Astrophysicist examines world’s largest telescopes
Rachel O'Grady | Wednesday, October 29, 2014
Notre Dame professor of astrophysics Peter Garnavich addressed a full room of students, faculty and members from the South Bend community Tuesday night on the topic of the universe’s largest telescopes.
Garnavich said the current era is what he calls the “golden age of astrophysical exploration,” a period that will garner some impressive discoveries over the next several decades.
“We see a time, after the Big Bang, which was sort of the dark ages, where no stars existed,” he said. “We understand very little about cosmology at this time, because we’re always stuck when light isn’t being created … but eventually, stars are starting to be formed and we can start to see what’s going on there.”
Garnavich said dark matter, despite its name, makes up much of what we know about the universe.
“A lot of what we think we know about the universe is actually dark; we think that dark matter makes up about one quarter of the universe,” he said. “… Dark matter may be some weird particle, some weird thing that we don’t know, but it’s a larger part of the universe.
“Then dark energy makes up about three-quarters of the universe, the mysterious energy that makes the universe actually accelerate instead of decelerate.”
Though dark energy and matter make up much of the universe, there are stars and other elements that make up a significantly smaller but important portion, Garnavich said.
“This really doesn’t leave a lot of room for the ‘ordinary’ stuff, so round-off error in astronomy means that atoms make up a very small fraction, less than 3 percent of the universe is made of hydrogen and helium and that little smattering of elements,” he said.
Garnavich tied this idea of understanding the universe to telescopes with the famed Hubble telescope.
“In about the 1920s, a guy named Hubble began to understand much more about the universe by studying distances in the universe,” he said. “This is a big problem when you don’t know the scale of the universe or the distance of the stars or the distance of the galaxies, in fact, back then they didn’t know there were other galaxies, they thought they were just fuzzy blobs within our galaxy.”
The telescope came about as a result of trying to find those distances, and Hubble was a trail blazer into the present golden age of discovery, Garnavich said.
“He actually found the distances of objects then comparing that to the velocity those objects were moving away and came up with a really nice relation … which obviously became so famous it got his name on a really big and really important telescope,” he said.