The UAA/APU Consortium Library is home to the quiet clack of keyboards, the soft squeak of dry-erase markers, whispers across study tables and catnaps in the fleeting winter sunshine of the Great Room. Amid all the calm hustle and quiet bustle sits the library's standout design element — perhaps the subtlest centerpiece on campus — the silent, swaying Foucault pendulum.

The pendulum anchors the building, connecting all three floors through the grand central staircase. At the base, a curving couch welcomes students to take a break and appreciate science in action. UAA's pendulum features a 52-foot cable and a 240-pound hollow brass bob hurtling back and forth over a granite base, grazing the names of 360 generous donors who each had a hand in making the pendulum happen.

The pendulum is a gift from the UAA Alumni Association to the university, and those names circling the ground floor guardrail serve as a thank you to the 360 alumni and friends who provided the pendulum with a home at UAA. Not only is the pendulum a perfect library feature — quiet, curious and educational — it also represents the progress of the UAA Alumni Association. As the pendulum turns 10 years old this semester, the Alumni Association can look back at 10 years of progress at UAA.

But first, the science...

Dizzying physics

The French physicist Léon Foucault (pronounced foo-KO) was the first to demonstrate the earth's rotation in simple terms by suspending a lead bob from the ceiling at the Panthéon in Paris and letting it swing. The pendulum appeared to change course gradually, despite no external forces.

"The Foucault pendulum was a simple experiment to show the earth rotates," explained UAA physics professor Jim Pantaleone, who first proposed installing a pendulum in the library. "You get the pendulum going and the earth rotates underneath it, but the plane that the pendulum keeps moving in stays the same."

The UAA/APU Consortium Library claims to have the northernmost permanent Foucault pendulum in the world. That's far from just a talking point, though, as the latitude of a pendulum has a direct effect on its perceived motion. The pendulum's base in Anchorage takes far less time to revolve under the pendulum than a similar setup in, say, Mexico City.

And yes, that's correct — the pendulum never actually rotates. It's the earth beneath that spins under the ceaseless back-and-forth of the pendulum — the bob only looks like it's changing course because the viewer, in fact, is the one moving around the plane of the pendulum. Wacky, right?

Now, back to latitude. The closer a pendulum is to the north or south poles, the shorter its rate of precession, or complete rotation. When a pendulum is placed at the North Pole, the bob will appear to make a complete rotation in 24 hours because, as we all know — or all used to know in grade school — earth makes a complete revolution in 24 hours.

"If you're right at the North Pole, you're at the axis of rotation and everything would rotate underneath you," Jim explained. However, down here in Anchorage at 61° North — roughly a third of the distance from the pole to the equator — the rate of precession is about 27 hours. Why? Because away from the pole, the earth still rotates every 24 hours, but the earth is carrying Anchorage, UAA, the Seawolf Shuttle and everything else on a loop around earth's axis at a wider circle than at the pole. The further you get from the poles, the wider the circle of rotation, until you arrive at the equator — 0° latitude — where the pendulum's effect is lost. At the equator, the pendulum's plane and the earth's direction of rotation are the same, meaning the bob will swing back and forth in the same line for infinity.

If physics isn't your thing, UAA's pendulum comes with a handy plaque and a simple equation — N = sine of latitude x 360 — to help you calculate the number of degrees a pendulum bob will pass in a 24-hour period, depending on its latitude.

At this point you're either ready to reenroll in physics or avoid it all together. You may recall Sir Newton's law that objects in motion stay in motion, but wouldn't the air resistance eventually halt the pendulum's swing? The answer lies in the library ceiling.

The pendulum bob remains in constant motion thanks to an electrically magnetized 'donut' in the ceiling of the library. This magnetic gadget delivers extra kicks of momentum to the pendulum cord every time it reaches the apex of its swing. It keeps the pendulum rolling without ever changing its back-and-forth plane of motion

Under construction

As a physics professor, Jim was eager to see a pendulum go into the library building. "Back in the day, there hadn't been any new buildings in 10 years or more. The library was the first new building to be built and I had this idea," he explained of his original pitch.

Steve Rollins — dean of the Consortium Library — loved the idea as well, and set to work adding it to the project. The central staircase changed to an open concrete cylinder to make room for the addition, but avenues of funding weren't panning out for the aesthetic addition. That's when the Alumni Association stepped in and donated the pendulum as their gift to the university.

But by that point, library construction was already underway. Howie Morse — the project manager for the installation — remembers drafting blueprints around the possibility of a pendulum, still unsure if it would actually happen.

"We were talking about that pendulum and we decided that the circular staircase would be a fantastic way to showpiece that thing if we were able to do it," he recalled, "but we left the pendulum out of it until after the project was bid and awarded. We built that staircase and platform with an idea that we would be getting a pendulum eventually."

Thankfully, the Alumni Association spearheaded the project, hatching a plan to find 360 donors at $100 a piece. The one requirement: donations could not be made in the name of a group or business, ensuring a personal touch to the final gift.

At the time, the UAA facilities crew was looking to replace the original slim guardrail (they'd polished the pendulum several times already to remove student fingerprints). The new railing not only limited human interference, but also provided plenty of space on a new circular shelf to thank alumni for their contribution.

In recognition of their gift, each of the 360 donors received an individual nameplate on the shelf circling the perimeter of the pendulum. In addition to the shelf, facilities also added cushions to the preexisting bench, making the pendulum area another welcoming study nook in the library building. The pendulum was fully funded as the 360th donor signed on for a degree in 2007.

A symbolic centerpiece

Now a permanent centerpiece of one of UAA's iconic buildings, the pendulum has silently shifted this way and that for a generation of students.

Dean Rollins even considers the pendulum to be a minor tourist attraction. "We definitely have people come by and take pictures of it. No doubt," he said.

"What I find the most valuable part of the pendulum is when people start to look at it and study it and talk about it and really understand what's going on," he said. "A kind of light bulb goes on and they realize it's not what they perceive it to be... I think that's one of those 'Eureka!' moments that people get, and I think that's a metaphor for education. That's another reason, in terms of its symbolism, that I like [the pendulum] being in the library so much — you have that moment of awareness that you're educating somebody."

Fitting of its academic home, the pendulum has served as an educational touchstone in Anchorage for the past 10 years. The physics department assigns projects for students to complete at the pendulum. When time allows, professors even take their class to the library to enhance their lectures on motion and inertia. Middle and high school classes have visited the pendulum to talk about physics, and parents often bring their kids to stop and stare.

"It brings science to life," Howie said of the project he oversaw 10 years ago.

Next time you're at the pendulum, take time to scan the railing framing the piece. 360 names, in a perfect circle, made the project a reality. Their momentum — to adopt a physics term — has carried the alumni association through the past decade and set the stage for the next.

Feel free to wish UAA's pendulum a happy 10th birthday next time you're on campus, and stay tuned for the next 10 years of developments with the UAA Alumni Association.

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Learn more about the library pendulum at the Consortium Library's website.