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Wed 4 May, 2005 08:18 am
Since Black Holes are capable of capturing light, they must also be able to divert it by bending it, 2degrees, 10degrees, 90degrees, even 180degrees.
At some distance from every black hole, there must be a place where the light you see is being redirected 180degrees from its original path, essentially creating a mirror like effect.
I wonder if it'll ever be possible to peer closely enough at that mirror point to be able to see back in time along the original path. We might capture light from our own sun as it was turned around 180degrees and back to us. We might be able to see the light from our Sun as it existed millions or billions of years ago.
Granted we don't have the telescopic technology for this currently, but it should work in theory, right?
It does make sense, like whipping a probe around a planet. I'm trying to picture this in my head -- would a stream of incoming light (from our sun, say), be refracted around the hole, so that any black whole should whip some light back in the direction from whence it came, or would there have to be a fortuitously situated whole for this to happen?
I don't know nearly enough about the physics of it to figure out how this should work. Got any diagrams/calculations?
What about an analogy (which admittedly is not a very good way to think about these things, but lacking the proper tools...
Thinking about a black hole like a golf hole. You can putt a ball such that it will come around the rim of the cup and shoot back at you, but it seems to me that this effect is dependent on the velocity (or is it momentum?) of the ball and of the curvature of the green around the cup.
Since the velocity of the light approaching the black hole is fixed (that is, not constant relative to the black hole itself, but offering very little variation over the range of wavelengths that might come back and be detectable by us), the only wiggle room is the curvature of space around the black hole (of the green around the cup). If I sent out a beam of laser light from the earth, is there necessarily an angle at which I can shoot it, relative to the black hole, that it will spin around the "cup" of the black hole and come right back at me?
Intuitively, it would seem to me that this should be the case. The space around the black hole must range from "flat" far away to "vertical" as one approaches the singularity, so there must be some point in there where the light should roll around the curvature and come back out parallel to the incident light and travelling in the opposite direction.
Are there any holes (no pun intended) in this line of reasoning, rosborne?
patiodog wrote:Thinking about a black hole like a golf hole. You can putt a ball such that it will come around the rim of the cup and shoot back at you, but it seems to me that this effect is dependent on the velocity (or is it momentum?) of the ball and of the curvature of the green around the cup.
Exactly
patiodog wrote:Intuitively, it would seem to me that this should be the case. The space around the black hole must range from "flat" far away to "vertical" as one approaches the singularity, so there must be some point in there where the light should roll around the curvature and come back out parallel to the incident light and travelling in the opposite direction.
Are there any holes (no pun intended) in this line of reasoning, rosborne?
No holes in the reasoning as far as I can see. It's the same conclusion I came to.
The few references I've found to this on the web seem to agree that it's possible in theory, but that the light we get back would be very dim and hard to use.
One reason it's hard to use is that the Earth has moved in relation to the black hole over the eons, so the actual light beam you're looking for if you want to see yourself is very hard to predict, and once you find it, there isn't going to be a whole lot of information left in so few photons.
Oh well, just an idea.
Something else that I wonder about with it: does the angle of light coming away from the object depend on the velocity of incident light (in which case all wavelengths of incident light would come out the same way), or does it depend on the momentum of the incident light. As I understand it, shorter wavelengths have greater momentum -- so if the departure angle is dependent on momentum, you would get a prismatic effect. This would make it even more difficult for us to detect and interpret anything, since we'd only get a tiny fraction of the incident light from, say, our sun back.
Just thinking. Very cool idea, is this mirror thing.
patiodog wrote:Something else that I wonder about with it: does the angle of light coming away from the object depend on the velocity of incident light (in which case all wavelengths of incident light would come out the same way), or does it depend on the momentum of the incident light. As I understand it, shorter wavelengths have greater momentum -- so if the departure angle is dependent on momentum, you would get a prismatic effect. This would make it even more difficult for us to detect and interpret anything, since we'd only get a tiny fraction of the incident light from, say, our sun back.
I wondered that too, but I don't know.
Now that I've muddied the waters with a general theory, we need Brandon or E_Brown to give us the details.
Hmm. I thought this was near your field -- or are you an engineer?
patiodog wrote:Hmm. I thought this was near your field -- or are you an engineer?
I have an unusual approach to science; I don't like the details, I like the ideas.
My profession was Computer Programming and then Internet Design and Network Engineering (until I started my own business), but I have always loved certain aspects of science, particularly Cosmology and Evolution, which I've been reading about and discussing for almost 20 years now.
Quote: have an unusual approach to science; I don't like the details, I like the ideas.
I tend to be the same way, though I'm starting to have to pay more attention to details of application. Damn clinical medicine just can't keep up with basic science.
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