Good vibrations

Brooks Pate
Photo by Jack Mellott

If there’s one theme in all of physical sciences, says chemist Brooks Pate, it’s this question: “What is the most important device we have to improve?”

“Across the board, the answer is the clock,” he says. “This goes back to Galileo and the pendulum, all the way up to the most recent Nobel prize in physics.”

The benefits of clock technology pervade everyday life, Pate explains, and for scientific purposes, the clock is indispensable for timing and monitoring experiments as precisely as possible.

Pate (Chemistry ’87), who is the William R. Kenan, Jr. Professor of Chemistry, is a recipient of a MacArthur Fellowship, colloquially known as the “genius award,” for his study of vibrational energy in molecules.

His research team has made strides in the study of precision measurements in spectroscopy, using lasers’ light energy to change the geometric shape of molecules through chemical reactions. Spectroscopy, the study of how molecules react with light, is now an important basis for the atomic clock, which almost all physical scientists depend on to calibrate the clocks they use in their experiments.

The atomic clock works similarly to a quartz wristwatch in that both clocks tell time by using a crystal oscillator, which vibrates at a consistent frequency, Pate explains. However, unlike the conventional quartz clock, the atomic clock is more reliable because its oscillator is monitored by an atomic system of the element rubidium, which uses its specific frequency, or difference in energy levels, to keep the oscillator ticking consistently. The rubidium ensures that the oscillator won’t drift out of position over time, affecting the clock’s precision.

While most people will never come into direct contact with an atomic clock, they use these effective time measuring machines in many everyday circumstances.

“We build measurement machines that can seem very esoteric to people,” Pate says. “However, people use these machines in more ways than they realize.”

For example, atomic clocks are used in satellites for the global positioning system (G.P.S.). “A lot of people now have these devices in their cars for driving, but they might not realize that the directions they receive are direct measurements from clock making,” Pate says. Synchronized clocks in these satellites put out pulses to a receiver on Earth that determines the satellites’ relative distances by timing their pulses. Using two satellites in geo-stationary orbit can determine the receiver’s relative position, but adding a third can tell its global position.

In the field of international banking, clock developments gain increasing importance with the demand for synchronized global transactions. “The question is, if someone makes a deposit in California, what time does it show up in Switzerland?” Pate explains.  The “stratum one” clock solves this problem by locking the company’s computers together to operate on a synchronized time, using clocks that are faster than computer time rates. Pate explains that this “clock issue” will make a big difference in the realm of international finance.

Despite the substantial developments in clock technology over the years, Pate says, the biggest goal for future clock developments, from a scientific perspective, is to obtain clocks that make even more precise measurements, as well as instruments that are more portable and less expensive.

“We all use clocks, so it’s something that people in the audience have an understanding of, but people in the field of physical sciences have a completely different understanding,” he explains. “Talking about the field of physical sciences is challenging because it’s a rather technical field, and the benefits to society, while significant, are not always readily apparent. I’d really like to give a talk that everyone can get something out of.”