Heinrich Jaeger is a professor of Physics at the James Franck Institute at the University of Chicago where he has taught since 1991. A native of Germany, Jaeger studied at the University of Kiel, Germany before coming to the United States as a Fulbright Scholar. In 1982, he obtained his M.S. in Physics at the University of Minnesota in Minneapolis, where he completed his Ph. D. in 1987.

Besides the dynamics of granular materials such as sand and coffee grounds, Jaeger's research interests include superconductivity, and the way polymer molecules can arrange themselves into nanoscale patterns. An author of more than 100 articles in peer-reviewed journals, Jaeger sits on the editorial board of the professional journal Granular Matter. He is also the recipient of a number of professional honors, including Sloan and Packard Fellowships, and is a member of the American Physical Society and the Materials Research Society.

2.06.01 Roger Malone asked:
I have two questions: 1) In New England, Massachusetts especially, rocks move up through the soil every year. What provides the shaking to move the soil out of the way? Water? 2) In an avalanche people are buried under grains of flowing snow and can not get on top so die. Would going down or swimming straight ahead and not up bring them to the top and out the way it does for the ball in sand?

Jaeger's response:
Q1: Rocks moving up through the soil is a remarkable phenomenon typically associated with freeze-thaw cycles. It is my understanding that such freeze-thaw cycles of the earth are rather unrelated to shaking of soil (as shown in the program by vibrating a container filled with seeds).

Q2: Probably not (at least, I'd be afraid to try it!). One reason the larger balls come to the top is the fact that they are larger than the average size of the moving particles (size separation). A person inside an avalanche may not fit that criterion and thus get buried very quickly. If you look closely at an avalanche of a pile of sugar, say, you'll find that only the largest pieces seem to "float" on top of the moving layer. Everything else moves down only a short stretch before moving inward toward the bottom of the flow zone where it gets stuck (the flowing layer during an avalanche works its way downhill somewhat similarly to the treads of a tank).

2.06.01 Ulrich Decher asked:
In making a cup of hot chocolate I add the hot water to the chocolate in a mug. Then I stir the chocolate to mix it. If now I keep tapping the bottom of the cup with a spoon, the frequency of the sound increases to an ever higher pitch. Why?

Jaeger's response:
Great observation! I have not noticed it before (probably need to drink more hot chocolate) and therefore have no clue.

2.06.01 Clayton Bruckert asked:
Could the example of the coffee stain apply to the bubble-like formation nebulae, and/or the Oort Cloud?

Jaeger's response:
That is certainly an intriguing question. As of now, I am not sure anyone has contemplated such a connection. In order to start thinking about this, one probably should identify those features during the formation of nebulae that look most similar to features during the formation of coffee stains. Since I am not in expert in nebulae I would have to toss this back to you and ask what specific correlations you saw that would warrant a detailed comparison.

2.06.01 Justin Tureson asked:
I just saw your show about the way coffee evaporates and how micro wires for computers could be made using the same principles. From this I assume that you are maybe into the field of nanotech. I have just learned about a new carbon structure C60. It is a soccer ball shape. I was thinking that this soccer ball structure could be used as a nano ball bearing. Is there any good thought in this? Could this be a practical application?

Jaeger's response:
Great idea. In fact, there is tremendous research activity going on these days aiming at exactly such type of application.