Space Contraction

Just as the time dilates as the speed of light is approached, the special theory of relativity predicts that space itself becomes contracted in the direction of motion as c is approached. This effect is called space contraction or the Lorentz contraction. The amount of contraction is given by the formula illustrated in the adjacent figure. In this formula, L is the observed length of an object measured in the direction of its motion, v is its relative velocity, c is the speed of light, and the length that would be observed at zero velocity is L0.

Thus, as objects approach the speed of light they appear to a stationary observer to shorten in the direction of motion, approaching zero apparent length as the velocity nears that of light. There is no effect in the directions perpendicular to the direction of motion. As discussed in the right panel, the source of this contraction is not a compression of the object itself but rather a compression of the very spacetime that contains the object.

Here is a calculator for space contraction.