Researchers Break a 150-Year-Old Math Law With a Surprising Donut Discovery

A 150-year-old geometry rule has been overturned after mathematicians found two different torus surfaces with identical metric and curvature. For more than 150 years, a principle attributed to French mathematician Pierre Ossian Bonnet has guided surface theory. It states that if the metric and mean curvature of a compact surface are known at every point, [...]