prize winners in physics who could spend one day locked in a bathroom observing how ants moved and marking their trajectories?
A lot of people, many teachers included, don’t really understand what they teach. Sure, they can recite definitions and use inference to proof things, they can juggle equations around, but they do not understand. And school education with its mindless memorization of definitions?
Feynman used to do this trick - he asked some fellow scientist about certain principle, he’d happily recite it. Then Feynman would ask a problem that could be solved by applying the principle they literally just recited - and they couldn’t. Just didn’t see how the abstraction applied to a real situation outside of what they were used to.
Another reason, and here I’m speculating, but based on quite a bit of observations, including here on Quora - often times Ego gets in the way. “Look we understand all this Crazy Greek letters and you don’t. We could try explaining them to you, but you need to go through 176 years of studying math to get it, go read some books”. There’s a degree of truth to it, especially in mathematics, but some intellectual arrogance often gets in the way of even trying to explain things in a normal language.
Feynman used to say - if we can’t explain something to a freshman, then we do not understand it. Great principle to do science by.
Feynman had a deep and great physical insight into the way the world works. He had a great mastery of math, but he used math to work out his physical sense, not the other way around. He was fascinated and intrigued by unanswered physics questions, but he always looked for the physics. Math, to Feynman, was merely a tool.
To give you the sort of answer to this question that another Nobel physicist, Paul Dirac, would have given to this question (but also see below):
If Feynman had said it, he would have meant “if you can't explain it simply, you don't understand it well enough yourself.” (sic!) (Dirac famously answered queries for an alternative explanation to something by simply repeating what he had said already - he was Aspie),
However, Feynman probably never said this as it’s not mentioned in:
But In the final section of the article “Disputed and/or attributed” it does say:
“On
To give you the sort of answer to this question that another Nobel physicist, Paul Dirac, would have given to this question (but also see below):
If Feynman had said it, he would have meant “if you can't explain it simply, you don't understand it well enough yourself.” (sic!) (Dirac famously answered queries for an alternative explanation to something by simply repeating what he had said already - he was Aspie),
However, Feynman probably never said this as it’s not mentioned in:
But In the final section of the article “Disputed and/or attributed” it does say:
“On p. 44, this book [Scary Monsters and Bright Ideas (2000) by science broadcaster Robyn Williams] claims: "Einstein said, 'You do not really understand something unless you can explain it to your grandmother'. Richard Feynman added, 'Physics is like sex: sure, it may give some practical results, but that's not why we do it'." Given that Einstein didn't really say the former, it's likely that Feynman didn't really say the latter.”.
Even so, I know full-well myself what Feynman likely didn’t really say in the above: what Feynman would have meant if he had said it - it’s that euphoric feeling: the ‘click’ of understanding something that - in my own experience comes, occasionally, when trying to understand something highly mathematical in theoretical physics. Then I do indeed understand it well enough to explain it to my intelligent but arts-educated wife, when she has the patience to listen to a full-enough explanation.
So, do you now understand it well enough yourself? ; - >
Study things the usual way, and you'll get what is usually gotten.
But if you follow autonomous interest, when you learn something new during your study, stop reading, and internalize. If it tickles with something you've learned in the past: try to combine it and see where it gets you.
Take your time, and dig deep. Don't time manage your autonomous interests. Reach that state of intuitive understanding by doing a lot of thought experiments and enhance them with rigour.
This way you can get where no one has gotten before. Richard Feynman was a prime example of that. That's why he took pride in not
Study things the usual way, and you'll get what is usually gotten.
But if you follow autonomous interest, when you learn something new during your study, stop reading, and internalize. If it tickles with something you've learned in the past: try to combine it and see where it gets you.
Take your time, and dig deep. Don't time manage your autonomous interests. Reach that state of intuitive understanding by doing a lot of thought experiments and enhance them with rigour.
This way you can get where no one has gotten before. Richard Feynman was a prime example of that. That's why he took pride in not having an extremely high IQ: he learned things by looking at it differently and by studying hard.
He liked taking the aliën approach, by looking at a subject we already have been brainwashed with over time, because of its familiarity, as if it were something completely new. This creates new questions everywhere, within a subject, sometimes not too easy to answer.
