@mcnees@mastodon.social
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mcnees

@mcnees@mastodon.social

Physicist and professor at a school on the north side of Chicago. Black holes, quantum gravity, cosmology. Rocky Top, Tar Heel. Science, dogs, lake photos. Faves are spooky action at a distance, boosts are Lorentz transformations to another inertial frame. Opinions are mine, not my employer’s. #Physics #BlackHoles #Gravity #SciComm #Dogs

Level 14 Prof of Physics, Neutral Good, S:11 I:16 W:15 D:11 C:12 Ch:11, HP: 68, THAC0: 11, Equipment: Vorpal Chalk, Periapt of Tenure, Tweed Jacket (Cursed)

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mcnees, to random
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It was... unnecessarily difficult, getting Mathematica to plot a small set of electric field lines for a simple set of charges.

None of the built-in plot types (StreamPlot, etc) are compatible with all the standard rules for field lines!

mcnees, to random
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RIP James Ward. If I ever hold public office, I’ll take my oath with my hand on this book he wrote.

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mcnees, to random
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Everything is blooming!

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mcnees,
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I mean, look at these handsome gentlemen.

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mcnees, to random
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Pretty wild that this chatbot-generated intro made it through every stage of the publication process.

Another in the long list of reasons to drop Elsevier.

https://www.sciencedirect.com/science/article/abs/pii/S2468023024002402

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mcnees, to random
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Happy π day! Here’s a color-coded representation of the first 10,000 digits.

Read it left-to-right, top-to-bottom.

mcnees,
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And here are the actual digits, with the same color coding used in the previous post.

mcnees,
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And a black and white symbol version, in case colors aren’t a good medium for you.

mcnees,
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@Professor_Stevens Of course!

mcnees,
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@garyjesionowski Keep trying!

mcnees, to random
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A thread about the announcement of Pluto's discovery, Percival Lowell’s insistence that Mars hosted a civilization, the relatively unknown woman whose calculations supported Lowell’s hunt for“Planet X,” and Clyde Tombaugh's ashes sailing off into the darkness of deep space.
https://mastodon.social/@mcnees/110016500960493362

mcnees, (edited ) to random
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This hawk just took a songbird in mid air, landed on a big branch outside our window, and ate the whole thing right there. It didn’t even flinch when I walked outside to get a closer look.

I was so close that you can hear the little bones crunching in the video.

mcnees,
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Here are some photos. A little too dark for the phone camera, but on the other hand it looks sort of badass in profile like that.

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mcnees,
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Arg! I attached the wrong video! Just replaced it with the one where you can hear the bones.

mcnees,
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@katzentratschen Oh wow! Those are marvelous! I'm trying to boost, but getting "server error" messages -- apologies if there's a series of boost / unboost.

mcnees, to random
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Vannevar Bush, an electrical engineer who built one of the first analog computers, was born in 1890.

He headed the Office of Scientific Research and Development during WWII, proposed what became the National Science Foundation, and devised an early hypertext system.

mcnees,
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Bush and Hazen built their analog “differential analyzer” at MIT in the late 1920s.

It incorporated ideas from both Babbage and Kelvin (whose work was apparently not known to Bush) and could solve differential equations via integration.

In 1936, Bush hired a young electrical engineering graduate student to be his research assistant in charge of running the differential analyzer. His name was Claude Shannon.

https://www.sciencedirect.com/science/article/abs/pii/S0016003227900970?via%3Dihub

PURPOSE. Engineers and physicists are depending increasingly upon mechanical devices as aids in computation. This tendency is bound to grow as analysis is extended to problems of greater inherent complexity. Business office practice has been revolutionized by the advent of computing machines. These deal almost entirely in terms of numbers, as indeed does the business man, and machines are available which will add, multiply, tabulate, and perform other useful operations on sets of figures introduced into the machines by pressing keys. Applied physics, and in fact many other branches of science, frequently deal, however, with functions as a whole, and usually resort to figures only as a rather laborious means of dealing with functions or the curves which represent them.

mcnees,
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Bush would serve as chairman of the National Defense Research Committee and later, during WWII, director of OSRD.

In these roles he shepherded efforts ranging from the Manhattan Project to medical research to the development of radar.

He was also (informally at first, and later on in an official capacity) the first Presidential Science Advisor, serving under both Franklin Delano Roosevelt and Harry S Truman.

mcnees,
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In July of 1945 Vannevar Bush wrote to President Truman, responding to a request made by Roosevelt in 1944.

He submitted "Science the Endless Frontier," a report outlining a plan for Federal support for the sciences and the establishment of the National Science Foundation.

mcnees,
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The report argues that we must address national security, economic, and social issues with the sort of concentrated scientific effort Bush had overseen throughout the war.

It was a call for dedicated support of science to advance the public good.

You can read a copy here: https://www.nsf.gov/about/history/vbush1945.htm

mcnees,
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That same month, July 1945, Vannevar Bush published "As We May Think" in The Atlantic.

It was a forward-looking essay that anticipated hypertext, the web, Wikipedia, and other information technologies in the form of a desk-like device he called a "memex."

We often think of these technologies as appearing very suddenly. But many scientists and engineers had known for decades that this was where we were heading.

https://www.theatlantic.com/magazine/archive/1945/07/as-we-may-think/303881/

mcnees,
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Vannevar Bush, back in 1945, calling out you, specifically, for all the bad articles in your mess of open browser tabs.

mcnees,
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Back in 1995, Macromedia made this little video in Director to commemorate the 50th anniversary of Bush's prescient article.
https://www.youtube.com/watch?v=c539cK58ees

mcnees, to random
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Pound and Rebka submitted "The Apparent Weight of Photons" to Physical Review Letters in 1960.

They described the measurement of minuscule gravitational red shifts and blue shifts as photons moved up or down in the Earth’s gravitational field. Einstein predicted this effect in 1911!

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.4.337

mcnees,
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The Equivalence Principle says that photons with energy E should lose / gain energy as they move up / down in a gravitational field, like an object with mass m = E/c².

For the 14.4 keV gamma rays used by Pound and Rebka, this amounts to ΔE = mgh = Egh/c² = 3.5 x 10⁻¹¹ eV. The difference between ΔE on the way down and on the way up should be about 4.9 parts in 10¹⁵.

Pound and Rebka’s careful experiment yielded (5.13±0.51) parts in 10¹⁵ — a spectacular confirmation of Einstein’s prediction!

mcnees,
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This was the last of Einstein's three "classical tests of general relativity" to be verified. The others were the anomalous precession of the orbit of Mercury, and the deflection of starlight by the gravitational field of the sun.

The paper is open access, so you should have no problem downloading it if you'd like to take a look.

Also, the American Physical Society has a lovely and very accessible discussion of the experiment here:

https://physics.aps.org/story/v16/st1

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