Thread: For those of us in math, science or philosophy, there are often a chosen few books which serve as "gateway drugs" during formative years. For me, one of the few such gateway drugs was Penrose's "The Emperor's New Mind" which I first discovered in college. When I first The Emperor’s New Mind, it felt magical, as if I had just entered a new universe. I’d vaguely heard about quantum mechanics, Gödel, and general relativity, but Penrose didn’t just explain them. He opened a door, and suddenly there was an entire landscape behind it.

Short thread: There are some seminal ideas in the history of science that can be called "wrong but brilliant". They might fail in their original formulation but become enshrined in science later. One of them was Hermann Weyl's idea of a gauge. In 1918, Weyl wanted to extend GR to include electromagnetism. In GR, the lengths of vectors are invariant under parallel transport in spacetime. Weyl wanted to give them an additional degree of freedom. He proposed that the vectors' length scale (or "gauge") could vary.

1/n: There are some academic papers that are so brilliantly and so accessibly written and so universal in scope that they transcend disciplines and stand as timeless testaments to both great thinking and great writing. Here's a short personal selection: Paul Krugman on Ricardo's principle of comparative advantage. Somehow Krugman, in explaining one of the subtlest and most interesting ideas in all of economics, manages to cram in brilliant and clear discussions of evolution, philosophy and history web.mit.edu/krugman/www/ri…

1/n: On one of Jefferson's most famous and most misunderstood quotes. This quote has often been misunderstood as a general bloodthirsty cry for revolution. In fact it's much more mundane, a specific response to a specific event. Jefferson's quote was part of a letter sent to John Adams's son-in-law William Smith on November 13, 1787 when Jefferson was in France as U.S. ambassador. The letter was in response to initial reports from the constitutional convention.

Thread: Oppenheimer was central to the Manhattan Project’s success and was a phenomenal and inspiring leader, but no one man could have made it work and it’s important to remember that it was still very much a team endeavor. Here are a few people whose key ideas made it possible: Seth Neddermeyer originally came up with the critical idea of implosion used in the plutonium bomb. Explosives expert George Kistiakowsky made a perfectly spherical explosion work.

A few recent books I have enjoyed reading:
1. Brenda Maddox's moving, informative portrait of Rosalind Franklin giving her her rightful place in history. amazon.com/dp/0060985089?… 2. Stanley Deser's revealing autobiography detailing his escape from the Nazis, work in general relativity, character portraits of famous physicists at Harvard, the IAS etc. amazon.com/dp/981123566X?…

This recollection of Ed Witten's early career by a friend from his college days is really something. It shows that even geniuses can meander and flounder quite a bit before making a mark. The friend is history professor Robert Weisbrot, of Colby College.

1/n: How Niels Bohr predicted Rydberg atoms: In Bohr's original 1913 formulation, the Bohr radius r was proportional to n^2, n being the principal quantum number. Highly excited states would correspond to very large values of n and Bohr predicted these "giant" atoms would exist. Since the volume scales as r^3 or n^6, for n=33 you should see a "hydrogenic" atom a billion times larger than a ground state hydrogen atom. However, no spectral lines corresponding to such atoms were observed. So was Bohr's theory wrong?

Mathematician Emmy Noether was born #OTD 1882. Among other important contributions she discovered Noether's Theorem linking symmetry with conservation laws, one of the deepest principles in all of physics. Noether was the first female professor in Germany (although an adjunct). Symmetry-conservation principles are elegantly explained in Landau and Lifshitz's "Mechanics" (p. 13). Symmetry and invariance in time implies conservation of energy; invariance in space implies conservation of momentum.

https://twitter.com/curiouswavefn/status/1626972120780771329

Famous putdowns in science:

Paul Ehrenfest to Wolfgang Pauli: "You know, Pauli, I like your papers better than I like you."

Pauli: "That's ok, Ehrenfest, I like you better than I like your papers." Famous putdowns in science 2:

Lev Landau was in a terrible accident which impacted his mind but left his vicious humor intact. His star student Yakov Zeldovich visits him.

Landau: "I don't think I can do physics like Landau again...but maybe I can do physics like Zeldovich."

Born #OTD 1917: Robert Burns Woodward, the greatest organic chemist of the 20th century. Woodward's feat in complex organic synthesis and his sheer stamina made him a living legend. Woodward has the most Nobel Prize nominations - 111 - and won it in 1965 Woodward was legendary for his three hour talks, his smoking and imbibing of entire Scotch bottles during these marathon sessions, his obsession with the color blue (suits, parking space, ceiling), his elegant writing style (even in scientific papers), and his 18-hour workdays.

