General relativity

1915

General relativity

The book of science

Tom Sharp

Albert Einstein physics

General relativity

Solutions

Moving

The common two-dimensional illustration, in which the weight of a planet is shown depressing the fabric of a sheet of space, is misleading. A ball bearing rolling on the sheet and approaching the planet would be pulled by gravity into the depression, but—wait—a planet is not pulled down by gravity, and it attracts an object in space toward its center.

Light takes longer to travel through a gravitational field, I understand, because increasing gravity is the same as increasing the density of space. Increasing gravity dilates time and increases electromagnetic frequencies; decreasing gravity compresses time and decreases electromagnetic frequencies.

Why this happens, why the shape or density of spacetime explains what we experience as gravity, to me, is still a mystery, unless gravitational acceleration occurs simply as a means of conserving energy and the weights we feel are inertial.

See also in The book of science:

Readings on wikipedia: