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Q & A: Bending light with gravity

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Most recent answer: 10/07/2015
Q:
Are we Sure Gravity bends light? While thinking of our speed through the universe and how gravity Stretches Space. It made me wonder if the observation of Light bending due to gravity is an illusion caused by the stretching of space near a high gravity object.So the light from the distant reference star, passing the near the sun is still traveling in a straight line but has to travel further due to the stretching of space near the star. While our planet is traveling through space, the light could "appear" to have its trajectory altered due to the delay in time it took to reach us as it had to go further through space. I was trying to find a Picture online of the observation of starlight too the expectation. If all Stars light is moved toward the center of the star, I am wrong. However if they all shift 1 direction then I may be on to something...Disclaimer, not a scientist so excuse me if this is the dumbest question ever!
- Vince (age 41)
Boynton Beach, FL
A:

Hello Vince,

In fact the light always moves toward the center of the star, or galaxy.   This effect will cause what is called an "Einstein ring" .

Take a look at for a nice explanation.  There are lots of nice astronomical photos there such as this one:

A Horseshoe Einstein Ring from Hubble.JPG

LeeH

True, but your idea about the effect of gravity on space causing light to have to travel farther is in fact exactly part of the General Relativistic picture. It accounts for half of the curvature of light passing the star. It causes curvature on the approach and departure, while the more familiar type of gravitational effect causes curvature mostly near the closest approach. So it's pretty cool you guessed something along those lines.  Mike W.


(published on 10/07/2015)

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