
At Texas Southern University, in Houston, on Thursday night, the major Democratic candidates for President will finally be assembled on one stage. For three hours, from 7 to 10 p.m. Central Time, they will deal with questions posed by representatives of ABC News and Univision, and voters and pundits will judge their performances and form conclusions about who is getting the better of whom.
Meanwhile, another contest with implications for both the 2020 election and our collective future will be unfolding. It involves the invisible parties known as centrifugal and centripetal force—the tendency of moving bodies to fly apart or come together, respectively.