We often tend to think of our vision as reaching out to observe things. However, in reality, views flow the other direction—to us, at the speed of light. Light is essentially enlightening us by bringing information of what’s out there to us.
For example, we could stand outside and look toward a birch tree. In our mind’s eye, we see a complete image. But the brain has assembled that image for us from only a series of tiny electrical impulses that have traveled up the optic nerve from our eyes. Those impulses carry depth, color, brightness, and size information. It’s all processed effortlessly and assembled into a sensible image in our mind.
Just before the eye sends the impulses to the brain, it receives thousands or millions of tiny packets of energy called photons (light). These photons have taken on the characteristics of the tree. The leaves look green because they mostly reflect green wavelengths of light and soak up all other wavelengths of visible light. That green color we’re seeing coming from the leaves, originated in the sun, not in the leaves. Therefore, we can’t technically say the leaves are green. It’s just that they reflect green light.
The trunk of the birch tree appears white because it reflects all wavelengths of light equally. Our eyes can detect the subtle differences in wavelengths of light, and the brain assigns a color to help us distinguish one from the other. A wavelength of about 450 nanometers (NM) appears blue to us, 550 NM appears green, and 700 NM appears red.
We can use this eye sensitivity to color to learn fun facts about the sun and stars. It’s possible to roughly determine the temperature of stars from your backyard. Some stars look “cool” and bluish while others look “warm” and yellow or red. It’s not hard to understand that red stars are hot; they’re about 3,000° Kelvin. On the other hand, blue stars are not cool; they are tremendously hot—about 30,000° Kelvin, 10 times hotter than red stars. The sun is a little over 5000° Kelvin. It has a balanced white color that’s very slightly skewed toward yellow. With this knowledge, you can tell at a glance how hot a star is.
Most light bulbs are sold using a color temperature rating that somewhat matches what we see in the stars. The warm glow of an old incandescent bulb with a filament is about 2,700K (the K stands for Kelvin). LED bulbs rated at 5,000K are much whiter and about the same color as the sun. Bulbs that are 6,500K and higher are noticeably bluer.
Light behaves in unusual ways. For example, it moves at 186,000 miles per second. If it passes through glass, it slows down by about a third. It then instantly reverts to its original speed after exiting the glass. At 186,000 miles per second, light is basically at its resting state. It will automatically revert to that speed if not being acted upon by some outside force. Even stranger, the closer something moves to the speed of light, the more time slows down for it. At the speed of light, time practically stands still.
Light has mysteries that haven’t been solved yet. One of them is exposed by the double slit experiment. If light is shone through one slit, you get just what you expect—a slit of light projected on a wall. If you shine a light through two slits placed side by side, you get something a little unexpected. There will be an interference pattern of not just two slits of light projected on the wall, but, instead, dozens of them.
You can try the experiment for yourself by splitting a laser beam with a pin. When the experiment was done in our house, we had about a 180° semicircle of tiny light pillars around the room. This demonstrates how light is made of individual packets of energy yet behaves with a wavelike function. The light waves either amplify or cancel each other out, causing the interference pattern.
The mystery deepens when one photon at a time passes through a slit. The interference pattern still appears. This means the photons must be interacting with themselves somehow. When researchers set up sensors to see where the photons were and which slit they were going through, they found the interference pattern disappeared. Through these experiments, scientists describe the non-locality of light. It’s virtually impossible to pin down the actual location of a photon.
Interestingly, these things remind us of God, Whom the Bible says “is Light.” God also has a type of non-locality—He is omnipresent. Also, pure light appears white, yet is a trinity of the primary colors red, green, and blue. God is one triune God, comprised of Father, Son, and Holy Spirit. And lastly, at the speed of light, time practically stands still. God is dwelling in eternity, the absence of time.
