Watching Photons Interfere: “Observing the Average Trajectories of Single Photons in a Two-Slit Interferometer”

It’s been a long and brutally busy week here, so I really ought to just take a day off from blogging. But there’s a new paper in Science on quantum physics that’s just too good to pass up, so here’s a ReasearchBlogging post to close out the week. Aw, c’mon, dude, I’m tired. What’s so […]

You Will Never Die

If I ever decided to abandon any pretense of integrity or credibility, and just shoot for making a bazillion dollars peddling quantum hokum, the particular brand of quantum philosophy I would peddle has already been laid out, in Robert Charles Wilson’s Divided by Infinity. In the story, the narrator is given a copy of a […]

The Real Point of Zero Point

While Kenneth Ford’s 101 Quantum Questions was generally good, there was one really regrettable bit, in Question 23: What is a “state of motion?” When giving examples of states, Ford defines the ground state as the lowest-energy state of a nucleus, then notes that its energy is not zero. He then writes: An object brought […]

Quantum Man by Lawrence Krauss

While I’ve got a few more review copies backlogged around here, the next book review post is one that I actually paid for myself, Lawrence Krauss’s Quantum Man: Richard Feynman’s Life in Science, part of Norton’s Great Discoveries series of scientific biographies. I’m a fan of the series– past entries reviewed here include Richard Reeves’s […]

What Counts as “Quantum Physics?”

In comments to yesterday’s post about precision measurements, Bjoern objected to the use of “quantum mechanics” as a term encompassing QED: IMO, one should say “quantum theory” here instead of “quantum mechanics”. After all, what is usually known as quantum mechanics (the stuff one learns in basic courses) is essentially the quantization of classical mechanics, […]

Quantum Mechanics vs. Relativity: It Depends on What “Understand” Means

Sean Carroll and Brad DeLong have each recently asserted that relativity is easier to understand than quantum mechanics. Both quote Feynman saying that nobody understands quantum mechanics, but Sean gives more detail: “Hardness” is not a property that inheres in a theory itself; it’s a statement about the relationship between the theory and the human […]

How Does Light Travel Through Glass?

I’ve mentioned before that I’m answering the occasional question over at the Physics Stack Exchange site, a crowd-sourced physics Q&A. When I’m particularly pleased with a question and answer, I’ll be promoting them over here like, well, now. Yesterday, somebody posted this question: Consider a single photon (λ=532 nm) traveling through a plate of perfect […]

Teleportation of Toddler Toys

Today is the official release date for the paperback edition of How to Teach Physics to Your Dog, so I wanted to write up something cool about quantum physics to mark the occasion. I looked around the house for inspiration, and most of what we have lying around the house is SteelyKid’s toys. Thus, I […]

Interference of Independent Photon Beams: The Pfleegor-Mandel Experiment

Earlier this week, I talked about the technical requirements for taking a picture of an interference pattern from two independent lasers, and mentioned in passing that a 1967 experiment by Pfleegor and Mandel had already shown the interference effect. Their experiment was clever enough to deserve the ResearchBlogging Q&A treatment, though, so here we go: […]