Which way is up?

If you are into science fiction, then anti-matter, anti-gravity and suchlike and everyday commodities. But, for those of us who live in the real world, they seem rather more exotic. And this raises an interesting question. Anti-matter is very rare, but scientists do not have a clear explanation for its infrequent appearance.

I stumbled across some interesting research which might give some insight …

Anti-matter is interesting stuff. According to atomic theory, every particle has a corresponding anti-particle. So, we have protons and electrons; anti-protons and anti-electrons [a.k.a. positrons] are known to exist. The particle pairs are identical in every respect – size, mass etc. – except their charge, which is reversed. A proton has a positive charge; an anti-proton has a negative charge of exactly the same magnitude.

The tricky thing about anti-matter is that, when it comes into contact with normal matter, they are both annihilated in a flash of energy. This has been mooted as a source of power, but, for the moment, that is still the stuff of science fiction. However, this points to a problem: how do you contain a sample of anti-matter, as, if it came into contact with its container, it would be destroyed? Up to a point, magnetic fields are the answer. [In Star Trek, they use the handy phrase “containment field” …]

Our whole world is made up of atoms, which are comprised of a number of particles, including protons and electrons. The number of protons is always exactly the same as the number of electrons, so their charges cancel out. So, a hydrogen atom, which has one proton and one electron, has no net charge. What about atoms of anti-matter? An atom of anti-hydrogen would have one anti-proton and one anti-electron. Interestingly, anti-hydrogen has been created – it is just hard to keep in in one place.

Some recent research was carried out at CERN using anti-hydrogen. There is more detail in this article. The scientists managed to contain a significant number of atoms of anti-hydrogen for long enough to make some measurements. They wanted to confirm that the anti-hydrogen was essentially identical to regular hydrogen in terms of mass etc. An interesting spin off was observation of the atoms’ response to gravity. For a short time, that was the only force to which they were subject and there was some indication that they were repelled by the Earth’s gravitational field instead of attracted. I hope that this is investigated further, as the transportation implications of having an anti-gravity machine are exciting.

This brings me back to my initial comments. According to most theories associated with the Big Bang, equal quantities of matter and anti-matter should have been produced. It might be expected that mutual annihilation would immediately occur, but that was clearly not the case [otherwise we would not be here!]. So where is all that anti-matter? It seems to me that the answer is “out there”. If anti-matter does gravitationally repel normal matter, it would seem logical that it went one way and our “normal matter” part of the Universe went another …