Search Results for: label/light-emitting diode
Why is the sky pink?
On Mars, the sky is pink during the day, shading to blue at sunset. What planet did you think I was talking about? On Earth, the sky is blue during daytime, turning red at as the sun sinks toward night. Scattering light Well, it’s not quite as simple as that: if you ignore your dear sainted mother’s warning and look at the Sun, you’ll see that the sky immediately around the Sun is white, and the sky right at the horizon (i…
Authored by Matthew R Francis on March 12, 2012
Making Light in Electronics
By DXS Physics Editor Matthew Francis A while back, I wrote about one of the most common ways of making electric light: fluorescent bulbs. Understanding fluorescent lights requires quantum mechanics! While a lot of quantum physics seems pretty removed from our daily lives, it’s essential to most of our modern technology. In fact, reading what I’m writing requires quantum mechanics, since you are using a computer (maybe a handheld…
Authored by Matthew R Francis on April 20, 2012
How fluorescent lights work: quantum mechanics in the home
We have a tendency to think that “quantum mechanics” is synonymous with “out of the ordinary.” I do that, too, since there’s so much strange to talk about: the blurring of particles and waves, the apparent randomness that drove Einstein crazy, and so forth. It’s easy to forget that quantum mechanics also is an everyday matter. The odds are pretty good you’re reading this post on a computer screen (as op…
Authored by Matthew R Francis on January 30, 2012
As Seen on TV! Restoring Hair with LASERS!!!!!!
The author’s rapidly-expanding forehead. Anyone who watches TV, reads magazines, or flips through catalogs has seen some interesting products. Maybe they seem plausible to you, maybe they don’t. However, a little investigation shows they are based less on science and well…actually working, and more on wishful thinking. At worst they’re actual con-jobs, designed to separate you from your money as efficiently as p…
Authored by Matthew R Francis on September 28, 2012
Why Can You Hear Around Corners But Not See?
…ecific wavelength of sound depends on the temperature and humidity of the air, but if we assume dry room-temperature air, a low-pitched sound has a wavelength of about 17 meters and high-pitched sounds have wavelengths around 2 centimeters. That’s a big range, and not all those sounds will travel around corners. Shorter wavelengths are ultrasound, which are probably most familiar for tracking the health of fetuses: these sound waves can pen…
Authored by Matthew R Francis on December 27, 2011
Did Einstein write his most famous equation? Does it matter?
in the reconstructed version (reproduced below)…there’s no E = m c 2. Instead, as I highlighted in the image, the equation is E 0 = m. Einstein set the speed of light – usually written as a very large number like 300 million meters per second, or 186,000 miles per second – equal to 1 in his chalkboard talk. Einstein’s most famous equation, sort of. This is the transcription of the chalkboard from a public talk Einstein gave in…
Authored by Matthew R Francis on May 21, 2013
Unicorns and Brainbows
orite, shown below: A cerebellar flocculus, a lobe in the cerebellum, from the original Brainbow paper (Source) Since its original description, researchers have used the Brainbow concept extensively — it has been cited 361 times, according to the Web of Science – and extended it into zebrafish and fruit flies, both species that researchers frequently use in experiments to trace gene expression and how animals develop. But though Lich…
Authored by Jeffrey Perkel on May 6, 2013
La vie est belle, n’est-ce pas?
…s to capture, store, and interpret — about a terabyte’s worth per hour. Using those data, Keller and Ahrens tracked the activity of individual neurons (well, more or less — they actually tracked neuron-sized 3D pixels, called “supervoxels”) as they turned on and off, from which they could identify collections of neurons (supervoxels) that appeared to act in synchrony and might therefore be part of the same neuron cir…
Authored by Jeffrey Perkel on April 14, 2013
Backyard Brains: Affordable neuroscience
Mouse neurons. Image via Wikimedia Commons. Originally published in PLoS Biology. Nerve cells, called neurons, are special cells. They interact with each other and with other tissues in part by using electrical impulses. The cool thing about these cells is that thanks to their electrical signaling, we can measure when they’re sending their messages. A neuroscientist friend of mine once poetically described as “exquisite̶…
Authored by Emily Willingham on November 29, 2011
How large is a proton?
…swering it leads us to the deepest mysteries of the Universe. I for one find that thrilling. Reference: Aldo Antognini et al., Proton structure from the measurement of 2S-2Sp transition frequencies of muonic hydrogen. Science 339 (2013), 417. Link (for subscribers to Science): DOI 10.1126/science.1230016…
Authored by Matthew R Francis on February 13, 2013