Science

Last week's series of posts on the hardware needed for laser cooling and trapping experiments dealt specifically with laser-cooling type experiments. It's possible, though, to make cold atoms without using laser cooling, using a number of techniques I described in two posts back in January. Those didn't go into the hardware required, though, so what's different about those techniques in terms of the gear? Less than you might think. In fact, most of the labs that do these experiments use exactly the same sorts of equipment that laser coolers do. Including some lasers. It's not all of them, but…

The third category in our look at lab apparatus, after vacuum hardware and lasers and optics is the huge collection of electronic gear that we use to control the experiments. I'll borrow the sales term "test and measurement" as a catch-all description, though this is really broader than what you'll usually find in that category. This category covers all sorts of stuff, from power supplies to data acquisition equipment, but we'll start with the oscilloscopes. The picture above shows two of the many oscilloscopes that rattle around my lab. These are used for almost everything that involves a…

Some folks I used to work with at NIST have looked at cheap green laser pointers, and found a potential danger. Some of the dimmer-looking green lasers are not so dim in the infrared, and in one case emitted 10X the rated power in invisible light. This could be a potential eye hazard. You can read their full report on the arxiv. It's got a nice description of how green laser pointers turn infrared light into visible light, which is really pretty awesome-- a guy I met at a conference once declared them the coolest invention ever, because it's "quantum optics in the palm of your hand." Better…

One of the subjects developmental biologists are interested in is the development of pattern. There are the obvious externally visible patterns — the stripes of a zebra, leopard spots, the ordered ranks of your teeth, etc., etc., etc. — and in fact, just about everything about most multicellular organisms is about pattern. Without it, you'd be an amorphous blob. But there are also invisible patterns that you don't normally see that are aspects of the process of assembly, the little seams and welds where disparate pieces of the organism are stitched together during development. The best known…

The problem with writing about fake physics is that once you start, it's hard to stop. And there's always something new and disreputable to find, such as this hideous bit of scammery. As I said in How to Teach Physics to Your Dog, if quantum physics really allowed you to amass vast wealth just by wanting it, Dave Wineland's publications wouldn't need to acknowledge funding from a handful of acronyms-- he'd be able to bankroll his own research out of his personal fortune.. Quantum physics is not magic. It allows many things that seem weird and counterintuitive, but those effects are very…

Following on yesterday's discussion of the vacuum hardware needed for cooling atoms, let's talk about the other main component of the apparatus: the optical system. The primary technique used for making cold atoms is laser cooling, and I'm sure it will come as no surprise that this requires lasers, and where there are lasers, there must also be optics. There are lots of different types of lasers used for laser cooling experiments, but they all need to have certain properties: tunability, stability, and adequate power. Tunability is important because laser cooling requires light at exactly…

Charlie Stross examines the economics and physics of colonizing other planets, and he isn't at all optimistic. Forget going to planets around other stars — the distances are absurdly excessive. But also forget about colonizing planets in our solar system: not only is it ridiculously expensive just to put a human being on another planet, it isn't even an attractive proposition. When we look at the rest of the solar system, the picture is even bleaker. Mars is ... well, the phrase "tourist resort" springs to mind, and is promptly filed in the same corner as "Gobi desert". As Bruce Sterling has…

...in not pointing out that one of my favorite blogs from the "old days" (as in four years ago) is back. The Second Sight, which closed up shop in 2007, reappeared a couple of months ago. It's as great as ever. Check it out.

Over in the reader request thread, Richard asks for experimental details: I'd be interested in (probably a series) of posts on how people practically actually do cold atoms experiments because I don't really know. I needed to take some new publicity photos of the lab anyway, so this is a good excuse to bust out some image-heavy posts-- lab porn, if you will. There are a lot of different components that go into making a cold-atom experiment, so we'll break this down by subsystems, starting with the most photogenic of them, the vacuum system: (Click on that for a much bigger version.) This…

A Japanese physicist who I worked with as a post-doc spotted the Japanese edition of How to Teach Physics to Your Dog in the wild, and picked up a copy. He sent along a scan of a couple of pages of the text, one of which I reproduce here: I had totally forgotten that Japanese books are often printed with the text in vertical columns from right to left, which creates a slightly weird effect. What's even stranger, though, is the way the equations are done-- they're also rotated to be vertical, but the kanji characters are rotated as well. Not that the rotation changes the readability in any…

