You say there is no such thing as “centrifugal force” (1 March, p 47). Yes, there is – in the right frame of reference. There is, of course, no centrifugal force in an inertial frame of reference (in ...

Einstein's theory of gravity predicts that a rotating body, such as Earth, partially drags inertial frames along with its rotation. Scientists suggest a novel approach to measuring what is referred to ...