Ciro Santilli @cirosantilli 35

Lecture notes that were apparently very popular at Cornell University. In this period he was actively synthesizing the revolutionary bullshit Richard Feynman and Julian Schwinger were writing and making it understandable to the more general physicist audience, so it might be a good reading.

Oh yes, see also: Dirac equation vs quantum electrodynamics.

Feynman's first wife, previously his local-high school-days darling. Feynman was like an reversed Stephen Hawking: he married his wife knowing that she had a serious illness, while Hawking's wife married him knowing that as well. Except that in Feynman's case, the disease outcome (tuberculosis) was much more uncertain, and she tragically died in 1945 much earlier while Feynman was at Los Alamos Laboratory, while Hawking, despite his decline, lived much longer.

Feynman first noticed Arline on the beaches on the region of his home in Far Rockaway, in the Queens, New York, near Long Beach. She lived a bit further inland in Cedarhurst. Arline was beautiful and boys competed for her, but Richard persisted, stalking her at an after-school social league sponsored by the local Synagogue and joining an art class she went to, until he eventually won it out. The region was highly Jewish, and both were from Jewish families, as also suggested by their family names.

Reading about her death e.g. at Genius: Richard Feynman and Modern Physics by James Gleick (1994) is a major tearjerker, it's just too horrible. The book mentions on chapter "The Last Springtime" that at last, during the last months of her life, after much hesitation, they did fuck in the sanatorium Arline where was staying at in Albuquerque, the nearest major city to Los Alamos (154 km), despite the risk of Feynman being infected, which would be particularly serious given that Feynman would be in constant contact with students and possibly infect others as part of his career as a researcher/teacher. Feynman would visit her on weekends by bus, and stay in Los Alamos during the week.

Arline finally died on June 16th 1945, exactly one month before the Trinity nuclear test was carried out. The atomic bombings of Hiroshima and Nagasaki were a little later on 6 and 9 of August 1945.

On one of his last trips to Oak Ridge town late 1945, after her death, Feynman walked past a shop window and saw a pretty dress. He thought to himself, "Arline would have liked that", and the reminder made him cry for the first time after Arline's death.

It is even sadder to think that the first antibiotics for tuberculosis, streptomycin, finished its first major clinical trial at around 1948, not long after her death.

Ciro Santilli considers this tragedy a cause of Feynman was a huge womanizer during a certain period of his life.

Ciro Santilli never did any illegal drugs, because he:so don't expect any amazing stories here.

Like LDS believers, Ciro never drinks coffee nor smokes, and only drinks alcohol and tea sparingly, because they are all addictive drugs and bring no net increase of energy and concentration.

Ciro prefers to only enjoy a glass of tea when going out cycling on a cold day (Earl gray, with milk, no sugar), or get a half pint of beer when going out with friends to a pub.

Ciro only got reasonably drunk twice on his life:

Later in life, around the time of his wedding, there were guests around all the time, and he was drinking beer with them all the time. Then one day, during lunch, Ciro felt a weirdly strong desire to drink one more pint. It was at this point that Ciro realised first-hand what mild, but real, alcohol addiction felt like, and he didn't get that drink, and swore from then on to never drink more than one glass a week, and only with friends at a bar after work. Richard Feynman tells a very similar story on his book Surely You're Joking, Mr. Feynman chapter O Americano, Outra Vez!, see: Section "Richard Feynman's drug use".

Where derivation == "intuitive routes", since a "law of physics" cannot be derived, only observed right or wrong.

TODO also comment on why are complex numbers used in the Schrodinger equation?.

Some approaches:

Amazingly confirms the wave particle duality of quantum mechanics.

The effect is even more remarkable when done with individual particles such individual photons or electrons.

Richard Feynman liked to stress how this experiment can illustrate the core ideas of quantum mechanics. Notably, he night have created the infinitely many slits thought experiment which illustrates the path integral formulation.

Ciro Santilli is old enough to remember his parents whispering its name with a respectful tone.

Genius: Richard Feynman and Modern Physics by James Gleick (1994) mentions several times how Richard Feynman was a reader of the encyclopedia. E.g. in youtu.be/ivxkd98mDvc?t=50 Richard's sister also talks about it.

Then the Internet came along and killed it.

The motivation model for collaborators was simple: to get famous. To be able to be selected contribute an article meant that you knew something or two! There was some physicist Ciro read the biography of who was really glad to be able to write an article on the encyclopedia after having worshiped it for so long, TODO find the reference.

While this is somewhat a part of Wikipedia motivation, it is much less so because there is no single article authorship. This is something OurBigBook.com aims to improve.

