Cooling close to absolute zero temperature:  a recipe for discoveries

Why do physicists freeze matter to extremely low temperatures? Why is it worthwhile to cool to temperatures
which are a billion times lower than that of interstellar space?  In this talk, I will experimentally demonstrate
phenomena at low temperature and discuss new forms of matter.  Of special interest are superfluids which can
flow without dissipation.  Recently, we have observed a supersolid which is gaseous, liquid and solid at the same
time.