In 2015, scientists caught evidence of a ­cosmic throwdown that took place 1.3 billion light-​years away. They spied this binary black-hole collision by capturing gravitational waves—­ripples in spacetime created when massive objects ­interact—​for the first time. But now physicists want to see even farther. Doing so could help them accurately measure waves…

Today, at a meeting of the National Space Council at the White House, President Trump announced that he was directing the Department of Defense to create a “Space Force” as a sixth branch of the military. Initially scheduled for 11:30 a.m. EDT, the meeting started 45 minutes late and opened…