Gravitational effect of a massive object on light?

Question

Okay, no light escapes from a black hole. Are there massive objects where only some light escapes, or where light just barely escapes? If so, is light shifted to the red spectrum, appearing as if the object is rapidly moving away, or is there some other measurable light shift perhaps indicating how massive the object the might be?

Answer 1

light... dark? absence of light is dark, or is the absence of dark light? bill clinton asked what the definition of is, is, but these things are not related any way whatsoever, but if you've got a big object, and how big are we talking here? maybe like the size of a peanut, but with more mass than the earth? or more mass than 10000 suns? and then what? lets get the math down here and lets decide how fast light travels and how great the gravitational pull of such a massive, tiny object would be... big bang? the peanut cannot be like a peanut, because then that would suggest two separate parts which is where the peas are, with a smaller part in the middle connecting the two, but what if, and get this... there is light on either end of the nut, and that light actually has mass and is in a sort of osmosis-like way pulling the nuts apart... pulls one nut and the other nut in opposite directions even though the light seems to be weightless... but if that were the case then it would be unaffected by gravity? so there is light pulling two balls apart and we are left to believe that the spectrum will be changed? the mass of the object can be defined as the weight-- yes, weight -- of the light being pulled and pushed in an equilibria that is equal to the amount of pull being exerted and the push being exerted by the connective tissue....

absolutely amazing and i agree, but it would be shifted to a whole different part of the spectrum, not red and not white, not infared and not microwave.... beyond ultraviolent and beyond visible light... to a different place we've never seen, which makes dillusions in the head and you can say i'm full of it, but you're asking

ps... am I full of it or is alminktakata or whatever just wondering what i mean? really, i'm not a very good grammar or english but i speak from heart

Answer 2

As already answered: the heavy object curves space time, and light is just following a straight line through this curved space time. It does not change, no redshift or similar. Even though the light is traveling in a straight line, we call it 'bent'.

You ask how to find out how massive the object might be. Think of a star, visible from Earth. It has an apparent position in the sky. Some heavy object is moving somewhere between this star and the Earth. Sometimes the apparent position of this heavy object is so that its border comes very close to the apparent position of the star. The light from this star is bent, and thus its apparent position changes (towards the center of the heavy object).

If you know at which distance this heavy object is, you can compute how much gravity is needed to shift this star's light in the sky.

Consider a triangle A-B-C. Point A is at or near the heavy object. B is the original apparent position of the star in our sky (line B-A will end up at the star if it would be extended), point C is the shifted apparent position of the star in our sky.

Line A-B is very long, line B-C is very short, the angle at A is very small.

The heavier the object, the larger the angle at A will be, and thus the longer the line B-C will be.

But also, the longer the line A-B, the longer B-C (for the same angle).

If you know one (either the angle, or the distance) you can compute the other.

Answer 3

Most of this question has already been answered, but I'll just address one point that I didn't see covered. There are no objects where only some light can escape due to gravity - since light of all frequencies travels at the same speed and on the same geodesic. Of course, near a black hole event horizon any light that goes in the direction of the black hole is absorbed, while light going away from it escapes, but I don't think this is what you meant.

(Another option would be to mount a giant prism near a black hole, to refract selected frequencies into the black hole!)

Answer 4

The path of light passing close to a very massive object is bent, similar to the way in which the path of light is bent by a lens.

In the case of a very massive object, the path of the light is bent because the massive object is bending space in its vicinity. Since light always travels in a straight line in space, its path through curved pace appears to bend. The spectrum of the light is not changed in this case.

This bending has been verified many ways. Some examples:

!. A total eclipse early in the 20th century. The light of stars behind the sun was bent around the sun so that they appeared in front of it.

2. Gravitational lenses: Light from distant galaxies has been observed to bend when it passes massive galaxies closer to us.

As far as light escaping from a massive object: yes, it would appear to be red-shifted by an amount proportional to the mass of the object. This effect, like the bending of light near massive objects, was also predicted by Einstein's General Theory of Relativity.

Note:

The red-shifting of light from distant galaxies cannot be accounted for by their masses alone. This is why the red shifts of distant galaxies are attributed to movement away from us.

PS: OK, I'll say it: "Streaking" is full of it.

Answer 5

Light would just barely escape a neutron star that was just under being dense enough to collapse to a black hole, but the light would be shifted to radio frequency.