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May 11, 2006

Professor recreates Galileo’s experiments

Any serious student of science is familiar with Galileo’s famed pendulum experiments. The 17th-century scientist’s discoveries about the regularity of a pendulum’s motion sparked further study and ultimately led to the development of more precise methods for measuring time.

Little is known about exactly how Galileo conducted the experiments in the early 1600s, but Paolo Palmieri, an assistant professor in the Department of History and Philosophy of Science, aims to use new technology to dispel some of the mystery.

Palmieri, who has made Galileo a focus of his academic career, has taken over a conference room on the ground level of the Cathedral of Learning in which to re-enact Galileo’s historic experiments. Tables and chairs have been pushed aside to make room for a modified easel from which Palmieri has suspended small lead fishing weights by long strings in replication of Galileo’s work.

But what Palmieri has that Galileo might never have imagined possible is an electronically equipped scaffold that transmits to a nearby computer information about the attached pendulum’s forces and tensions. The data will allow a mathematical model to be created, speeding the process of testing different variables using information derived from the real model.

To Palmieri, the combination of technology paired with classic experiments represents a whole new academic approach, which he calls “experimental history of science.”

“We will replicate the experiments, but it will be a kind of hybrid,” he said. “Part of the game is the model, part is the computer.”

Scholarship in the humanities largely has been based on reading and writing. “The ambition and mission of this project would look to partner with technologies that will allow us to go beyond the technology of reading and writing,” he said.

Recreating Galileo’s experiments isn’t new. But Palmieri said he is breaking new ground. With the addition of technology, “We are inventing a new kind of document,” he said.

Although Galileo was a pioneer in approaching the standards of modern experimentation, little is known about exactly how he conducted his work. “The detail Galileo gave is vague,” Palmieri said. For instance, he said, the length of the pendulum was given in terms of “brachia” — a unit of measurement that varied from place to place.

Likewise, the exact weight of the lead bobs and the type and thickness of string used to suspend them is not documented precisely. So Palmieri chose materials based on circumstantial evidence and consideration of what Galileo might have used in 17th-century Italy.

Palmieri reasoned that lead musket balls would be easily available in Padua in Galileo’s day, so he sought out antique ammunition to determine that a weight of one to two ounces would be a reasonable guess. Likewise, he obtained different kinds of string — a thick hemp twine as well as a fine linen cord to test in his model.

Re-conducting Galileo’s experiments with the advantage of adding the latest computer technology is one part of the project. But the bigger goal, Palmieri said, is to prove that experimental history of science is a viable new dimension in the field of research.

Using the data from his actual experiments, Palmieri’s mathematical models can adjust for a variety of variables to help unlock the mystery of exactly how Galileo did what he did.

“It would be impossible to multiply all the possible strings, all the possible lead balls, all the possible heights, all the possible combinations,” Palmieri said. “With the computer, you can. It takes a fraction of a second.”

He plans to publish his results in a scholarly book, but he is adding a modern, interactive twist.

When he finishes filming the experiments, video clips will be posted on line. In addition, computerized animations resulting from any virtual experimentation can be generated and viewed. The results, Palmieri said, are much richer than what might be taught in a typical college math or physics class.

Theoretical physics can yield formulas to describe natural phenomena as they might exist under perfect conditions in a vacuum, but experiments such as Galileo’s were conducted in the air, with imperfect materials.

“We need to know how non-perfect materials behave,” he said. And, for students, seeing the demonstration itself can be more edifying than reading a dry description in a textbook.

“Because the experiments are a dynamic phenomenon, they’re better understood when they’re viewed, rather than merely read about. You can have a good description of things, but it’s always going to be better to view them,” he said.

Palmieri has already reserved the web address as a home for his work. The site is expected to go live sometime this summer.

The pilot project is one he hopes can be expanded to bring a dynamic aspect to other experiments.

“Historians and philosophers tend to ask, ‘What did Einstein believe, how did he come to his conclusions?’ This whole project suggests other questions: Not ‘What do you think?’ but ‘What do you do about Galileo, about Einstein?’”

“It’s not all about thinking,” he said. “It’s about doing.”

—Kimberly Barlow

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