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Posts Tagged ‘Feynman

“Physics is like sex: sure, it may give some practical results, but that’s not why we do it”*…

 

Feynman and Dirac

Two of Marek Holzman’s photographs of Feynman and Dirac together in Warsaw in 1962

 

Beloved late physicist Richard P. Feynman (1918–1988) first met his hero Paul Dirac (1902–1984) during Princeton University’s Bicentennial Celebration in 1946 and then again at least twice, in 1948 and 1962. Most notably, the two came to heads during the so-called Pocono Conference when Feynman gave a lecture on a nascent “Alternative Formulation of Quantum Electrodynamics”, reformulating the theory which had earned Dirac the Nobel Prize in Physics in 1933. A star-studded audience of 28 of the world’s leading physicists attended the conference, including J. Robert Oppenheimer, Niels Bohr, Eugene Wigner, John von Neumann, Enrico Fermi, Hans Bethe and of course, the inventor of the theory himself, Paul Dirac.

Feynman’s reformulation of Dirac’s theory was not well received at Pocono, as Bohr, Teller and Dirac all raised objections. Feynman’s disappointment from the audience’s reaction motivated him to write up his work for publication instead. He did so, and in the next three years went on to publish four major papers describing his now well-developed theory and its implications…

Feynman and Dirac [met for the last] time, at the International Conference on Relativistic Theories of Gravitation in Warsaw, Poland in 1962… Their conversation, as overheard by a nearby physicist, was so remarkable that he jotted it down:

F: I am Feynman.
D: I am Dirac.
(Silence)
F: It must be wonderful to be the discoverer of that equation.
D: That was a long time ago.
(Pause)
D: What are you working on?
F: Mesons.
D: Are you trying to discover an equation for them?
F: It is very hard.
D: One must try.

feydirac270

Another of Holzman’s photographs from Warsaw

Feynman’s work earned him a share of the Nobel Prize in Physics in 1965.

Paul Dirac died in 1984 at the age of 82 years old. Two years later, Feynman was invited to give one of three Dirac Memorial Lectures. He did so, with a lecture entitled “Elementary Particles and the Laws of Physics”, which he opened as follows:

When I was a young man, Dirac was my hero. He made a new breakthrough, a new method of doing physics. He had the courage to simply guess at the form of an equation, the equation we now call the Dirac equation, and to try to interpret it afterwards.

 

How Paul Dirac, Richard Feynman’s hero-turned-opponent, motivated a life’s work which not only altered the trajectory of modern physics, but also erected Feynman’s legend as one history’s finest scientist: “When Feynman met Dirac.”

* Richard Feynman

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As we chase after clarity, we might send very tiny birthday greetings to Wolfgang Paul; he was born on this date in 1913.  A physicist, he developed the non-magnetic quadrupole mass filter which laid the foundation for what is now called an ion trap— a device (also known as a Paul trap) that captures ions and holds them long enough for study and precise measurement of their properties.  During the 1950s he developed the so-called Paul trap as a means of confining and studying electrons.  He shared the Nobel Prize in Physics in 1989 for his work.

He humorously referred to Wolfgang Pauli as his imaginary part.

220px-Wolfgang_Paul source

 

“Time … thou ceaseless lackey to eternity”*…

 

600BC-chronus-deity

Source art: Chronos and His Child by Giovanni Francesco Romanelli

 

The human mind has long grappled with the elusive nature of time: what it is, how to record it, how it regulates life, and whether it exists as a fundamental building block of the universe…

Quanta‘s fascinating timeline traces our evolving understanding of time through a history of observations in culture, physics, timekeeping, and biology: “Arrows of Time

* Shakespeare, The Rape of Lucrece

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As we try to Be Here Now, we might send amusingly insightful birthday greetings to Richard Philips Feynman; he was born on this date in 1918.  A theoretical physicist, Feynman was probably the most brilliant, influential, and iconoclastic figure in his field in the post-WW II era.

Richard Feynman was a once-in-a-generation intellectual. He had no shortage of brains. (In 1965, he won the Nobel Prize in Physics for his work on quantum electrodynamics.) He had charisma. (Witness this outtake [below] from his 1964 Cornell physics lectures [available in full here].) He knew how to make science and academic thought available, even entertaining, to a broader public. (We’ve highlighted two public TV programs hosted by Feynman here and here.) And he knew how to have fun. The clip above brings it all together.

