Robert+McLaughlin


 * Gravity Warping Light**

A General Overview
Light warping is a phenomenon predicted by Einstein's Theory of Relativity. As pictured above, Relativity predicts that objects with mass will //warp// space-time, as a ball would when placed on a trampoline. As a consequence, light will be slightly skewed when it travels near to an object. **What is space-time?** Space-time is a special invention of Einstein's, but was widely accepted at the time of its release to the general public. Before, people only thought of space in three "dimensions" (directions): Up/down, left/right, and forward/backward. But Einstein needed another dimension to explain the things he was noticing: time. Thus, he "invented" space-time, a system of measurement where there are //four// important dimensions: up/down, left/right, forward/backward, and time.

What makes it bend?
Space-time is bent by any object with mass. You yourself, probably sitting in a chair reading this post, are warping the space-time around you, ever so slightly. It is warped in such a way that objects are attracted toward (what they observe to be) the center of the warp's pull. So yes, you are slightly pulling that chair up toward you, but it is pulling back with the same amount of force, so you won't notice any change. (there is an inverse-square relationship, for those who are interested) Einstein also accurately predicted that this very gravitational force will bend light.

So light can be bent?
Strictly speaking, no. Light is made up of particles which are immeasurably small, and the particles themselves are never bent, their path through space-time is shifted. Imagine walking in a straight line, but someone lasso's you, and pulls to the side. You're still walking straight to your best ability, but you are also being pulled toward the side. The same thing happens with photons; they still behave like they are traveling in a straight path, but gravity pulls them slightly to the side. As soon as the particles leave the object's grasp, they continue on their straight path.

Seeing ghosts
This creates some interesting situations. According to this information, stars which would normally appear behind the sun could be visible at the very edge of the sun. Unfortunately, attempting to view these stars through a telescope would also focus the sun's rays on the observer. If a person attempted this, they would probably blind themselves. If they were to use a camera to capture the picture, the camera would melt from the sheer heat of the sun. The only safe way to attempt to observe this would be to wait until a solar eclipse, where the sun is blocked out but the stars on the edge are visible. As predicted by Einstein, there are stars clearly visible on the edge of the sun which should have been impossible to see otherwise.

Double Vision
Another interesting situation arises when the object is perfectly behind a mass. This effect is called gravitational lensing. The effect is that on earth, certain stars or galaxies will appear in double, tripple, or quadrouple their original image. The image below demonstrates the effect: two streams of light make it to the earth, but from different angles and slightly different places. An observer on the earth would see two images.

Categories: Light, Mass, Gravity Works Cited []

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High Energy Astrophysics Science Archive Research Center. "Gravitational Lensing." Goddard Space Flight Center. NASA, Mar. 2007. Web. 20 Dec. 2011. .

Serway, Raymond A, and Jerry S Faughn. Physics. New York, NY: Holt, Rinehart and Winston, 2002. Print.