In Primer, did they really need to do the time travelling themselves?

Question

Is there any reason given either in the movie, or by any of its many analysts, why Abe and Aaron must make the 6 hour trip backwards themselves?

Could they not have designed an intelligent device, as discussed in this article, that would allow them to just send a piece of paper backwards in time at 2:30PM with the stock market information from the day, which they would have picked up at 8:30AM when they power up the machine?

Here's the relevant paragraph from the article I linked above:

Almost immediately once they discover this, Aaron and Abe reason that if they could create a device which had some degree of intelligence, like a programmable miniature robot or something, they could program the object to measure the amount of time that has passed and then spontaneously trigger the collapse of its own waveform from inside the box, thus selectively exiting the box at point B or point A. From this they imagine a box where the robot is inserted at 12:01pm, point B, waits for one minute, climbs out of the box at point A (12:00pm), and thereby travels backwards in time."

Answer 1

Several difficulties/problems come to mind:

Given the time setting of the movie (based on the type of computers and cell phones they use), they don't have the same technology we currently have. It would have been hard to design something that autonomous that still worked inside the storage unit. I don't think looking up the stock info from inside the storage unit was possible (why else would they go to the library?).

If they wanted to design something like that, it would need software to program all its actions. Abe and Aaron are not that skilled at programming (I remember them saying they didn't need Robert/Philip because the device didn't need software). They are better in physics and mechanical engineering so they build a bigger box instead of programming a robot.

Finally, going back in time yourself would be the next logical step because it offers so much more possibilities (like them engineering the party event). They're engineers looking for profit and publishing. They would have inevitably taken their research to the next level.

Answer 2

Along with the answer given by another, it would create a paradox given the way that time travel works in Primer. The alteration of one's past self creates a paradox self, which is why, later in the film, one pair of Abe and Aaron lose the ability to write. With them going back in time, it allows them to take the full benefit of time travel without the risk of altering their past selves and creating a paradox.