– From Open Culture (where one can also find Feynman’s elegant and accessible 1.5 minute explanation of “The Key to Science.”)

 

Written by LW

May 11, 2020 at 1:01 am

“At my age, the radiation will probably do me good”*…

 

The “banana equivalent dose” (BED) is a measure of radiation used to illustrate levels of emissions.  Bananas contain lots of potassium, which contains 0.01% potassium-40– which is radioactive.  The radiation exposure from eating a banana is deemed “1 BED,” roughly equivalent to 0.01 millirem (mrem).  (Happily, one would never be able to eat enough bananas to be dangerous, as our bodies excrete the potassium we’re consuming before it can do exposure damage.)

The existence of a clearly-understandable unit of this sort allows for easily-understood apples-to-apples (or, bananas-to-bananas) comparisons…

This is also roughly the exposure from having a single smoke detector.

 

Due to increased altitude; Mt Everest is more like 800 mrem (80,000 bananas) per year.

 

The granite in the walls is mildly radioactive. By comparison, the Vatican is about 800 mrem (80,000 bananas) per year.

 

More fruity comparisons at Mad Art Lab‘s “Yellow Alert

* Sir Norman Wisdom

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As we peel, we might send thoughtful birthday greetings to Richard Philips Feynman; he was born on this date in 1918.  A theoretical physicist, Feynman was probably the most brilliant, influential, and iconoclastic figure in his field in the post-WW II era.

Richard Feynman was a once-in-a-generation intellectual. He had no shortage of brains. (In 1965, he won the Nobel Prize in Physics for his work on quantum electrodynamics.) He had charisma. (Witness this outtake [below] from his 1964 Cornell physics lectures [available in full here].) He knew how to make science and academic thought available, even entertaining, to a broader public. (We’ve highlighted two public TV programs hosted by Feynman here and here.) And he knew how to have fun. The clip above brings it all together.

– From Open Culture (where one can also find Feynman’s elegant and accessible 1.5 minute explanation of “The Key to Science.”)

email readers click here for video

 

Written by LW

May 11, 2015 at 1:01 am

Testing…

 

In general we look for a new law by the following process. First we guess it. Then we compute the consequences of the guess to see what would be implied if this law that we guessed is right. Then we compare the result of the computation to nature, with experiment or experience, compare it directly with observation, to see if it works. If it disagrees with experiment it is wrong. In that simple statement is the key to science. It does not make any difference how beautiful your guess is. It does not make any difference how smart you are, who made the guess, or what his name is – if it disagrees with experiment it is wrong.

– Richard Feynman

Paul Dirac is famous for suggesting, “predicting,” in 1929, that there must be a positively-charge electron– or “positron.”  But until 1932, and Carl Anderson’s confirming cloud chamber experiments at Cal Tech, antimatter was just that– a suggestion, a prediction, a theory.  Anderson’s elegant experimental work showed anti-matter for the first time; it confirmed Dirac’s theory.

Similarly, Albert Einstein’s Theory of General Relativity and Arthur Eddington’s confirmation…  or Murray Gell-Mann’s theoretical quarks, and the Stanford Linear Accelerator team (Henry Kendall, Jerome Friedman and Richard Taylor) who actually found them…

Why do theorists become famous, while experimentalists don’t?  Ashutosh Jogalekar looks at “Theorists, experimentalists and the bias in popular physics.”

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As we note that it’s all about the story, we might send nourishing birthday wishes to Sir Frederick Gowland Hopkins; he was born on this date in 1861.  A chemist by training, Hopkins was fascinated from an early age by physiology.  He succeeded in marrying the two passions– and helping to create the field of Biochemistry (of which he was the first professor at Cambridge).

Hopkins discovered the amino acid tryptophan and the anti-oxydent glutathione.  But he is surely best remembered for his discovery of the “nutrient factors,” now known as “vitamins,” essential in animal diets to maintain health– work for which he received the Nobel Prize in Physiology or Medicine in 1929.

 source

 

Written by LW

June 20, 2013 at 1:01 am

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