Why does light not need a medium?

Answer 1

Visible light is a small part of the frequency spectrum of electromagnetic radiation. It behaves both as a wave and a particle (photon), and travels by virtue of the energy expenditure required to "create" it (I use quotes because light, like all energy, cannot truly be created, only changed in form. The light we're most familiar with, sunlight, is released through the fusion of hydrogen atoms into helium, a process that transforms a tiny portion of the atoms' mass into energy).

Unlike sound, which as a mechanical waveform requires a medium such as air or water to propagate, light can instead find its progress impeded or blocked by various media.

Answer 2

Light is a very strange thing. Look up entangled photons and you'll see that light has characteristics that cannot be explained within our own universe.

Answer 3

One clear evidence is that sun's light reaches to the earth passing through the vacuum which is not a material.