The knowledge that light is polarized precedes the knowledge of the existence of the photon, see polarization of light for the classical point of view.

The polarization state and how it can be decomposed into different modes can be well visualized with the Poincaré sphere.

One key idea about photon polarization is that it carries angular momentum. Therefore, when an electron changes orbitals in the Schrödinger equation solution for the hydrogen atom, the angular momentum (as well as energy) change is carried out by the polarization of the photon!

After removing it:

Of course, we already knew that minimal plaster work would be needed from the start, since we have to hammer two small nails into the wall. But that level of damage might have been easily dealt with by a non-professional tenant himself. But the level I had was a bit more than I felt I should handle myself.

Relates particle momentum and its wavelength, or equivalently, energy and frequency.

The wavelength relation is:but since:the wavelength relation implies:

Particle wavelength can be for example measured very directly on a double-slit experiment.

So if we take for example electrons of different speeds, we should be able to see the diffraction pattern change accordingly.

Basic component in spintronics, used in both giant magnetoresistance

Skullcandy earphones, first one circa. 2016 most likely. Used them a lot, these are good.

2023-07: one of the sides broke near center, rebuying.

2021-07: wire half broke near connector, only works in some positions. The funny thing is: only voices seem to be blocked out! Rebuying.

2021-06: a small bottom piece of the left earpiece broke. Wire seems find, that is like a little extension to protect wire. Let's see for how long.

2020-20: wires at one of ears broke, not sure how.

Look they looked exactly like: "Skullcandy Smokin' Buds 2 In-Ear Audio Earbud Headphones with In-Line Microphone - Black".

Re-buying that one 10 pounds:

Tech specs:

The new default homepage for a logged out user how shows a list of the topics with the most articles.

This is a reasonable choice for default homepage, and it immediately exposes users to this central feature of the website: the topic system.

Doing this required in particular calculating the best title for a topic, since it is possible to have different titles with the same ID, the most common way being with capitalization changes, e.g.:would both have topic ID javascript.

With this in place we also added the preferred topic title to the top topic page.

The algorithm chosen is to pick the top 10 most upvoted topics, and select the most common title from amongst them. This should make topic title vandalism quite hard. This was made in a single SQL query, and became the most complext SQL query Ciro Santilli has ever written so far: twitter.com/cirosantilli2/status/1549721815832043522

The first human-made nuclear chain reaction.

Physics (like all well done science) is the art of predicting the future by modelling the world with mathematics.

And predicting the future is the first step towards controlling it, i.e.: engineering.

Ciro Santilli doesn't know physics. He writes about it partly to start playing with some scientific content for: OurBigBook.com, partly because this stuff is just amazingly beautiful.

Ciro's main intellectual physics fetishes are to learn quantum electrodynamics (understanding the point of Lie groups being a subpart of that) and condensed matter physics.

Every science is Physics in disguise, but the number of objects in the real world is so large that we can't solve the real equations in practice.

Luckily, due to emergence, we can use uglier higher level approximations of the world to solve many problems, with the complex limits of applicability of those approximations.

Therefore, such higher level approximations are highly specialized, and given different names such as:

As of 2019, all known physics can be described by two theories:

Unifying those two into the theory of everything one of the major goals of modern physics.

This shows that viewing electromagnetism as gauge theory does have experimentally observable consequences. TODO understand what that means.

In more understandable terms, it shows that the magnetic vector potential matters where the magnetic field is 0.

A different and more elegant way to express Maxwell's equations by using the:instead of the:

Cool that there is actually a page for a change: www.ox.ac.uk/students/academic/exams/timetables e.g. working in 2024: web.archive.org/web/20240305013807/https://www.ox.ac.uk/students/academic/exams/timetables

And translating from their arcane vocabulary: