First, all we need to do is make some sort of wormhole, space warp transporter that can take us across the universe in an instant.
Then we send a fairly large sum of mercury or other reflective luquid (maybe a molten metal that will be reflective once it solidifies)(glass would not be used for the risk of shattering on the trip there) through said portal thing into an empty space in space 65 million light years away where we could see Earth pretty well.
The liquid would quickly spread out into a large reflective mirror- like plane that we could train our best telescopes on (predictibly they would be exponentially better than current ones at this point in technology). After a little calculated searching we would zoom in on the light that 65 million years ago bounced off Earth and see dinosaurs!
Other "time mirrors" could be placed at a few light-hours to a few light-days away for finding unfilmed instant- replays and cathing criminals in the acts of crimes they committed recently-- jellyfisherman, Jun 13 2008 A similar situation ... http://en.wikipedia...he_Squire_of_GothosSeeing the past ? [8th of 7, Jun 13 2008] Gravity Time Mirror Gravity_20Time_20MirrorPretty much the same thing, but no FTL travel required [ldischler, Jun 13 2008] Search for Terrestrial Intelligence Search_20for_20Terrestrial_20Intelligencerecover lost documents of broadcasting history [xaviergisz, Jun 13 2008] Why not just put the telescope at the "far point" and relay the images back ?-- 8th of 7, Jun 13 2008 we would still have to tell them where to look and our instructions could not travel any faster than light, so they would not know until the opportunity had passed. Unless, we sent the signals through the portal which would require opening it many times (as we would also have to do when any breakthroughs in telescope technology were made)-- jellyfisherman, Jun 13 2008 However, it will take the light 65 Million years to get back to your planet...... an all that time, inverse square law will be eating away at the signal ...
You'll need to keep your wormhole open, and pass the data back through it.-- 8th of 7, Jun 13 2008 I believe that is true. My mirror system won't work for seeing dinosaurs. However, i do believe it is more efficient for the police-type work and other uses of seeing the recent past-- jellyfisherman, Jun 13 2008 Mirror, mirror on M84, Will I see a dinosaur?-- Amos Kito, Jun 14 2008 random, halfbakery