time
Tag archives for time
How long does a Solar Eclipse last?
Posted by Ethan on June 1, 2012 
“The moon shuts off the beams of the sun as it passes across it, and darkens so much of the earth as the breadth of the blue-eyed moon amounts to.” -Empedocles, ~450 B.C. Less than two weeks ago, I saw my first annular eclipse, with some spectacular results at the moment of maximum eclipse. This…
A Brief History of Time… in the New World!
Posted by Ethan on February 12, 2010 However time may be measured at the Naval Observatory, the clock seems to tick slowly here when Congress is out of town. -Richard Corrigan The following is the mostly true (but somewhat fictionalized) story of the first clocks in the Americas. In the 17th Century, the finest clockmakers in the world were Dutch, going back…
Energy Conservation and an Expanding Universe
Posted by Ethan on April 11, 2008 So, what’s the deal with this one? startswithabang.com reader Scott Stuart asks the following question: I was reading “The First Three Minutes” last night and came across an interesting section about blackbody radiation and energy density. The author states that as the universe expands, the number of photons running around (in the CMB, for example)…
Why doesn’t Light Age?
Posted by Ethan on April 2, 2008 There’s a graduate student that I’m sort-of mentoring/working with at Arizona, named Xiaoying Xu (hi Xiao!). She’s bright and curious, and she asks some very good questions. She asked me one yesterday that’s pretty tough to wrap your head around: How do I explain to someone why light doesn’t age? Well, here on Earth, time…
