Category: Science

Wind and Temperature: Why Doesn’t Windy Equal Hot?

I got forwarded a physics question last night asking about the connection between wind and temperature, which I’ll paraphrase as: Temperature is related to the motion of the atoms and molecules making a substance up, with faster motion corresponding to higher temperature. So why does it feel warmer when the air is still and why… Continue reading Wind and Temperature: Why Doesn’t Windy Equal Hot?

Algebra and Circuit Breakers

A couple of “kids these days are bad at math” stories crossed my feed reader last week, first a New York Times blog post about remedial math, then a Cocktail Party Physics post on confusion about equals signs. The first was brought to my attention via a locked LiveJournal post taking the obligatory “Who cares… Continue reading Algebra and Circuit Breakers

What Do You Need to Make Cold Atoms? Appendix: “No-Laser” Methods

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… Continue reading What Do You Need to Make Cold Atoms? Appendix: “No-Laser” Methods

What Do You Need to Make Cold Atoms? Part 3: Test and Measurement

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.… Continue reading What Do You Need to Make Cold Atoms? Part 3: Test and Measurement

Do Not Look In Laser Pointer With Remaining Eye

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… Continue reading Do Not Look In Laser Pointer With Remaining Eye

What Do You Need to Make Cold Atoms? Part 2: Lasers and Optics

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… Continue reading What Do You Need to Make Cold Atoms? Part 2: Lasers and Optics

What Do You Need to Make Cold Atoms? Part 1: Vacuum Hardware

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… Continue reading What Do You Need to Make Cold Atoms? Part 1: Vacuum Hardware

How to Teach Physics to Your Dog, Sideways

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… Continue reading How to Teach Physics to Your Dog, Sideways