Condensed Matter
drorzel | August 3, 2010In the reader request thread, Brad asks about superconductors:
Why is a room temperature superconductor so hard? Why do things have to be cold for there to be no resistance (I can guess, but my knowledge of super conductors consists of the words "Cooper pairs" which does not get me very far.)
Since next year will mark 100 years since the initial discovery of superconductivity in mercury by Heike Kammerlingh Onnes, this is a good topic to talk about. Unfortunately, it's a bit outside my field, but I can give you what I know from my not-much-better-than-layman's understanding of the field, and…
drorzel | July 30, 2010There's some good stuff in yesterday's post asking what physics you'd like to read more about. I'm nursing a sore neck and shoulder, so I'll only do one or two quick ones today, starting with James D. Miller in the first comment:
1) Is it true that our understanding of quantum physics comes from studying systems with only a small number of particles and there is a good chance our theories won't hold in more complex systems.
It all depends on how you define your terms-- what counts as a "small number" of particles, and what counts as not holding?
It's certainly true that most of the…
drorzel | July 27, 2010When one of the most recent issues of Physical Review Letters hit my inbox, I immediately flagged these two papers as something to write up for ResearchBlogging. This I looked at the accompanying viewpoint in Physics, and discovered that Chris Westbrook already did most of the work for me. And, as a bonus, you can get free PDF's of the two articles from the Physics link, in case you want to follow along at home.
Since I spent a little time thinking about these already, though, and because it connects to the question of electron spin that I talked about yesterday, I think it's still worth…
drorzel | July 26, 2010The subject of the "spin" of the electron comes up again and again, so as pointed out in a comment, I really ought to do a post explaining what it is and how it works. As a bonus, this gives me the opportunity to do the dorkiest thing anyone has ever done with a cute-toddler video, namely this one:
(That's an early version of SteelyKid's new favorite game. I'll put a clip of the final version of the game at the end of this post.)
So, electron spin. Electrons, and all other fundamental particles, have a property known as "spin." This is an intrinsic angular momentum associated with the…
drorzel | July 20, 2010Yesterday's post about how nobody cares about condensed matter physics produced a surprising number of comments of the form "I was really hoping you would post about topological insulators," which surprised me a bit. Anyway, since people asked for it, I'll give it a shot. The important caveats here are that 1) this isn't my field, and 2) I have not read a great deal of the primary literature on this, so my understanding is not that deep.
We'll do this in Q&A format, as that's been working well for ResearchBlogging posts lately.
So, what's a "topological insulator," anyway? You make a…
drorzel | July 19, 2010I had planned to spend some time this weekend trying to make sense of this new result on topological insulators, and maybe even write up the relevant paper for ResearchBlogging. Family life intervened, though, and I didn't have the time. I get enough of it to understand the basics of what's going on, but there's a whole lot I don't understand about topological insulators generally, so I'd need to do a bunch of reference chasing to get to something I can understand well enough to work back up to this week's Nature paper.
And, to put it bluntly, there just isn't that much reward for the work…
drorzel | July 14, 2010With the rumors of a Higgs Boson detected at Fermilab now getting the sort of official denial that in politics would mean the rumors were about to be confirmed in spectacular fashion, it's looking like we'll have to wait a little while longer before the next "Holy Grail" of physics gets discovered.
Strictly speaking, the only thing I recall being officially dubbed a "Holy Grail" that's been discovered was Bose-Einstein Condensation (BEC), first produced by eventual Nobelists Carl Wieman and Eric Cornell in 1995. Somebody, I think it was Keith Burnett of Oxford, was quoted in the media calling…
drorzel | June 22, 2010A press release from Harvard caught my eye last week, announcing results from Markus Greiner's group that were, according to the release, published in Science. The press release seems to have gotten the date wrong, though-- the article didn't appear in Science last week. It is, however, available on the arxiv, so you get the ResearchBlogging for the free version a few days before you can pay an exorbitant amount to read it in the journal.
The title of the paper is "Probing the Superfluid to Mott Insulator Transition at the Single Atom Level," which is kind of a lot of jargon. The key image is…
drorzel | June 21, 2010An experiment in Germany has generated a good deal of publicity by dropping their Bose-Einstein Cendensate (BEC) apparatus from a 146 meter tower. This wasn't an act of frustration by an enraged graduate student (anybody who has worked with BEC has probably fantasized about throwing at least part of their apparatus down a deep hole), but a deliberate act of science: They built a BEC apparatus that is entirely contained within a two-meter long capsule inside the evacuated drop tower at the Center of Applied Space Technology and Microgravity (which in German leads to the acronym ZARM, which…
drorzel | April 30, 2010We're just over 600 votes in the Laser Smackdown poll in honor of the 50th anniversary of the laser, as of early Friday morning. I notice that it has moved off the front page of the blog, though, so here's another signal-boosting repost, just so we have as many votes as possible, to establish maximum scientific validity when we declare the winner the Most Amazing Laser Application of All Time
Which of the following is the most amazing application of a laser?Market Research
Voting will remain open until next Sunday, May 2, just two days from now, with the ultimate winner announced on Monday…
drorzel | April 29, 2010Over in Twitter-land, S. C. Kavassalis notes a Googler who's not afraid to ask the big questions:
Weird Google search of the week: 'the "one" scientific idea that we need to believe'. Uh um, I'm sure my blog couldn't possibly answer that.
