To really understand the inner workings of electromagnetic radiation, we need to understand blackbody radiation, which is covered under 'quantum physics'.
Many materials that appear opaque to us when we rely on the visible spectrum, are transparent at other wavelengths such as X-rays and ultraviolet radiation.
In 1845, Michael Faraday found that light propagation in a material can be influenced by external magnetic fields (rotation of polarized light by magnetism).
In 1850, Michael Faraday experimented to find the link between gravity and electromagnetism, but all his efforts failed, a situation that continues today.
In 1861, James Clerk Maxwell set out his four laws of electromagnetic fields, proving mathematically that there was such a thing as electromagnetic radiation.
In 1864, James Clerk Maxwell published on his dynamical theory of the electromagnetic field, and his equations of electromagnetic wave propagation in the ether.
In 1873, James Clerk Maxwell published his Treatise on electricity and described the electromagnetic nature of light and predicted radio waves.
In 1883, George FitzGerald developed a theory of radio transmission, and explained how to create electromagnetic waves such as radio waves, but did not do so.
In 1894, Heinrich Hertz reported that radio waves travel at speed of light and can be both refracted and polarized. He had measured their wavelength in 1888.
In 1879, Joseph Stefan pointed out that the total radiant flux from a black-body is always proportional to the fourth power of its temperature.
In November 1895, Wilhelm Röntgen discovered some of the effects of X-rays, and spent almost two months identifying as many of their other effects as possible.
Cherenkov radiation is produced as bright flashes when high speed particles enter a medium, travelling faster than the speed of light in that medium.