Cosmologist discusses scientific facts, unknowns

2/10/2012

By KLINT SPILLER

kspiller@dailynews.net

Visiting Kansas State University cosmologist Bharat Ratra stood in front of a crowd at Fort Hays State University and admitted human's understanding of the universe is limited.

Data gathered from the Wilkinson Microwave Anisotropy Probe, a NASA Explorer mission, has shown the universe is made up of 4.6 percent ordinary matter, such as solids, liquids, gases and plasma, which make up planets, living organisms, gas clouds, stars, dust, 23 percent dark matter and 72 percent dark energy.

Since nearly all scientific fields have been investigating only ordinary matter for thousands of years, Ratra said humans still have much to learn about the universe.

"The only thing we really understand at some level -- with all of science so far -- is about 4.6 percent," Ratra said. "It is everything in biology, everything in chemistry, everything in planetary science and pretty much everything in astrophysics."

Ratra spoke at a Science Cafe gathering Thursday night at Tomanek Hall on the FHSU campus. His presentation was titled "Dark Matter, Dark Energy and the Accelerating Universe."

Ratra's main area of research is cosmology and astroparticle physics. He develops models for large-scale matter and radiation distributions in the universe and tests those models by comparing their predictions to observational data.

His presentation showed how scientists have come to believe there are other forms of matter and energy in the universe humans haven't physically observed yet -- dark matter and dark energy.

Dark matter is believed to account for a large part of the mass of the universe, but it doesn't emit or scatter light, so it can't be seen directly with telescopes.

Dark energy is a hypothetical form of energy that is spread throughout space and tends to accelerate the expansion of the universe.

"The only place where (dark energy) starts mattering is maybe at the center of some stars and with the universe at large," Ratra said. "We have no idea what the particles are that make this stuff up. They are undiscovered. It is a really bizarre universe, but our model is pretty predictive and accurate. It is a really exciting area in science."

Though scientists don't know what makes up dark energy, Ratra said its effects on the rest of the universe are apparent through observing the universe as a whole, analyzing the density of the universe and examining the rate at which galaxies are moving apart.

"The simplest model starts out with the presumption that the only effects that dark energy has on visible matter is through the gravitational field created by dark energy," Ratra said. "But it does not directly couple to visible matter through something like electromagnetic force."