age
Tag archives for age
How Big is Our Observable Universe?
Posted by Ethan on March 1, 2013 
“The mind, once expanded to the dimensions of larger ideas, never returns to its original size.” -Oliver Wendell Holmes When General Relativity supplanted Newton’s work as our theory of how gravity works in the Universe, it didn’t just change how we view how masses attract, it gave us a new understanding of what the questions where…
Yes, we really, REALLY need Dark Matter!
Posted by Ethan on December 7, 2012 
“If you wish to make an apple pie from scratch, you must first invent the Universe.” -Carl Sagan The Universe is a lot like an extremely intricate cake. We view it today as a snapshot in time, now that it’s complete. We can view the whole thing from one point of view, determined by where…
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…
