Ciro Santilli $$ Sponsor Ciro $$ 中国独裁统治 China Dictatorship 新疆改造中心、六四事件、法轮功、郝海东、709大抓捕、2015巴拿马文件 邓家贵、低端人口、西藏骚乱
Currently an informal name for the Standard Model
Chronological outline of the key theories:
The neutron temperature example is crucial: you just can't give the cross section of a target alone, the energy of the incoming beam also matters.
Video 1. How to make a cloud chamber by Suzie Sheehy (2011) Source.
Most important application: produce X-rays for X-ray crystallography.
Note however that the big experiments at CERN, like the Large Hadron Collider, are also synchrotrons.
Predecessor to the synchrotron.
Nuclear physics is basically just the study of the complex outcomes of weak interaction + quantum chromodynamics.
A proton or a neutron.
Side effect of the strong force that in addition to binding individual protons and neutrons as units, also binds different protons and neutrons to one another.
Ciro Santilli finds it interesting that radioactive decay basically kickstarted the domain of nuclear physics by essentially providing a natural particle accelerator from a chunk of radioactive element.
The discovery process was particularly interesting, including Henri Becquerel's luck while observing phosphorescence, and Marie Curie's observation that the uranium ore were more radioactive than pure uranium, and must therefore contain other even more radioactive substances, which lead to the discovery of polonium (half-life 138 days) and radium (half-life 1600 years).
Most of the helium in the Earth's atmosphere comes from alpha decay, since helium is lighter than air and naturally escapes out out of the atmosphere.
Wiki mentions that alpha decay is well modelled as a quantum tunnelling event, see also Geiger-Nuttall law.
As a result of that law, alpha particles have relatively little energy variation around 5 MeV or a speed of about 5% of the speed of light for any element, because the energy is inversely exponentially proportional to half-life. This is because:
  • if the energy is much larger, decay is very fast and we don't have time to study the isotope
  • if the energy is much smaller, decay is very rare and we don't have enough events to observe at all
Video 2. Quantum tunnelling and the Alpha particle Paradox by Physics Explained (2022) Source.
Uranium emits them, you can see their mass to charge ratio under magnetic field and so deduce that they are electrons.
Caused by weak interaction TODO why/how.
The emitted electron kinetic energy is random from zero to a maximum value. The rest goes into a neutrino. This is how the neutrino was first discovered/observed indirectly. This is well illustrated in a decay scheme such as Figure "caesium-137 decay scheme".
Most commonly known as a byproduct radioactive decay.
A decay scheme such as Figure "caesium-137 decay scheme" illustrates well how gamma radiation happens as a byproduct of radioactive decay due to the existence of nuclear isomer.
Gamma rays are pretty cool as they give us insight into the energy levels/different configurations of the nucleus.
They have also been used as early sources of high energy particles for particle physics experiments before the development of particle accelerators, serving a similar purpose to cosmic rays in those early days.
But gamma rays they were more convenient in some cases because you could more easily manage them inside a laboratory rather than have to go climb some bloody mountain or a balloon.
The positron for example was first observed on cosmic rays, but better confirmed in gamma ray experiments by Carl David Anderson.
The half-life of radioactive decay, which as discovered a few years before quantum mechanics was discovered and matured, was a major mystery. Why do some nuclei fission in apparently random fashion, while others don't? How is the state of different nuclei different from one another? This is mentioned in Inward Bound by Abraham Pais (1988) Chapter 6.e Why a half-life?
The term also sees use in other areas, notably biology, where e.g. RNAs spontaneously decay as part of the cell's control system, see e.g. mentions in E. Coli Whole Cell Model by Covert Lab.
Some of the most notable ones:
TODO can you do Stern-Gerlach experiment with alpha particles?
Ciro Santilli once visited the chemistry department of an university, and the chemists were obsessed with NMR. They had small benchtop NMR machines. They had larger machines. They had a room full of huge machines. They had them in corridors and on desk tops. Chemists really love that stuff. More precisely, these are used for NMR spectroscopy.
Basically measures the concentration of certain isotopes in a region of space.
Video 3. Introduction to NMR by Allery Chemistry. Source.
  • only works with an odd number of nucleons
  • apply strong magnetic field, this separates the energy of up and down spins. Most spins align with field.
  • send radio waves into sample to make nucleons go to upper energy level. We can see that the energy difference is small since we are talking about radio waves, low frequency.
  • when nucleon goes back down, it re-emits radio waves, and we detect that. TODO: how do we not get that confused with the input wave, which is presumably at the same frequency? It appears to send pulses, and then wait for the response.
