# Length contraction

**Length contraction**, according to

Albert Einstein's

special theory of relativity, is the decrease in

length experienced by people or objects traveling at a substantial fraction of the

speed of light. It is experienced only in the direction in which the body is travelling and not transverse to this direction, which in turn is dependent on the

frame of reference relative to which that motion is being measured.

It is important to note that this effect is negligible at everyday speeds, and can be ignored for all regular purposes. It is only when an object approaches speeds on the order of 30,000,000 m/s; 1/10 of the speed of light, that it becomes important. As the magnitude of the velocity approaches the speed of light, the effect becomes dominant, as we can see from the formula:

Where L

_{0} is the distance travelled measured by a stationary observer and L

_{1} is this distance measured by an observer travelling at velocity

*v*. From this simple maths which is part of the

Lorentz transformations, we can see that an observer travelling at the speed of light (which, according to

general relativity, is impossible for any object with a non-zero

rest mass) would measure all distances in the direction of motion as 0.

See also: