The Alcubierre drive or Alcubierre warp drive is an idea for a faster-than-light travel engine. The Mexican theoretical physicist Miguel Alcubierre created this idea using Albert Einstein's field equations in general relativity. The main principle of this idea is by creating an energy-density field lower than that of a vacuum (that is, negative mass) to make the space in front of the ship contract and the space behind the ship expand. In theory, this would create a bubble in space-time around the craft, allowing it to stay still while the space around it moves. This would effectively avoid breaking Einstein's rule that no object in our universe may go as fast or faster than the speed of light, while still allowing an object to go to another very distant part of space much faster than light.