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What's the difference between looking at a star from a black hole and looking at it from empty space? My guess is that the curvature of space-time distorts the wavelength of light thus changing the color observed by observer 1. Is the size of the observed object distorted? enter image description here Adopted from Being optically fooled by gravity [closed]

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This question may not be specific enough to have a definite answer. The answer may depend on whether you're (1) hovering outside the event horizon, (2) free-falling outside the event horizon, or (3) free-falling inside the event horizon. The link given by Brandon Enright seems to be analyzing case 1 and specifically stating that it gives a different result than free fall. –  Ben Crowell Apr 29 '13 at 13:00

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In your diagram where the black hole is just behind the observer on the line between the observer and the object being observed the answer is "yes", the apparent size of the object will shrink. The color of the object will be blue-shifted and the whole universe will appear to contract.

There is a great demo of the effect at Journey into a Schwarzschild black hole (scroll down to the "Engulfed in blackness? NO!" section).

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It would be nice to have an actual analysis. The link just gives some extremely vague hand-waving that wanders around the point and basically just asserts the result. They seem to be asserting that it can be treated analogously to special-relativistic aberration. That would require some justification, since we're dealing with curved spacetime. The business about "swimming like crazy" throug through spacetime an the "inrushing flow of space" is hard to take seriously. Maybe this is OK as a popularization, but I wouldn't consider it a valid argument by a long shot. –  Ben Crowell Apr 29 '13 at 12:48

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