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
Dip your dollar into liquid anhydrous ammonia, dry it, and repeat. The surface tension of the boiling and evaporating ammonia shrinks the bill. Caveat: It could prove difficult to use a mini-dollar and mutilating a bill may even be illegal. (Applied Science via Weird Universe)
In many states in America, legislatures have erected punitive, vindictive barriers for women seeking contraception, requiring them to get prescriptions for safe, widely taken medications.
Designer Art Donovan writes, “I’m always looking for new and unique inspiration for my lighting commissions and the latest, cutting edge scientific devices offer a boatload of great design inspiration. From the cool, new ‘James Webb Space Telescope’ to the myriad of complex details in the L.H.P.C. at Cern- it’s a cornucopia of rich imagery.”
Taking pictures can be challenging. There are a million factors that can influence each shot you take – and unless you’re a trained photographer, you often just focus, click…and cross your fingers.Of course, you can take some of the ambiguity out of your picture-taking with this Hollywood Art Institute Photography Course & Certification package, now […]
Experienced shutterbugs with DSLR cameras have boatloads of lens options for capturing the moment. Unfortunately, smartphone photographers often get stuck with their one crummy lens, which means limited zoom and focus for their final image.Step up your smartphone’s photographic power with the Acesori 5-Piece Smartphone Camera Lens Kit, now just $9.99 in the Boing Boing Store.Magnetic rings easily […]
Some truths are universal. For one, your phone will always run out of power when you most need it. For another, the charging cords that come packaged with your Apple device will fray, split, and rip faster than Usain Bolt in a game of tag.Instead, pick up a charging cord that anyone would have a tough […]