Genesis 1:3-5 Let There be Light CLICK TITLE FOR AUDIO
In Gen. 1:3-5, God created light. This was not sunlight because the sun was not created until the fourth day. Notice in Ps. 74:16 that there is a difference between the sun and this light that God formed (Is. 45:7) and made to shine out of darkness (2 Cor. 4:6). In reality, the energy from the sun would not be visible if God had not created light.
There would be no life on this earth if there was no light. And as there is no life apart from light, even so there is no life apart from the Lord Jesus Christ (1 Jn. 5:12). Therefore, Jesus said, “I am the light of the world,” (Jn. 8:12). The existence of light is one of the greatest testimonies for the existence of God and for our individual need of “the Light of the world.” Without him, we end our lives on this earth in “outer darkness,” (Matt. 8:12).
Light is a form of radiation visible to the human eye. Radiation from the sun provides the energy needed for plant growth. Photosynthesis is the chemical process whereby the energy in sunlight is stored in plants. Petroleum, coal and natural gas are the remains of plants and they release the chemical energy converted from sunlight when they burn. Animals release the energy stored by photosynthesis when they digest the plants and animals that they eat.
Light is referred to as radiation simply because it “radiates”. Most radiation you hear about is harmful, however, only the very high energy radiation is capable of damaging tissue. The smaller the waves get, the more energy they have. Ultraviolet is an example. Just above visible light, it causes sunburn. Excess exposure will result in cancer. X-rays and gamma rays are even more damaging.
The waves associated with light and radiation are called electromagnetic waves, or electromagnetic radiation (EMR). Electromagnetic waves range from the longest radio waves to the shortest gamma rays. The range runs radio, microwave, infrared, visible light, ultraviolet, x-rays, and gamma rays. These waves behave like a rope when it is moved up and down. Essentially, then, radio waves are audible (through a radio), yet invisible, and visible light waves are visible, yet inaudible. Today, we use fiber optic cables to carry on telephone conversations around the world.
All electromagnetic waves travel at the same speed. So, in one second, more short waves will pass by a certain point in space than will longer waves. This means that shorter waves have a higher frequency than longer waves. For comparison, light waves are measured in nanometers (one billionth of a meter) and radio waves are measured in meters. The wavelengths of visible light range from 400 to 700 nanometers (nm) and the wavelengths of radio waves range from several meters to several thousand meters.
Each different wavelength of visible light causes our eye to see a slightly different color (as in a rainbow). The longest wavelength we can see is deep red at about 700 nm. The shortest wavelength we can see is deep blue or violet at about 400 nm. Human eyes respond best to green (550 nm), which is the brightest color in sunlight at the earth’s surface.
There are different sources of light. If the energy comes from heat then the source is called incandescent. The sun, then, is an incandescent light source. If the energy is chemical or electrical, the source is called luminescent. The color of incandescent sources is related to their temperature. Hotter sources are bluer and cooler sources are redder. About 75% of the radiation from an incandescent bulb is infrared. So you can pass the light through a glass and it will be just as bright but the glass will be hot.
The color of a luminescent light source is not related to its temperature. Luminescent light is cooler than incandescent. A fluorescent light is a type of luminescent source that makes use of chemical compounds called phosphors. Phosphor compounds are also used to convert electron energy to light in a television picture tube. The aurora borealis is also luminescent. Many creatures, from bacteria to fish, make light by manufacturing luciferase and luciferin (notice the root word Lucifer in these words. Lucifer was the light bearer before he fell and now he has transformed himself into an angel of light). Luciferase helps luciferin combine with oxygen to produce light. Fireflies use flashes of light to attract mates and fish use light to attract prey or confuse predators.
A laser is a special radiation source whose regular waves permit the light to be very tightly focused. Lasers are used in medicine, research, military technology and communications. They can drill holes in diamonds, help doctors perform surgery without damaging the surrounding tissue, and are useful in space communications because they carry a great deal of information and travel long distances without losing signal strength.
Radiation is detected by two primary methods: the photoelectric effect and the photochemical effect. Solar cells use the photoelectric effect to convert sunlight into electricity. Photographic film uses the photochemical effect to chemically change photosensitive chemicals on the film and capture a permanent image when the film is processed. Light of different frequencies causes different chemical changes in the human eye, generating nerve impulses that the brain interprets as color, shape, and location of objects.
Radiation can be absorbed; causing the material that absorbs it to heat up. Light can be reflected when it hits the boundary between two materials, such as the boundary between air and a smooth lake (which forms a mirror image). Light can be refracted, that is bent at different angles, such as when sunlight passes through a glass prism. Light can be scattered. The sky is bright because molecules and particles in the air scatter sunlight.