If you ever watch CSI, Law & Order, or any other such show or film involving detective work, you’ll notice there’s always some guy or gal with a camera. They’re not extremely disturbed tourists; it’s easier to look at a snapshot again and again, take a break, then look some more to find the evidence you need.
The same concept will be at work over the next five years. A team of more than 120 scientists from around the world will be photographing and observing the southern sky during the Dark Energy Survey from the Cerro Tololo Inter-American Observatory in Chile looking for – you guessed it – dark energy. And the highly specialized camera called the Dark Energy Camera (DECam) used to take the wide-angle snaps was made right here in Illinois at Fermilab. The camera has a variety of aspects that make it perfectly suited to conducting the survey, but I’ll let survey director Dr. Josh Frieman go into those details a little later.
Naturally, the employment of a custom built camera and international fleet of scientists means the work is pretty important. Dark matter is important – if it exists. At the moment, dark matter is theoretical. Researchers found out about 14 years ago that not only is the universe expanding, the expansion is accelerating. They previously theorized that gravity within the universe would cause the opposite, and that expansion would slow down. So what’s causing the acceleration? It could be dark energy.
But there’s a problem. We can’t really see dark energy; that’s where the cameras come in.
An image of the night sky isn’t just a geographic landscape, it’s also a timeline. Some stars are so far away that they’ve actually burned out billions of years ago, and their light traveling across the universe is just reaching us now. Scientists in the survey are largely interested in a certain kind of star: a dying one. The DECam will photograph about 4,000 supernovae during the survey. Then, wavelengths of light from supernovae will be measured to see how much they’ve been stretched by the expanding universe since their star exploded.
So far, all this is in keeping with Einstein’s theory of relativity (something I was a little confused about, but hey, physics was never my strong subject). But Dr. Frieman says, it could turn out that dark energy doesn’t exist at all, and something else is at work that defies our most famous physicist’s most famous equation.
But Dr. Frieman is more capable of explaining the work ahead. To learn more about dark energy, the DECam, and the nature of the universe, listen to the full interview with Dr. Frieman below.