The basics of general relativity


The elevator, the rocket, and gravity: the equivalence principle

Information about the principle that Einstein took as a starting point for developing his general theory of relativity

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Gravity: from weightlessness to curvature

So what is gravity in Einstein’s theory? The answer: in part, an illusion; in part, an aspect of geometry.

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…that all coordinate systems are created equal

Why, in general relativity, all observers are on an equal footing – and why, nevertheless, you can say that the earth orbits the sun, but not the other way around

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Inertial and Gravitational Mass

About the different roles played by mass, and the weak equivalence principle

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A subtle change in direction: Geodetic precession

In Einstein’s theory, gravity is related to space-time curvature. This text explores what curvature is – and how the way it influences geometry can be measured directly, with the help of gyroscopes.

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