  Supernovae are nature's grandest explosions and an astrophysical laboratory
in which unique conditions exist that are not achievable on Earth. They are
also the furnaces in which most of the elements heavier than carbon have been
forged. Scientists have argued for decades about the physical mechanism
responsible for these explosions. It is clear that the ultimate energy source
is gravity, but the relative roles of neutrinos, fluid instabilities, rotation
and magnetic fields continue to be debated.
