Expand AU Menu

CAS Success Story

  • Print

Exploring the Universe's Expansion Rates

Erek Alper's Award Winning Project

Erik Alper and Phil Johnson

Erek Alper is tackling the big questions. In his honors capstone project, “Modeling Spacetime Dynamics,” the then-senior physics major explored the mechanism behind the universe’s expansion rates by using Einstein’s Theory of Relativity to model a possible answer to one of contemporary physics’ greatest mysteries.  

Alper’s project received both a 2009 Honors Capstone Research Conference Award and the 2009 Robyn Rafferty Mathias Student Research Conference award for best science paper by a junior or senior.

For most of the past century, physicists assumed that the massive gravitational force of the universe’s contents was causing its expansion to slow. This all changed in 1998, when, “to everyone's complete bafflement and amazement, it was discovered that it was not slowing down, but that, billions of years ago, it started accelerating again,” says physics professor Philip Johnson, who worked closely with Alper on his project. “It's doing the opposite of what common sense and every theory said it would be doing.”

If this rate continues, the universe will eventually expand to the point where we will not be able to see anything outside the local supercluster of galaxies in the night sky.

Since this discovery, physicists have turned to the idea of “dark energy”—a theoretical invisible energy that, if found to exist in the universe, could explain accelerations in its expansion. To date, however, most dark energy models do little to help determine where this energy is actually coming from.

Alper’s project offers a more concrete explanation of what dark energy is and how it interacts with the universe’s other elements to create “anti-gravity,” a force that pulls bodies apart instead of together. Using Einstein’s Theory of Relativity, Alper simulated the effects of novel ultracold quantum gas—a specific theorized matter—on the universe’s expansion.

Alper and Johnson’s work modeling the effects of ultracold quantum gases on the universe’s expansion has been promising. “So far, our model really beautifully describesinflation, the initial accelerated expansion of the universe right after its conception, and the transition to steady expansion afterwards, but it doesn’t yet explain why the effects of dark energy turned back on,” says Alper. He plans to keep working with Johnson this summer to extend the model to also explain the second wave of accelerated expansion. The two plan to write their results up for publication.

Alper’s freshman year astronomy class inspired him to major in physics at AU. As his undergraduate experience drew to a close, it was a decision he was glad to have made. “You get an unbelievable amount of interaction time with the physics professors here, and they are always happy to carve out a chunk of time for you,” says Alper. “I don't think I would have been able to have conducted this sort of research at a bigger institution.”