We have chosen you to assist us in an important research project, because our investigation has found you to be a science fiction enthusiast. We believe you have a better chance of comprehending the scope of our research than would most people of your time.
As you may have suspected, time involves a countless number of varying probability universes, all coexisting in the same time dimension. It is much like a giant tree, with branches sprouting from the root—the very beginning of time—and subsequent branches sprouting from others; and so, on and on.
Our research teams have travelled successfully into the past. However, in attempting to return, they have been faced with innumerable branches in time-probability, with no way of determining which branch led to our universe!
Only a few have succeeded in returning—by recording the complete facts of history as they went into the past, then stopping and checking those facts every few years on their return. When the facts didn't check, they knew they were off on another branch leading to another universe; they would back-track, try again, and check until they were on the right branch.
Even so, many members of our research teams died before they could return—and our average life-span is five thousand years! You may understand, then, that this is an intolerable situation that needs correcting.
The purpose of this project is to determine the amount of probability stress which causes a branch in time, this allowing us to check back and spot every moment that such branches occur! With that, we can compute the moments of stress and the number of branches in all time-probability! Consequently, our research teams may then travel safely to any time-era, in any probability universe, with a yard-stick which can always lead them back to our own universe.
And so, in order to measure the probability stress which causes time-branching, we have decided to introduce such stress ourselves. Enclosed is a product of our civilization. You would probably call it a robot. It should never have existed in your time; therefore, it will induce considerable stress upon probability. A branch in time should result, if not when the robot arrives, certainly when you make use of it. That, of course, is where you come in.
We have sent this robot because it will repay you many times over for your assistance in our project. We have scanners focused on your time, ready to record the branching and probability stress when it occurs. We ask only your cooperation. You may keep the robot, of course.
It will fashion any object you desire from surrounding matter—solid objects, air molecules, anything within a thousand yards of it—if you but type out the name and description of the desired object on its keyboard. Thus, if you wish an automobile, take the robot to a deserted road and type on its keyboard the word, "automobile." By influencing the sub-atomic forces of the dirt in the road, the empty air over the road, perhaps the grass along the side of the road, the robot will make you an automobile.
You may desire objects which do not exist in your time. If you type the word, spaceship, for example, be sure to include a description of its performance, range, amount of supplies, etc.—and be on a large, open field when you do so.