As Jodie Foster showed us in Contact, scientists around the world are listening to signals from space to learn about the universe.

But while the search for aliens continues, another band of scientists is pointing their instruments downward to see what the signals from the earth's interior can tell us about our own planet.

Although many seismologists have all but forsaken their "Holy Grail"--accurately predicting when and where an earthquake will strike--a new generation of scientists has taken on the challenge of deducing the precise structure and motion of the earth's mantle and core. They are using data collected by 100 stations around the world and shared in digital form over the Internet.

And Harvard is leading the way.

Seismology has come a long way from wobbly pens recording earthquakes as spikes on a roll of paper. Today's equipment, using technology designed by Dr. Joseph M. Steim '78 for his Harvard Ph.D. thesis, measures the motion of the earth as an electric signal which is recorded into a computer.

The primary advantage of Steim's Very Broad Band (VBB) technology is that it allows a single instrument to accomplish the work of dozens of specialized devices.

When Steim's seismograph was installed at Caltech in 1988, it replaced "something like over 40 specialized seismographs," according to Adam Dziewonski, professor of geophysics at Harvard.

The device brings together a spectrum of signals much as a piano combines a range of pitches of varying volumes.

In contrast to a tuning fork which can produce only one pitch at one volume, Steim's seismograph works like a grand piano by harmonizing various signals from one source to create a more polished and rich composition.

"It's as if there were previously one instrument to measure very dim blue light and another to measure very bright red light," Steim says. "You can imagine it was very difficult to put that together to get a clear rendition of the signal, for example, if the source were white light" which is composed of all colors.

Another crucial advantage, Steim says, is the ability to store data in digital form--a practice that has revolutionized the way scientists share and analyze findings. Back in the days when seismic waves were recorded on paper, "it took years to gather data--it was literally mailed from researcher-to-researcher," Steim says.

But with the advent of the Internet, the exchange of data has been facilitated, Steim says, but he adds that it was not crucial to the early success of the project.

"The Internet has made processes that we already found ways to deal with much easier and less expensive, but the project was in no way waiting for the Internet," Steim says.

Using the Internet, seismologists routinely send each other the latest data in a matter of seconds, and can even take remote readings from outlying stations.

"It's much easier now for a researcher to send their preliminary results to another," Steim says. "There are stations in eastern Siberia where the Internet connection exists, but physically it's very difficult to get there."