Physicist David Bohm, who developed a non-local formulation of quantum mechanics that he hoped would evade some of the conceptually thorny aspects of the Copenhagen Interpretation, and would later inspire the work of John Bell, was born #OTD in 1917.

Replace “crystals" and “horoscopes" with "cell phones” and "facebook” and it could be mistaken for something written yesterday.

The subject of those quotes had been on his mind for a while.

Here is a prescient passage Carl Sagan wrote one year before that last interview, in his book “The Demon Haunted World.”

@polarbear

If you don't read the whole thread (which you should, she was amazing), at least enjoy this passage from a letter du Châtelet sent to her nemesis the King of Prussia.

Take this vis viva out into the world with you today, and leave a trail of wrecked monarchs behind you.

A belated happy birthday to Émilie du Châtelet, who was born on December 17, 1706.

She hypothesized conservation of energy, established kinetic energy as distinct from momentum and proportional to (speed)², and combined Newton, Leibniz, and her own original ideas in "Institutions de Physique.”

A thread from last year:

https://mastodon.social/@mcnees/109530172077988652

☝️Albert Michelson, aether, gravitational waves, and... the TV show Bonanza?

Gather round children, and attend to the dark tale of the necromancer whose old silk hat animated that terrible snowman.

@mimsical Lollll

@edwiebe See the next post!

It’s funny that attendees of the conference almost overlooked Kerr's talk. We now understand that quasars are powered by supermassive black holes at the centers of distant galaxies, and these black holes are precisely described by Kerr's marvelous solution.

Subrahmanyan Chandrasekhar would later say that realizing the Universe is full of "untold numbers" of black holes described by Kerr's elegant solution was "the most shattering experience" of his scientific career.

The meeting was focused on quasars, so Kerr's presentation prompted many in the audience to leave or ignore his talk. Their attention was elsewhere. Most of them didn't appreciate the [ahem] gravity of what they were seeing.

Achilles Papapetrou, a giant of the field, was furious when he saw his colleagues ignoring Kerr's announcement. He stood and demanded the crowd's attention, noting that he had tried and failed to solve the problem for 30 years. They were witnessing something important.

But the most important development at the conference came when a young physicist named Roy Kerr presented his solution of the field equations of general relativity describing a rotating black hole.

This solution describes the exterior of essentially every black hole in the Universe.

Image 2: James, Tunzelmann, Franklin, and Thorne

We now refer to these objects – active galactic nuclei powered by supermassive black holes – as "quasars." But that name wouldn't be used until 1964, when it was introduced by Hong-Yee Chiu in an article for Physics Today.

https://physicstoday.scitation.org/doi/10.1063/1.3051610

The meeting is now known as the 1st Texas Symposium on Relativistic Astrophysics. It's an ongoing series of meetings on gravity, cosmology, and relativity that takes place in December of most years.

The emphasis that first year was on quasi-stellar radio sources, which had been identified a few years earlier. In February of 1963, Maarten Schmidt recognized the Balmer series in their spectra and concluded they were very far away and ultra-luminous.

The International Symposium on Gravitational Collapse and Other Topics in Relativistic Astrophysics met #OTD in 1963 to discuss recently discovered "quasi-stellar radio sources." But the meeting is best known for a surprising announcement about black holes.

Image: Physics Today

Was it a mistake to put this on the last page of the final exam.

@mckra1g The Appalachians were part of the same chain as Morocco’s Little Atlas! Because North America and Africa were in contact when they all formed!

Virtually indistinguishable.