you getting bigger i remember when you was a little

The supernova sends out almost all its light in a specific wavelength of blue. There’s a really convenient way of getting that.

Then you want to know how much the universe has expanded since each explosion occurred. How did those supernovas reveal the way the universe is expanding? We used these Type Ia supernovas as our distance indicators. Fortunately, it’s also the brightest of the group, so it’s the one you could follow farthest away. It wasn’t until the 1980s that scientists realized there are subgroups of supernovas, and that one of them, called Type Ia, is very consistent in its brightness. But it turned out that the more you looked at supernovas, the wider the variety you saw, and that consistency disappeared. If every supernova had almost exactly the same brightness, then you could use how bright it appeared from Earth to measure its distance. There were some very early papers in the 1930s that proposed using supernovas-really, really bright exploding stars-to measure the universe’s expansion because it appeared there was consistency in how bright they got. How do you approach such a complex problem as the history of the universe’s expansion? The basic idea is that when you look at farther and farther distances, you’re looking further and further back in time.

And the way you answer questions about the future is by looking at the past. How do we know the universe will last forever? These are the obvious things you want to know when you say we live in a changing, expanding universe. But the very next thing out of people’s mouths was more questions: Will it keep expanding? Could it stop expanding? Maybe it could turn around and collapse. What was the underlying motivation behind the research that led to your discovering dark energy in 1998? In the 1920s, Edwin Hubble showed that the universe is expanding. He spoke to DISCOVER about his strange discovery, the latest ideas about dark energy, and the projects that have the best shot at making sense of this cosmic mystery. Theories abound about the nature of this elusive energy, and Perlmutter is hotly pursuing observational evidence to help find the answer. Since 1998 Perlmutter has worked to refine his measurements of the accelerating universe and the dark energy causing it. Perlmutter’s findings have forced them to consider that it might instead expand away into nothingness or, worse, end in a “big rip” as the ingredients of stars and galaxies are literally pulled apart. (The remaining 22 percent of the cosmos is so-called dark matter, unrelated to dark energy except in its ability to defy all current methods of detection.) Scientists had also long assumed that the universe would either slow infinitely or eventually stop expanding and collapse in on itself. Now it is generally accepted that matter makes up merely 5 percent, its share dwarfed by the mysterious antigravity energy that is propelling space apart. Scientists had long assumed that atoms-the constituent parts of stars, planets, and people-dominated the universe. Through his groundbreaking research, the then 38-year-old physicist at Lawrence Berkeley National Laboratory in California basically turned our model of the universe on its head. That invisible energy, which accounts for a whopping 73 percent of everything in the cosmos, is stretching the fabric of space and could cause a runaway expansion of the universe.

Saul Perlmutter is one of them, for his central role in the 1998 discovery of dark energy. This article is a sample from DISCOVER's special Extreme Universe issue, available only on newsstands through March 22.Īlso see the video from DISCOVER's Mysteries of the Cosmos event, in which Perlmutter was a panelist.įew scientists can say their work forever changed how we see the universe.

You getting bigger i remember when you was a little