Podcast #128: We chat with Kent C Dodds about why he loves React and discuss what life was like in the dark days before Git. Listen now.

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Spins are angular momenta. Angular momentum is a vector, and conservation of angular momentum imposes the sign on the spin found. If in a reaction the electron goes off with a spin -1/2, the antineutrino-electron ( which conserves lepton number) has to have +1/2. The title though Why do antinutrinos have a spin of 1/2? is not concerned with the vector ...

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So this is really the twist in the construction of QFT that is still sometimes misunderstood. Historically, people like Dirac noticed that solutions to relativistic field equations such as the spinor equation for $\psi(x)$ admitted apparent negative mass-energy densities. However, once you go into QFT, either from a "second quantization" or a Fockian bottom-...

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If there were different regions, some with matter and others with antimatter, we would see the telltale signs of annihilation at the boundaries between them, there is none. As to why there's only matter when both matter and antimatter should be produced in equal amounts, don't know, pretty big mystery.

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This is because of a principle known as lepton number conservation. "Leptons" are a class of elementary particles which includes both electrons and neutrinos (the only stable examples), as well as their associated anti-particles. The lepton number is the total count of leptons in a physical system, where that anti-leptons are counted as though they were a "...

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When you time-reverse a black hole, you get a white hole. Therefore you don't see black holes as antimatter fountains. White holes would be antimatter fountains, but that doesn't say much because everything falls out of white holes anyway.

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There is no evidence - either direct or indirect - of matter or antimatter suddenly appearing anywhere in our universe. The only theoretical mechanism that we know of that could connect distant points in spacetime is an Einstein-Rosen bridge. This has also never been observed, and it has such unusual properties that many physicists think it is physically ...

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The main thing to say is that the numerous popular articles which say that Hawking radiation is particle/anti-particle pairs in which one of each pair gets swallowed by the black hole are misleading. Hawking radiation is almost entirely electromagnetic radiation---that is, photons. You can still use the language of particle/anti-particle, but it is a bit ...

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Light is electromagnetic radiation and has different frequencies. "Glow" that humans could see would need to be in the visible spectrum and not infrared for example. It is true that particle-antiparticle pair combination produces photons but their energy might not be high enough to be visible to us. That is an example of mass converting to energy. The ...

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In fact, the pair production describes that energy can be converted into both mater and antimatter through photon over or equal to a threshold of 1.02 MeV. Since Albert Einstein’s infamous equation, E = mc^2 tells us that matter and energy is interchangeable so if matter can become energy, then energy can become matter. I am actually doing a research project ...

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Antimatter is not the negative energy solutions to the energy-momentum relation! Even in the Dirac sea model it isn't. In the Dirac sea model, the negative-energy modes are all filled with electrons, and the absence of one of those electrons is a positron. Just as the absence of a positive-energy particle has (relatively speaking) a negative energy, so the ...

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The solar wind has a density of about 6 atoms per cubic centimeter at Earth orbit. If we say it moves at 500 km/s at Earth orbit that means that a naked surface will be hit by 30 billion antiprotons per second. That is about 9 watt of annihilation energy per square meter - three orders of magnitude below the energy in sunlight, but in the form of gamma rays. ...

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As in my answer here the electron positron annihilation lines would be very evident in the solar wind - earth atmosphere overlap. It is the reason we know the sun is made of matter. If the sun were antimatter, there would be a lot more cosmic rays coming from annihilations of antiprotons on protons, the effect on the satellites would be very large etc. Of ...

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Antimatter stars would behave exactly like ordinary stars except they would radiate antiparticles instead of particles (or vice versa). So for example if the Sun would radiate an electron, an anti-Sun would radiate a positron. We can be certain our Sun is not an antistar because if it did, the solar wind would annihilate with and destroy the Earth. ...

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The solar wind is composed by charged particles. Photons travel with the velocity of light in straight lines and do not form a "wind" superposed give the electromagnetic spectrum, including light to see by. The only difference of an antimatter star to a matter star would be that it would be composed by antiparticles of the standard model table. Photons are ...

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There is no difference between photons and antiphotons. Photons are their own antiparticle. So the electromagnetic radiation from matter stars and (probably nonexistent) antimatter stars is similar. The solar wind consists of charged particles. The particles in the solar wind from an antimatter star would have the opposite charge from those from a matter ...

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All particles have an antiparticle, their transform under C. You may be asking "when is a particle's antiparticle it itself?" Dirac Fermions cannot be their own antiparticle, as their corresponding fermion number transforms nontrivially under C; this then applies to all types of baryon, lepton, etc numbers. Majorana fermions can. They are their own ...

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The set of all gluons contains the antiparticles of each member of itself. But while there is only one photon which is own antiparticle (it is a singlet), each specific gluon has an antiparticle distinct of itself. But its antiparticle is just another gluon and does not deserve to be called an "antigluon". It is like saying that the $\pi$ meson is its own ...

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Photons are neutral bosons, they are their own antiparticle. Seen another way, the photon can be considered as its own antiparticle (thus an "antiphoton" is simply a normal photon). https://en.wikipedia.org/wiki/Photon Neutrinos are fermions, they do have antiparticles, with opposite lepton number and chirality. https://en.wikipedia.org/wiki/Neutrino ...

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