[katieHaylor (OP)]

Paul says:

I am trying to figure out if there will ever be a way to retrieve the past with photons.
The earth is a point in space and light is either reflected from earth or originates from earth and that light spreads out the further it gets from earth. To retrieve that light and re-compose it into a scene, sounds impossible. Is the info on a photon virtually the same as the info on a pixel? Is our galaxy moving in a circle or a spiral? If it is moving in a circle? I've just shot down one idea I had. The galaxy would not be travelling at the speed of light or above that speed in order to catch up with those photons earlier generated. I wonder if it is possible to set up some sort of field around the earth that would reflect photons back to earth and concentrate them so that a scene can be re-composed.

Are all photons equal? Could someone out in space see a photon and determine it originated on earth?

What do you think?

[McKay]

If you traveled at the speed of light 1 light year away and instantly set up a huge mirror, people back on earth could see no further (and no less) back in time than the instant you left - 1 year ago. It would always be 1 year ago. If you set up a mirror 2ly away, then we could see 2 years back (but 2 years will go by before anyone can put the mirror in place). Not sure of practicality of such a system, other than, perhaps, if the mirror is truly humongous and our telescopes are up to the task, 100, 1000 or 10000 year mirror as a gift for future archaeologists.

[guest4091]

Are all photons equal? Could someone out in space see a photon and determine it originated on earth?

We observe light from other sources which are easily identified.

[jeffreyH]

We only ever see into the past.

[Colin2B]

I am trying to figure out if there will ever be a way to retrieve the past with photons.

This is what we do every time we view the moon, or any other object. The time into the past is dependent on the distance to the object - time taken for the light to travel.

To retrieve that light and re-compose it into a scene, sounds impossible.

Again, this is what we do every time we view or photograph something.

Is the info on a photon virtually the same as the info on a pixel?

More or less, just very, very fine detail.

Is our galaxy moving in a circle or a spiral? If it is moving in a circle? I've just shot down one idea I had.

not sure what you are thinking here.

I wonder if it is possible to set up some sort of field around the earth that would reflect photons back to earth and concentrate them so that a scene can be re-composed.

Far easier to send up a satellite.

Could someone out in space see a photon and determine it originated on earth?

Yes, photons travel in straight lines. Although they  can be deflected by strong gravitational fields it is still possible to work out where they came from.

[yor_on]

no. All 'photons' are 'equal' in that way. They don't bear a stamp of origin.