In the movie "Deja Vu" with Denzel Washington, can someone explain how "Snow White" works?

Question

"Snow White" is apparently a program that allows you to "fold time". I don't understand the concept behind it though. And is something like that completely impossible?

Answer 1

in the movie, they were exploiting a wormhole, which acted as a shortcut tunnel between two locations in space-time.  One end of the wormhole was in the 'now' and the other end was in the '3 days ago'

it was a fictional construct.

All the more so because it acted as a bi-directionally traversible tunnel, and not just as a magic 'see the light from N days ago' which in theory would be possible without too much head scratching.

1.) place a mirror 1.5 light-days from earth

2.) use a really great telescope to look at it, and thus see photons that left earth 3 days ago.

voila, a 3 days ago read-only 'time machine'

And there are some who would tell you that since mass can curve the path light takes, there are already some masses out there which are bending light from earth 180 degrees and sending it back to us.

So all we really need is the insanely great telescope, since Abraham Lincoln's hat is definitely less than one pixel with current technology.