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Richard Feynman at 100 - Nature May 2018
Paul Halpern celebrates the oeuvre of the brilliant, unconventional scientist.
physics  quantum-mechanics  Richard-Feynman  people  biography  NatureJournal 
may 2018 by pierredv
The geometry that could reveal the true nature of space-time | New Scientist issue 3136, 29 Jul 2017
"The discovery of an exquisite geometric structure is forcing a radical rethink of reality, and could clear the way to a quantum theory of gravity"

[Andrew Hodges, one of Penrose’s colleagues at Oxford] "showed that the various terms used in the BCFW method could be interpreted as the volumes of tetrahedrons in twistor space, and that summing them up led to the volume of a polyhedron."

"So why invoke virtual particles at all? ... The first is that dealing with them rather than with fields makes the maths more tractable. The other great advantage is that they help physicists visualise everything as the well-defined interactions between point-like particles, as opposed to the hazy goings-on between particles and fields. This fits nicely with the intuitive principle of locality, which holds that only things in the same spot in space and time can interact. Finally, the technique also helps enforce the principle of unitarity, which says that the probability of all outcomes should add up to 1."

Gluon interactions seemed to complex, but "In 1986, Stephen Parke and Tomasz Taylor from Fermilab near Batavia, Illinois, used Feynman diagrams and supercomputers to calculate the likelihoods of different outcomes for interactions involving a total of six gluons. A few months later, they made an educated guess at a one-line formula to calculate the same thing. It was spot on. More than 200 Feynman diagrams and many pages of algebra had been reduced to one equation, and the researchers had no idea why."

"In 2005, Ruth Britto, Freddy Cachazo, Bo Feng and Edward Witten [BCFW] were able to calculate scattering amplitudes without recourse to a single virtual particle and derived the equation Parke and Taylor had intuited for that six-gluon interaction"

[Nima Arkani-Hamed and his team at IAS] "arrived at a mind-boggling conclusion: the scattering amplitude calculated with the BCFW technique corresponds beautifully to the volume of a new mathematical object. They gave a name to this multi-dimensional concatenation of polyhedrons: the amplituhedron."

"It may transform physics, too ... because the amplituhedron does not embody unitarity and locality, those core principles baked into reality as described by Feynman diagrams. ... If so, locality is not a fundamental feature of space-time but an emergent one."
NewScientist  geometry  physics  gravity  field-theory  quantum-mechanics  twistors  Roger-Penrose  Richard-Feynman  Ed-Witten  maths 
december 2017 by pierredv
Do not remain nameless to yourself
Feynman replied with an enquiry about Mano’s current job, to which Mano responded that he was “studying the Coherence theory with some applications to the propagation of electromagnetic waves through turbulent atmosphere […] a humble and down-to-earth type of problem.” Feynman responded with this letter.
Richard-Feynman  advice  from instapaper
december 2017 by basus
Who Discovered Why The Challenger Exploded?
Everyone knows Richard Feynman’s famous televised demonstration that the Challenger had exploded because its O-rings got stiff when they were cold -- but it wasn’t Feynman’s discovery. It was Sally Ride’s.'

(via Tony Finch)
richard-feynman  sally-ride  history  space  challenger  o-rings  science  engineering  nasa 
march 2017 by jm
"Let George Do It" - The Pleasure of Finding Things Out: The Best Short Works of Richard P. Feynman - Richard Phillips Feynman, Jeffrey Robbins - Google Books
<< To do high, real good physics work you do need absolutely solid lengths of time, so that when you're putting ideas together which are vague and hard to remember, it's very much like building a house of cards and each of the cards is shaky, and if you forget one of them the whole thing collapses again. . . . it needs a lot of concentration---that is, solid time to think---and if you've got a job in administrating anything like that, then you don't have the solid time. So I have invented another myth for myself---that I'm irresponsible. I tell everybody, I don't do anything. If anybody asks me to be on a committee to take care of admissions, no, I'm irresponsible, I don't give a damn about students---of course I give a damn about the students but I know that somebody else'll do it---and I take the view, "Let George do it," a view which you're not supposed to take, okay, because that's not right to do, but I do that because I like to do physics and I want to see if I can still do it, and so I'm selfish, okay? I want to do my physics.>>
richard-feynman  productivity  academia  higher-education  sociopathy  via:twitter 
february 2016 by absfac

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