Feynman and what comes next...

As you may be aware of, I am a Feynman aficionado:

1. My scientific motto is a (not so famous) quote of Feynman: "All we do is draw little arrows on a piece of paper - that's all!"
2. My Twitter visual profile is dedicated to him.
3. I love viewing videos of his lectures or his interviews.
4. I regularly go across his written works.
5. I've spotted errata in his Physics Lectures, volume III (Quantum mechanics), most of them typo, but some substantial errors.

Curiously, I discovered him relatively late. When I followed quantum mechanics courses at university (somewhere between 1985 and 1989), my courses didn't refer to his lectures. I consider that as a missing. It was only after I took time to dig deeper into the quantum foundations (after 1996) that I came across his works. Reading his works was so enlightening for my comprehension of the fundamental laws of nature, that there are pieces that I could read tens of times and each time I would learn new things. Or better said: approach known things from a new point of view.

Feynman is deservedly one of the most quoted people (at the Selected Pages section of Wikiquote, he figures along with people like Aristotle, Buddha, Confucius, Einstein, Jesus or Shakespeare...). His words are inspiring and often explain physical truths in plain language, comprehensible to the layman. As for all quotes, there is a caveat: they must not be seen as an absolute truth. Or as Feynman stated it himself: Learn from science that you must doubt the experts.

Very early I was skeptic about one of Feynman's most famous quotes: nobody understands quantum mechanics. This is often requoted in a more or less transformed way (for example Dawkins' version: "If you think you understand quantum mechanics, you don't understand quantum mechanics"). Does this quote have a general and definitive value of truth? Or was it just that Feynman didn't know of anyone who could explain quantum mechanics in an understandable common sense way?

Chapter 1 of Feynman's quantum lectures gives some insight in the reasons of his belief that nobody understands quantum mechanics: "We choose to examine a phenomenon which is impossible, absolutely impossible, to explain in any classical way, and which has in it the heart of quantum mechanics." He goes on to describe the double-slit experiment (with electrons), showing that it is impossible to think of waves alone or of bullets alone (such explanations have been taken over by popular media like that given by "Granddaddy of all Quantum Weirdness"). And Feynman concludes with "No one has found any machinery behind the law. No one can explain any more than we have just explained. No one will give you any deeper representation of the situation." These are terrible sentences when repeated to hundreds of thousands, maybe millions of physics students since 1965. They mark a halt for any further investigation of the subject.

Fortunately, there are inventive unconventional physicists. There were already deeper theoretical representations given by physicists like De Broglie or David Bohm, showing how a particle may be directed by a guiding wave and thus yield all the experimental results of the double slit experiment, but this had never been put to proof during their lifetime with an experimental model.

Today, I think I can safely say that the quote "nobody understands quantum mechanics" is experimentally outdated. Couder and Fort, two French physicists, experimented with bouncing droplets on a liquid subtract and discovered that they exhibited quantum behaviour, without looking for any quantum analogy:

• droplet travelling in its wave,
• diffraction and interference patterns of travelling droplets similar to photon and electron diffraction patterns,
• attraction and repulsion of droplets embedded in their waves,
• symmetric and anti-symmetric orbital motion of droplets.

Visuals presented by Couder are breathtaking. Even if you don't understand french, I highly recommend watching bouncing droplets orbiting around each other (for example at 25:35 of his 2006 presentation).

An upcoming paper of Couder's group in Physical Review Letters even suggests a quantum tunneling analogy with ordinary droplets: "Unpredictable tunneling of a classical wave-particle association", by A. Eddi, E. Fort, F. Moisy, and Y. Couder.

So today, Feynman's defeatist words about nobody understanding quantum mechanics are outdated. Please, experimental physicists, go ahead, be inventive and focus on experiments where ordinary macroscopic individual particles simulate quantum behaviour, polarization, bosonic and fermionic behaviour, inward bound forces, entanglement, quantum erasure, coupling of ordinary particles to their pilot-wave fields (gravitation, electromagnetism). Because all these quantum phenomena may be rationally understood with the help of experimental models. It's just a matter of inventivity. And we "will find someday that, after all, it isn't as horrible as it looks." ~ Feynman's Epilogue to his Lectures on Physics.

Physics Quote of the Day (May 31 - June 6)

"We live of novelty in science. So when you do something new, you have to overcome certain beliefs that it cannot be done, that it's not interesting and so on." Heinrich Rohrer, born 6 June 1933.

"The future cannot be predicted, but futures can be invented. It was man's ability to invent which has made human society what it is." Dennis Gabor, born 5 June 1900.

"The national research effort, upon which so much depends, will remain healthy only so long as there is sound core of disinterested search for new knowledge..." Alan Waterman, born 4 June 1892.

"Too much equipment can be, however, something that hampers scientific development." Georg von Békésy, born 3 June 1899.

""Have we discovered our Galaxy yet?" And I think the answer to this question is "No, not quite". There is plenty of work ahead for the next generation of astronomers." Heather Couper, born 2 June 1949.

"Simplicity is the touchstone in finding new physical laws." Kip Thorne, born 1 June 1940.

"A theory is only as good as its assumptions. If the premises are false, the theory has no real scientific value. The only scientific criterion for judging the validity of a scientific theory is a confrontation with the data of experience." Maurice Allais, born 31 May 1911.

Physics Quote of the Day (May 24 - May 30)

"Scientists tend to resist interdisciplinary inquiries into their own territory. In many instances, such parochialism is founded on the fear that intrusion from other disciplines would compete unfairly for limited financial resources and thus diminish their own opportunity for research." Hannes Alfvén, born 30 May 1908.

"(Physics) is about understanding! Understanding the world!" Peter Higgs, born 29 May 1929.

