Browsing: Physics

Happy Pi Day! No, not pie day, Pi Day. That Greek character pi, π, that you’ve heard of but aren’t quite sure what the big deal is. Pi is the ratio of a circle’s circumference to its diameter. As yawn-inducing as that may sound, it’s an important ratio because pi is the same no matter the size of the circle. This magical ratio, pi, is true for the circle describing the tire of an automobile or a circle going around the entire Earth. We can use pi to calculate a diameter. If the circumference of the Earth at the equator is 40,075 kilometers, which it is, then the diameter of the Earth is equal to the circumference divided by pi,…

Of all the many useful and interesting periodic tables on the Internet—the periodic tables of the animals, vegetables, and minerals—and U.S. Presidents, Vienna® Chicago-style hot dog condiments, SQL server dynamic management objects, and paleo food—the original Periodic Table of the Elements remains my favorite. It’s not mine alone. While the multiplication table and tables of logarithms are pretty much forgotten, the meme of choice for purveyors of hot dog condiments or SQL-DMOs, is the Periodic Table of the Elements! There’s even a new Periodic Table Battleship game that has been designed to teach children the properties of the elements. You can download NIST Special Publication 966 to get the game boards for this. The NIST SP 966 code can also…

Flu season typically peaks between December and February, but by the time the winter holidays roll around, many of us will have already waited in line at area clinics, grocery stores, and pharmacies to get our annual flu shot. The Centers for Disease Control reports that U.S. vaccination efforts since 1994 have prevented an estimated 16 million illnesses every year. Even so, some people choose to avoid vaccination, citing reasons like a lack of confidence in its usefulness, complication risks, or religious beliefs. Some news outlets thrive on the controversy, sensationalizing reports of disease outbreaks, possible vaccine failures, and anti-vaccination propaganda. Yet the public debates have missed a critical factor in vaccine effectiveness: temperature. That’s right. To work correctly, all…

As a physicist who explores ways to measure light more accurately, it should come as no surprise that I’m fascinated by even common optical phenomena that we see all around us. For instance, rainbows occur because light travels through water and air at different speeds and because different colors of light travel at different speeds through water. Oil slicks on water, opal and butterfly wings look the way they do because of the way light waves bouncing off of different surfaces or facets interfere with one another. But while these effects are beautiful, they have practical aspects as well. For instance, the same effect that causes rainbows also allows fiber optic cables to faithfully carry information thousands of miles. Our…