在现代物理学中，人们做了许多实验，以极高的精确度证明，物体的惯性质量总是和它的引力质量成正比，在选用适当的单位的情况下，可使惯性质量和引力质量在量值上完全相等，所以我们通常对物体的这两种质量不再加以区别。在爱因斯坦建立的广义相对论中，也认为惯性质量和引力质量是等同的。当物体的运动速度接近光速时，情况会怎样呢？下面我们对这种情况进行研究。(In modern physics, many experiments have been done with high accuracy to prove that the inertial mass of an object is always proportional to its gravitational mass. With the proper unit chosen, the inertial mass and gravitational mass Equally in magnitude, so we usually do not distinguish between the two qualities of an object. In Einstein's general theory of relativity, it is also considered that inertial mass and gravitation mass are equivalent. What happens when the speed of the object approaches the speed of light? Below we study this situation.)