Chronoscope: Not literally possible, but the combination of ubiquitous computer/sensor technology coupled with ridiculously huge amounts of computing power to assemble the evidence into a picture can do a damn good imitation of a past-viewing chronoscope. Doing the same thing with prognostication software is, alas, rather more limited, and becomes extremely unreliable more than a couple of seconds out.
(And with a powerful enough telescope, let’s not forget simply looking into/receiving signals from the past with the able assistance of light-lag.)
I’d imagine, though, that those extra couple of seconds can make all the difference in the right circumstances.
Which, incidentally, leads me to wonder: Have there ever been any duels won in zero strokes?
In the “my tactical prolepsis shows that I have p<δ of victory, therefore I concede” sense? Certainly.
Why is it so glibly deemed impossible? Given that this universe is bloc, it would seem to be in principle not impossible.
The blockness of the universe is actually half the reason why it’s considered impossible, coupled with the observer effect.
Since you can’t observe a particle without interacting with it, the lack of a bunch of otherwise-inexplicable particle interactions (which would have to have already happened, per the block universe) around significant past events, including but not limited to those chunks of space and time specifically set aside for testing such things, is considered a high-probability proof that no-one’s watching from elsewhen.
I read a story years ago, I could find it again, because it started with the death of a famous atheist because terrorists attacked the datacenter that his upload was running in, where they proved in-universe that pure material atheism was not the case because there were places and times where entangled observer interactions were happening from “Outside”.
It was after I had read the story, that all of the sudden it hit me what the “Outside” was, and who the Outsiders were. It was the readers of the very story….
Ha! Nicely done, that writer.
The Death of Richard Dawkins by Steve Yegge
And the phrase that blew my mind the day after reading it: “there are many more observers this time — and only this time — than even you may suspect or be able to detect”