Last June, researchers from the Hong Kong University of Science and Technology published the results of an experiment that proved that light does not move faster than light—specifically, that single photons can't move faster than the official speed of light under certain conditions.
Today, Skulls in the Stars—the nom de Internet of a UNC Charlotte physics professor—has a really great blog post up about this paper. It's very much worth a read. After all, this was basically a test to double check something we were already pretty sure was true. And what's the benefit to proving something you already knew?
A big part of why I'm recommending this post is because Skulls in the Stars does a good job of explaining some tangly optical physics in a way that is quite clear and should make good sense even if you don't have a deep background in this stuff. If you follow along, you'll come away with a good idea of why this particular study matters, and with a deeper understanding of the speed of light itself.
Let’s talk about how we measure the speed of an object first. If we’re looking at the motion of a rigid object, like a speeding car or a thrown baseball, the speed can be determined simply by measuring how much time it takes for an object to travel a distance. The speed is simply the distance divided by the time
There’s a small subtlety to this definition: cars and baseballs are extended objects! To accurately measure an object’s speed, we have to be consistent in how we define its position. For a car driving down the road, for instance, we should do all measurements of its position from a fixed position, such as the front bumper, to measure the speed.
But what do we do when the object doesn’t have a fixed position on it? For example, what is the best way to measure the speed of a hurled bucketful of water?
Image: Tap's eye view of water falling into bucket., a Creative Commons Attribution Share-Alike (2.0) image from kamathln's photostream
Urine is golden so it must have some link to gold, thought medieval alchemists seeking to devise methods to transmute base metal into gold. Not quite, but they did discover that pee is rich with the miraculous bearer of light, aka phosphorus. (American Chemical Society)
I’ve heard — and repeated — the theory that addiction rates among indigenous people in the Americas was caused by genetics — specifically, that “new world” populations hadn’t gone through the European plague years’ genetic bottleneck that killed everyone who couldn’t survive on alcoholic beverages (these having been boiled during their production and thus less […]
The PocketLab is billed as a “Swiss Army Knife of science.” Launched via Kickstarter, the small device contains numerous sensors to measure acceleration, force, angular velocity, magnetic field, pressure, altitude, and temperature and send that data to smartphones or laptops. According to inventor Clifton Roozeboom, it’s a tool for students and citizen scientists who can’t […]
Shake, stir, and muddle your way to delicious homemade cocktails with this must-have bar set. Expect only the finest quality tools from MakersKit — enabling you to unleash your inner mixologist.Top 12 Favorite Things of 2014, Sunset MagazineQuart-size vintage-style Mason jar shakerRetro double jigger for accurate measurementsStrainer & spouts for a mixologist-style smooth pourHardwood muddler […]
The Lytro Illum dares to be different, boasting even more robust features than its first generation predecessor and a sleek design reminiscent of professional DSLRs. What’s so cool about it? Most cameras capture the position of light rays, producing a statoc 2D image.
SitePoint Premium is the ultimate e-learning library for web developers, designers, and digital professionals. Famous for their web development books written by industry leaders, they’ve expanded their content library to include in-depth video courses and short, handy screencasts partnering with A Book Apart and UX Mastery. Whatever you want to achieve in your web career, […]