Gott's proposal relies on idealized versions of cosmic strings. In order to be em-ployed in the service of a time traveler, two cosmic strings, perfectly parallel and traveling at nearly the speed of light, must whiz past one another like two cars traveling in opposite directions on a highway. As the strings pass each other, space-time would become profoundly distorted by the influence of these fast-moving filaments. A savvy time traveler, waiting in a nearby spaceship, could exploit those distortions by flying around the coupled strings. If he timed it just right, the twists in space-time would enable him to return to his starting point before he began-making the voyage a one-way trip back in time. Which means that, according to the laws of physics, journeys through time are conceivable, if rather difficult to arrange. It may be only a matter of time.