Commenter miller asks: It’s often said that virtual particles can “borrow” energy, as long as it’s for a short enough time to be compatible with the uncertainty principle. This never made sense to me, because the uncertainty principle says that product of uncertainty in energy and uncertainty in time is greater than h-bar over 2,… Continue reading Reader Request: Borrowing Energy
Category: Quantum Optics
Reader Request: Quantum Complexity
There’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… Continue reading Reader Request: Quantum Complexity
Measuring Temperature by Counting Atoms: “Suppressed Fluctuations in Fermi Gases”
When 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… Continue reading Measuring Temperature by Counting Atoms: “Suppressed Fluctuations in Fermi Gases”
Electron Spin for Toddlers
The 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… Continue reading Electron Spin for Toddlers
Quantum Mechanics Is Square: “Ruling Out Multi-Order Interference in Quantum Mechanics”
This week’s big story in physics is this Science paper by a group out of Austria Canada (edited to fix my misreading of the author affiliations), on a triple-slit interference effect. This has drawn both the usual news stories and also some complaining about badly-worded news stories. So, what’s the deal? What did they do… Continue reading Quantum Mechanics Is Square: “Ruling Out Multi-Order Interference in Quantum Mechanics”
Launch Pad for Quantum Physics
Over at Jeff Vandemeer’s blog, Rachel Swirsky has a series ofm guest posts (start here if you prefer direct post links) about the recently completed Launch Pad workshop. this is a NASA funded workshop bringing a group of writers together for six days of lectures on modern astronomy from working astronomers. From the workshop web… Continue reading Launch Pad for Quantum Physics
Protons: Even Smaller Than We Thought
The big physics story at the moment is probably the new measurement of the size of the proton, which is reported in this Nature paper (which does not seem to be on the arxiv, alas). This is kind of a hybrid of nuclear and atomic physics, as it’s a spectroscopic measurement of a quasi-atom involving… Continue reading Protons: Even Smaller Than We Thought
Watching Individual Atoms Make a Phase Transition
A 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… Continue reading Watching Individual Atoms Make a Phase Transition
Dropping Bose Condensates for Fun and Science
An 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),… Continue reading Dropping Bose Condensates for Fun and Science
Relativity on a Human Scale
While I mostly restricted myself to watching invited talks at DAMOP last week, I did check out a few ten-minute talks, one of which ended up being just about the coolest thing I saw at the meeting. Specifically, the Friday afternoon talk on observing relativity with atomic clocks by Chin-Wen Chou of the Time and… Continue reading Relativity on a Human Scale