Guest Bloggers
bergman | August 25, 2007For those of you willing to stay up late, there will be a total eclipse of the moon on August 28 visible to various extents over most of the western hemisphere and some of east Asia. The show is a little late for me (some might call it early) as I'm on the east coast right now, but if you're up for it, enjoy. After the jump are two photos I took of a total lunar eclipse on 10/27/04:
bergman | August 24, 2007Or, "Stealing Chad's Ideas: First in a Series".
When you write 'log', do you mean base 10 or base e? What field do you work in?
Update: Or base 2 for you CS-types.
bergman | August 23, 2007As I mentioned earlier, I'm currently attending the Simons Workshop in Mathematics and Physics at Stony Brook University. The weather finally warmed up today, and we relocated to Smith Point Beach to hear Juan Maldacena tell us a bit about AdS/CFT and gluon scattering. If you're looking for a precis of the talk, I'm afraid I'm not going to give it a try, but I'll commend you to the paper if only so you can read about the beautiful wire frames.
This is actually the second workshop for me this summer. Before coming here, I had the opportunity to spend three weeks at the Aspen Center for Physics…
lundblad | August 23, 2007Some things I've noticed lately:
Anton Zeilinger (Vienna) has a blog. It's in German, but that shouldn't be a problem, right?
I found that out at Michael Nielsen's place, where he's started blogging again after a little hiatus.
In an effort to improve on my bibdesk+bibtex+folder-full-of-local-pdfs system, I've been playing around citeulike, Papers, and Nielsen's Academic Reader. Papers is crippled for physicists by its sole reliance on PubMed for metadata, but shows a lot of potential. I'm also definitely curious to see where Academic Reader goes as it grows; as it's being developed…
lundblad | August 22, 2007Lest this blog turn into a one-trick pony, let me tell you what I did today that's of a little different flavor.
I epoxied some stuff onto some other stuff. More importantly, I calculated a band structure.
This amazes me. Sure, all you squa^Wsolid-state types out there do this every day, over your cereal even, and (in some cases) just have it done for you by the undergrad, but I'm an AMO physicist. I haven't calculated a band structure since I first made sweet love to the Kronig-Penney potential back in the warrens of LeConte and Campbell, guided by the two-who-are-one, Cohen and…
bergman | August 22, 2007The LHC is coming, and it's time to place your bets. What do you do? (Fun though it may be, shooting the hostage doesn't really help here.) We're committed Bayesians (for the sake of this post, at least), and we want to assign a probability that the LHC will see supersymmetry. More generally, we have a set of possibilities for our observable physics, and we would like to assign probabilities to each. This is called the problem of finding a measure. Since the theory of eternal inflation with its "bubbling universes" is the context where the multiverse often comes up, this is often referred to…
bergman | August 21, 2007I'm here at the Simons Workshop at Stony Brook out on Long Island. I'd like to talk a bit about the workshop later, but right now I just want to note that it is 56 degrees out. In New York. In the middle of August.
Thunderstorms I'd understand, but cold, dreary drizzle? It's August, not November. I didn't exactly pack for this.
bergman | August 21, 2007When we left our story, we were stuck in the unfortunate position of living somewhere in a multiverse without any a priori way to figure out where we live. What might we do?
One thing we can do is let the dreaded anthropic principle rears its head. At its most basic essence, the anthropic principle is the statement that we exist. This is data, and we can draw conclusions from this data. The most famous examples of this are Hoyle's prediction of a particular nuclear resonance based on the need for enough carbon in the universe for us to exist and Weinberg's bound on the cosmological constant…
bergman | August 20, 2007Thanx to everyone for all the interesting questions in the previous thread. I apologize for not being able to answer every one of them. I just arrived at a workshop on Long Island, and I'm also feeling a bit under the weather. From what I've seen so far, I think I will do a post on what is perturbative string theory and what does it have to do with spacetime and gravity (maybe it will even lead into a post on what is background independence). Feel free to use this thread for more questions if you like.
bergman | August 20, 2007Let's say you have a theory, and, let's say it happens to have a whole lot of solutions. Maybe it's the theory you're thinking about, but it doesn't have to be. Nothing of what I'm going to say depends on any details besides this surfeit of solutions.
