Galactic mirror revisited

[Argos]

I posted this crazy idea a long time ago, but I had few responses, probably due to bad formulation – or simply dumbness. I´ll try once more:

Since a strong g field can bend the trajectory of a light ray, what is the possibility that light followed such a path around a strongly warped space-time in the vicinity of a deep gravitational well (a giant BH, for example), that it would occasionally head 180 degrees backwards? This implies that some galaxies that we see now could be only mirror images of our own galaxy. What would be the theoretical restrictions? If a light beam can be bent 45 degrees (as it may happen in g lensing), why can´t it be warped further, to 180?

I know I may be risking my reputation with this, but I can´t refrain. :)

[papageno]

Why just one?

Why not three black holes that bend the light 60 degrees each?
Or six for 30 degrees each?

:-k

Actually, it would be nice to see a mirror image of the Milky Way.

Maybe it happens, but the light is too weak to be observed.

[Amadeus]

even if the limit is 45 degrees then it could still possibly be reflected back if it hit 3 more to make 180 degrees. Unlikey but possible I guess.

[Glom]

In order for the image not to be hugely distorted, the mirroring cluster would have to be at great distance. At great distance, the light is tenuous and so would be difficult to resolve.

[dvb]

In order for the image not to be hugely distorted, the mirroring cluster would have to be at great distance. At great distance, the light is tenuous and so would be difficult to resolve.

That's a good point.

Every mirror would have to be precise in order for the perception of every galaxy that we see to be accurate representations.

[Normandy6644]

And plus you would get a lot of abberation simply for the dust particles in the Milky Way itself, so the mirror image wouldn't necessarily look like our galaxy.

[Argos]

Thanks for the inputs, guys.

If this a theoretical possibility (and you seem inclined to believe it is), then a huge number of objects we detect might be only images that bounced back and forth through the universe. Moreover, even with distortion, the images would be able to carry much information. I think the idea could be tested by searching objects in the sky that presented identical optical/spectrographic/red-shift properties.

[Amadeus]

Does not light changed colour with distance, redshift?
The could we not detect such a reflection by seeing if the redsift is greater then it should be over the apparrent distance?

[electromagneticpulse]

Well gravity can be used to slingshot probes around them so i dont see why it couldn't be used to do the same with light and a greated gravity. I think a complete 180 in the light wouldn't be easy with a black hole as it would need to go in just off directly into the event horizon and be "aimed" back at a minute difference in its original entry trajectory for it to even hit earth. A more simple way would be if white holes existed in our galaxy as they would need a -g to them so a beam of light hitting them at 180 degrees would come back but it would gain energy and probably come back as a gamma ray so you probably wouldn't want to look at it.

[MrObvious]

Just thinking aloud, but, for light to be reflected back to the original source it would need to be a point source to begin with. If it wasn't then it would be spread out everywhere. Our galaxy couldn't then be visible to ourselves as it wouldn't look anything like our galaxy.

If the BH was far enough away that our galaxy was almost a point source then by the time it came back to reach us it wouldn't have any useful detail to be identifiable.

I could be totally out, but it was a thought.

[Argos]

The could we not detect such a reflection by seeing if the redsift is greater then it should be over the apparrent distance?

That would be a possible approach.

I think a complete 180 in the light wouldn't be easy with a black hole as it would need to go in just off directly into the event horizon and be "aimed" back at a minute difference in its original entry trajectory for it to even hit earth.

Still, such a trajectory is possible.

Just thinking aloud, but, for light to be reflected back to the original source it would need to be a point source to begin with.

In the macro-scale of the universe, every light source is a point source.

[electromagneticpulse]

i agree the trajectory is possible but highly improbable. But i think the universe is highly improbable in the first place so i guess its not that hard.

[Argos]

Some interesting links about the idea

The Schwarzschild black hole as a gravitational mirror (http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=AJPIAS000061000005000 448000001&idtype=cvips&gifs=yes)

References (http://antwrp.gsfc.nasa.gov/htmltest/gifcity/nslens_ref.html)