Two surfaces meet with G0 corner (top), G1 tangent (left), and G2 curvature-matching (right) continuity. The Zebra Stripes map shows how light will reflect from the surface in an exaggerated manner.

Last time we talked about what curvature means, looked at geodesics, ... A tangent vector to its world line doesn't stay tangent under parallel transport. So it's not a geodesic.

Instead, he said, it's a manifestation of spacetime curvature. Sounds great. ... The vector tangent to curve one at point A remains tangent all along curve one as we parallel transport it to point B.

Berry Curvature. For years, physicists have worked towards the ability to directly measure Berry curvature. Often discussed as a "holy grail," this observation has seemed impossible to make until now.