Light can be defined as electromagnetic radiation within a certain portion of the electromagnetic spectrum, which is visible to the human eye. It consists of particles called photons, which have both wave-like and particle-like properties. Light is characterized by its wavelength and frequency, and it can travel through space at a constant speed of approximately 299,792 kilometers per second (or about 186,282 miles per second) in a vacuum.
Regarding the relationship between light and mass, light itself does not have mass. According to the theory of special relativity proposed by Albert Einstein, massless particles, such as photons, always travel at the speed of light in a vacuum. This means that photons have both energy and momentum but lack rest mass.
Einstein's equation E=mc², where E represents energy, m represents mass, and c represents the speed of light, relates energy and mass. It states that mass and energy are interchangeable and can be converted into one another. The equation suggests that a small amount of mass can be converted into a large amount of energy and vice versa.
While light does carry energy, it already exists in the form of energy and does not possess mass. Therefore, the equation E=mc² does not apply directly to the conversion of light into energy. However, the equation is relevant when considering the conversion of matter (which has mass) into energy, as demonstrated in nuclear reactions or particle interactions. In such processes, a small change in mass results in a significant release of energy according to the equation.