"Only by doing the best we can with the very best that an era offers, do we find the way to do better in the future." Frank Drake, born 28 May 1930.

"Good physics can be done if we have a good shop. ... Given a good shop and good measurement equipment a sound physicist can do wonderful work." W.W.Hansen, born 27 May 1909.

"When you're getting ready to launch into space, you're sitting on a big explosion waiting to happen." Sally Ride, born 26 May 1951.

"The problem of transmitting scientific knowledge is a very difficult business." Jack Steinberger, born 25 May 1921.

"Every failure is a step to success." William Whewell, born 24 May 1794.

Physics Quote of the Day (May 17 - May 23)

"Science is a field which grows continuously with ever expanding frontiers. Further, it is truly international in scope. Any particular advance has been preceded by the contributions of those from many lands who have set firm foundations for further developments." John Bardeen, born 23 May 1908.

"For the mere purpose of entertainment and the excitement of wonder, a display of brilliant electric experiments, even when performed in the most promiscuous and confused order, never fail to afford ample gratification to the curiosity. The studious observer, however, whose business is to inquire into the true beauties of the science, requires the most judicious arrangement of the phenomena that can possibly be devised, in order to facilitate his acquaintance with them, and with the laws by which they are displayed and associated with each other." William Sturgeon, born 22 May 1783.

"(Fresh and deep) ideas, after all, can arise only in discussion, in the face of objections, only if there is a potential possibility of expressing not only true, but also dubious ideas." Andrei Sakharov, born 21 May 1921.

"I think there is a need for something completely new. Something that is too different, too unexpected, to be accepted as yet." Anton Zeilinger, born 20 May 1945.

"...a number of current theoretical explorations will turn out to be passing fancies..." Abraham Pais, born 19 May 1918.

"The most essential characteristic of scientific technique is that it proceeds from experiment, not from tradition. The experimental habit of mind is a difficult one for most people to maintain ; indeed, the science of one generation has already become the tradition of the next..." Bertrand Russell, born 18 May 1872.

"I knew my purpose well and clear: to show how Nature behaves without cluttering its beauty with abtruse mathematics. Why cloud the charm of a Chladni plate with a Bessel function?" Julius Sumner Miller, born 17 May 1909.

Physics Quote of the Day (May 10 - May 16)

"A philosopher is a person who knows less and less about more and more, until he knows nothing about everything.
A scientist is a person who knows more and more about less and less, until he knows everything about nothing." John Ziman, born 16 May 1925.

"An ordinary mistake is one that leads to a dead end, while a profound mistake is one that leads to progress. Anyone can make an ordinary mistake, but it takes a genius to make a profound mistake." Frank Wilczek, born 15 May 1951.

"I think it is a sad reflection on our civilisation that while we can and do measure the temperature in the atmosphere of Venus, we do not know what goes on inside our souffles." Nicholas Kurti, born 14 May 1908.

"A theory can never be proven absolutely true, therefore there is no end to scientific endeavor." Kristine Larsen, born 13 May 1963.

"Would it not be better if one could really 'see' whether molecules...were just as experiments suggested?" Dorothy Hodgkin, born 12 May 1910.

"I never pay attention to anything by 'experts'." Richard Feynman, born 11 May 1918.

"Nature is not embarrassed by difficulties of analysis. She avoids complication only in means." Augustin Fresnel, born 10 May 1788.

Physics Quote of the Day (May 3 - May 9)

"Concepts like these can seem remote, until you explain with analogies taken from everyday life." Leonard Mandel, born 9 May 1927.

"...still many physicists are convinced to "see" the particle in a cloud chamber or on a scintillation screen, therefore accepting classical particle coordinates as pieces of reality. But what one concludes to see depends on the chosen model of reality..." Dieter Zeh, born 8 May 1932.

"An essential aspect of creativity is not being afraid to fail." Edwin Land, born 7 May 1909.

"... an experimentalist should not be unduely inhibited by theoretical untidyness. If he insists in having every last theoretical T crossed before he starts his research the chances are that he will never do a significant experiment." Robert Dicke, born 6 May 1916.

"Anything worth doing is worth doing twice, the first time quick and dirty and the second time the best way you can." Arthur Schawlow, born 5 May 1921.

"... numbers, even whole numbers, are words, parts of speech, and [...] mathematics is their grammar." Carl Eckart, born 4 May 1902.

"The landscape is magic, the trip is far from being over." Carlo Rovelli, born 3 May 1956.

Physics Quote of the Day (April 26 - May 2)

"Research can be undertaken in any kind of environment, as long as you have the interest. I believe that true education means fostering the ability to be interested in something." Sumio Iijima, born 2 May 1939.

"It is so difficult to find something interesting and new, but instead of helping me to develop fledgling ideas in their infancy, you guys immediately look for a way to attack them." Gersh Budker, born 1 May 1918.

"You know that I write slowly. This is chiefly because I am never satisfied until I have said as much as possible in a few words, and writing briefly takes far more time than writing at length." Carl Friedrich Gauss, born 30 April 1777.

"Time and Space... It is not nature which imposes them upon us, it is we who impose them upon nature because we find them convenient." Henri Poincaré, born 29 April 1854.

"Oh, that's nothing - I could coach a coal scuttle to be Senior Wrangler." Peter Guthrie Tait, born 28 April 1831.

"Part of the strength of science is that it has tended to attract individuals who love knowledge and the creation of it. Just as important to the integrity of science have been the unwritten rules of the game. These provide recognition and approbation for work which is imaginative and accurate, and apathy or criticism for the trivial or inaccurate... Thus, it is the communication process which is at the core of the vitality and integrity of science..." Philip Abelson, born 27 April 1913.

"If you don't want to be replaced by a machine, don't try to act like one!" Arno Penzias, born 26 April 1933.