Moving Sidewalks
Moving Sidewalks
[Cueball and Megan on the opposite far ends of a bidirectional moving sidewalk.  Arrows indicate that one half will carry Cueball from left to right, while the other half will carry Megan from right to left.  In each direction, the sidewalk is made up of a series of individual conveyors.] Cueball: Ready? [A diagram labels various individual conveyors as follows.] [Outermost conveyors:] Moving Sidewalk [Second and second-last conveyors:] Moving Sidewalk (2x Speed) [Next conveyors:] 3x Speed [Next conveyors:] 4x Speed [Innermost conveyors:] 5x Speed [Spot between the two sidewalks, directly in the center:] High-Five Location Megan: Ready.
This comic was originally uploaded with all the arrows facing in the opposite direction, before Randall updated it with the current image.

Cueball and Megan are getting ready to ride an array of mini-conveyor belts, each going at a speed multiple of the first ones. Assuming they both take the one in front of them, each conveyor belt will speed them up a little bit more with little effort on their part, ultimately reaching a point where they are going very fast and are close enough to be able to high-five each other.
The average moving walkway speed globally is 3 feet/second (~1m/sec), so Cueball and Megan would only be travelling about 2/3 average human running speed by the time they meet.  Even with the opposing forces added to their high five, it would be very unlikely for them to injure each other (though the slap would more than likely be painful).
The title text may be a reference to a music video made by OK Go, "Here It Goes Again", in which the band jumps on and off of various treadmills in a similar fashion.
A series of parallel accelerating conveyor belts is also a long distance travel mechanism used in Robert A. Heinlein's The Roads Must Roll and in Isaac Asimov's Robot Detective novels.
[Cueball and Megan on the opposite far ends of a bidirectional moving sidewalk.  Arrows indicate that one half will carry Cueball from left to right, while the other half will carry Megan from right to left.  In each direction, the sidewalk is made up of a series of individual conveyors.] Cueball: Ready? [A diagram labels various individual conveyors as follows.] [Outermost conveyors:] Moving Sidewalk [Second and second-last conveyors:] Moving Sidewalk (2x Speed) [Next conveyors:] 3x Speed [Next conveyors:] 4x Speed [Innermost conveyors:] 5x Speed [Spot between the two sidewalks, directly in the center:] High-Five Location Megan: Ready.
This comic was originally uploaded with all the arrows facing in the opposite direction, before Randall updated it with the current image.
