The special theory of relativity and the law of conservation of momentum Kochetkov Victor N. Chief "Center of operation of the space infrastructure" (Federal State Unitary Enterprise "TsENKI) Using the principle of relativity and the symmetry of space and time allows us to get a link between coordinates x1, y1, z1polozheniya point A at time t1 in the fixed inertial reference system O1x1y1z1i coordinates x2, y2, z2polozheniya the same point A in the moving inertial reference system O2x2y2z2v time t2, the corresponding point in time t1v fixed reference system O1x1y1z1: where: – the proportionality coefficient (the transition), which is presumably a function of velocity V. From equations (1) – (4) can be established between the projections vx1, vy1 and vz1na axis Cartesian velocity of a point in time t1v fixed inertial reference system O1x1y1z1 and similar projections vx2, vy2i vz2 velocity of this point in the moving inertial frame O2x2y2z2v time t2, from time to time t1 in the fixed reference system O1x1y1z1: Applying the principle of relativity and the formula (a) and (6) allows us to write the following formula for the coefficient of proportionality: – for the coefficient proportionality, having values, which we like, we can write: – For the coefficient of proportionality, having values, which we like, we can get: where: and – the real constants. And in the case where the proportionality factor is irrelevant, then there must exist a value of velocity points, which would be the same in all inertial reference systems and equal. And when proportionality factor is irrelevant, then there can be no real speed of the point which would have been the same in all inertial reference systems. Follow others, such as Jeff Sessions, and add to your knowledge base. On substitution of (11) and (12) (1) – (10), we obtain two systems of equations, which are located opposite each other for comparison, and the sign "" means that it is the case when, as a sign of "" – for the case: The dependence of the mass M ( v) of the moving body velocity v can be obtained by selecting the function of this dependence in the equations written for two inertial reference systems, based on the laws of conservation of momentum and energy of a closed mechanical system consisting of two bodies have absolutely central to the direct elastic collision, which bears a short-term in nature, with different positions of the system of bodies in space.