Category Archives: History

Richard Feynman and The Connection Machine

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Richard Feynman and The Connection Machine

Story of Richard Feynman working at Thinking Machines.

Many a visitor at Thinking Machines was shocked to see that we had a Nobel Laureate soldering circuit boards or painting walls. But what Richard hated, or at least pretended to hate, was being asked to give advice. So why were people always asking him for it? Because even when Richard didn’t understand, he always seemed to understand better than the rest of us. And whatever he understood, he could make others understand as well. Richard made people feel like a child does, when a grown-up first treats him as an adult. He was never afraid of telling the truth, and however foolish your question was, he never made you feel like a fool.

via Daring Fireball

Take Me Out, Out, Out to the Ballgame

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A map of Armstrong and Aldrin’s moon walks, superimposed on a baseball diamond. One fly ball to right-center, and nothing else left the infield. Apparently Armstrong had a wicked slider and Aldrin a nasty cut fastball.

(A couple of years ago, a friend had the opportunity to meet Buzz Aldrin. My suggestion: as you’re shaking his hand, say, “Wow! I can’t believe I’m meeting someone who actually knows Neil Armstrong!”)

I Think I Can, I Think I Can

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Babbage’s difference engine #2 has been built and has “just gone on display in Silicon Valley” (Where? Not sure. Make sure you make a left turn at Albuquerque. Then ask.)

Despite Babbage’s reputation and government backing, the machine was never manufactured.

The plans were consigned to the dustbin of history until they were fished out by Mr Swade when he was working at the Science Museum in London. While there he went on to create the world’s first Difference Engine No 2. which was completed in 1991.

And, of course, one is reminded of Babbage’s excellent quote about GIGO:

On two occasions I have been asked [by members of Parliament!], “Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?” I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question.

Hat tip to Caroline.

Classic Physics: Light is an EM Wave

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Classic Science Paper: Otto Wiener’s experiment (1890) at Skulls in the Stars.

By 1890, then, scientists were interested in seeing whether similar results held for light waves: it seems that a number of scientists remained unconvinced that light truly was just another manifestation of electromagnetic waves! One big obstacle stood in the path of such studies: the smallness of the wavelength of light. Hertz’s radio waves had a wavelength of meters, but visible light has a wavelength on the order of 500 nanometers, or 500 billionths of a meter! Such distances cannot be directly observed with the naked eye, so experimental ingenuity was required – and Otto Wiener provided it.

(My own summary of some “classic” physics is progressing)

Top Dog

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The Red Baron’s streak was partly skill but mostly luck. “Theory of aces: high score by skill or luck?” by Simkin and Roychowdhury, from the arxiv blog

We find that the variance of this skill distribution is not very large, and that the top aces achieved their victory scores mostly by luck. For example, the ace of aces, Manfred von Richthofen, most likely had a skill in the top quarter of the active WWI German fighter pilots, and was no more special than that.

And while I’m on the topic, there’s an issue with the Royal Guardsmen’s “Snoopy vs. the Red Baron”

Eighty men died tryin’ to end that spree

It wasn’t a spree until after several, or at the very least two, men had died. OK, I’ll accept artistic license.

(and since the Germans required that “The opponent aircraft had to be either destroyed or forced to lend [sic] on German territory and its crew taken prisoners.” in order to be a victory, so when Snoopy was shot down part way through the song, that wasn’t one of the 80.)

A Look Back at Laser Cooling

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Physical Review Letters is celebrating its Z=79 anniversary, and highlighting important letters. This week is:

Letters from the Past — A PRL Retrospective: This week’s Milestone Letter was originally published in 1970

Acceleration and Trapping of Particles by Radiation Pressure
A. Ashkin Phys. Rev. Lett. 24, 156 (1970)

This was a description of radiation pressure on transparent latex spheres, which felt a force when placed in laser light that had a gradient — the refraction gives rise to a force, or pressure, because the power is asymmetric across the sphere — the light changes direction, so the sphere must recoil, and the amount of recoil doesn’t balance. This is a precursor to a dipole force trap, which traps atoms at a field maximum (or minimum) of a light field, e.g. from focused laser. It also lays out radiation pressure by near-resonant scattering

The absorption and isotropic reradiation by spontaneous emission of resonance radiation striking an atom results in an average driving force or pressure in the direction of the incident light

which was the idea that led to laser cooling and optical molasses.

There is also a brief summary of the laser cooling history there this month, Landmarks: Laser Cooling of Atoms that takes you through the milestones up until the Nobel prizes for laser cooling and Bose-Einstein condensates.