We talk of positively and negatively charged particles. But what actually is a charge, what is the property of charge caused by?

Asked by: Keni P.

Answer

The only honest answer any physicist can give to this question is 'we don't really know'. The facts we know for electrical charges can be summarized rather easily, some particles have this property which we call a 'charge', which comes in two opposite varieties, which tend to cancel each other out; if they do, they interact through what we call the electromagnetic interaction, if not, they don't.

Even at the deepest level we know, of elementary particles, charge seems to be an integral part of the particles, quarks (which form protons and neutrons, and other heavy particles) are charged, and so are electrons, muons, and taus. There does not seem to be a 'particle' as such, which makes them charged, and there has never been observed an electron which has 'lost its charge', for example.

This is perhaps another demonstration of our fundamental ignorance of nature. The very fundamentals, we do not know how or why. We just take them as axioms, similar to Euclidean geometry and build upon them. While the existence of charge is not in question, what it is, what it is caused by, and why it exists are questions we are unable to answer.
Answered by: Yasar Safkan, Ph.D. M.I.T., Software Engineer, Istanbul, Turkey