Dr. Robert Kirshner: Well, I'm an observational astronomer.
I make measurements of things, usually using telescopes - I do pretty much
what you think an astronomer does do. I go to a telescope and make
measuremenst of things. In this case it's exploding stars and the
purpose of those measurements is to find out the history of how the
universe has been expanding.
Narrator:Astronomers now believe that the mysterious dark
energy makes up 70% of the composition of our universe, while dark
matter makes up another 25%. Robert Kirshner, Kluse Professor of
Astronomy at Harvard University, is an astronomer at the Harvard
Smithsonian Center for Astrophysics.
Evidence that his team gathered has revealed that our
universe is expanding at an ever increasing rate.
I got interested in astronomy pretty early, There was a neigbhor
who had a telescope and he was kind of having trouble setting it up.
I thought "How hard can this be?" So we figured out which way the
North Star was and got the axles pointed the right way. But I do
remember just being impressed with the mystery of it, and with the visual
Well, we've gotten a really big surprise, which is that the
universe seems to be expanding outward faster over time, not slowing down the
way we expected. And so we thinkg there must be something that has this kind of
anti-gravity quality to it, which we call the dark energy. So finding
out what is making the universe expand is something which is actually
within our grasp. And the technique for doing it that I have been
working on is to use these exploding stars - these supernovae - to
try to measure the history of cosmic expansion.
It turns out that a certain kind of supernova is pretty much the same from
one galaxy to the next - they have the same brightness. So that means
we can judge their distance from their apparent brightness. Now that's
one part of the story, how far away are they. The other part
is really how fast is the universe expanding.
This video opens with an image of distant galaxies, while the narrator talks about dark energy and dark matter. Then it's a video of Dr. Robert Kirshner explaining his interest in astronomy. While he talks about his neighbor, there is an older picture of a young boy with a telescope. Then there is an image of a sky full of stars. The final image is of a supernova on the edge of a galaxy.