I should begin by saying what it means for a theory to have a lot of solutions. In fact, given any set of equations, one will almost always have many solutions. A polynomial of degree n will generically have n roots, for example. In classical physics, instead of a finite number of solutions, you will almost always have an infinite number. If you…
bergman | August 20, 2007When Chad first asked me to guest blog here, my first response was that I didn't have anything to say. After a little thought, however, it occurred to me that this would be an opportunity to do a little exposition. Unfortunately, my research area is quite a bit on the esoteric side, so I had to look elsewhere for possibilities. Thus, the "ask a string theorist" post below. But, the next thing that occurred to me was to talk about multiple universes.
Why do that? Not because I believe that it's central to string theory, and not because I believe that it's even necessarily science. What I do…
lundblad | August 18, 2007I see below that (in what comes as a total surprise) the string thread has already gotten lively. As an experimentalist doing quantum mechanics at the ultra-low-energy end, I don't have a strong opinion on string theory qua theory, and I really don't have a strong opinion on the sociology-of-theory business, beyond saying that I'm not a cynic, and that I find articles in the popular press about Str1ng Warzz a bit tacky.
I'm also not really qualified to weigh in: my only particle theory background was a year of QFT from a phenomenologist out of Peskin & Schroeder, and while I came…
lundblad | August 18, 2007While I'm sure there will be a lot of chatter around here in the next few weeks about the vacuum (or, God help me, vacua), I feel like I should lay the groundwork by talking about laboratory vacuum. I know I'm here to talk about cold atoms and the hot stuff going in in experimental physics right now, but I've spent a lot of time in the last couple days dealing with vacuum, and I want to tell you about it.
If you want to do most sorts of atomic physics experiment, it's essential that you isolate what you're interested in studying (atoms) from stuff that will either knock those atoms away,…
bergman | August 17, 2007Over at Andrew Sullivan's place, he's been presenting candidates for best movie line ever. Since I seem to have control of a blog of my very own, I'd like to present my nomination:
Holly Gennero McClane: After all your posturing, all your speeches, you're nothing but a common thief.
Hans Gruber: I am an exceptional thief, Mrs. McClane. And since I'm moving up to kidnapping, you should be more polite.
(transcription from IMDB)
Apparently my affection for this line is not widely shared, however, as finding the clip online has proven to be beyond my google skills. On the other hand, I did…
lundblad | August 17, 2007Well, I just flew in from DC, and boy, are my arms tired. But seriously, folks....
It's a fine thing to be asked to guestblog by the eminent Dr. Oilcan, and I'll do my best to entertain you sporadically over the next few weeks. Like he said, I first met Chad back in his Usenet days, which was back in my Usenet days as well. That's obvious, yeah, but it's key that we both refer to time on Usenet as long past. I haven't read or posted to a newsgroup in five years, and even then my interest had been pretty much dead for a couple years.
I first encountered Usenet as a wide-eyed…
bergman | August 17, 2007One of the things Chad didn't mention about me in his introduction is that in addition to being a physics major as an undergraduate, I also majored in mathematics. My research interests these days tend towards the exciting confluence of mathematics and high energy physics. So, in honor of that (but really completely unrelated), I give you:
60499999499 / 490050000000
If you like, consider it an easy puzzle to understand the significance of this number.
bergman | August 17, 2007First of all, I'd like to thank Chad for the keys to his internet-house for the next few weeks. If you're here, you know that one of the things Chad believes in (and is quite good at) is using his weblog for the exposition of science for the general public. While I don't think I can manage any funny dog stories, I'd like to try to follow his example. I have some ideas already planned (such as, god help me, a three part series on the multiverse), but I thought as an initial post here, I'd go straight to the public. What do you want to hear about? Is there some aspect of string theory, quantum…
drorzel | August 16, 2007As mentioned several times hereabouts, Kate and I are headed to Japan on Saturday, where we'll be spending three weeks touring around and attending the World Science Fiction Convention in Yokohama. We will have at least some Internet access, and I may post the occasional travel update from Japan, but I'm not going to try to schedule three full weeks worth of posts to keep the blog going during my absence.
If, for some strange reason, you find that you are wholly dependent on Uncertain Principles for your computer-based entertainment needs, have no fear-- I'm not going to leave you totally…