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If a telescope can see the past, can it look into the opposite direction and see the future?

I suppose I am trying to put time into a single line. (timeline) with a beginning and end, and we are in the middle.

If I can look out in any direction and see the photons that are billions of years old. That would mean the past is surrounding me in every direction. I'm in the present. It seems like that puts me in the center.

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    $\begingroup$ A telescope doesn't "see the past": it fetches photons that have been propagating forward in time since their emission. Since no photons travel backwards in time none can be fetched. $\endgroup$ – gented Dec 9 '16 at 17:02
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    $\begingroup$ Hi Catzmuze, have a look at Does the universe have a center? and Did the Big Bang happen at a point? for some background on this. The universe is (as far as we know) roughly the same everywhere so every alien being anywhere in it sees the universe to look the same in all directions. $\endgroup$ – John Rennie Dec 9 '16 at 17:03
  • $\begingroup$ I did look at the Does the universe have a center. It is kind of confusing. It helped a bit. $\endgroup$ – Catzmuze Dec 9 '16 at 17:27
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I don't think so.

  1. Looking into the past means seeing light rays that were emitted many many years ago. But you can't see light rays that are going to be emitted from some source.

  2. I don't completely your logic in the second statement , how can seeing the past put you in the center of the universe.

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When you see or hear anything you are perceiving the past. Any sound, any lightwave, takes a finite amount of time to travel from its source to its receiver. The telescope is just a fancy version, for light waves, of a hearing horn used by deaf people before electronics.

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No we cannot. Or at least in physics we don't believe so, simply because we have never observed an antecedent cause come before its consequent effect. If it were otherwise, a being in the future could in principle signal us and have a casual influence on our future. This is simply the same reasoning that makes us skeptical that e could ever eat the boiled eggs for breakfast before e cooked them! The other answers give you some good intuition for how a telescope fits into this reasoning.

Two comments in answer to your last paragraph: You might like to look up the notion of a Minkowski, or space time diagram. The telescope then looks along the past lightcone of the observer wielding it. So things are not as symmetrical as you seem to be thinking. Secondly, even thinking spatially without time, rather than concluding that you are at the center of the Universe from your reasoning, witness that the same thoughts (or like ones) simply argue for spatial homogeneity; any other observer in the universe would reason likewise and therefore the description of the universe cannot be affected by a shift in the coordinate origin. This is similar to observing that, for many purposes, you could shift the zero point on the number line to anywhere else, subtract the new zero point from all numbers and you'd wind up with a number line indistinguishable from the first one

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protected by Community Nov 22 '17 at 2:01

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