Light is the electromagnetic radiations that our human eyes are able to perceive. In a technical or scientific context and as we will see later, in a symbolic and religious context too, light definition includes all electromagnetic radiations of any wavelength, even the ones we can't see. Light (i.e electromagnetic radiation of any wave length) have 3 basic dimensions: Intensity (amplitude), Frequency (Wave length) and Polarization. Polarization is difficulty visible by humans eyes (though a training can make the eyes more sensitive to this propriety of light). Some animals use it to navigate by using the Sun light polarization as reference because it stay the same. Intensity is the brightness of the light and the frequency is the color of light. Light can be seen as a wave or composed of particles, the photons. Quantum theories state that light is divisible by the Plank value, the minimum amount of energy, time and space.
Light have a great symbolic meaning. It symbolizes the knowledge and the power. It also seems to symbolize the evil. Indeed, the devil is known as "Lucifer" which means the one who have the knowledge (light). Knowledge and power can be used in a evil purpose but light is also seen as the good power, the one which bring clarity and beauty. Light is said to be in any people and symbolize life and spirit. Also light as opposed to darkness seems to represent the order (as opposite to the chaos). Light is the good force who bring happiness and order in the world. The gods are said to be composed of pure light and are the good spirit in the world. They have the knowledge and the power.
In the same time, several traditions (like the Vedic traditions) say that everything on Earth is composed of light and that the gods (who are composed of pure light) are the force that make the universe evolving and being as it is. In scientific terms, the gods could be compared to the force emanating from the stars and planets for example and for any particles in more details. They are the radiations who create heat on Earth and the several natural phenomenon. As invisible light they are the electromagnetic radiations which make the world as it is. In India they were said to generate the physical world as an illusion. Everything being light (electromagnetic radiations), our own spirit interprets these light and create its own interpretation of the universe ( people, object, events, place...). We should note that it is in India that the speed of light have been measured for the first time in the 14Th century commenting the Vedas (which are old as India, probably 10000 years ago).
