On Monday night Andy Murray played the latest match ever at Wimbledon, pushing through five sets under the center court's new retractable roof. The lanky Scot complained that the "very, very heavy and very humid" atmosphere inside was distorting his serve—and scientists say he's got a point. "When you play outside, there is usually a breeze of some sort. You don’t get that in a carefully controlled environment," one engineer tells the Times of London.
The roof shielded Murray from record heat outside the stadium, but the cooler conditions meant that his serve was slowed by at least 1 mile per hour, giving his opponent an extra 1/20 of a second to react. One coach suggested that players at Wimbledon should prepare for the different conditions of indoor and outdoor play: "With more notice, he might have had two or three rackets set at different tensions for the cooler conditions."