He also started trigonometry as a young kid;
"While I was doing all this trigonometry, I didn't like the symbols for sine, cosine, tangent, and so on. To me, "sin f" looked like s times i times n times f! So I invented another symbol, like a square root sign, that was a sigma with a long arm sticking out of it, and I put the f underneath. For the tangent it was a tau with the top of the tau extended, and for the cosine I made a kind of gamma, but it looked a little bit like the square root sign. Now the inverse sine was the same sigma, but left-to-right reflected so that it started with the horizontal line with the value underneath, and then the sigma. That was the inverse sine, NOT sink f--that was crazy! They had that in books! To me, sin_i meant i/sine, the reciprocal. So my symbols were better.
Now that's original…
I’m no Feynman Scholar, but the quote resonates with me, so I can tell you what I take from it.
When he suggests that we be undisciplined, I think he means not to push yourself because of a sense of what you feel you should or need to do to reach some goal, but rather to be pulled along by a sense of curiosity and passion. This sort of advice is common in creative professions. “Learn to embrace the process, not the end product”, they say.
By being irreverent, I think he means that we should not take for granted that just because some line of reasoning or way of thinking about a subject is establ
I’m no Feynman Scholar, but the quote resonates with me, so I can tell you what I take from it.
When he suggests that we be undisciplined, I think he means not to push yourself because of a sense of what you feel you should or need to do to reach some goal, but rather to be pulled along by a sense of curiosity and passion. This sort of advice is common in creative professions. “Learn to embrace the process, not the end product”, they say.
By being irreverent, I think he means that we should not take for granted that just because some line of reasoning or way of thinking about a subject is established, well regarded by all the important people, and never publicly questioned or criticized, we should not revere it on that basis. If it deserves questioning or criticism, then we should feel as free as the wind to question or criticize it.
I think the benefits of being original are pretty obvious, and are sort of implied by the previous two things. Don’t take things for granted, especially not just because everyone else takes them for granted.
It’s hard to write a brief answer to this because there’s so much to say about it. But basically, I think what he meant was, to really see just how weird the quantum mechanical description of nature is - compared to your normal macroscopic intuitions and experience - one has to study it deeply, looking at many examples and thinking about them carefully. It you don’t find it weird, it usually means you haven’t yet studied it deeply enough to unearth the weirdness.
Perhaps a slightly different way to phrase his statement is: If you think you understand quantum mechanics, you likely have not studi
It’s hard to write a brief answer to this because there’s so much to say about it. But basically, I think what he meant was, to really see just how weird the quantum mechanical description of nature is - compared to your normal macroscopic intuitions and experience - one has to study it deeply, looking at many examples and thinking about them carefully. It you don’t find it weird, it usually means you haven’t yet studied it deeply enough to unearth the weirdness.
Perhaps a slightly different way to phrase his statement is: If you think you understand quantum mechanics, you likely have not studied it enough to appreciate just how wacky it really is.
This question is answered elsewhere a number of times including my answer.
I still answer here shortly. What Feynman meant was that, though the mathematics of quantum mechanics works well with empirical support, the conceptual foundations on which the subject is based is counterintuitive and it is not clear why it works so successfully. From this “discomfort” arose Wigner's (or Mermin or Feynman) slogan “Shut up and calculate”: just use the equations and get your results and don't ask why the equations work, because nobody knows that.
First, Feynman didn’t “study” subjects; instead, he tried to understand phenomena or puzzles in the real world, to see how they could be that way.
So what he’s saying is, Don’t just apply the “canonical” standard approach to solving the problem. Instead, apply every approach you can think of, and see if they give different answers. If they all give the same answer, that’s great. But if they don’t, why are they giving different answers? Are some of the approaches more limited in their applicability, and if so, why? Or do different approaches make different assumptions about which factors are mos
First, Feynman didn’t “study” subjects; instead, he tried to understand phenomena or puzzles in the real world, to see how they could be that way.
So what he’s saying is, Don’t just apply the “canonical” standard approach to solving the problem. Instead, apply every approach you can think of, and see if they give different answers. If they all give the same answer, that’s great. But if they don’t, why are they giving different answers? Are some of the approaches more limited in their applicability, and if so, why? Or do different approaches make different assumptions about which factors are most important?
Don’t be fooled into thinking that the answer in the book is the only or best answer: It may not even be correct.
One time I asked him to explain why the stroboscopic photograph of a violin being stroked looked as it did: a sawtooth function running around within an envelope shaped like a leaf. He spent half an hour thinking up different approaches, and we never got to an answer.
But you could learn more from watching Feynman fail to solve a problem than from almost anyone else (even if s/he had the actual solution). And it was a real high: “I just asked a simple question that stumped RPF for half an hour!”