Physics professor slows down 'The Accelerating Universe'

Studies of distant galaxies show the expansion of the universe is accelerating.

By John Montesantos

Published Oct. 9, 2009

MU physics professor Bahram Mashhoon held a discussion on various theories of cosmology, or the study of the universe, Wednesday night.

The presentation was this month's installment to the Cosmic Conversation series hosted by the MU Department of Physics and Astronomy, the Laws Observatory and the Central Missouri Astronomical Association, which has been held for three years. The lectures are held on the first Wednesday of every month at 7 p.m.

This year's lectures have been given special status, as 2009 is the designated International Year of Astronomy.

The 400th anniversary of Galileo's first astronomical observations and the 40th birthday of the moon landing are part of this year's milestones.

Mashhoon, a scholar of relativistic astrophysics, cosmology and Einstein's theory of relativity spoke about recent concepts in his field.

"The main obstacle in observational cosmology is how to determine the actual distance of far-away galaxies," Mashhoon said.

Studies of distant galaxies by various groups have led to the conclusion that some objects are getting farther away, while others appear to be getting closer. The conclusion, Mashhoon said, is that the universe is expanding due to leftover energy from a big bang 14 billion years ago.

Later study determined not only is the universe expanding outward, but the rate of that expansion is actually increasing.

"It turned out that the universe is actually getting faster," Mashhoon said. "The universe is accelerating."

Sophomore Chris Porter, in attendance as part of his physics course, said he was taken aback by this notion.

"Just that the universe's expansion is getting faster as time goes on is pretty amazing," Porter said. Mashhoon also discussed his own work on the subject.

Mashhoon said he wants to see students apply what they learn in class.

"What we would like to do is take the science that we learn in the laboratory and apply it to the universe," Mashhoon said.

In doing this, cosmology leads to ever-changing and improving models of the universe he said.

The professor also gave a brief history of cosmology. His background information covered everything from the development of the heliocentric model to Newton's theory of infinite space and time.

Highlighted in his discussion were the works of Missouri born astronomers Harlow Shapley and Edwin Hubble. According to Mashhoon, their studies contributed to the theory of a cosmological balance between a force of repulsion and gravitation among astronomical objects.

Of all the advancements in cosmology discussed, he mentioned the value of the discovery of a finite speed of light to astronomical study.

"When you consider the fact that the speed of light is finite, you realize that when you look at the universe, you're looking into the past history of the universe," Mashhoon said. "For instance, when we look at the stars, you see the stars how they were several years ago. This is because light from the nearest stars takes years to reach us."

Near the end of his speech, Mashhoon reminded the audience of how much we still don't know. In a breakdown of the believed makeup of the universe, he said 73 percent is dark energy and 23 percent is dark matter, both of which are very unknown. Matter, such as gas, dust and galaxies, may make up only 4 percent.

"This is a very strange idea because it means that we don't know 96 percent of what is out there," Mashhoon said. "We have absolutely no idea what it is. Of all the things that are out there, we only know about 4 percent."

MU freshman Taylor Smallwood is not enrolled in any physics classes at MU and said he had much to learn from the session.

"I couldn't believe there is still so much we don't know about the universe around us," Smallwood said.