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RJ Emery
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- TL;DR Summary
- matter, anti-matter pair
I seek an explanation as to how a particle can be its own anti-particle. I would think the instant such a particle comes into existence, it would self-annihilate.
Why? There is absolutely no rationale for such an argument.RJ Emery said:Summary:: matter, anti-matter pair
I would think the instant such a particle comes into existence, it would self-annihilate.
Can two photons annihilate? I would think not because they don't interact very strongly. But they can interact. Delbruck scattering is an example. I'm confused.mfb said:A photon (which is its own antiparticle as well) can't decay, it is stable.
There is the maxim that "if a process does not violate a conservation law, it should happen".mfb said:A photon (which is its own antiparticle as well) can't decay, it is stable.
Yes. Since an electron-positron pair can annihilate to two photons, two photons (given sufficient invariant mass for the pair) can reverse this process. What the cross section is is another matter.Paul Colby said:Can two photons annihilate?
They can react (and we have found reactions), but I don't think "annihilation" is a good name for that.Paul Colby said:Can two photons annihilate? I would think not because they don't interact very strongly. But they can interact. Delbruck scattering is an example. I'm confused.
There is some symmetry that tells you the cross section is exactly zero, I forgot the name.snorkack said:Classically it´ s obvious - a plane wave of a given frequency cannot spontaneously change its frequency. But viewing it as a photon subject to conservation laws only, which one specifically forbids it to do such an absurd thing?
In QED a positron and electron can annihilate to form 2 photons. Just run the reaction diagrams backward in time and I'm good to go. So yeah, looks like annihilation of photons to me.mfb said:They can react (and we have found reactions), but I don't think "annihilation" is a good name for that.
Then what are the rules? Particle meets antiparticle to produce other particles is the definition of particle annihilation hocked up by Google when queried. Is there a more technically correct one?mfb said:There is no rule that would give time-reversed processes the same name.
But ultimately it doesn't matter. You can call annihilation what you want as long as it doesn't lead to confusion.mfb said:If the reaction products are massless or much lighter (which is again possible but not guaranteed) we typically call this reaction "annihilation".
This phenomenon is known as particle-antiparticle duality, where a particle and its antiparticle have the same mass but opposite charge. This is possible because in quantum mechanics, particles are described as wave-like entities, and their properties, such as charge, can be positive or negative.
One of the most well-known examples is the electron and positron. When these two particles collide, they can annihilate each other and produce high-energy photons. This process has been observed in particle accelerators, providing strong evidence for particle-antiparticle duality.
No, not all particles have antiparticles. Only particles that are their own antiparticles are called "Majorana particles." These include the neutrino and hypothetical particles such as the Majorana fermion.
The Big Bang theory suggests that the universe was initially filled with equal amounts of matter and antimatter. As the universe expanded and cooled, particles and antiparticles began to annihilate each other, leaving behind a small amount of matter that makes up our present-day universe.
Particle-antiparticle duality does not violate the law of conservation of energy and mass. When a particle and antiparticle annihilate each other, they produce energy in the form of photons. This energy is equivalent to the mass of the particles, according to Einstein's famous equation E=mc^2.