By Andy Haas, an experimental particle physics professor: as.nyu.edu/content/nyu-as/as/faculty/andy-haas.html What an awesome dude!
Missileers by BBC (2000)
Source. Documentary about American ICBM crews working on the Francis. E. Warren Air Force Base. Wiki mentions that there are 3 main sites in the USA, and plainshumanities.unl.edu/encyclopedia/doc/egp.ii.042 suggests all/most of them are in the Great Plains area. They operate a Minuteman system, which as of 2021 is the only nuclear ICBM system in the USA.
Good documentary, shows well the day-to-day life of the operator, including outside of the work site.
- youtu.be/w1tMx27Q4O0?t=1390 they drive 100 miles to get to work. They do 8 alerts per month.
- youtu.be/w1tMx27Q4O0?t=1473 the actual missiles are a few miles away from the control center, scattered in a few different locations
- youtu.be/w1tMx27Q4O0?t=1619 they have a television in there at least. Presumably a pre-recorded selection.
Logistics support management by USAF
. Source. Shows logistic operations behind the American ICBM system of the time. Reuploaded to showcase the IBM 705 system used to track parts, notably the usage of a punch cards.How MRI Works Part 1 by thePIRL (2018)
Source. - youtu.be/TQegSF4ZiIQ?t=326 the magnet is normally always on for the entire lifetime of the equipment!
- youtu.be/TQegSF4ZiIQ?t=465 usage of non-ionizing radiation (only radio frequencies) means that it is very safe to use. The only dangerous part is the magnetic field interacting with metallic objects.
Dr Mansfield's MRI MEDICAL MARVEL by BBC
. Source. Broadcast in 1978. Description:Tomorrow's World gave audiences a true world first as Dr Peter Mansfield of the University of Nottingham demonstrated the first full body prototype device for Magnetic resonance imaging (MRI), allowing us to see inside the human body without the use of X-rays.
Google 2FA app token can be updated without checking the old 2FA by
Ciro Santilli 37 Updated 2025-06-17 +Created 1970-01-01
To send voice and music, amplitude modulation had to be developed. And a key ingredient of this is the carrier wave.
The problem is, the carrier wave needs to have somewhat high frequencies, in the hundreds of kHz TODO why. But as you might imagine, that is hard to achieve by mechanical means such as a hand cranck like Hippolyte Pixiis alternator!
Interestingly, some of the first carrier wave generators were actually mechanical, e.g. the Alexanderson alternator.
But clearly such mechanical machines were not very scalable, and soon more electronic devices were introduced, notably the vacuum tube.
It is hard to do something useful with a devboard by
Ciro Santilli 37 Updated 2025-06-17 +Created 1970-01-01
In the 2010's/2020's, many people got excited about getting children in to electronics with cheap devboards, notably with Raspberry Pi and Arduino.
While there is some potential in that, Ciro Santilli always felt that this is very difficult to do, while also keeping his sacred principle of backward design in mind.
The reason for this is that "everyone" already has much more powerful computers at hand: their laptops/desktops and even mobile phones as of the 2020s. Except perhaps if you are thing specifically about poor countries.
Therefore, the advantage using such devboards for doing something that could useful must come from either:
- their low cost. This would be an important consideration if you were to mass produce your product, but that is not going to be the case for learners, at least initially.
- their portability, and closely linked their ability to act as sensors
- their ability to act as actuators, which is often missing from regular computers
- them having hardware accelerators that are not normally present in regular computers, e.g. FPGAs or AI accelerators. And then the demo project must demonstrate that the project is able to do something significantly faster/cheaper on the devboard than on a desktop computer.
Deriving magnetism from electricity and relativity by
Ciro Santilli 37 Updated 2025-06-17 +Created 1970-01-01
It appears that Maxwell's equations can be derived directly from Coulomb's law + special relativity:
This idea is suggested by the charged particle moving at the same speed of electrons thought experiment, which indicates that magnetism is just a consenquence of special relativity.
Why moving charges produce magnetic field? by FloatHeadPhysics (2022)
Source. If it only it were written in JavaScript instead of Haskell (!?), then Ciro might have used it as the basis for OurBigBook Markup.
A tiny idealized magnet! It is a very good model if you have a small strong magnet interacting with objects that are far away, notably other magnetic dipoles or a constant magnetic field.
The cool thing about this model is that we have simple explicit formulas for the magnetic field it produces, and for how this little magnet is affected by a magnetic field or by another magnetic dipole.
Representation theory of the Lorentz group by
Ciro Santilli 37 Updated 2025-06-17 +Created 1970-01-01
Physics from Symmetry by Jakob Schwichtenberg (2015) page 66 shows one in terms of 4x4 complex matrices.
More importantly though, are the representations of the Lie algebra of the Lorentz group, which are generally also just also called "Representation of the Lorentz group" since you can reach the representation from the algebra via the exponential map.
Bibliography:
- Physics from Symmetry by Jakob Schwichtenberg (2015) chapter 3.7 "The Lorentz Group O (1, 3)"
There are unlisted articles, also show them or only show them.