For the first time, a part of the dark matter “skeleton” of the universe has revealed itself. The discovery strengthens our understanding of the universe’s history and tells us more about the formation of galaxies like our own, billions of years ago.
Current theories about the largest structures in the universe predict the existence of giant structures made of dark matter — the unseen substance that comprises over 80% of the matter in the universe — between most galaxy clusters. Now, for the first time, a team of cosmologists led by Jörg Dietrich at University Observatory Munich has found hard evidence that the long-sought-after strands of dark matter actually exist….
Read more "Seeing Strands in the Cosmic Web"
I’ve been out on the East Coast for the last two weeks, and I’m headed back west later today. While I was out here, my friends Yuko and Conrad put me in touch with Rym and Scott, who run GeekNights, and I ended up recording an interview with them. They posted it as a podcast, and you can listen to it here….
Read more "GeekNights Interview"
This is a picture taken by a robot over one-and-a-half million kilometers away from the earth — over three times farther away than the moon — of the oldest light in the universe. This is impossibly faint light: it took a full year for the robot to collect enough light to take this picture. And even if it weren’t so faint, we wouldn’t be able to see this light with our eyes because it’s beyond the range of visible light, stretched by the expansion of the universe over the last 14 billion years…
Read more "Postcard from the Edge"
Energy isn’t conserved. It can be — and is — created and destroyed. Your high school physics teacher lied to you. Or, more likely, your high school physics teacher was mistaken. And your college physics professor was probably mistaken too….
Read more "Getting Nothing for Something (and Vice Versa)"
Figuring out what happened during the first billionth of a billionth of a second after the Big Bang is rather hard, mostly because there’s no light we can see from that time. In fact, there’s no light that we can see from the first 380,000 years after the Big Bang. For most of that time, light was trapped in a plasma, a dense soup of electrically charged particles a lot like the interior of the Sun….
Read more "What I Do: Part II"
Physicists are notorious for oversimplifying things in the name of mathematical modeling. There’s the old joke about spherical cows, radiating milk isotropically, which I’ll spare you here, but the reason we do this is that you can often learn an awful lot about something by simplifying it down to the interesting and easy-to-model parts — which are hopefully the same! The trick is knowing which parts can safely be ignored, but if you do that right, you can get an amazing amount of information about something with a very simple model of it….
Read more "What I Do"