Added by Anup vasudevan on July 21, 2001 at 11:14:51:
A theory put forward by the famous German-born U.S. scientist Albert Einstein telling that mass of an object approaches infinity as the speed of the object approaches the speed of light.
According to the formula,
m = m0 / (1 - ((v^2)/(c^2)))^1/2
where m0 is the initial mass of the object , v is the velocity of the object , c is the speed of light in vacuum(approximately equal to 299,792.458 km/s) and m is the mass of the object in motion. This happens because when the velocity of the object increases it's kinetic energy also increases as kinetic energy k = m*(v^2).
But when the speed of the object is more than the velocity of light the mass of the object is a complex number(multiple of i where i = -1^2).