In modern physics, antimatter is defined as matter composed of the antiparticles (or "partners") of the corresponding particles in "ordinary" matter, and can be thought of as matter with reversed charge, parity, and time, known as CPT reversal. Antimatter occurs in natural processes like cosmic ray collisions and some types of radioactive decay, but only a tiny fraction of these have successfully been bound together in experiments to form antiatoms. Minuscule numbers of antiparticles can be generated at particle accelerators; however, total artificial production has been only a few nanograms. No macroscopic amount of antimatter has ever been assembled due to the extreme cost and difficulty of production and handling.

In theory, a particle and its antiparticle (for example, a proton and an antiproton) have the same mass, but opposite electric charge, and other differences in quantum numbers.

A collision between any particle and its anti-particle partner leads to their mutual annihilation, giving rise to various proportions of intense photons (gamma rays), neutrinos, and sometimes less-massive particle–antiparticle pairs. The majority of the total energy of annihilation emerges in the form of ionizing radiation. If surrounding matter is present, the energy content of this radiation will be absorbed and converted into other forms of energy, such as heat or light. The amount of energy released is usually proportional to the total mass of the collided matter and antimatter, in accordance with the notable mass–energy equivalence equation, E=mc2.

Antiparticles bind with each other to form antimatter, just as ordinary particles bind to form normal matter. For example, a positron (the antiparticle of the electron) and an antiproton (the antiparticle of the proton) can form an antihydrogen atom. The nuclei of antihelium have been artificially produced, albeit with difficulty, and are the most complex anti-nuclei so far observed. Physical principles indicate that complex antimatter atomic nuclei are possible, as well as anti-atoms corresponding to the known chemical elements.

There is strong evidence that the observable universe is composed almost entirely of ordinary matter, as opposed to an equal mixture of matter and antimatter. This asymmetry of matter and antimatter in the visible universe is one of the great unsolved problems in physics. The process by which this inequality between matter and antimatter particles developed is called baryogenesis.

Antimatter particles carry the same charge as matter particles, but of opposite sign. That is, an antiproton is negatively charged and an antielectron (positron) is positively charged. Neutrons do not carry a net charge, but their constituent quarks do. Protons and neutrons have a baryon number of +1, while antiprotons and antineutrons have a baryon number of –1. Similarly, electrons have a lepton number of +1, while that of positrons is –1. When a particle and its corresponding antiparticle collide, they are both converted into energy.

Megathreads and spaces to hang out:

reminders:

Links To Resources (Aid and Theory):

Aid:

Theory:

  • Frank [he/him, he/him]
    ·
    2 years ago

    There's never been a bad era for movies. Some of the very first moving pictures are great.

    • VHS [he/him]
      ·
      2 years ago

      A lot of the German Expressionism films from the 20s and 30s hold up great. There are good movies from every era, but of course it's fair to criticize things like the Hays Code, DoD/CIA influence, and now shitty CGI that actively make movies worse

      • Frank [he/him, he/him]
        ·
        2 years ago

        Sure, but there were movies that were great in part because they had to be clever to evade the Hays code. Most of the Marvel movies suck but Winter Soldier manages to combine Marvel's trademarket explosive action slop with stylish callbacks to 70s political thrillers and a bizarrely unexpected criticism of the US intelligence services and the Obama-era drone program. Like I don't know how or why it happened but they might have well replaced Robert Redford (himself a veteran of 70s political thrillers) with a black actor and made it obvious to everyone.

        CGI is in a very weird place right now. It was originally developed to create things which were otherwise difficult or impossible, best shown by the stunning and still gorgeous dinsoaurs in 1994s Jurassic Park, but in the present day some studios and directors use it as both a cost cutting measure to avoid building sets and filming on location, and as a sloppy, disorderly way to avoid thinking out their production, allowing them to make constant last-second revisions even up to or after release. When it's done well it's an incredible tool, when it's done poorly it has as much weight as Hanna Barbera's worst animation. I did recently hear Neil Gaiman discuss using CGI in Sandman the way matte paintings are used - create what you can with the set, then use CGI or your matte painting to extend that out in to the background.

        I dearly wish we'd get more inventive, surrealist films. CGI could, and occaisonally does, enable some truly astonishing, surreal visuals and I wish we could get more of that. Stories like Paprika or Little Nemo could be realized with CGI and it just doesn't happen that often. To much obsession with realism. : p