Exams as a prerequisite for a degree are useless. Exams as part of a degree must be abolished. And degrees must be abolished. Ultimately the only metrics that really matter are money and fame. See also: motivation.

The only thing exams should matter for is as a screening tool to select people with specific abilities that you care about as an employer or principal investigator. If:then exams are useless for your purposes. then might as well just go by interviews (basically what all employers do already, though not PIs). Degrees are too course grained to mean anything to anybody. Employers and PIs likely only care about very few specific subjects.

Once the question of an exam has been formulated, the usefulness of the problem is already been completely destroyed, because formulating the problem that matters is the most important part of things. And any problem with an answer, is useless to put effort into: give answers.

Furthermore, preventing people from searching for answers while answering an exam, AKA preventing "cheating", also makes absolutely no sense. In the real world, we want people to find answers as quickly as possible! We should be teaching people how to "cheat"! What we should teach them instead is what a fucking license is, and what you have to do to comply with it.

And if you must absolutely have exams, they must be open to anyone who wants to applies. Then people have to pay to take the exam, with subsidies for "official course takers", who are spending 100x more anyways due to not living with their parents.

And if you pass the exam, you pass the course, without any further time requirements.

And those exams must be applied by professional test application companies to ensure no cheating and to factor out the anti-cheat work, while still making the tests available to people anywhere.

A quote from Richard Feynman present in the book Surely You're Joking, Mr. Feynman chapter O Americano, Outra Vez!:

The only metric that matters is "to feel that you've satisfied youre curiosity". When one studies for that, it can take a lot more time to actually learn everything, because it is sometimes not as clear when you should stop. But it is the only way to go deeper.

A person's understanding is the most illiquid asset that exists, to judge that based only on standardized exams, is a certain way to fail to identify top talent.

Related: exams and homework are useless, only projects matter

Head of the theoretical division at the Los Alamos Laboratory during the Manhattan Project.

Richard Feynman was working under him there, and was promoted to team lead by him because Richard impressed Hans.

He was also the person under which Freeman Dyson was originally under when he moved from the United Kingdom to the United States.

And Hans also impressed Feynman, both were problem solvers, and liked solving mental arithmetic and numerical analysis.

This relationship is what brought Feynman to Cornell University after World War II, Hans' institution, which is where Feynman did the main part of his Nobel prize winning work on quantum electrodynamics.

Hans must have been the perfect PhD advisor. He's always smiling, and he seemed so approachable. And he was incredibly capable, notably in his calculation skills, which were much more important in those pre-computer days.

Richard Feynman's mentor at Princeton University, and notable contributor to his development of quantum electrodynamics.

Worked with Niels Bohr at one point.

Web of Stories interview (1996): www.youtube.com/playlist?list=PLVV0r6CmEsFzVlqiUh95Q881umWUPjQbB. He's a bit slow, you wonder if he's going to continute or not! One wonders if it is because of age, or he's always been like that.

Originally it was likely created to study constrained mechanical systems where you want to use some "custom convenient" variables to parametrize things instead of global x, y, z. Classical examples that you must have in mind include:

When doing lagrangian mechanics, we just lump together all generalized coordinates into a single vector $\overrightarrow{q}(t):\mathbb{R}\to {\mathbb{R}}^n$ that maps time to the full state:where each component can be anything, either the x/y/z coordinates relative to the ground of different particles, or angles, or nay other crazy thing we want.

The Lagrangian is a function ${\mathbb{R}}^n\times {\mathbb{R}}^n\times \mathbb{R}\to \mathbb{R}$ that maps:to a real number.

Then, the stationary action principle says that the actual path taken obeys the Euler-Lagrange equation:This produces a system of partial differential equations with:

The mixture of so many derivatives is a bit mind mending, so we can clarify them a bit further. At:the $q_i$ is just identifying which argument of the Lagrangian we are differentiating by: the i-th according to the order of our definition of the Lagrangian. It is not the actual function, just a mnemonic.

Then at:

However, people later noticed that the Lagrangian had some nice properties related to Lie group continuous symmetries.

Basically it seems that the easiest way to come up with new quantum field theory models is to first find the Lagrangian, and then derive the equations of motion from them.

