Antimatter and matter canceling out

[Lunct]

Antimatter and matter cancel each other out. What does this mean? Do the particles just cease to exist? Does this go against the law of the conservation of energy?
HELP

 

[sophiecentaur]

You would first have to learn what is meant by Antimatter. For instance, it does not consist of Negative Mass (that's a popular misconception).
As usual, Wiki, although not a definitive source, can be a good place to start. You should read that link.

 

[Drakkith]

Antimatter and matter cancel each other out.

I wouldn't say that they "cancel each other out". The process is called "annihilation", and always results in the creation of other particles and/or EM radiation.

Does this go against the law of the conservation of energy?

Nope. Energy and mass are fully conserved through the creation of other particles and radiation which carry away whatever mass and energy the original particles had.

 

[Lunct]

You would first have to learn what is meant by Antimatter. For instance, it does not consist of Negative Mass (that's a popular misconception).
As usual, Wiki, although not a definitive source, can be a good place to start. You should read that link.

I think I understand, the particles turn into energy, and the amount of energy is in accordance the equation E=mc^2.
That would make sense.

 

[Lunct]

I wouldn't say that they "cancel each other out". The process is called "annihilation", and always results in the creation of other particles and/or EM radiation

Pop science has to over simplify everything...

 

[jtbell]

Also: https://en.wikipedia.org/wiki/Annihilation

Bottom line: energy and momentum are conserved.

 

[Lunct]

Also: https://en.wikipedia.org/wiki/Annihilation

Bottom line: energy and momentum are conserved.

makes sense...
but is it possible for photons to turn back into matter?

 

[Nugatory]

but is it possible for photons to turn back into matter?

Yes.
Google for "pair production" - a sufficiently energetic photon in the vicinity of a heavy nucleus can turn into an electron-positron pair.
(The heavy nucleus is needed because without it there's no way of conserving both energy and momentum).

 

[Lunct]

Yes.
Google for "pair production" - a sufficiently energetic photon in the vicinity of a heavy nucleus can turn into an electron-positron pair.
(The heavy nucleus is needed because without it there's no way of conserving both energy and momentum).

but wouldn't the positron and electron want to collide together as they have opposite charges and annihilate?

 

[sophiecentaur]

but wouldn't the positron and electron want to collide together as they have opposite charges and annihilate?

Not if they have sufficient resulting Kinetic Energy to take them apart ( aka Escape Velocity).

 

[Nugatory]

but wouldn't the positron and electron want to collide together as they have opposite charges and annihilate?

They might, and then you get a pair of photons out. That case looks from the outside as if the nucleus absorbed the incoming photon and immediately emitted two less energetic photons. However, if the electron and positron have enough kinetic energy (the incoming photon has substantially more than two electron masses worth of energy, by $E=mc^2$) then the two particles will fly apart more quickly than the attractive force can pull them together.

 

[Lunct]

They might, and then you get a pair of photons out. That case looks from the outside as if the nucleus absorbed the incoming photon and immediately emitted two less energetic photons. However, if the electron and positron have enough kinetic energy (the incoming photon has substantially more than two electron masses worth of energy, by $E=mc^2$) then the two particles will fly apart more quickly than the attractive force can pull them together.

makes sense, you are very good at explaining things.
Thanks