Colloquium

Superfluid Helium: Tidal Waves and Other Magic with Helium in Two Dimensions

Bob Hallock
UMass Amherst
Wednesday, April 18, 2007
Higgins 310, 4 pm

Once liquefied at -451.8 degrees Fahrenheit, Helium undergoes a remarkable transition to a spectacular new liquid state if one cools the liquid below -455.4 degrees Fahrenheit. For lower temperatures Helium becomes what is known as a superfluid, and displays totally unexpected and magical properties. We will discuss some of these properties, including the remarkable phenomena of film flow, in which films of helium only a few atoms in thickness can move freely and support waves similar in some ways to tidal waves on the ocean. In doing so, we will test your intuition. We will also discuss some experimental observations with mixtures of 3He and 4He that were unexpected and not yet explained.

The talk will be understandable to undergraduates and they are encouraged to attend.