I have been a faithful subscriber to Science News for a long time, since I subscribed for my kids in the 1960s. I don’t have a degree but was a naval aviator for 32 years. I just cannot get used to converting kilometers per hour to miles per hour each time I encounter astronomical rates of speed in your articles. My flight career in the U.S. Navy began from helicopters, through patrol planes, then F-4B Phantom jets. Everything was in knots, nautical miles and Mach number. During combat tours in Vietnam we got used to kilometers, but miles and miles per hour never left us. Your use of kilometers per hour causes me to stop and convert.
Joe R. Brewer, Pensacola, Fla.
Please excuse me for being pedantic, but ponder what information is conveyed by “observed lithium levels are three or four times lower than Big Bang physics predicts” “Lithium