根据相对性原理和光速不变原理不仅可以得到洛伦兹变换关系，而且可以证明运动的相对性条件，即爱因斯坦条件成立. 同时表明在相对性原理假设下，光速不变原理、间隔不变性和洛伦兹变换关系这三者等价.

According to the principle of relativity and the principle of invariance of light speed, not only Lorentz transformation can be derived, but also the relativity of motion, that is, the Einstein condition is true. It is also shown that under the condition of the principle of relativity, the principle of invariance of light speed, interval invariance and Lorentz transformation relationship are equivalent.