"Let there be light," were the first words spoken by the Creator in the formation of this world. The source of this light, which started the daily cycle of "mornings and evenings," is a moot question; was it from a special divine source or did the sun begin to shine? Sunlight is the source of energy for all life on earth. Without light living things could not survive. Besides furnishing warmth, light furnishes the energy for green plants to manufacture food by the process of photosynthesis; it lifts tons of water from the oceans to reservoirs to furnish hydro-electric power; it is the source of energy for electricity from fossil fuels; it produces the wind which turns windmills and turbines and pumps water.
We know all the wonderful things light can do, but what is it? It is invisible until it interacts with matter, and many of its properties are puzzling and even contradictory. For instance, light can travel through a vacuum; the light from stars travels for years through empty space, with no apparent loss of energy, before it reaches earth. This led Sir Isaac Newton and others to believe that light must be tiny particles projected through space, known as the "particle theory." However, phenomena such as diffraction, interference, and polarization caused some to believe that light was composed of waves, known as the "wave theory." But how does a wave travel through space? What is waving?
Christiaan Huygens came up with a very logical answer. He postulated that a substance he called "the ether" filled space and the whole universe, and so it was "the ether" that was vibrating. Then along came Albert Michelson and Edward Morley who performed their now famous Michelson-Morley experiment that completely exploded the "ether" theory. So if ether wasn't the answer, then how do light waves travel through space? The controversy raged back and forth. Olaus Roemer, Armand Fizeau, Jean Foucault, Thomas Young, Jean Fresnel, Max Planck, Albert Einstein, and many others entered the fray. Finally, the paradox was resolved in 1924 by Louis deBroglie with his wave theory of matter; that matter actually has wave properties. From this theory came the idea that light is composed of wave particles called photons.
The Bible has much to say about light. Jesus said that we are the light of the world; He said that we are to let our light shine so that all can see; He said that we should not hide our light under a barrel, but put it on a pedestal; He said that a lighted city on a hill cannot be hid. Of course He was talking about spiritual light, heavenly light. Darkness can only be defined as an absence of light. Many parts of the world are in spiritual darkness because they have not received the light of the gospel. Even here in the USA there are what we call "dark counties." We have been told to go to these dark places to preach the gospel because we are "the light of the world."
