The only isotope found on Earth because it occurs as part of the uranium 238 decay chain, i.e., it is not a primordial nuclide.

Interestingly it is a bit less stable than other isotopesL such as Polonium-208 (3 y) and Polonium-209 (124 y), but those aren't in any Earthly radioactive chain so they don't show up on Earth.

Ah, Ciro Santilli was not expecting this. What a unique mixture of humour, technology, politics and bravery. No wonder it was a box flop, there's something good about this film.

Subgroup of the Poincaré group without translations. Therefore, in those, the spacetime origin is always fixed.

Or in other words, it is as if two observers had their space and time origins at the exact same place. However, their space axes may be rotated, and one may be at a relative speed to the other to create a Lorentz boost. Note however that if they are at relative speeds to one another, then their axes will immediately stop being at the same location in the next moment of time, so things are only valid infinitesimally in that case.

This group is made up of matrix multiplication alone, no need to add the offset vector: space rotations and Lorentz boost only spin around and bend things around the origin.

One definition: set of all 4x4 matrices that keep the Minkowski inner product, mentioned at Physics from Symmetry by Jakob Schwichtenberg (2015) page 63. This then implies:

Proportionality factor in the Planck-Einstein relation between light energy and frequency.

And analogously for matter, appears in the de Broglie relations relating momentum and frequency. Also appears in the Schrödinger equation, basically as a consequence/cause of the de Broglie relations most likely.

Intuitively, the Planck constant determines at what length scale do quantum effects start to show up for a given energy scale. It is because the Plank constant is very small that we don't perceive quantum effects on everyday energy/length/time scales. On the ${\lim }_{h\to 0}$, quantum mechanics disappears entirely.

A very direct way of thinking about it is to think about what would happen in a double-slit experiment. TODO think more clearly what happens there.

Defined exactly in the 2019 redefinition of the SI base units to:

Allows you to connect two adjacent pins of a pin header. Sometimes used as a hardware configuration interface!

Interesting fractal approach to a phylogenetic tree: www.onezoom.org/

Mostly data driven.

Mentioned at: en.wikipedia.org/wiki/Phase_transition#Modern_classifications

The more familiar transitions we are familiar with like liquid water into solid water happen at constant temperature.

However, other types of phase transitions we are less familiar in our daily lives happen across a continuum of such "state variables", notably:

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.