The time asymmetry of chance

If there are real chances, then it seems as though there are ‘more’ of them, in some sense, in the future. To illustrate, take some events which are governed by stochastic laws. For instance, at the tip of my nose, there is an atom of carbon-14, the radioactive form of carbon. Being radioactive, there is some chance that the atom will undergo radioactive decay. The typical type of decay for carbon-14 is known as beta-minus decay. This is a process whereby an atom emits two particles: an electron and an electron anti-neutrino, and in addition one of the atom's neutrons is converted to a proton. The result, when this occurs in an atom of carbon-14, is that it becomes an atom of nitrogen-14.

Whether this particular atom of carbon-14 will decay in the next year is a matter of chance. The chance is very small, but greater than zero. In contrast, for the year that has just passed, it seems that there is nothing chancy about what happened to the atom. The atom of carbon-14 ‘got here’ in one particular way – though we may not know what that is – and there is no chance that it in fact developed in any different way.