At the centre of every atom is a tiny dense nucleus that
makes up most of its mass, and determines what kind of element it
is. All the elements that are necessary for life on earth have been
formed in stars long ago, and spread out by supernovae explosions to
form the ingredients of the earth and other planets.
In order to understand how all these elements are
produced, we have in Nuclear Physics to understand not just the
elements we find on earth now, but also those varieties of elements
that appeared fleetingly in stellar explosions. In the last 20
years, physicists have been able to recreate many of these
short-lived varieties, and have discovered many new features not
seen in their long-lived cousins.
Most stable nuclei have approximately equal number of
protons and neutrons (the protons have a positive charge, while the
neutrons form a neutral glue holding the nucleus together). Now,
however, we discover that there was once, and are now again in the
laboratory, some exotic nuclear varieties with many more neutrons
than protons. Sometimes these extra neutrons form a large halo
around the protons, in the nucleus at the centre of the atom. We
have discovered that the halo is much larger in size than the range
of the force which contains it.
I will look especially at some this and other strange
properties of nuclear haloes: how we need to use the wave features
of modern quantum physics to see how they can even exist at all, how
we measure their properties, and what possible use such atoms may
have again.