Light does not have mass. It consists of particles called photons, which are massless elementary particles. According to Einstein's theory of relativity, massless particles like photons can still carry energy and momentum without possessing mass.
The propagation of light through a vacuum occurs through the interaction of electric and magnetic fields, as described by Maxwell's equations. These equations explain how changing electric fields generate magnetic fields, and vice versa, creating electromagnetic waves.
Unlike mechanical waves, such as sound waves or water waves, electromagnetic waves like light do not require a medium to propagate. They can travel through a vacuum, empty space, as well as through various materials, including air, water, and transparent solids. This is because electromagnetic waves are self-sustaining and consist of oscillating electric and magnetic fields that can propagate on their own.
The high velocity at which light travels, often referred to as the speed of light, is a fundamental constant in physics and is approximately 299,792,458 meters per second in a vacuum (denoted as "c"). This speed is a fundamental property of electromagnetic waves and is a consequence of the laws of electromagnetism. It is important to note that the speed of light is the same for all observers, regardless of their relative motion.
In summary, light travels at such high velocities through a vacuum because it consists of massless particles called photons, and its propagation is based on the interaction of electric and magnetic fields rather than the motion of particles through a medium.