Tom Ristola asked:
Given that the heaviest elements are forged during a supernova event, is it theoretically possible that there could be heavier naturally occurring elements that we don't know about if there was a star massive enough to forge them?
Dominic - Yes, it is quite an awesome thought that all of the heavy elements in the universe were made in the nuclear furnaces inside the centres of stars. So all of the carbon that we’re made of and all of the oxygen in the atmosphere was all made in the centres of stars and then blown out of those stars in supernova explosion subsequently to form into the solar system. Now, the more massive a star is, the heavier the elements it makes and the more heavy elements it makes, and the bigger the supernova explosion at the end and the more widely distributed that material is. But in terms of heavy elements that we don't yet know about, what you find is that the heavier an element is, the more unstable that atomic nucleus is, and the more radioactive it is. So for example, uranium is quite a massive atom and that is, of course, radioactive and we use that as a power source. As you move to more and more massive atoms, the life times of those radioactive elements goes down and you start to find that your average decay time is less than a second or perhaps only a millisecond. And so, even if those atoms were formed, they wouldn’t last very long and we certainly wouldn’t find them in the universe.
Ben - Do you think it’s likely that we would see evidence of them having existed, maybe the energy from their decay?
Dominic - I think some of the atoms which people have been making in the lab as I say, have life times of orders of milliseconds, so that is really so incredibly short, but it would be very difficult to track any signature at all.