Matter destroyed?

[Thomas Kirby]

One of the first things we learn in science is that matter can neither be created nor destroyed. But what about when matter and antimatter collide? I've been reading "The Elegant Universe"; and it talks about matter and antimatter colliding and destroying each other. So how does this all fit together? Has that law since been changed?

 

There are a lot of quotes out there that people don't usually remember or apply but the first line of, but like "My country, right or wrong", almost none of them are relevant to this thread.

 

The "when right, to keep it right, when wrong to make it right" part of this one:

 

Matter and energy can neither be created or destroyed. They can only be converted from one form to another. (This means matter to matter, energy to energy, matter to energy, energy to matter.)

 

Changes the meaning quite a bit, doesn't it? Like a lot of quotes that come in two or more parts, it means something a lot different when you have the entire thing.

[swansont]

Matter is not a conserved quantity. Antimatter has been observed to convert to matter in CP violation interactions, specifically with e.g. Kaons and B mesons. Energy is, however, conserved under the conditions I described earlier, from Noether's theorem.

[DQW]

One of the first things we learn in science is that matter can neither be created nor destroyed. But what about when matter and antimatter collide? I've been reading "The Elegant Universe"; and it talks about matter and antimatter colliding and destroying each other. So how does this all fit together? Has that law since been changed?

There was a Law of Conservation of matter/mass, which, after Einstein must be modified (to incorporate mass-energy conversions) such that it becomes identical to the Law of Conservation of Energy (which is now the relativistic energy and includes a rest energy term, [imath]m_0c^2[/imath]).

 

When matter and anitimatter annihilate each other, they emit photons of total energy equal to the total relativistic energy of the colliding particles. In other words, the mass of the particles gets converted into the energy of the emitted photons.

 

Also, exercise some caution when reading "EU".

[Lance Cho]

Well To answer the first question in this thread:

 

Here is my answer. If matter and anti-matter were to collide the resulting would not be a destruction of matter. It'll just be the transfer of matter into a new substance, a new item. So my answer is no the laws have not been changed, it is just how you interprit the writing.

 

 

Lance Cho

tr8b2@bellsouth.net

AIM: Lancecho007

[Cap'n Refsmmat]

The "new substance" happens to be energy. That has already been explained and verified.

[Severian]

Imagine a matter particle and an anti-matter particle colliding. The matter particle has an amount of matter equal to +1 (ie. it is one matter particle) while the antiparticle has matter -1. So before they collide, the total matter of the system is (+1)+(-1)=0. then they collide and annihilate each other, turning into a photon with all their combined energy (which is conserved). The photon has matter 0 (since it is not matter by definition of 'matter'), so the amount of matter after the collision is 0, just as it was before. Therefore matter (in this interaction) is conserved.

 

(As Swansont pointed out, this matter conservation can be violated in certain other processes.)

[JPQuiceno]

I like superstring theory cus it tastes like chicken.

 

Added to my signature.