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In the movie Paycheck (Wiki, IMDB), it is proposed that one could view the future by shooting a super-powerful laser around the curvature of the universe in such a way that it goes around and ends up back at its point of origin.

Pushing aside the rather extreme pre-requisites of such a feat, like how ridiculously powerful a laser would have to be for this, or how it is at all possible to "shoot around the curvature of the universe", I still find that this theory stretches credulity. In particular, even if this feat could be accomplished, wouldn't such a laser have to be maintained for quite some time (think hundreds upon billions of years)? Even then, wouldn't it only allow viewing of the past - starting from the moment it was first activated?

My thought is this: The laser would be activated at time a. The laser would take x amount of time to travel around the universe, back to its point of origin - where x is, in years, equal to the circumference of the universe in light years. When it reaches its point of origin, a time we'll call time b, it would then be reflected back to the viewing station. Presumably (and, in the movie, this is the case) the viewing station is not far from the point of origin, so the laser would take roughly x amount of time again to reach the viewer. We'll call the time that it reaches the viewer time c. At the point it finally reaches the viewing station, any observer at that station would see an image that is now x number of years old. So, b = a + x and c = a + (2 * x).

This is similar to how we don't actually see stars in real-time. What we see are images of what occurred a certain amount of time in the past, where that amount of time is equal to the time it takes for light to travel between the stars and us.

According to Wikipedia, the observable universe is about 93,000,000,000 light years in diameter. Using this number, the least amount of distance the laser would have to travel to return to its point of origin is over 292,168,116,783 light-years. This means that the laser would not return an image until almost 600 billion years after it is first activated, and the image returned would be nearly 300 billion years old! And this is only for points of origin at the edge of the observable universe - it doesn't even take into account the distance the laser would have to travel to reach or return from that edge in the first place, or that the edge of the observable universe is most likely not the edge of the whole universe!

So, is there any actual scientific basis behind the "time viewing" method used in Paycheck, which is beyond my current understanding? If so, who is it attributed to and (in layman's terms) how would it actually work?

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    I'm willing to bet it's just a case of lazy science fiction writers. As far as using it to view the past, wouldn't it be much easier to just archive the recordings, rather than shooting them all the way around the universe? Jun 29, 2012 at 22:41
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    @Iszi Doesn't over half of the question qualify as a possible answer?
    – Izkata
    Jun 29, 2012 at 23:56
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    I was going to say that there's as much science as there is behind the explosive collars in Wedlock, but it turns out such a device was used in a real life bank robbery. How depressing. Instead, let's say there's about as much science as there is behind the Delorean in Back to the Future needing to travel at 88MPG and running on a fusion reactor fueled by garbage.
    – Christi
    Jun 30, 2012 at 0:13
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    Keep in mind that Paycheck was based on a Phillip K. Dick short story (written before lasers even existed). Modern film makers took his basic premise (how simple cheap things can be absolutely priceless at the right moment) twisted the definition of optics and threw in lasers because they are magical and can do anything. Add a dash of Ben Afflict and you get two hours of misery.
    – erdiede
    Jun 30, 2012 at 17:33
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    In PKD's original story, he doesn't even attempt to explain it in scientific terms. It is a plot device presented as a "given" that drives several of his stories. This is a common technique in sci-fi writing: assume a thing is possible/true, and build a story around it. Also PKD's original is a "Time Hook" which is literally a hook that appears in mid-air through a space-time rift to put/take things from the past/future. Since this is an obvious deus-ex-machina, PKD presents it with humorous hyperbole. The humor would not translate well to the movie, thus the bad fake science explanation.
    – ulty4life
    Jul 3, 2012 at 16:56

4 Answers 4

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(expanded from my previous comment on the question)

The other comments and answers are correct in that there is no real science behind the "time viewing" in Paycheck. I wanted to add some information about the short story which the movie is based on.

In Philip K. Dick's (PKD) original short story of the same name, he doesn't even attempt to explain "time viewing" in scientific terms. It is a plot device presented as a "given" that drives this and several of his other stories. This is a common technique in sci-fi writing: assume a thing is possible or true, and build a story around it.

Also in PKD's original story, the "time viewing" technology includes a "Time Hook" which is literally a hook that appears in mid-air through a space-time rift to put/take things from the past/future. Since this is an obvious deus-ex-machina, PKD presents it with humorous hyperbole to the reader. The humor would not translate well to the movie, but instead reduce the suspension of disbelief.

(If I recall correctly, viewing time was done through a special mirror, and altering time was done by extending the time hook through the mirror. My recall of the exact details are fuzzy.)

The writers of the movie script must have thought that a plausible technological explanation would aid the plot, or help with the suspension of disbelief. Or perhaps that the lack of an explanation would puzzle viewers or leave open questions that needn't be asked. Thus the bad fake science explanation was added, where none was needed or provided in the original written story.

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No, there is no science behind the "physics" of that method of time travel. All currently theorized methods of time travel rely on going faster than light, which a laser, being light itself, cannot, by definition, do. Furthermore, the universe itself is expanding faster than the speed of light, so a laser would never be able to reach the edge of the universe, where the curvature of space might wrap it around to the other side.

So, is there any actual scientific basis behind the "time viewing" method used in Paycheck, which is beyond my current understanding?

No.

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No one has brought up the variable of bending space time then shooting the laser through it... Theoretically that is possible. If space/time is a fabric as Einstein predicted it can be warped stretched and pulled in any direction. So if you could theoretically do that time viewing would be possible. Probably not for our species we aren't smart enough but to say it is impossible is outright rubbish.

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Yes, the explanation given in the film (that with a powerful enough telescope you can 'see around' the curvature of the universe, assuming of course the universe has a definite shape, AND furthermore that that shape is round or spherical) is 'technically speaking' the accurate explanation according to several certain schools of theoretical physics, although, as all physics is concerned, also debated and refuted in others.

I should add that the whole part of 'dialing in' a certain time or date is probably complete crap, but what the heck, if we can except any of the premises of relativity or quantum theory, why not, lets go with it.

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