Is it possible to create an object that is composed of antimatter only?
Asked by: Ted Jacobs
At least in principle it is possible to create an object out of antimatter.
Antimatter is defined as a matter built out of atoms that are 'charge conjugates' of ordinary atoms. What does charge conjugate mean? Well, it means that the atom is built of anti-particles which have opposite charge to the corresponding ordinary particles. For example, we all know of an electron (which is one of the fundamental particles), well electron has its anti-particle which is called positron. Positron is same to the electron in every aspect (mass for example) but its charge is positive - i.e. opposite to that of an electron. Ultimately it is not just the charge that is conjugated (opposite) but it is a whole set of quantum values - collectively called charges.
Anti-particle to the electron - the positron - was discovered in 1932 by C.D. Anderson. He was studying cosmic rays (shower of energy and particles that constantly bombards Earth) and he noticed that the highly energetic photon from this shower of cosmic rays would sometimes spontaneously convert into two particles - one electron and other one of the same mass but positive (later named positron). He also noticed that the two would then sometimes come into contact again and disappear with releasing an equivalent amount of energy in the form of photons. This process of re-combination of a particle with an anti-particle is called annihilation.
Many anti-particles have been discovered since. The anti-proton was discovered in 1955 by E. Segre and his coworkers at the Lawrence Berkeley Laboratory using a high-energy particle accelerator. Most other anti-particles have been discovered at particle accelerators under carefully designed conditions.
Many experimental groups have also reported constructing bigger entities than just anti-particles. Namely, whole anti-nuclei have been constructed, for example: anti-hydrogen nuclei, an isotope of anti-helium, etc.
So as you can see it is in principle possible to construct larger objects of anti-matter, it is just very hard and cumbersome. The reason for the problem lies in the previously mentioned annihilation. Namely, most of the world around us is made out of matter. As soon as you have a little bit of anti-matter it is bound to bump into the matter that surrounds it and annihilate. So the lifetimes of this anti-matter are very short.
So there you go ... now you have a recipe for how to convert yourself into a pure photon energy: you just need to create anti-you and then have a date with 'it'.
Answered by: Anton Skorucak, M.S. Physics, PhysLink.com Creator
'The strength and weakness of physicists is that we believe in what we can measure. And if we can't measure it, then we say it probably doesn't exist. And that closes us off to an enormous amount of phenomena that we may not be able to measure because they only happened once. For example, the Big Bang. ... That's one reason why they scoffed at higher dimensions for so many years. Now we realize that there's no alternative... '