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If gravity bends light, how do we know we're not looking at the same old light going round and round in circles?

I've been musing over this for years but never thought of putting it on here. Happily, I came across Jah Kable's post suggesting the same thing. His conversation was closed though, but I don't think the question was answered. The question is; if light can be refracted by a strong gravitational field, black hole, sun, etc. then given enough objects in its path, could it not be slingshot all over the universe? If this is true, all the stars we can see at night might be (have once been) in a radically different position to where we see them now. We might even be seeing light from the same star in two places, or more. Imagine light is a ribbon strewn around the universe, twisted round gravitational objects. If that ribbon happened to pass by Earth more than once, we'd count it more than once in our sky, and each time it would look a different age and as if it were coming from a completely different direction.
There must be someone who can calculate whether this is possible or not! Trouble is, how would we know which objects are (were) real and therefore capable of bending the light and which are the resultant image of light that's already done umpteen laps of the cosmos?! It's bending my head, I know that much!


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  • Jun 26 2013: Hi Edward, thanks for your reply! What I was thinking about was Einstein's now proven theory of light deflection, leading to phenomena such as gravitational lensing. Ok, so light is radiated spherically from the source, but we only see the bit of it that hits us. That bit travelled in a straight line. But if that "straight line" passes by a large mass, or black hole, it is deflected slightly, like rolling a ball into one edge of a dip, it drops into the dip and follows the geodesic, until it pops back out again in a new direction. Or like the bat-mobile harpooning a lamp-post to go round a corner. Or is it? This is what I understand. Or does the light enter the space-time curvature, follow the geodesic, and pop out on the same path as before?
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      Jun 27 2013: You describe the path of a single photon which is not what illuminates our world. That doesn't seem to fit the question. Also, if the bending force is from a spherical celestial body in what direction is the light bent? Doesn't it depend on which side of the bending body the light traversed? It seems unlikely that all of the bent light would be focused into a pinpoint (Doomsday) beam. I may have just falsified the old saying that there are no stupid questions. :-)

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