Robert Urch

Experimental evidence for curved space-time

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The experimental evidence for curved space-time
The Einstein field equations are a set of 10 equations used in the theory of general relativity and they describe the interaction of gravitation due to the curvature of space-time from matter and energy [1]. The field equations were designed to apply to a static universe, as was believed to be the case at the time. Einstein’s equations and theory of general relativity have helped us to come to an understanding that our universe exists within a curved space-time. What evidence currently exists to substantiate these claims?

Earliest Discoveries
The earliest evidence for the curvature of space-time lies in light from stars being bent about gravitationally dense objects. In 1922, during a solar eclipse in Western Australia, it was realized that the light from stars in the same general area of the sky as the Sun are visible during the day, and example is shown in fig. 1a. If light from these stars is affected by the curvature of space-time due to the Sun's mass, then this would be measurable as a deflection (or a change in location) of the star's position on the sky. The stars closer to the position of the Sun in the sky would suffer a larger deflection; in general the deflection would be proportion to the stars distance from the Sun's location on the sky [4]. This is due to a prediction of general relativity which predicts that spherical masses can distort space-time, shown in fig. 1b, similar to how a bowling ball can warp the surface of a trampoline. Since that time astrophysicists have learned to use this effect on a much larger scale, called gravitational lensing which can be seen in fig. 2, below. Fig. 1a. Image taken of solar eclipse, stars can be seen in the background whose light has been bent around the sun
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