# Antimatter and Matter

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What causes Antimatter and Matter to annihlate each other? If it were charge they would just cancel out, right?

That is one of the reasons that I think that there is another fundamental difference between antimatter and matter.

Does anyone know what causes them to annihlate each other, or what the fundamental difference is?

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What´s the difference between annihilating and canceling out? You mean because they don´t simply vanish to nothing? Particles and anti-particles both have positive energy. Since energy is a conserved quantity an encounter of both cannot result in nothingness.

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What causes Antimatter and Matter to annihlate each other? If it were charge they would just cancel out, right?

Exactly right and thats what they do.

Don't forget: matter and energy cannot be created nor destroyed but can be converted from one too another, in this case both the particles "canceled out" and produce gamma photons as the energy

Here are some reads for you:

http://en.wikipedia.org/wiki/Anitmatter

http://en.wikipedia.org/wiki/Annihilation

Cheers,

Ryan Jones

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They annihilate because the resulting system (usually a photon) has a smaller rest mass. They are very happy to annihilate to photons, which has a zero mass, but in principle they will annihilate to any available lighter state which has the right quantum numbers. Since particles and antiparticles have opposite quantum numbers, they have to annihilate into something which is neutral and colorless, just like the photon (but in principle a very heavy particle-antiparticle pair could annihilate into something else, like a Z boson).

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They annihilate because the resulting system (usually a photon) has a smaller rest mass. They are very happy to annihilate to photons, which has a zero mass, but in principle they will annihilate to any available lighter state which has the right quantum numbers. Since particles and antiparticles have opposite quantum numbers, they have to annihilate into something which is neutral and colorless, just like the photon (but in principle a very heavy particle-antiparticle pair could annihilate into something else, like a Z boson).

Just out of interest has an annihilation ever been observed where a photon hasn't been the resulting particle?

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Just out of interest has an annihilation ever been observed where a photon hasn't been the resulting particle?

Happens all the time. In fact, physicists rely on it in accelerators that collide particles and antiparticles.

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I know that matter/energy can not be created or destroyed, but can go between each state.

I am probably missing something, but why do they annihlate? How come they just don't become a larger, neutral mass?

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I know that matter/energy can not be created or destroyed' date=' but can go between each state.

I am probably missing something, but why do they annihlate? How come they just don't become a larger, neutral mass?[/quote']

Two opposing charges do not just combine to make one larger neutral force, they just cancel each other out which is what happens in this case.

Have a search of Google, it turned up some good descriptive results - they should help you also.

Cheers,

Ryan Jones.

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And because energy has to be conserved when they "cancel each other out" their energy is released, which is why matter/anti-matter annihlation releases a lot of energy.

If you had 1/2g of matter and 1/2g of antimatter and they annihlated then you'd a total of 1g annihlating which releases 90TJ or 21.4 kilotons of energy. This is a bit more powerful than the nuclear bomb dropped on Hiroshima at the end of WW2. A lot of energy!

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Okay, thanks. I sort of understand it now.

So when they cancel out, the energy that each particle had, needs to be conserved, so they annihlate each other?

Would that happen every time particles with opposite charges meet?

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Since particles and antiparticles have opposite quantum numbers, they have to annihilate into something which is neutral and colorless, just like the photon (but in principle a very heavy particle-antiparticle pair could annihilate into something else, like a Z boson).
don't only additave quantum numbers matter in matter/antimatter annhialation?

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don't only additave quantum numbers matter in matter/antimatter annhialation?

Whether or not a quantum number is additive or multiplicitive is completely semantic. If I have multiplicative quantum numbers of two particles A and B being $q_A$ and $q_B$, then the quantum number of the combined state is $q_Aq_B$ if the quantum number is conserved. But I could have defined $Q_i=\log(q_i)$ as my quantum number. Then the combined object has quantum number $\log(q_Aq_B)=\log q_A+\log q_B = Q_A+Q_B$. In other words, $Q_i$ are additive.

The only important thing is whether or not the quantum number is conserved.

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