There are many immigrant-friendly countries in the world today, but as Freeman Dyson says here, the United States is unique in providing unprecedented mobility, with first generation immigrants becoming big CEOs, society presidents and defense consultants in just a few years. (at 18:10)

Thread: Since it's Robert E. Lee's birthday and there's no reason to celebrate it, let's ponder another question: Why don't we find as many statues of Confederate general James Longstreet - Lee's right hand man - as those of Lee, Stonewall Jackson or Jefferson Davis? Longstreet made major contributions to a number of Confederate victories and was closer to Lee than Jackson. He should have been a hero to the South but he isn't. The answer to this question sheds a lot of light on the topic of Confederate statues and why they should be removed.

Indian-American astrophysicist and Nobel laureate Subrahmanyan Chandrasekhar was born #OTD 1910. Perhaps the greatest mathematical astrophysicist of the 20th century, Chandra as he was known applied hard math to black holes, stellar dynamics, radiative transfer and other fields. The Chandrasekhar limit describes the maximum stable mass for white dwarfs; they undergo gravitational collapse into neutron stars or black holes if they exceed it. Chandrasekhar worked out the preliminaries of this limit as a 20-year-old student on a ship bound for Cambridge.

1/n: Aug 12th, 1887 is Erwin Schrödinger's birthday. He was undoubtedly one of the greatest physicists in history. But it's high time that we admit to a painful truth, and there's no easy way to say this: the man was a sexual predator. Acknowledging our heroes' flaws is critical. This is from Walter Moore's biography. I say this as some one who greatly admires Schrödinger's seminal physics contributions and his remarkable anticipation of molecular biology in "What is Life?". I even own a first edition of the book.

1/n: A few thoughts on AlphaFold making 350,000+ protein structures available: It's a significant advance, one whose real benefits are intangible, but some caveats are in order. Firstly, the structures are all *predicted*, and only experiments can truly validate these predictions Agreed that the predictions are very good now, but the devil is in the details - parts of proteins that are important may be better or worse predicted than others. But there's a more important problem here, illustrated by the Human Genome Project. Genes were not everything.

Born #OTD 1920: Rosalind Franklin, crystallographer without parallel whose X-ray diffraction data was critical for Watson and Crick’s solution of the structure of DNA. Franklin persevered in a male-dominated scientific establishment and died tragically early. Although she got a shoddy treatment from Watson in his memoirs, she was good friends with Crick and stayed with him and his wife Odile. Franklin died in 1958 of ovarian cancer at 38. Four years later Watson, Crick & Wilkins received the Nobel Prize

1/2: Saddened to know of the passing of Steven Weinberg. Not just one of the most brilliant theoretical physicists of the 20th century but also a pedagogical master, writing highly readable technical as well as popular works. A personal Weinberg story indicating his helpfulness: Three years ago I was working on a project and emailed Steve to ask if he knew something about it. He immediately asked me to call him, on 10 AM on a Sunday, and generously spoke to me for more than an hour. Still have the recording. A great physicist but also a real gentleman.

Thread 1/n: I define as "simple-complex questions" (SCQs) questions whose "obvious" answers we rote-memorized in school and college without *really* thinking deeper. Here's one example: why do antibonding orbitals exist? This leads to an even more surprising question. Defining antibonding orbitals seems to be like proving the existence of a negative. But it becomes clear when we realize that electrons repel each other. The *real* SCQ then becomes: why do *bonding* orbitals exist? Why does the shared electron bond even form if electrons repel?!

An important and easily forgotten lesson: it's very easy to believe that brilliant scientists like von Neumann, Bethe or Einstein didn't have to work hard because they were brilliant. In fact they worked twice as hard, because the problems they were working on were twice as hard The idea that intelligence, even very high intelligence, can compensate for tenacity and hard work is one of the most pernicious myths you can believe. Hard work without intelligence may help you succeed, but intelligence without hard work will almost certainly make you fail

Thread: Hans Bethe, one of the greatest theoretical physicists of the 20th century, was born #OTD 1906. Bethe made so many contributions to so many fields that the joke was that there was a conspiracy by dozens of people to publish their paper under the name 'Hans Bethe' Bethe's stamina, concentration, all-encompassing knowledge of physics and contributions made him a legend. His most famous student, Freeman Dyson, once joked to me that if he really focused on a problem he could be one tenth as good as Bethe. Physicist David Wark captured the awe