TED Conversations

This conversation is closed. Start a new conversation
or join one »

If gravity bends light, how do we know we're not looking at the same old light going round and round in circles?

I've been musing over this for years but never thought of putting it on here. Happily, I came across Jah Kable's post suggesting the same thing. His conversation was closed though, but I don't think the question was answered. The question is; if light can be refracted by a strong gravitational field, black hole, sun, etc. then given enough objects in its path, could it not be slingshot all over the universe? If this is true, all the stars we can see at night might be (have once been) in a radically different position to where we see them now. We might even be seeing light from the same star in two places, or more. Imagine light is a ribbon strewn around the universe, twisted round gravitational objects. If that ribbon happened to pass by Earth more than once, we'd count it more than once in our sky, and each time it would look a different age and as if it were coming from a completely different direction.
There must be someone who can calculate whether this is possible or not! Trouble is, how would we know which objects are (were) real and therefore capable of bending the light and which are the resultant image of light that's already done umpteen laps of the cosmos?! It's bending my head, I know that much!

+1
Share:

Showing single comment thread. View the full conversation.

  • Jul 8 2013: Hang on a minute, since light travels along a path unless acted upon by an external force (in this case gravity) then it literally moves away from the point of origin, ie the emitter. Now unless one can prove that the whole path is enclosed, ie the universe is contained within and inside a sphere, then how would you ever be able to assume that light would return to either the point of origin or the observers frame of reference. Now trying string theory might help proving this, but I believe it assumes that we are all on the surface of a sphere, not contained within. The only possible way I could envisage this if one was trapped between two black holes, then you might get a Lorenz attractor scenario where one mass of one black hole would sling shot light in a path that would be inversely effected by the other. Since it's believed that there is a possibility of a black hole at the center of our galaxy, it would mean for us, that another galaxy would have to be currently colliding with ours for us to observe this. I suppose we should be grateful it isn't.
    • thumb

      A wal

      • 0
      Jul 8 2013: Just imagine that straight lines eventually lead back to their starting point if you travel far enough. If it's spherical then it's the same distance in every direction until you arrive back at the starting point, including in time if it's a four dimensional sphere (hypersphere).
      • Jul 9 2013: Yes but that does not state, nor prove, in anyway shape or form that the universe is of that nature. Which is why you'd need to analyses the theories of super-string theory in relation to astrophysics probably and in conjunction with quantum dynamics. As co-joined, you could then potentially theorize state that there is only 1 photon in the whole universe.
        • thumb

          A wal

          • 0
          Jul 9 2013: "Yes but that does not state, nor prove, in anyway shape or form that the universe is of that nature."

          No it doesn’t. You were saying you were having trouble visualising it. String theory isn’t needed for the universe to be spherical. That’s the only way it can make sense imo. I don’t believe in infinity in any real sense and I don’t see the universe having edges somehow, so that’s the only way I think it can work. Relativity doesn’t prove it but it definitely suggests it.
      • Jul 9 2013: I think you misread what i said by you saying..."You were saying you were having trouble visualising it"

        I don’t believe in infinity in any real sense ... that may well be a problem specifically regarding the mathematics of all the disciplines involved. Specifically if one requires to have any kind of proof, rather than a supposition.
        • thumb

          A wal

          • 0
          Jul 22 2013: What? Mathematics isn't proof of anything. It's just a way to tighten a description because maths is totally unambiguous and isn't open to interpretation.

          Are you talking about the mathematics of a hypersphere? That's already known. If you're talking about the difference between the mathematics of describing the universe in this way vs the maths of describing it beginning from a gravitational singularity then there's no difference because from our perspective the universe does shrink into a singularity as we look back into the past, because it's a sphere. It's not just what it looks like from our perspective, it's what actually happened from our perspective, but that's not what it would look like if we were there. It would look just like this.

          It makes so much more sense than thinking the universe is actually smaller in the past. As we look across the curved surface objects get more red-shifted as we're looking across more of a curved surface. If we look far enough in any dimension then everything funnels into a singularity. Look up dark flow.
      • Jul 24 2013: Mathematics isn't proof of anything.......... You need to go back to school.
        • thumb

          A wal

          • 0
          Jul 24 2013: How rude!

          You have some very deep misconceptions about mathematics if you think it can be used as evidence of anything. It's a description of a model, nothing more. It can be used to make predictions, but even that's not real proof. It's impossible to prove a theory right. It can only be proved wrong. All you can do is say that the data matches the model. To do that the model needs to be unambiguous. That's what mathematics is for.

          You need to forget schooling because it obviously didn't work properly and learn to think for yourself. Good luck.

Showing single comment thread. View the full conversation.