Lots of people believe that Einstein's theory of general relativity states that gravity is due to curvature in fourth dimension. As an example, here's a recent question uploaded on Quora: ""Einstein tells us that gravity is motion in curved space-time, so why do scientists still refer to it a force?".
Forgive me for screaming, but this one truly makes me insane. EINSTEIN DID N'T SAY THAT! In his theory of general relativity, developed in 1915, gravity is a force field, somewhat different from the electro-magnetic (EM) field. It is NOT four-dimensional curvature. But first a bit of history.
The field idea was presented into physics in 1845 by Michael Faraday through his studies of electric and magnetic phenomena. When James Maxell generated formulas for Faraday's field in 1864, the field view of EM forces was commonly accepted. But Isaac Newton's theory of gravity, which consisted of "action at a distance", remained unchanged. Newton's theory was hugely successful, and is still taught in elementary physics programs at present, but Newton was not satisfied with the idea of "action-at-a-distance", saying "That one body may act upon another at a distance, through a vacuum, without the mediation of anything else ... is to me so great an absurdity, that I believe no man who has in philosophical matters a competent faculty of thinking can ever fall into it."
This altered, of course, when Einstein offered his principle of general relativity in 1915. In Einstein's words: "As a result of the more careful study of electromagnetic phenomena, we have come to regard action at a distance as a process impossible without the intervention of some intermediary medium ... The effects of gravitation also are regarded in an analogous manner ... The action of the earth on the stone takes place indirectly. The earth produces in its surroundings a gravitational field, which acts on the stone and produces its motion of fall ... [T] he intensity and direction of the field at points farther removed from the body are thence determined by the law which governs the properties in space of the gravitational fields themselves."...
Find out more on the Fields of Color website!!