Video 4. How to Prepare and Run a NMR Sample by University of Bath (2017) Source. This is a more direct howto, cool to see. Uses a Bruker Corporation 300. They have a robotic arm add-on. Shows spectrum on computer screen at the end. Shame no molecule identification after that!
Video 5. Proton Nuclear Magnetic Resonance by Royal Society Of Chemistry (2008) Source. Says clearly that NMR is the most important way to identify organic compounds.
Video 6. Introductory NMR & MRI: Video 01 by Magritek (2009) Source. Precession and Resonance. Precession has a natural frequency for any angle of the wheel.
Video 7. Introductory NMR & MRI: Video 02 by Magritek (2009) Source. The influence of temperature on spin statistics. At 300K, the number of up and down spins are very similar. As you reduce temperature, we get more and more on lower energy state.
Video 8. Introductory NMR & MRI: Video 03 by Magritek (2009) Source. The influence of temperature on spin statistics. At 300K, the number of up and down spins are very similar. As you reduce temperature, we get more and more on lower energy state.
The equation is simple: frequency is proportional to field strength!
Used to identify organic compounds.
Seems to be based on the effects that electrons around the nuclei (shielding electrons) have on the outcome of NMR.
So it is a bit unklike MRI where you are interested in the position of certain nuclei in space (of course, these being atoms, you can't see their positions in space).
Video 9. What's Nuclear Magnetic Resonance by Bruker Corporation (2020) Source. Good 3D animatinos showing the structure of the NMR machine. We understand that it is very bulky largely due to the cryogenic system. It then talks a bit about organic compound identification by talking about ethanol, i.e. this is NMR spectroscopy, but it is a bit too much to follow closely. Basically the electron configuration alters the nuclear response somehow, and allows identifying functional groups.
Using NMR to image inside peoples bodies!
Video 10. How MRI Works Part 1 by thePIRL (2018) Source.
This is a good book, it gives a summary of biographies, and a reasonable description of the main ideas, with many illustrations. Each subject is not presented in incredible detail, but it is a good overview of events.
The book unfortunately does not cover the history of quantum mechanics very, the author specifically says that this will not be covered, the focus is more on particles/forces. But there are still some mentions.
Some light YouTube channels, good for the first view, but which don't go into enough detail to truly show the subject's beauty:
Always a bit too much on the superficial side, but sometimes OK, 5-10 minute videos.
These feel good. Targeted at upper undergrads, so he says he holds back on some stuff, but gives a good level of detail for people who have a life.
Too many fun skit videos for Ciro Santilli's taste, but does have some serious derivations in quantum electrodynamics.
Covers some specific hardcore subjects, notably quantum electrodynamics, in full mathematical detail, e.g.: "Quantum Field Theory Lecture Series" playlist:
Unfortunately the channel is too obsessed with mathematical detail (which it does amazingly), and does not give enough examples/application/intuition, which is what would be useful to most people, thus falling too much on the hardcore side of the missing link between basic and advanced.
This channel does have on merit however: compared to other university courses, it is much more direct, which might mean that you get to something interesting before you got bored to death, Section "You can learn more from older students than from faculty" comes to mind.
Videos generally involves short talks + a detailed read-through of a pre-prepared PDF. Dietterich has refused however giving the PDF or LaTeX source as of 2020 on comments unfortunately... what a wasted opportunity for society. TODO find the comment.
Full name as shown in channel content: Samuel Dietterich. Other accounts:
Video 11. The Ultimate Goal Of My YouTube Channel by Dietterich Labs (2020) Source. In this video Dietterich gives his ideal for the channel. Notably, he describes how the few experimental videos he has managed to make were done in a opportunistic way from experiments that were happening around him. This resonated with Ciro Santilli's ideas from videos of all key physics experiments.
Video 12. Sam Dietterich interview by Dietterich Labs (2022) Source. TODO find patience to watch and summarize key points.
Those guys are really good, Ciro Santilli especially enjoyed their quantum mechanics playlist:
The quantum electrodynamics one was a bit too slow paced for Ciro unfortunately, too much groundwork and too little results.
Accompanying website with a tiny little bit of code:
TODO: authors and their affiliation.
Videos licensed as CC BY-SA, those guys are so good.
These videos can give some geometric insight and do have their value.
And when things get "mathy", it sticks to a more qualitative view which may not be enough.
Very over the top with sexy demons and angels making appearances, and has some classic aesthetic artistic value :-)
Publishes through the Fermilab YouTube channel under the playlist "Fermilab - Videos by Don Lincoln"
Some insights, but too much on the popular science side of things.