https://www.reddit.com/r/askscience/comments/1gwe9ip/what_causes_the_mutual_annihilation_of/
created by holiestMaria on 21/11/2024 at 11:39 UTC
77 upvotes, 3 top-level comments (showing 3)
Antimatter partickes are the same as normal matter particles, but eith the opposite charge and spin, so what causes antimatter and matter to react so violently?
Comment by agaminon22 at 21/11/2024 at 18:50 UTC
65 upvotes, 3 direct replies
First of all, antimatter and matter don't always have to annihilate. Sometimes they can collide and scatter, look up Bhabha scattering. This is the process by which an electron and a positron scatter elastically, not annihilating. Furthermore, annihilation is not necessarily always into photons, it can lead to oher particles, such as neutrinos.
What I'm trying to point towards is that these kinds of fundamental reactions happen probabilistically and only when no conservation laws are broken. But if no conservation laws are broken, that essentially implies that they *will* happen. When matter and antimatter collide, there is no conservation law being broken through annihilation, and therefore it's a possible process that will happen. At low energies, it's the dominant process.
If you think about it in terms of quantum numbers, with positrons and electrons for example, the charges are opposed to form a state of zero change. The lepton quantum number is also zero. Essentially it's all lined up to form particles of zero charge, without lepton number, with the appropiate spin: photons. But you can also produce two neutrinos (a neutrino and an antineutrino), or really any other compatible possibility.
Comment by SystemofCells at 22/11/2024 at 03:05 UTC*
18 upvotes, 0 direct replies
There are different fundamental forces acting between particles of normal matter.
The gravitational force attracts matter to matter, it also attracts matter to antimatter. It gets stronger as things get closer together.
The strong force attracts things together at small scales, and is much greater than the gravitational force. But it and something called the Pauli exclusion principle prevent neutrons from falling into each other normally.
The electromagnetic force makes particles with opposite charge attract each other, and particles with similar charge repel each other. So protons repel protons, electronics repel electrons. But in antimatter charges are inverted, so a proton attracts an anti proton.
With normal matter, gravity and the strong force bring things together, then the electromagnetic force, strong nuclear force, and Pauli exclusion principle keeps them far enough apart that they don't try to occupy the same space at the same time. When matter and antimatter collide, the electromagnetic force doesn't counteract the strong force - it helps it along. So it's much more likely particles end up colliding with high energy.
This makes something that's usually hard to do with normal matter (forcing them to occupy the same space at the same time) much more likely. And when matter collides in this way, it gets destroyed and releases energy.
In standard fusion and fission reactions, only part of the matter (the binding energy) gets converted to energy. The number of neutrons and protons doesn't change, just how they're bonded to each other. In a matter-antimatter annihilation, a much higher proportion of the total mass can get converted to energy.
Comment by skr_replicator at 22/11/2024 at 01:02 UTC
3 upvotes, 0 direct replies
Antimatter particle has everything opposite about it, so for the reaction to conserve all the things that need to be conserved like charge etc, the result must have zero of all of that except the very energy itself, which photons are good carriers for energy wihtout any other such variables.