If life seems to speed by on the Colorado College Block Plan, be thankful campus isn’t atop Pikes Peak, where time moves even faster. Or better yet, consider a Block Break at sea level since time moves more slowly the lower in elevation you go.
It’s this well-documented gravitational time dilation effect that has a team of professors and students from CC and the U.S. Air Force Academy shuttling up and down the 14,115-foot peak above Colorado Springs with specialized atomic clocks.
“Time really does tick at a different pace at different altitudes,” CC Physics Professor Shane Burns says. He is leading the time dilation research project with Brian Patterson, professor of physics at the Air Force Academy.
But truthfully, you wouldn’t be able to tell any difference in tempo. A day on top of Pikes Peak is about a 40–billionth of a second longer relative to one at sea level. “If you lived all of 80 years on the top of Pikes Peak, you would have lived just one millisecond longer compared to 80 years at sea level,” Patterson says. Hardly enough to catch up on that project you need to complete.
“It’s just a small effect here on earth, but the importance and significance of relativity for our universe is incredible,” Michael Leveille ’16 says. For example, it’s because of this effect that the earth’s core is 2.5 years younger than its surface. Leveille, who has been working with the atomic clocks since the project started, graduated with a degree in physics last May. Now he’s helping run the project as the physics department’s paraprofessional while considering grad school in astronomy.
The time dilation work began when the Air Force Academy acquired six of the highly sensitive clocks designed to produce the most accurate measurement of time, and invited Colorado College to collaborate. With the help of grants from both the Mellon Foundation (for civilian/military collaboration) and CC’s Center for Immersive Learning and Engaged Teaching, planning and preparation began in 2014.
The initial idea was to compare the time the precise cesium atomic clocks would measure at the Air Force Academy versus that measurement at CC, but Burns said they quickly realized that expanding the project would render more significant results.
“As often happens with research, you learn as you go and gradually make changes that improve the work.”
In addition to measuring time at seven locations of varying altitudes, they ended up comparing those measurements to GPS time, which has been established to tick along at sea-level pace. “I’ve learned so much from being part of this project from the beginning, being involved in the planning and designing as well as the field work,” says Emiliano Morales ’17, a senior majoring in physics who is thinking of going into architectural design.
“It’s been really cool to get to personally understand this effect.”
That’s really the point, Burns says, noting they didn’t set out to discover or prove anything. The idea was to give students a hands-on experience about Einstein’s theory of general relativity which predicts that time moves more slowly deeper within a gravitational field, such as toward the center of the earth.
“Time is thought of as being absolute. This is a demonstration that it is not. It actually depends upon where you are,” Burns says. Time being relative is “counter-intuitive and intriguing,” note the researchers in their report to the Mellon Foundation. While physics students are typically introduced to this theory, “they rarely have the opportunity to see it in action.”
Burns and Patterson kicked off the project with a series of talks followed by small-group planning sessions, some at each institution. The presentations covered general relativity concepts, how an atomic clock works, and even a discussion of the physics in the movie “Interstellar.” More than 20 students from both CC and the Air Force Academy participated on their own time, rather than for classroom credit. In the beginning, students took time readings only at their own institution, and it took many trials to get everything working just right.
“In the fall of 2015, we did a dry run on Pikes Peak, putting the GPS antenna inside the summit house but the data was so noisy. We found out having the antenna outside is a lot better,” Patterson says.
Through a research class in the spring of 2016, Burns led five CC students around the state, taking time measurements at a ranch in La Junta (4,393 feet), at CC’s cabin outside Woodland Park (8,801 feet), at the base of the Arapahoe Basin ski area (10,808 feet), higher at the resort’s ski patrol headquarters (12,417 feet), as well as near the top of Pikes Peak (14,068 feet) and at CC (6,065 feet). The Air Force Academy’s measurements were taken at an elevation of 7,231 feet.
“The ski patrol strapped the equipment on the back of a snowmobile and took it up A-Basin,” says Burns about the adventure of getting the atomic clocks to all of the testing spots. Typically, the group used two clocks at each location, averaging those readings and then comparing the result to the GPS reading they collected at the same time.
“By using two clocks, we have a better estimate of the uncertainty — that’s the sticky part of the analysis,” Burns says about figuring out how far off in nanoseconds the clocks’ readings are from GPS time. It also was important, say both professors, that the students got to see the team effort involved — especially collaborating with others from a totally different institution.
“Research is a social enterprise, especially in experimental science,” Burns says. “Gone are the days of the scientist working in his lab solo,” says Patterson.
Both CC and Air Force Academy students have been involved in writing papers, giving presentations, and creating campus displays about the work. “This gave me a chance to interact with a lot of people and share the research we had been doing,” says Air Force Academy Cadet Jonathan D. Schiller, who’s been with the project since its beginning. In the fall of 2015, Schiller and three other cadets presented the research at the American Physical Society — Four Corners Section annual conference in Tempe, Arizona, and five CC students presented at the Midstates Consortium for Math & Science at the University of Chicago. Last spring, Schiller, another cadet, and two CC students presented at the Colorado Springs Undergraduate Research Forum. Schiller and Patterson, of the Air Force Academy, are wrapping up a paper for The Physics Teacher journal, to let high school and college instructors know about the value of this project for teaching physics, while CC’s Leveille and Burns are writing a paper for the American Journal of Physics with more of the project’s technical details.
Precise Time Keeping
The U.S. Air Force Academy received six cesium-beam atomic clocks that had been retired from use in marine navigation systems for the U.S. Coast Guard. As newer equipment is developed more of these specialized devices are becoming available for research and teaching.
Also called a “cesium-beam frequency standard,” the clock exposes cesium atoms to microwaves so the atoms vibrate at a very rapid and consistent pace. Counting the corresponding cycles gives a highly accurate measure of time. A set number of vibrations is the accepted standard of what a second is.
Cesium is the atom selected for this measurement because most of its 55 electrons orbit within stable shells of electromagnetic force — that, and keeping the atoms stored in a vacuum mean they move in a narrow spectral line allowing the wavelength to be determined precisely. For more details, see 2cc.co/cesiumbeam or 2cc.co/atomic-clock