faster-than-light (FTL) travel
Although Einstein's special theory of relativity insists that it is impossible to accelerate an object up to the speed of light and beyond (see light barrier), there has been no shortage of speculation on how ways may be found to circumvent this natural speed restriction. First, Einstein's theory allows in principle the creation of bizarre particles, known as tachyons, that have speeds permanently greater than that of light. Second, an object may be able to travel, apparently superluminally, between two far-flung points in the cosmos, providing it does not make the journey through conventional space-time. This opens up the possibility of using space-time gateways and tunnels, known as wormholes, as a means to circumvent the normal relativistic constraints.