This composite image shows the Cassiopeia A supernova remnant as seen with light from across the electromagnetic spectrum: gamma rays (magenta) from NASA's Fermi Gamma-ray Space Telescope; x-rays (blue, green) from NASA's Chandra X-ray Observatory; visible light (yellow) from Hubble; infrared (red) from NASA's Spitzer Space Telescope; and radio (orange) from the Very Large Array.
Dear Fermi: What it means to see the universe's extremes
High above Earth, a particle detector records the cosmos's most violent phenomena. Here's how—and why.
In the 11 years since a controlled explosion lofted you into space, you have shown me a universe I could never have dreamed: full of exploding and colliding stars, actively feeding black holes, and high-energy particles that whiz through the cosmos. You capture the energy—the excitement—of the universe, because you read the information carried in gamma rays, the highest-energy form of light. Fitting, then, that you are named for the pioneer in high-energy physics Enrico Fermi.
Seventeen years ago this summer, I was working at the University of Chicago, where your namesake spent the final decade of his life and career. I worked on a piece of equipment that detected cosmic rays, the high-energy protons and other nuclei