Mass in General Relativity
In general relativity, the equivalence principle is any of several related concepts dealing with the equivalence of gravitational and inertial mass. At the core of this assertion is Albert Einstein's idea that the gravitational force as experienced locally while standing on a massive body (such as the Earth) is the same as the pseudo-force experienced by an observer in a non-inertial (accelerated) frame of reference.
However, it turns out that it is impossible to find an objective general definition for the concept of invariant mass in general relativity. At the core of the problem is the non-linearity of the Einstein field equations, which makes it impossible to write the gravitational field energy as part of the Stress–energy tensor in a way that is invariant for all observers. For a given observer, this can be achieved by the Stress–energy–momentum pseudotensor.
Read more about this topic: Mass
Famous quotes containing the words mass, general and/or relativity:
“The great mass of people ... will more easily fall victim to a big lie than to a small one.”
—Adolf Hitler (1889–1945)
“It was the words “descended into Hades”
That seemed too pagan to our liberal youth.
You know they suffered from a general onslaught.
And well, if they weren’t true why keep right on
Saying them like the heathen? We could drop them.”
—Robert Frost (1874–1963)
“By an application of the theory of relativity to the taste of readers, to-day in Germany I am called a German man of science, and in England I am represented as a Swiss Jew. If I come to be regarded as a bête noire the descriptions will be reversed, and I shall become a Swiss Jew for the Germans and a German man of science for the English!”
—Albert Einstein (1879–1955)