I was just thinking about watching Back To The Future when the thought hit me: if you are looking at the sun right now, you are looking at what the sun looked like 8 MINUTES AGO since it takes roughly 8 minutes for light from the sun to reach the Earth. So technically, you’re looking BACK IN TIME.
But then, I had another idea. Now, suppose you put a massive mirror 1/2 a light year away from the Earth and have a system set up to ensure that the light from the Earth reaches the massive space-mirror without getting scattered and distorted in space. Then, you’d be able see 1 year into the past (it would take 1/2 a year for light to travel to the mirror and another 6 months for it to come back). So theoretically, a year from now, you could use your telescope to see yourself right NOW!
Now, what if we implement this system spanning hundreds and hundreds of light-years with bigger and bigger mirrors?
Mind = Blown