When the observer's motion state changes, different forms of energy in an isolated system will undergo changes (this is the relativistic effect of energy). If the coefficients of the relativistic effects of different forms of energy are different, changing the observer's state of motion can become a condition for breaking energy conservation. This situation is the principle of energy conservation state change (PECSC). It can serve as a theoretical criterion for testing the correctness of physical theories. Through quantitative analysis of several cases, it was found that PECSC holds true: the principle of narrow relativity can lead to the destruction of the conservation of quantities in the system. This conclusion prompts us to seek new perspectives on spacetime. Considering that the phrase ‘spacetime undergo changes due to absolute motion’ coordinates the relationship between relative and absolute, a relatively-absolute view of spacetime (RAVS) that is compatible with each other can be chosen, and a RAVS which is compatible with both relative and absolute can be chosen. The advantages of RAVS have been proved. Applying the RAVS to analyze previous experimental data, it can be predicted that the absolute motion speed of the Earth is 0.0005c.