They shatter a wine glass with a high pitch sound, use a ripple tank to demonstrate wave interactions and blast off across the lecture hall in a carbon dioxide-propelled rocket. Who are the people who perform these spectacular demonstrations during science lectures?

Wolfgang H. Rueckner, Daniel B. Rosenberg, Nils J. Sorensen and Douglass B. Goodale, members of the Lecture Demonstrations Services, create, design and perform science demonstrations for many science Core, physics and chemistry classes.

Working from a core of about 800 demonstrations, the team can do pretty much anything a professor asks for, says Peter Siska, visiting Professor from the University of Pittsburgh, who teaches Chemistry 5, "Introduction to Principles of Chemistry," this semester.

"I have been able to arrange almost anything I can come up with through the wonderful collection of chemicals, glass and gadgets available in the Cabot Science Center facilities, the genius and skill of our head demonstrator, Daniel Rosenberg, and the help of a marvelous undergraduate volunteer, Keith Santiago '00," Siska says.

And in return, Sorenson says the undergraduates respond with "a lot of applause."

Students agree that the demonstrations are not only helpful but fun.

"The Physics 11a demonstrations are excellent," says David Schultz '01. "The effort they take to prepare and clearly illustrate concepts is evident in the quality of their demonstrations. I enjoyed watching Barney get nailed with a large metal ball fired across the lecture hall."

The demonstrations are also a great way to lighten up lectures, students say.

"The demos help add variety to class," says Jodie L. Pearl '01, who is also a Crimson editor. "They provide a nice break where you can learn something without 100 percent concentration."

One of the most challenging demonstrations for Rueckner lies in the area of quantum mechanics. In the "single photon interference demo," the team sends single photons, one at a time, through slits in a screen. Even though the photons are sent sequentially, students watch the interference patterns as they are projected onto a screen. The result is "completely mind boggling," says Rueckner, but a visual demonstration, rather than a classical explanation, aids the students' understanding.

For James E. Davis, head tutor in chemistry, such visualizations play a key role in understanding chemical processes.

"Daniel Rosenberg and the Science Center Demonstration team make tremendous contributions to the undergraduate science courses here," he says. "It's wonderful for the students to be able to see chemical processes in action, not just to read about them or watch them in pictures."

Preparation time for these demonstrations varies. According to Rueckner, the staff may spend anywhere from a couple of minutes to an entire afternoon preparing the materials for a demonstration.

"Some are things we literally take off the shelf," he says. "Others we have to build from scratch."

Usually, a professor lets the team know which demonstrations he or she will need a few days in advance, but the demonstration team says it has to be prepared for anything.