time

Tag archives for time

A month and a half ago, I reported on a simple experiment to measure the performance of a timer from the teaching labs. I started the timer running at a particualr time, and over the next couple of weeks checked in regularly with the Official US Time display at the NIST website, recording the delay…

A scientific theory hasn’t really arrived until the cynical and unscrupulous find a way to use it to extract money from the credulous and gullible. This has posed a significant obstacle for general relativity, dealing as it does with gravity, which requires really gigantic masses to produce measurable effects. That makes it a little difficult…

The Astrophysics of Bedtime Stories

SteelyKid is a big fan of the classic children’s book Goodnight Moon, which, if you haven’t spent the last sixty-odd years in a cave, you probably know features a bunny saying goodnight to a variety of objects in a great, green room. The attentive toddler will find a lot to look at in the pictures–…

Counterfactual Physics: Lorentz Variance?

The theory of relativity takes its name from a very simple and appealing idea: that the laws of physics should look the same to moving observers as to stationary ones. “Laws of physics” here includes Maxwell’s equations for electricity and magnetism, which necessarily means that moving observers must see the same speed of light as…

Physics Quiz: Accelerated Twins

Just about everybody has heard of the Twin Paradox in relativity: one twin becomes as astronaut and sets off for Alpha Centauri, the other remains on Earth at mission control. Thanks to time dilation, the two age at different rates, and the one who made the trip out and back ends up younger than the…

The Football Positioning System

It’s NFL playoff time, which means that sports fans will be treated to the sight of the most high-stakes farce in sports, namely the ritual of “bringing out the chains” to determine whether a team has gained enough yards for a first down. We’ve all seen this: the play is whistled dead, a referee un-stacks…