Tag: light

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See Through Objects

See Through Objects
How is it possible for us to see through objects (like air, water, and windows) and not through others (like wood, steel, and window blinds)?

Light is a form of electromagnetic wave energy oscillating in a particular frequency range and energy level. There are many more frequencies (and energy levels) in the spectrum of electromagnetic waves. X-rays are electromagnetic waves at a higher frequency than light. Radio waves from cell phones, radio, and Bluetooth devices are also electromagnetic waves at a lower frequency than light. We can’t see the waves that are above or below light frequencies because our eyes were not designed to see them.

We say that an object is opaque if we can’t see through it and transparent when we can see through it. When some light passes through an object, we say that it is translucent. Wood is opaque to visible-light frequencies, but it is transparent to electromagnetic waves in other frequency ranges. For that reason, we can listen to the radio or use our cell phones or wi-fi inside our houses. Our bodies are partially transparent to X-rays. That allows doctors to use X-rays to check for broken bones.

If our eyes were sensitive to radio waves and not light frequencies, we would be able to see through most solid objects. Then we would not only lose our car keys, but we would also lose our car–and our house too! The things we need to see would be invisible, and all of the electromagnetic waves around us would fill our vision with confusion.

Electromagnetic waves of different frequencies can pass through some materials but not others because of their wavelengths and the energy levels of the electrons in the atoms of the materials. So X-rays can pass through skin and muscle better than through bones. Radio waves can pass through wood, but not through steel. Light can pass through clear glass, but not wood or steel or cookie dough.

The complexity of this system allows us to see those things we need to see, like solid objects that our bodies cannot pass through. It also enables us to see through objects that we can pass through, like the air or water. It even allows us to see through objects which can protect us, like glass windows in our homes and cars. At the same time, it enables us to have cell phones, MRIs, and wireless headphones which use electromagnetic waves that can pass through objects without being seen. This very complex system took some incredible engineering by a Master Engineer.
–Roland Earnst © 2018

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What Is Light?

What Is Light?
A question that scientists cannot fully solve is the nature of light. What is light? Is it a wave or is it a particle?

Light has wave properties. It travels in straight lines, but it can be reflected from objects like mirrors, or refracted as it travels through objects like water or glass. Different frequencies of light waves are bent in varying amounts by a prism to show the colors of the spectrum. Light, like sound waves, can travel through gases (air), through liquids (water), or through solids (glass).

But light can also do something that waves normally cannot do. Light can travel through empty space. Because of that and other properties of light, we say that light consists of particles called photons, which act as if they have mass. Photons can knock electrons out of crystals in what we call the photoelectric effect. That’s how solar panels generate electricity from sunlight. So light in motion seems to have mass since it can pass through a vacuum or knock electrons out of their orbit. However, when we stop light, it has no mass. If you shine a light on an object, the light doesn’t make the object any heavier.

What is light? While science ponders that question, we use light every day, and we couldn’t live without it. The question of how light can have properties of both a wave and a particle has baffled scientists for centuries. Even though that answer to that question may never be fully understood, we continue to enjoy and use it every day.

We can see that the simple phrase “let there be light” (Genesis 1:3) is an incredibly complex command.
–Roland Earnst © 2018

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Why Are Plants Green?

Why Are Plants Green?
Why are plants green? The answer to this is some pretty basic physics.

The colors of light that we receive from the Sun have different energies. Red is the lowest of these energies followed by yellow, green, and blue. The sunlight with the highest energy that actually reaches the surface of the Earth is green. Blue light, which is more energetic, is refracted away by Earth’s atmosphere and scattered as it interacts with molecules in our upper atmosphere. That’s why the sky is blue.

When you look at an object, the color you see is the color reflected by that object. A red ball is red because it reflects red and absorbs all other colors. A green leaf is green because it reflects green and absorbs all other colors. If the highest energy of light reaching the surface of the Earth is green, and if the leaf reflects green, what does this do for the leaf? The answer should be pretty obvious – it keeps the leaf from absorbing too much energy and getting cooked. In the fall of the year when the leaves lose their chlorophyll A, which gives them the green color, what happens? The leaf gets cooked, falls off the tree, and we have to scrape it off the yard.

If a planet had a different atmosphere so that a different energy of light reached its surface, its plants would have to be a different color. To quote Kermit the Frog “It’s not easy being green.” Why are plants green? They are green because green is essential to life on Earth.

This explanation is greatly oversimplified. Obviously, not all plants have green leaves. Some plants live under a canopy of other trees and have to use a different system. The design of life on Earth is incredible, and the green trees and grass around us testify to the wisdom of God in making a place for life to exist.

We have a children’s book titled Why Is the Sky Blue, Why Is the Grass Green. You can read it and all of our children’s books on our Grandpa John’s Science Club site using THIS LINK.
–John N. Clayton © 2018

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Color Vision Gender Differences

Color Vision Gender Differences
There are many differences between men and women, but you realize that there are color vision gender differences?

Light is electromagnetic radiation that stimulates our eyes. There are only specific frequencies of the electromagnetic frequency spectrum that we can see. Frequencies below the range of visible light are called infrared. We can sometimes feel infrared radiation as heat, but we can’t see it, although some animals can. Frequencies higher than visible light are ultraviolet which we can’t see, but it affects our skin and can cause sunburn. Some animals can see infrared light.

Within the visible spectrum of light that humans can see, different bands of frequencies affect our eyes differently. Most of us have receptors in our eyes for the wavelengths which we call red, green, and blue. When light stimulates those receptors, they send a signal to our brain which combines the signals to allow us to see many variations in colors.

People with colorblindness (mostly men) have one of those color receptor categories missing. The missing color may be either red or green. Why are men colorblind more often than women? The genes that encode the red and green receptors are located in the X-chromosome. Men have one X- and one Y-chromosome. Women have two X chromosomes. That means that if a man has a defective X-chromosome, he is out of luck. A woman would need to have two defective X-chromosomes to be colorblind.

It’s interesting that the chromosome pair that creates the sex differences also explains the color vision gender differences. God said, “It is not good for man to be alone” and He took something out of the man to create a woman. Then He put them together to complete each other. In many ways, men and women really do need each other to be complete.
–Roland Earnst © 2018