Yes, according to Einstein's theory of relativity, mass and energy are equivalent and can be converted into one another. This concept is described by the famous equation E = mc², where E represents energy, m represents mass, and c represents the speed of light in a vacuum.
The equation states that energy (E) is equal to the mass (m) multiplied by the square of the speed of light (c). It implies that even a small amount of mass can contain a large amount of energy.
This relationship is exemplified in nuclear reactions, such as in nuclear power plants or nuclear weapons, where a small amount of mass is converted into a significant amount of energy. The most well-known example is the conversion of mass into energy in the sun, where nuclear fusion reactions produce the energy that sustains life on Earth.
Therefore, mass and energy are interconnected and can be seen as different forms of the same underlying phenomenon.