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?
Tag: physics
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
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
Technology, Entertainment, and Quantum Kookiness
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… Continue reading Technology, Entertainment, and Quantum Kookiness
Many-Worlds in Fiction: “Divided by Infinity”
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,… Continue reading Many-Worlds in Fiction: “Divided by Infinity”
What’s a Photon, and How Do We Know they Exist?
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… Continue reading What’s a Photon, and How Do We Know they Exist?
How Do Superconductors Work?
In 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… Continue reading How Do Superconductors Work?
Quantum Measurement Lotto
Thoreau at Unqualified Offerings gets credit for inspiring two posts today with his proposed Murphy’s Law experiment and this one, about an unrelated issue in quantum measurement. This is an analogy suggested by a colleague a couple of years ago, comparing the projection of a quantum wavefunction in the measurement process to the lottery. The… Continue reading Quantum Measurement Lotto