Superfluidity 1 Gordon Baym University of Illinois, Urbana 18-20 January 2010

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2. Friction is very useful, Climbing mountains, to pick a good Aspen example, even walking, driving, biking, all require friction. We also know how to start a fire by turning a stick rapidly. Friction is very useful, Climbing mountains, to pick a good Aspen example, even walking, driving, biking, all require friction. We also know how to start a fire by turning a stick rapidly.

3. Liquids also have a form of friction, called viscosity. Here is a viscous oil being poured. If you have ever made coffee using a push-pot (French press) you know about the friction of water going through coffee grounds. Even pulling a milkshake through a straw requires work � against internal friction. Glaciers are slowly flowing viscous liquids. So is ice cream. Lava lamps show viscous fluids playing around. Liquids also have a form of friction, called viscosity. Here is a viscous oil being poured. If you have ever made coffee using a push-pot (French press) you know about the friction of water going through coffee grounds. Even pulling a milkshake through a straw requires work � against internal friction. Glaciers are slowly flowing viscous liquids. So is ice cream. Lava lamps show viscous fluids playing around.

4. Even electricity when it flows encounters a form of friction, called electrical resistance. Very useful for toasters and lamps. Terrible for transmission of electricity through power lines, since it causes expensive losses.Even electricity when it flows encounters a form of friction, called electrical resistance. Very useful for toasters and lamps. Terrible for transmission of electricity through power lines, since it causes expensive losses.

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12. Story began in the Netherlands in Leiden just 100 years ago. KO wanted to develop a facility for doing research at very low temperatures. Liquid would be the source of cold.Story began in the Netherlands in Leiden just 100 years ago. KO wanted to develop a facility for doing research at very low temperatures. Liquid would be the source of cold.

15. While more metals were shown to become superconductors over the next twenty years, little progress was made in understanding why materials became superconducting. A crucial step was made by Meissner and his assistant Ochsenfeld in 1932-33. Expelled field provides a cushion in the levitation experiment. A consequence of this discovery was the realization that sc. were diamagnets, not perfect conductors. Let me explain!While more metals were shown to become superconductors over the next twenty years, little progress was made in understanding why materials became superconducting. A crucial step was made by Meissner and his assistant Ochsenfeld in 1932-33. Expelled field provides a cushion in the levitation experiment. A consequence of this discovery was the realization that sc. were diamagnets, not perfect conductors. Let me explain!

16. While more metals were shown to become superconductors over the next twenty years, little progress was made in understanding why materials became superconducting. A crucial step was made by Meissner and his assistant Ochsenfeld in 1932-33. Expelled field provides a cushion in the levitation experiment. A consequence of this discovery was the realization that sc. were diamagnets, not perfect conductors. Let me explain!While more metals were shown to become superconductors over the next twenty years, little progress was made in understanding why materials became superconducting. A crucial step was made by Meissner and his assistant Ochsenfeld in 1932-33. Expelled field provides a cushion in the levitation experiment. A consequence of this discovery was the realization that sc. were diamagnets, not perfect conductors. Let me explain!

18. Important conceptual advance. Could now deal with trying to understand a unique state.Important conceptual advance. Could now deal with trying to understand a unique state.

20. The two fluid model was the immediate explanation of the fountain effect.The two fluid model was the immediate explanation of the fountain effect.

22. One of the most unusual properties of superfluids are the way they respond to being rotated. If one rotates a glass of water, now matter how slowly one rotates, the water also rotates! But not with superfluid helium. The Georgian physicist in 1946.One of the most unusual properties of superfluids are the way they respond to being rotated. If one rotates a glass of water, now matter how slowly one rotates, the water also rotates! But not with superfluid helium. The Georgian physicist in 1946.