Einstein’s Theory of General Relativity


Einstein’s theory of general relativity predicted that the space-time around Earth would be not only warped but also twisted by the planet’s rotation. Gravity Probe B showed this to be correct. Credit: NASA. View full size image

In 1905, Albert Einstein determined that the laws of physics are the same for all non-accelerating observers, and that the speed of light in a vacuum was independent of the motion of all observers. This was the theory of special relativity. It introduced a new framework for all of physics and proposed new concepts of space and time.
Einstein then spent ten years trying to include acceleration in the theory and published his theory of general relativity in 1915. In it, he determined that massive objects cause a distortion in space-time, which is felt as gravity.

The Tug Of Gravity

Two objects exert a force of attraction on one another known as “gravity.” Even as the center of the Earth is pulling you toward it (keeping you firmly lodged on the ground), your center of mass is pulling back at the Earth, albeit with much less force. Sir Isaac Newton quantified the gravity between two objects when he formulated his three laws of motion. Yet Newton’s laws assume that gravity is an innate force of an object that can act over a distance.
Albert Einstein, in his theory of special relativity, determined that the laws of physics are the same for all non-accelerating observers, and he showed that the speed of light within a vacuum is the same no matter the speed at which an observer travels. As a result, he found that space and time were interwoven into a single continuum known as space-time. Events that occur at the same time for one observer could occur at different times for another.
As he worked out the equations for his general theory of relativity, Einstein realized that massive objects caused a distortion in space-time. Imagine setting a large body in the center of a trampoline. The body would press down into the fabric, causing it to dimple. A marble rolled around the edge would spiral inward toward the body, pulled in much the same way that the gravity of a planet pulls at rocks in space.

Experimental Evidence

Although instruments can neither see nor measure space-time, several of the phenomena predicted by its warping have been confirmed.


Einstein’s Cross is an example of gravitational lensing. Credit: NASA and European Space Agency (ESA)
View full size image

Gracvitational Lensing

Light around a massive object, such as a black hole, is bent, causing it to act as a lens for the things that lay behind it. Astronomers routinely use this method to study stars and galaxies behind massive objects.


2 thoughts on “Einstein’s Theory of General Relativity

  1. Pingback: Warp Speed, Scotty? Star Trek’s FTL Drive May Actually Work | Mad Science Tech

  2. Pingback: Warp Drive & Transporters: How ‘Star Trek’ Technology Works (Infographic) | Mad Science Tech

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