According to Einstein's theory of relativity, mass and energy are two interrelated forms of the same underlying concept. This concept is often summarized by the famous equation E=mc², where E represents energy, m represents mass, and c represents the speed of light.
The equation shows that mass (m) can be converted into energy (E) and vice versa. It implies that mass can be seen as a concentrated form of energy, and energy can be manifested as mass under certain conditions.
This understanding is supported by various observations and experiments, such as nuclear reactions where a small amount of mass is converted into a significant amount of energy, as seen in atomic bombs or nuclear power plants. Additionally, particle accelerators can create high-energy particles by converting energy into mass.
In summary, mass can be considered a form of energy, and the relationship between mass and energy is described by Einstein's theory of relativity.