The Ancients were a people who would bend space and time to their will, allowing them to perform what is essentially magic. One of their most important tricks was to twist time, allowing their machines to do astounding things quick enough to be useful. Almost all artifacts have a temporal accelerator in them. When the accelerator breaks, it is really obvious as the machine apparently doesn’t work or acts very slow.

But those are minor issues compared with the effect that terrified engineers. Any Mutant Future character that attempts to discover the function of an artifact (p. 42) with a functional accelerator and fails with a 99-00 roll has a 50% chance of aging 1d20 years (no save). Even the Ancients couldn’t make people younger, so only machines serviced the factories where the temporal tech devices were constructed.

This also means there are places in the world of Mutant Future where time is at a standstill and others where it is accelerating to the point where nothing can survive (they starve instantaneously). Fortunately those endpoints are rare and much milder temporal effects are much more common. Some are refuges for those who want to see the current world pass or discourage raiders who don't want to be sitting ducks.