Having spent the last couple of days dealing with pure woo, such as germ theory denialism and naturopathic quackery, I think now's as good a time as any to move on to a more serious topic. One of the most important aspects of science is the publication of scientific results in peer-reviewed journals. This publication serves several purposes, the most important of which is to communicated experimental results to other scientists, allowing other scientists to replicate, build on, and in many cases find errors in the results. In the ideal situation, this communication results in the steady…

SteelyKid had her two-year checkup this morning, which means we got new weight and length measurements for her. It's been a while since I did anything really dorky with her data, so here are a couple of graphs tracking her growth: (Yes, they're in English units, not SI. Deal with it.) Using the rule of thumb somebody mentioned a while back that a person's final height is double their height at age 2, this projects her to be a bit over 5'9", so that's a prediction we'll be able to test in another fifteen years or so. There's some fairly large uncertainty in these, though, especially today's…

A reader emails to ask about a new-to-me theory of physics, called "Quantum Space Theory" being promoted by a fellow named Thad Roberts. I wouldn't usually bother with this, but Roberts was one of the speakers at TEDx Boulder. this is disappointing, to put it mildly-- TED is a respected organization, and I don't like seeing them lend their support to something that is just dripping with kook signifiers. The key paragraph of the overview of the theory is: To start grasping this higher-dimensional intuÂitive picÂture check out the book excerpts in the book excerpts secÂtion. If you are more…

So, last week, I talked about how superconductors work, and I have in the past talked about the idea of making cold atoms look like electrons. And obvious question, then, whould be: Do cold atoms systems allow us to learn anything about superconductivity? The answer here is, unfortunately, "Yes and no." That's pretty weaselly, dude. Yeah, well, there's nothing I can do about that. There are a huge number of experiments out there using ultracold atom systems to look at Bose Einstein Condensation, which is related to superconductivity, and that transition has been studied in great detail. Those…

Nope, sorry, take your Hubble Space Telescope and aim it where the sun don't shine. Biology rules. (via Deep Sea News)

the hot topic in mathematical sciences at the moment is the draft proof that P≠NP (warning: PDF). This is one of the biggest issues in computer science, and one of the Clay Mathematics Institute's Millennium Problems, so a proof would be Big News in math/CS, and earn the prover a cool $1,000,000. Reaction among blogging theorists is mixed, with some intrigued and at least one willing to bet against it. So what do I think of the proof? Honestly, this is so far out of my areas of competence that I need Google to remind me what the symbols mean. About all I know is that it's a Big Deal in…

In comments to yesterday's post about my favorite Many-Worlds story, a couple of people mention "All the Myriad Ways," a Larry Niven short story. I don't think I've ever actually read the story, but it gets brought up all the time, so I'm familiar with the concept. It's an angle on Many-Worlds that I don't like, and has something in common with the central conceit of Inception, which is also not high on my list of literary tropes, though my reaction isn't anywhere near as negative as Scott's. If you're not familiar with it, here's the summary from Wikipedia: A police detective, pondering a…

If there's one aspect of medical education that I consider to be paramount, at least when it comes to understanding how to analyze and apply all the evidence, both basic science and clinical, it's a firm grounding in the scientific method. I advocate science-based medicine (SBM), which is what evidence-based medicine (EBM) should be. SBM tries to overcome the shortcomings of EBM by taking into account all the evidence, both scientific and clinical, in deciding what therapies work, what therapies don't work, and why. To recap, a major part of our thesis is that EBM, although a step forward…

Today, Tor.com has posted the complete story "Divided by Infinity" by Robert Charles Wilson. This remains probably the best science fiction story ever using the Many-Worlds interpretation of quantum physics (though it doesn't call it that explicitly), and also the creepiest: In the year after Lorraine's death I contemplated suicide six times. Contemplated it seriously, I mean: six times sat with the fat bottle of Clonazepam within reaching distance, six times failed to reach for it, betrayed by some instinct for life or disgusted by my own weakness. I can't say I wish I had succeeded,…

A reader emailed me with a few questions regarding How to Teach Physics to Your Dog, one of which is too good not to turn into a blog post: What is a photon from an experimental perspective?... Could you perhaps provide me with a reference that discusses some experiments and these definitional issues? The short form of the experimental answer is "A photon is the smallest amount of light that will cause a detector to 'click.'" (For some reason, hypothetical light detector technology has never really advanced past the Geiger counter stage-- even though it's all electrical pulses these days, we…