Hacker News
- How the Speed of Light Was First Measured http://www.todayifoundout.com/index.php/2013/08/how-the-speed-of-light-was-first-measured/ 37 comments
- How was the speed of light first measured to some degree of accuracy? https://www.reddit.com/r/askscience/comments/50p6jc/how_was_the_speed_of_light_first_measured_to_some/ 7 comments askscience
- For the first time, astronomers have directly measured how fast a black hole spins, clocking its rotation at nearly half the speed of light. http://www.nasa.gov/mission_pages/chandra/news/black-hole-spin.html#.ux_xwz9dvn8 4 comments space