It's a good question, though, ad there are a couple of different ways to take it. You could read it as "What one scientific idea is supported by the most experimental proof?" or you could read it as "What one idea is most central to science generally?"
"The Standard Model" was quickly suggested on Twitter, which could fit either. I think it might be…
drorzel | April 26, 2010As of 1:45 Monday, 217 people have cast votes in the Laser Smackdown poll. That's not bad, but it's currently being handily beaten by the 271 people who have voted for a favorite system of units.
The nice thing about using actual poll services for this sort of thing, though, is that I can re-post the poll to boost signal a little. So, here it is again, a list of the twelve most amazing laser applications suggested by my wise and worldly readers, with links to short explanations of the pros and cons of each:
Which of the following is the most amazing application of a laser?Market Research…
drorzel | April 23, 2010In 1960, the first working laser was demonstrated, and promptly dubbed "a solution looking for a problem." In the ensuing fifty years, lasers have found lots of problems to solve, but there has been no consensus about which of the many amazing applications of lasers is the most amazing.
Now, in 2010, as we celebrate the anniversary of the laser, we finally have the technology to definitively answer the question: radio-button polls on the Internet!
Which of the following is the most amazing application of a laser?Market Research
Each of the choices above links to a post I wrote here giving…
drorzel | March 25, 2010I did one sketchy update from Portland last Tuesday, but never wrote up my impressions of the rest of the March Meeting-- when I got back, I was buried in grading, and then trying to put together Monday's presentation. And, for reasons that will become apparent, I was unable to write anything up before I left Portland
Anyway, for those who care, here are my impressions from the rest of the meeting:
Tuesday
In the 8am session, I went to the polymer physics prize talk by Michael Rubinstein, which was a sort of career retrospective, talking about how he wandered into the disreputable field of…
drorzel | March 24, 2010Several people have sent me links to news stories about last week's Nature paper, "Quantum ground state and single-phonon control of a mechanical resonator." (It was also presented at the March Meeting, but I didn't go to that session). This is billed as the first observation of quantum phenomena with a "macroscopic" or "naked eye visible" object.
Of course, there's a nice bit of irony in a story about quantum effects in a "naked eye visible" object that is accompanied by an image of the object in question taken with a scanning electron microscope. The longest dimension of the object in…
drorzel | March 15, 2010I'm terrible about taking notes on conference talks, especially when I'm jet-lagged and was sleep deprived even before I got on the plane. I do jot down the occasional paper reference, though, so here are the things I wrote down, and the talks they were associated with. This should give you some vague idea of what the meeting was like on Monday.
From Joel Moore's talk on topological insulators, one of the Hot New Topics in condensed matter, a review in Nature.
From Phillip Treutlein's talk on optomechanics, a recent preprint on coupling atoms to mechanical oscillators.
From Nathaniel Brahms'…
drorzel | March 11, 2010Lots of good suggestions as to Portland activities for my trip to the March Meeting next week. There's a second, related problem that I also need help with: What should I do at the meeting itself?
My usual conference is DAMOP, which I'll be going to in May, so while DAMOP is a participating division, and offers some cool-sounding sessions, it seems a little silly to go to the March Meeting and go to DAMOP talks. The whole point of being at the gigantic meeting is to see different stuff than usual.
The problem is, the scientific program includes forty-odd parallel sessions in each time slot,…
drorzel | December 29, 2009If you're still not sure whether you should be teaching physics to your dog, here's another good reason: Superconductors.
The "super" in "superconductor" refers to the fact that these materials conduct electric current with absolutely zero resistance, better than the best ordinary metals. This has obvious applications in the green technology field (which dogs should definitely be interested in, as discussed in a previous installment)-- if you could remove the resistance of power lines, you would lose less energy on the way from the generating plant to your home, increasing the energy…
drorzel | December 17, 2009Quantum physics can sometimes seem so arcane that even humans don't need to worry about it, let alone dogs. It's actually tremendously important to our modern world. In fact, if you're reading this on a computer (and how else would you be getting it?), you have quantum physics to thank for it.
Computers are based on millions of tiny transistors manufactured on chips of silicon. These transistors are combined together to make "bits" that can be in one of two states, which we call "0" and "1." Manipulating these bits lets us do mathematical operations, write books about dogs, and watch videos…
drorzel | December 11, 2009One of the things I forgot to mention in yesterday's post about why I like AMO physics is that AMO systems have proven to be outstanding tools for solving problems from other fields of physics. In particular, ultra-cold atoms have proven to be a fantastic venue for studying problems from condensed matter physics. There's a comprehensive review of the subject in this Reviews of Modern Physics paper, which is also freely available on the arxiv. I say "comprehensive review," but, of course, it's almost certainly already out of date, given how much work is going on in this area.
To understand why…