Big news this week! The full data set from the Planck satellite has finally been released to the public and the scientific community at large. Cosmologists around the world have been itching to see this data for years, and with good reason: Planck has given us our sharpest full-sky image of the cosmic microwave background radiation, the oldest light in the universe….Read more "A Cosmic Picture of Your Ancestors"
Some of my friends and I use big computers to try to find out where stuff was — all of the stuff, in every place out in space — in the first tiny part of a second, at the beginning of time. We do this by looking at where all of the stuff in space is now, and trying to guess what that means about where stuff was before. But it is very hard to do that, even with a big computer….Read more "Where were all of the things a long time ago? Can we find out by looking at things now?"
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"
You may have seen some news reports over the last week or two saying that scientists had made a substance with the hottest temperature ever recorded — but that temperature was somehow below absolute zero, a negative temperature on the Kelvin scale. Weirdly enough, this is absolutely true….Read more "What’s Cooler Than Being Cool?"
Back to the Feynman lectures! The writing is quite beautiful — Feynman is very clear and readable, while still packing a great deal of information into a small space. There’s no way one blog post of reasonable length could cover all of the ground that Feynman does in each chapter. And this chapter is especially densely packed, because this chapter is setup. After some brief introductory remarks — and some philosophical comments on the nature of science that I’ll get to in a later post — Feynman gives the class a killer hook, and then uses that hook to reel the students (and readers) in through a quick introduction to many, many concepts that will come up again later in the text….Read more "Feynman Lectures, Chapter I: The Most Important Idea in Science"
I’m trying something new here, starting with this post: I’m blogging the Feynman Lectures on Physics, chapter-by-chapter (approximately). For those of you unfamiliar with the Feynman Lectures, they’re a classic set of introductory college physics lectures given by the great Richard Feynman 50 years ago at Caltech, compiled into book form. But despite their provenance, the books are not really introductory. They’re more like a rite of passage…Read more "Blogging the Feynman Lectures"
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"
The Second Law of Thermodynamics — entropy never decreases in a closed system — is among the more famous laws of physics. If you’re reading this blog, I’d be surprised if you’ve never heard of entropy before. You’ve probably also heard that entropy has something to do with disorder, and that the Second Law basically says that the universe tends toward disorder, but that’s not quite what the second law says — entropy isn’t really the same thing as disorder, though they’re related.
So what’s entropy? To answer that, I’ll steal a little bit from Kurt Vonnegut…Read more "Entropy and Billy Pilgrim"