On opening weekend, some New York Yankees stepped to the plate with bats that looked slightly off, thick in an unusual place, tapered in a way baseball fans are not used to seeing. Then came the home runs, and suddenly one oddly shaped piece of lumber became one of the first big talking points of the new MLB season. The bat is now widely known as the torpedo bat. Its shape has drawn comparisons to what might happen if someone started turning a bowling pin on a lathe and then switched midway to making a baseball bat. That unusual profile, with a swollen area set farther down the barrel, has caught the attention not only of fans and teams but also of physicists and engineers who study how baseball equipment works. “The same bat design has been in existence for a century and a half, maybe,” Alan Nathan, professor emeritus of physics at the University of Illinois Urbana-Champaign, says. “And to come up with something new, to me, is always very exciting.” That reaction says …