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. It’s a fantastically detailed set of “baby pictures” of our universe when it was less than 0.003% its current age. Planck has already told us that our universe has a little more dark matter and “regular” matter — stuff made of atoms — than we had previously suspected, and a little less dark energy. Planck also indicates that the universe is a little older than we had thought, to the tune of about 100 million years (so a little less than 1% older). And Planck may not be done changing our understanding of the universe: over the next few years, cosmologists around the world will be trawling through this data set, hunting for something new and strange. Phil Plait has an excellent summary with more details here.
The difference in temperature between the reddest red spot and the bluest blue spot in the Planck image is only about one part in 100,000 — about 0.0003 degrees Celsius. But the thing that always gives me the chills — in a good way — about this kind of image is the fact that these tiny differences are what led, very directly, to you and me. Those little temperature differences were caused by tiny clumps of matter in the universe 13.8 billion years ago. And over all that time between then and now, those tiny clumps got huge — the clumps attracted other clumps through gravity — and became the galaxies and stars and planets we see in the universe today. So everything you see around you, everything you know and love, everything from the stars in the sky to the fish in the ocean to the computer you’re reading this on, all of it is directly descended from those tiny temperature differences in the image from Planck. In other words: that’s a picture of you, and me, and everyone and everything else, 13.8 billion years ago.
There’s also news of another sort: for the next six months, I’ll be working at New Scientist’s San Francisco office, creating interactive online graphics and reporting on news in astronomy, physics, and other areas of science. My first set of graphics — about Planck, naturally — went live on the New Scientist site today! I’m really excited to be working at NS, and I hope to have more of my work with them to post here soon.
I took a stab at writing about my research using only the thousand most common words in English, with the help of the upgoerfive text editor — and I had a blast. Restrictions breed creativity, and I like anything that makes it easier to get ideas across to a wider audience. Hopefully, you’ll find it interesting too.
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.
Part of the reason it is hard is that the first tiny part of a second was a long time ago — say the word “hundred” five times, and then say “years,” and that will be close to how long ago it was. Because it was so long ago, most of the things that were around then are not around anymore — they changed, because time changes things.
Science writing is something I enjoy immensely — hence this blog — so when I found out that the AAAS runs a Mass Media Fellowship for science students and recent graduates, I jumped on it. As part of the application, I wrote a 750-word news story about a scientific paper that came out in July. This story will never appear in any news outlet, but I figured you all might find it interesting to read. (Science news outlets did cover this paper back in July.) So, hot off the presses, I give you a story about the hidden structure of our own universe:
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.
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. A lot of the other stuff that showed up in those stories was completely false — my favorite was a statement that this would let us build a 100% efficient engine, breaking the laws of thermodynamics — but there is such a thing as a negative absolute temperature, and those negative temperatures are hotter than any positive temperature. In fact, these scientists pushed a substance a few billionths of a Kelvin below absolute zero, which is far and away the hottest temperature ever recorded. But the surprise is that they managed to do it with this substance in this particular way, not that negative temperatures are so hot. The idea of negative absolute temperature has been around for decades, and this isn’t the first substance to be prodded into a negative temperature.
So what is “negative absolute temperature”?
Well, that’ll teach me to make promises about when the next post will be. In totally unrelated news, I hate moving to a new apartment.
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.
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 for advanced students within the field. One of my professors in college actually did assign the Feynman Lectures as supplementary texts for his intro-level class, but he explicitly said that they were “not really for the beginning student — but every good physicist, at some point or another, should read the Feynman Lectures.”
Here’s my dirty little secret: I’ve never read the Feynman Lectures. Continue reading
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. You can also download it here, or get it free on iTunes here.
We talked about the Big Bang as a giant particle accelerator, what a freelance astrophysicist actually does, and Teenage Mutant Ninja Turtles, among many other things. It was a blast to record it, and I hope you enjoy listening to it!
Coming up later this week: a little Richard Feynman. (Well, actually, a lot of Feynman. An awful lot.)
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: Continue reading
Over the summer, the big physics news was the discovery of a new particle which is, in all likelihood, the Higgs boson. I’m not going to give a detailed explanation of what the Higgs is and how it was found — Bruce Bassett wrote a great post about that here, there’s a more detailed post here, and a set of more detailed posts here.
Instead, here’s an e-mail exchange I had with a friend about the Higgs — he had a question, and I answered it, but there’s a bit more to it than that…
Freelance Astrophysicist is back! I’ve finished graduate school and moved across the country to California, and now I’m figuring out whether it’s possible to actually be a freelance astrophysicist. In the meantime, I’m working on a full site redesign with my friend Nick James; we’ll be rolling it out over the next week or so. There are already a few tweaks in place, most notably the new banner image at the top of the page.
So what’s the new banner picture? It’s 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, out of the infrared and well into the microwave range. And even this robot, with its microwave-tuned eyes that can stare at the whole sky for years on end, even this robot has trouble seeing this ancient light, because there’s something much brighter blotting it out over a huge swath of the sky: our own galaxy, the Milky Way, the luminous purple ribbon stretching across the middle of the image. The ancient light — which is called the cosmic microwave background radiation (CMB) — is just that red-orange mottled pattern in the background. But despite all these difficulties, the robot (called Planck, after the great Max Planck) has still managed to take a more detailed picture of the CMB over the entire sky than anyone else ever has. And that picture, in turn, holds a vast quantity of information about what our universe looked like in its infancy, a mere 380,000 years after the Big Bang. That information is being analyzed right now by the team responsible for building, deploying, and running Planck; they will be releasing the data and their analysis early next year.
I like being alive now, at this moment in history — we live in a time of wonders.