The Universe is a little less than 14 billion years old. Humanity, maybe 200,000. We have reached for knowledge at every step, and recorded what we could. The pace of our knowledge seems to accelerate; the 20th century tranformed our understanding of reality, as had the previous millenium. In 2011, we gather more information than ever before, and our knowledge seems almost complete. But it’s funny how things change. On Built on Facts, Matt Springer says James Clerk Maxwell’s electromagnetic equations are as good today as they were in the 1860’s, despite a little thing called relativity. Matt writes, “Lorentz covariance is built right in, though it’s a bit hidden. But Maxwell and Faraday and Ampere and the rest didn’t know that.” On Starts With a Bang, Ethan Siegel shows how improving telescopes turned an 18th century “smudge” into a 19th century “nebula.” It took until 1929 for a man named Hubble to discover that M31 is a separate galaxy: Andromeda, our nearest neighbor. Twenty years ago, NASA launched a telescope into orbit and named it after Hubble. They pointed it at the darkest part of the sky for days, and discovered little galaxies everywhere. But Hubble’s heyday is over, and its successor is on the chopping block.