For every continuous symmetry in the system (modelled by a Lie group), there is a corresponding conservation law: local symmetries of the Lagrangian imply conserved currents.
Genius: Richard Feynman and Modern Physics by James Gleick (1994) chapter "The Best Path" mentions that Richard Feynman didn't like the Lagrangian mechanics approach when he started university at MIT, because he felt it was too magical. The reason is that the Lagrangian approach basically starts from the principle that "nature minimizes the action across time globally". This implies that things that will happen in the future are also taken into consideration when deciding what has to happen before them! Much like the lifeguard in the lifegard problem making global decisions about the future. However, chapter "Least Action in Quantum Mechanics" comments that Feynman later notice that this was indeed necessary while developping Wheeler-Feynman absorber theory into quantum electrodynamics, because they felt that it would make more sense to consider things that way while playing with ideas such as positrons are electrons travelling back in time. This is in contrast with Hamiltonian mechanics, where the idea of time moving foward is more directly present, e.g. as in the Schrödinger equation.

Furthermore, given the symmetry, we can calculate the derived conservation law, and vice versa.

And partly due to the above observations, it was noticed that the easiest way to describe the fundamental laws of particle physics and make calculations with them is to first formulate their Lagrangian somehow: why do symmetries such as SU(3), SU(2) and U(1) matter in particle physics?s.

TODO advantages:

Bibliography:

2s/2p energy split in the hydrogen emission spectrum, not predicted by the Dirac equation, but explained by quantum electrodynamics, which is one of the first great triumphs of that theory.

Note that for atoms with multiple electrons, 2s/2p shifts are expected: Why does 2s have less energy than 1s if they have the same principal quantum number?. The surprise was observing that on hydrogen which only has one electron.

Initial experiment: Lamb-Retherford experiment.

On the return from the train from the Shelter Island Conference in New York, Hans Bethe managed to do a non-relativistic calculation of the Lamb shift. He then published as The Electromagnetic Shift of Energy Levels by Hans Bethe (1947) which is still paywalled as of 2021, fuck me: journals.aps.org/pr/abstract/10.1103/PhysRev.72.339 by Physical Review.

The Electromagnetic Shift of Energy Levels Freeman Dyson (1948) published on Physical Review is apparently a relativistic analysis of the same: journals.aps.org/pr/abstract/10.1103/PhysRev.73.617 also paywalled as of 2021.

TODO how do the infinities show up, and how did people solve them?

www.mdpi.com/2624-8174/2/2/8/pdf History and Some Aspects of the Lamb Shift by G. Jordan Maclay (2019)

Amazing talk by Richard Feynman that describes his experiences at Los Alamos National Laboratory while developing the first nuclear weapons.

Transcript: calteches.library.caltech.edu/34/3/FeynmanLosAlamos.htm Also included full text into Surely You're Joking, Mr. Feynman.

This is notably what the United States emerged to be after World War II. But it was likely what Nazi Germany also was, and many other superpowers.

Ciro Santilli feels that much more relevant would be to also include academia as in "military-industrial-academic" complex, the Wikipedia page actually mentions precedents to this idea.

The addition of congress/politicians is also relevant.

But hey, the name wouldn't sound so slick with three parts.

It is basically in this context that American science and technology flourished after World War II, including notably the development of quantum electrodynamics, Richard Feynman being a prototypical example, having previously worked on the Manhattan Project.

This is a well known though experiment, which Richard Feynman used to emphasize

In the above experiment:

The solution to this problem is length contraction: the positive charges are length contracted and the moving electrons aren't, and therefore they are denser and therefore there is an effective charge from that frame.

This is also mentioned at David Tong www.damtp.cam.ac.uk/user/tong/em/el4.pdf (archive) "David Tong: Lectures on Electromagnetism - 5. Electromagnetism and Relativity" "5.2.1 Magnetism and Relativity".

Term invented by Ciro Santilli, it refers to Richard Feynman, after helping to build the atomic bomb:

This one might actually be understandable! It is what Richard Feynman starts to explain at: Richard Feynman Quantum Electrodynamics Lecture at University of Auckland (1979).

The difficulty is then proving that the total probability remains at 1, and maybe causality is hard too.

The path integral formulation can be seen as a generalization of the double-slit experiment to infinitely many slits.

Feynman first stared working it out for non-relativistic quantum mechanics, with the relativistic goal in mind, and only later on he attained the relativistic goal.

TODO why intuitively did he take that approach? Likely is makes it easier to add special relativity.

This approach more directly suggests the idea that quantum particles take all possible paths.

Can be used to detect single photons.

Richard Feynman likes them, he describes the tube at Richard Feynman Quantum Electrodynamics Lecture at University of Auckland (1979) at one point.

It uses the photoelectric effect multiple times to produce a chain reaction. In particular, as mentioned at youtu.be/5V8VCFkAd0A?t=74 from Video 1. "Using a Photomultiplier to Detect single photons by Huygens Optics" this means that the device has a lowest sensitive light frequency, beyond which photons don't have enough energy to eject any electrons.