Astronomer explores darkest depths of universe

September 10, 2009 by Maria Roncal 

Professor talks about science of seeing the invisible

In the latest installment of the Barrick Lecture Series, professor George Rhee took matter into his own hands. Dark matter, that is.

The UNLV community filled the Barrick Museum Auditorium’s seats and aisles to listen to Rhee’s explanation of the theory of dark matter last night.

Rhee said the stars account for less than 1 percent of the universe. The remaining mass is composed of 3.6 percent hot gas, 22 percent dark matter and 74 percent dark energy.

What exactly is dark matter?

“Answering that is where we run into problems,” Rhee said.

Rhee explained that this invisible matter could consist of the lighter elements – like hydrogen, helium, lithium, boron and beryllium – stars, atoms and gas between clusters of galaxies.

“Dark matter is a ghostly element,” Rhee explained. “The only way dark matter interacts with the universe is through gravity.”

Astronomers observe and research dark matter through use of telescopes.

“[Astronomers] go out to observatories and we take pictures of the sky,” said Rhee while displaying in the background images of star-filled skies sprinkled with galaxies resembling fuzzy patches of light.
In addition to examining the universe with telescopes, Rhee said astronomers infer the existence of the invisible by how it affects those things that we can see.

“We see the dark matter through its effect on visible matter,” he said.

Rhee used the moon as an example.

“We know there are tides on earth that are caused by the moon. With our theories of gravity, we know that there’s a moon causing that, even if it was a cloudy day and we couldn’t see it,” he said.

Rhee exlained that just because we can’t see dark matter doesn’t mean it doesn’t exist.

He described how its gravitational effects on the universe and the visible elements of galaxies and galaxy clusters do not have enough mass to sustain their high-speed orbits with just the mass that is visible.

Dark matter allows galaxies and galaxy clusters to maintain that speed.

“By measuring the orbiting speed of galaxies, we can calculate the mass and the force… We find that the galaxy clusters themselves do not have enough mass to refrain them from crumbling to smithereens,” Rhee said.

Rhee and his colleagues in the physics and astronomy departments continue researching how such a complex universe emerged.

“What biologists do for life and the theory of evolution, astronomers are trying to do for the universe, [figuring out] how stars and galaxies formed,” Rhee said.

While attendees lergely enjoyed Rhee’s presentation, many were overwhelmed by the complexity of the theories he discussed.

“I liked the lecture from the standpoint that I thought it was definitely entertaining,” said nursing major Michelle Maurer. “However, I wish that he would have simplified or rather clarified some of the terminology used so that it would have been more easily understood by those that don’t necessarily fall into the astronomy major category.”

Meagan Wizened, a former student of Rhee, said, “Dr. Rhee always puts on a great lecture… In taking his class and researching it myself, I have a hard time disagreeing with the present views, but as in every branch of science, what we know changes and evolves, so even the picture we have now is an incomplete picture.”