Simonetti talked about how Albert Einstein’s concept of the accelerating universe was not a “blunder” as Einstein thought. The universe is constantly expanding, as scientists discovered and proved almost a century ago, but it is also accelerating.

The universe is made up of ordinary matter, dark matter and dark energy. Ordinary matter comprises 4 percent of the universe, consisting of protons, neutrons and electrons; these are known as baryons — the elements found on the periodic table. Dark matter is not made of baryons and also interacts gravitationally, making up 23 percent of the universe. Dark energy, which makes up the remaining 73 percent, was a concept introduced by Einstein in 1917; scientists have yet to determine what it is comprised of.

Einstein’s Theory of General Relativity of 1915 discussed how space can expand or contract. Space is an “actor” or part of the action; matter and energy only act on space.

Simonetti also discussed the “Big Bang” theory.

“There is not a specific place where the Big Bang happened … space expanded, there was no explosion,” said Simonetti.

In the past, the universe was very hot and dense. There was only ordinary matter (free protons, neutrons and electrons) trapped in a “fog,” which was mostly hydrogen. As the universe expanded, it cooled. Hydrogen and helium were formed and the universe became transparent. The Big Bang theory helped scientists determine the age of the universe, which is estimated to be 13.7 years old, plus or minus 0.2 billion years.

Simonetti is a member of the Tech physics department and has appeared on radio and television numerous times explaining astronomy to the public. Simonetti’s research concentrates on small-scale structure in the interstellar medium of the Milky Way galaxy.

He is currently using a wide-field camera designed to obtain extremely sensitive images of the night sky to study the structure of the bright interstellar plasma.

Students attending the event found Simonetti’s lecture stimulating and educational.

“His lecture was easy to understand and very informative,” said Corianne Tatariew, freshman university studies major.

“I really enjoy physics and thought Simonetti put it all together very well,” said Beth Fairchild, freshman general engineering major.