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Posts Tagged ‘quantum theory

“Bohr was inconsistent, unclear, willfully obscure, and right. Einstein was consistent, clear, down-to-earth, and wrong.”*…

The founders of quantum mechanics understood it to be deeply, profoundly weird. Albert Einstein, for one, went to his grave convinced that the theory had to be just a steppingstone to a more complete description of nature, one that would do away with the disturbing quirks of the quantum.

Then in 1964, John Stewart Bell proved a theorem that would test whether quantum theory was obscuring a full description of reality, as Einstein claimed. Experimenters have since used Bell’s theorem to rule out the possibility that beneath all the apparent quantum craziness — the randomness and the spooky action at a distance — is a hidden deterministic reality that obeys the laws of relativity.

Now a new theorem has taken Bell’s work a step further. The theorem makes some reasonable-sounding assumptions about physical reality. It then shows that if a certain experiment were carried out — one that is, to be fair, extravagantly complicated — the expected results according to the rules of quantum theory would force us to reject one of those assumptions.

According to Matthew Leifer, a quantum physicist at Chapman University who did not participate in the research, the new work focuses attention on a class of interpretations of quantum mechanics that until now have managed to escape serious scrutiny from similar “no-go” theorems.

Broadly speaking, these interpretations argue that quantum states reflect our own knowledge of physical reality, rather than being faithful representations of something that exists out in the world. The exemplar of this group of ideas is the Copenhagen interpretation, the textbook version of quantum theory, which is most popularly understood to suggest that particles don’t have definite properties until those properties are measured. Other Copenhagen-like quantum interpretations go even further, characterizing quantum states as subjective to each observer…

… which has, as you will see as you read on in the piece excerpted above, some pretty profoundly weird implications. Either the rules of quantum mechanics don’t always apply, or at least one basic assumption about reality must be wrong: “A New Theorem Maps Out the Limits of Quantum Physics.”

See also “Reality is that which, when you stop believing in it, doesn’t go away.”

* John Stewart Bell

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As we pity Schrödinger’s cat, we might we might send penetrating birthday greetings to Henry Way Kendall; he was born on this date in 1926. A particle physicist, he shared the Nobel Prize in Physics in 1990 (with Jerome Isaac Friedman and Richard E. Taylor) “for their pioneering investigations concerning deep inelastic scattering of electrons on protons and bound neutrons, which have been of essential importance for the development of the quark model in particle physics.”

In 1969, Kendall helped found the Union of Concerned Scientists. In 1997, in connection with the Kyoto Climate Summit, he helped produce a statement signed by 2,000 scientists calling for action on global warming.

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“You’re mad, bonkers, completely off your head. But I’ll tell you a secret. All the best people are.”*…

Edward Brooke-Hitching grew up in a rare book shop, with a rare book dealer for a father. As the author of histories of maps The Phantom Atlas, The Golden Atlas and The Sky Atlas, he has always been “really fascinated by books that are down the back alleys of history.” Ten years ago, he embarked on a project to come up with the “ultimate library.” No first editions of Jane Austen here, though: Brooke-Hitching’s The Madman’s Library collects the most eccentric and extraordinary books from around the world.

“I was asking, if you could put together the ultimate library, ignoring the value or the academic significance of the books, what would be on that shelf if you had a time machine and unlimited budget?” he says.

Following up anecdotes, talking to booksellers and librarians and trawling through auction catalogues, he came across stories like that of the 605-page Qur’an written in the blood of Saddam Hussein. “If that was on a shelf, what could possibly sit next to it?” he asks. “I mentioned it to a bookseller and they told me about a diary that they’d had, from the 19th century, written by a shipwrecked captain who only had old newspaper and penguins to hand. So Fate of the Blenden Hall was written entirely in penguin blood.”

There’s the American civil war soldier who inscribed his journal of the conflict on to the violin he carried. There’s the memoir of a Massachussetts highwayman, James Allen, which he “requested be bound in his own skin after his death, and presented to his one victim who had fought back as a token of his admiration.” Or the diary of the Norwegian resistance fighter Petter Moen, pricked with a pin into squares of toilet paper and left in a ventilation shaft; although Moen was killed in 1944, one of his fellow prisoners returned to Oslo after it was liberated from the Nazis and found the diary. Or the entirely fabricated book An Historical and Geographical Description of Formosa: its author George Psalmanazar, a blond-haired, blue-eyed, pale-skinned man with a thick French accent, arrived in London in about 1702 and declared himself to be the first Formosan, or Taiwanese, person to set foot on the European continent. (“Obviously no one had been there and nobody knew what Taiwanese people looked like, and he became the toast of high society,” says Brooke-Hitching.)

The joy for the author in his discoveries – and make no mistake, The Madman’s Library is an utterly joyous journey into the deepest eccentricities of the human mind – was that they “make you realise that, above everything, people have always been funny, been weird, been unquenchably curious in every possible arena”…

The Madman’s Library, the ultimate collection of bizarre books down the ages: “From cut-out confessions to cheese pages: browse the world’s strangest books.”

[TotH to buddy MK]

* Lewis Carroll, Alice’s Adventures in Wonderland

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As we get weird, we might recall that it was on this date in 1935 that physicist Erwin Schrödinger published his famous thought experiment– now known as “Schrödinger’s cat“– a paradox that illustrates the problem of the Copenhagen interpretation of quantum mechanics.

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“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

“Real randomness requires an infinite amount of information”*…

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If you have ever tossed dice, whether in a board game or at the gambling table, you have created random numbers—a string of numbers each of which cannot be predicted from the preceding ones. People have been making random numbers in this way for millennia. Early Greeks and Romans played games of chance by tossing the heel bone of a sheep or other animal and seeing which of its four straight sides landed uppermost. Heel bones evolved into the familiar cube-shaped dice with pips that still provide random numbers for gaming and gambling today.

But now we also have more sophisticated random number generators, the latest of which required a lab full of laser equipment at the U.S. National Institute of Standards and Technology (NIST) in Boulder, CO. It relies on counterintuitive quantum behavior with an assist from relativity theory to make random numbers. This was a notable feat because the NIST team’s numbers were absolutely guaranteed to be random, a result never before achieved.

Why are random numbers worth so much effort? Random numbers are chaotic for a good cause. They are eminently useful, and not only in gambling. Since random digits appear with equal probabilities, like heads and tails in a coin toss, they guarantee fair outcomes in lotteries, such as those to buy high-value government bonds in the United Kingdom. Precisely because they are unpredictable, they provide enhanced security for the internet and for encrypted messages. And in a nod to their gambling roots, random numbers are essential for the picturesquely named “Monte Carlo” method that can solve otherwise intractable scientific problems…

Using entanglement to generate true mathematical randomness– and why that matters: “The Quantum Random Number Generator.”

* Tristan Perich

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As we leave it to chance, we might send learned birthday greetings to Athanasius Kircher; he was born on this date in 1602.  A scholar, he published over 40 works. perhaps most notably on comparative religion, geology, and medicine, but over a range so broad that he was frequently compared to Leonardo Da Vinci (who died on the date in 1519) and was dubbed “Master of a Hundred Arts.”

For a look at one of his more curious works, see “Wonder is the beginning of wisdom.” And his take on The Plague (through which he lived in Italy in 1656), see here.

220px-Athanasius_Kircher_(cropped) source

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