Why light can travel through vacuum?

Answer 1

BASIC REASON

Light consists of electric and magnetic fields, both off which can be generated as well as propagated through vaccum.

EXPLANATION

To understand its behaviour, we must first know what light is, which requires to understand, what electromagnetic fields are.

ELECTRIC FIELD: when you place a charged particle in space, it creates a certain force field around itself. It is this field, that other charge particle will understand and react to (attract or repel). Very similar and as fundamental, as to the gravitational field around earth (earth creates a field around itself in space, and an apple behaves in accordance with the value of gravitational field at its location). Note that two charged particle won't stop forcing each other even if they are placed in vaccum. (fortunately gravitation also behaves similary, and that's what holding our vaccum universe together). So one can conclude that electric field can be created in vaccum as well. Though properties of electric fields generated by same source differ in different medium.

MAGNETIC FIELD: when a charge moves, it creates an additional, but quite a different kind of force field. This field exhibit same properties as that of a field created by rock magnet. That is, this field can be responded to by both, a moving charge or a stationary magnet. This field is magnetic field. Again a magnet can effect another magnet in vaccum as well as in some medium. (though the magnitude may differ in different medium). hence magnetic field can also be created in vaccum.

both of these fields have a particular magnitude and direction at any point in space. such fields are called vector fields. vector that have a value for all the points in space are called field vectors.

SINSOIDAL WAVE: an information (in sinosoidal form) that progresses in time from one point to the other.

LIGHT: Light is a mutually perpendicular, in phase wave of an electric field and a magnetic field, moving together and supporting each other,travelling in a direction that is perpendicular to both of them. As each of these fields can be created and propagated through vaccum as well, light itself is capable of traveling in vaccum. In fact, light travels fastest in vaccum, as compared to any medium say air or water or glass. the speed varies accross different medium because of ther different electric and magnetic properties, as mentioned above.