How gravity causes a perfectly spherical ball to roll down an inclined plane is part of the elementary school physics canon. But the world is messier than a textbook. Scientists in the Harvard John A.

How gravity causes a perfectly spherical ball to roll down an inclined plane is part of elementary school physics canon. But the world is messier than a textbook. Scientists in the Harvard John A.

A number of mysterious large spherical objects have washed up on the beaches of the Black Sea between March and July, sparking confusion online and speculation that they may be linked to Russia's ...