A thought experiment.
A black hole is a place where light cannot escape from, that is, the escape velocity exceeds the speed of light.
But from the equations, there is a distance from the center of the Black Hole where light can "orbit". Light can literally "flow" around the Black Hole just like any other object in orbit.
Consider this: What would happen if a circular space station around this black hole were constructed at about the same distance as this critical distance?
What would happen?
More elaboration is needed. Ignoring any engineering problems, or tidal effects (the former can be conquered over time, the latter by finding an extremely large black hole), you will have this: a hoop-shaped space station with a black hole at it's center. The radius of this "hoop" is the same radius as the critical radius for light. That is, light at this radius neither enters or leaves the black hole, it just circulates around it.
And the space station is built around this critical radius.
The question is.....if you were "on" this exact critical radius, which is now inside the space station, what would you see?
Two things are clear:
First, the space station will look straight, and not curved in any way.
Second, since the light goes around the black hole and will actually hit you on the back of your head, the REAL effect (not illusion) will be that at some distance away along the "straight" corridor, you really will be looking at the back of your own head. Or rather, an infinite many of them at regularly spaced intervals.
It is a weird, but real, effect, caused by the equations of General Relativity.
Here is the rub, and a question for which I have no answer:
Knowing that the space station is circular, yet seen as straight, what would happen if a broomstick was slowly pointed forward along the "straight" corridor? What would you see as you pushed the long stick further out from you?
Thursday, May 29, 2008
Gedanken for the Memory
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12 comments:
Just a guess without thinking, but would you perhaps see a point? If the broom is still attached to the handle, perhaps lots of points (broom straws) followed by a lagging behind point, the handle.
I might also consider the possibility of seeing many lines followed by a long line, the handle. I think it would be a lot like the affect of traveling down a road at high speed while looking at the center line, but if you saw the back of your head as many, then you also might see many brooms. Thinking on it, the many broom idea strikes me as best. Think if you know what light would look like going down this corridor, then you should be able to deduce what a broom would look like. Hmmm!!! I must think on this some more. Think this effect once popped up on an episode of Star Trek.
Most interesting!
Since they say Black Holes eventually evaporate, I was wondering what becomes of your Space Station. Danke, fur Ihre Gedanken. That means thanks for the thought. Auf Wiedersehen!
This has nothing to do with travelling fast. No addition of speeds was ever mentioned. It has to do with the General Relativistic effect that light, given certain conditions, will "orbit". All I am asking is what will you see. The space station is stationary, or at the very least, rotating at non-relativistic speeeds. DaveH has treated it as a Special Relativistic poser, whereas it is a General Relativistic poser. Ti know the difference Dave, go back to my GR and SR posts.
No, the question I am asking, to which Wyman has correctly addressed, is one from a purely general relativistic approach.
What would you see?
I have my own ideas, but I still do not have an answer.
You would see infinitely many of you pushing infinitely many brooms forward, until one of the infinitely many brooms struck the back of your head (like the light you mentioned). That's the best I can come up with at the moment, but I think this is the correct answer or close to it.
So in other words, the broomstick bands right around the black hole without breaking?
Actually, your corridor, if a space station, would have plenty of room for the broom to move in without bending. But, if the corridor was a confined space for any reason, then GR says the broom would seemingly bend without breaking. I think it is being stretched or deformed.
I do not have your background, but I think what you describe is what I would call a deformed-space feedback loop. It may be that if the corridor is small enough the broom's constituent parts(atoms) may disassociate from the broom, contract (much of an atom is empty space I hear) and may still visually appear as the broom to you or I. This might explain how the broom bends as well, if it does bend.
My thinking on this is....well, I will let you guys (all 2 of you!) know presently. I am sure more peeps are reading this. Any thoughts anyone?
You see, you know the spaceship curves, yet you see it as straight, and you know the broomstick is straight as you push it out. Do you see the end of it poke the ceiling, as it must, or does the visual effect make it "seem" to point straight when it actually does not?
- Inspired bt DaveH
but surely the stick is a stick anf won't "bend" just because the light from it does funny things? it must poke the ceiling, and you must be able to see that it does?
...therefore you will see a straight spacestation and a broom poking the ceiling? That would mean you see the broom curving UPWARD to meet it you idiot!
Well, at some stage, the broom, being straight, will meet the ceiling, because it is a curved spacestation, given that the broom is long enough.
The point IS: WHAT will you actually SEE?
Let us start with this, what do I see if your space station is see-through and I look at all this from a distance outside the criticaal distance? I will call this the Classical View, whatever it is.
What do I see if I am beyond the critical distance (inward) and I look back at your see-through station? I am guessing I see a space station frozen in place.
My guess is that GR says, in your space station, this is non-Euclidean, therefore a straight line is a curve, so contrary to normal thinking, the broom is curved itself, but appears straight to curved you. Watch out, that broom is about to hit you in the back of your curved head!!!
I hope you've got that straight now. Well, do you, punk!?! (I never was a good Clint Eastwood.)
No Anal Sys please, just observation. What will you actually SEE?
I see myself giving up on this until the college grads, Masters degreed students, and you PhDers have had a go at this. Even if I had the right answer it would be rejected, because it would be implausible for me to have the right answer.
I have to ask myself though, since we "know" the space station is circular but appears straight to us at this particular location, how do we "know" the broom is straight and not curved at this same location? Oh well, that is why I need a break from this, so I can see what people trained in this stuff have to say. Sorry I could not offer anything better than I have. I understand questions like this are very subtle; quite often so are the answers. It is a great mental exercise for aerobic minds.
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