Posted by jlwile on March 24, 2014
Last week was really busy. That’s why I haven’t written a post since the 13th. It started with a trip to The Homeschool Gathering Place in Raleigh, North Carolina. That’s where the photo above was taken. The owners of the store, who have been a blessing to homeschoolers for the past 18 years, arranged for me to speak at a nearby church, Colonial Baptist. It was a huge church, and the homeschool group there is quite large, so the turnout was great.
At the church, I showed several videos that demonstrate mutualism, which is something I find incredibly fascinating (see here, here, here, and here for a few examples). I also showed videos about some of the amazing design you see in nature, such as the way octopodes (the best plural of octopus) camouflage themselves. I then spoke about the recent scientific studies that either confirm the predictions of creation science or falsify evolutionary predictions, most of which has been discussed on this site. Not surprisingly, the videos were the biggest hit.
After the event at the church, I went back to The Homeschool Gathering Place and gave a talk about teaching science using history as a guide. That’s how my new elementary science series is designed. The talk was much more intimate, by design, and it generated a lot of good discussion. I also got to talk with students while I was there, as the picture above shows.
In between these appearances, I got to spend some time with an old friend, who I call “Roxy.” I think I might be the only one who still calls her that. She and I grew up together, but she left Indiana, and the last time I had seen her was more than 10 years ago. We seem to have the beginnings of a mutual admiration society going. She kept telling me how proud she was of what I had accomplished over the years, and I kept telling her how impressed I was with her. She is a very talented dancer, and I always looked up to her as we were growing up. Today, she is a mother who has raised great young adults. She also teaches dance and history to groups of homeschooled students. I got to help her teach two of her classes (history, not dance!), and those young students are incredibly blessed to have her! She is changing lives, and I am proud to call her my friend.
I got a lot of great questions during all those appearances, but the one I want to address here came from an elementary-aged student in one of Roxy’s classes. The class had been discussing inventions from wars, so I talked about microwave ovens, which arose from radar development in World War II. While working for Raytheon, a self-taught engineer named Percy Spencer was working on an active radar set. He noticed that the radar melted the Mr. Goodbar in his pocket, so he decided it could heat food. He experimented with the idea and ended up popping popcorn with radar waves. Raytheon filed a patent, did some tweaking, and by 1947, the “Radarange” became available. We now call them microwave ovens, because the waves used in radar are more generally called “microwaves.”
In the course of the discussion, I put a bar of Ivory soap in a microwave oven, and in about a minute, it expanded into a lovely pile of what looked like meringue. Other brands of bar soap will expand, but not nearly as wonderfully as Ivory soap, because Ivory has a lot of air pockets in it. I then took the turntable out of the oven and put a plate of egg whites in there. Without the turntable, the egg whites cook much more quickly in specific places, because the microwaves are…well…waves. As a result, the egg whites cooked where the crests and troughs of the waves were. They were still liquid everywhere else. You can actually measure the distance between the centers of the cooked regions and multiply by 2 to get the wavelength of the microwaves.
I had the students draw waves and then explained to them that the only difference between the waves that come from light bulbs and the waves used by microwave ovens is the distance between the crests and troughs of the waves, which is half of the wavelength. The microwaves used in ovens have wavelengths on the order of 12 centimeters, while the light coming from the light bulbs have wavelengths on the order of several hundred billionths of a meter. I then used my cell phone camera to show them the infrared light used by a remote control (you can see it with any cheap digital camera) and told them that infrared light has a wavelength of about a millimeter.
I told them that collectively, we call all of these waves “electromagnetic radiation,” and a girl’s hand popped right up. She asked, “Isn’t all radiation bad?” I told her that I completely understand why she would think that, since the media does such a horrible job at discussing science. However, radiation can be good, bad, or neutral, depending on its wavelength. Visible light is radiation, and it is clearly good, because it allows us to see. Infrared light is radiation, but it is also good. Not only can we use it to be lazy (with remote controls, for example), but it is the principle way that warm substances transmit their heat over long distances. You feel the warmth of a fire primarily because it emits infrared light, which your skin then absorbs.
However, as the wavelength of radiation gets smaller and smaller, the waves get more energetic. If the wavelength gets small enough, the radiation can actually cause damage to living tissue. Ultraviolet light, for example, has wavelengths of 10 to only a few hundred billionths of a meter. As a result, it can damage living tissue. When you are out in the sun too long, you can get a sunburn, because some of the sun’s light is ultraviolet, and it can damage skin cells. Now…your body is designed to lose skin cells all the time, so some exposure to ultraviolet light will not cause a problem. Your body can fix the damage that is done. Too much exposure kills too many skin cells too quickly, however, and the result is a sunburn.
Of course, radioactive substances can also emit radiation that has enough energy to kill cells and damage DNA. Once again, then, too much exposure to that kind of radiation can cause burns or cancer. However, your body is designed to deal with some exposure to that kind of radiation. For example, every person you meet is radioactive, because the human body contains at least eight different radioactive substances. The most important ones are potassium-40 and carbon-14. In addition, the more fat you have, the more potassium-40 you hold, so the more radioactive you are!
In the end, then, radiation is only “bad” if it is the right kind (very short wavelengths) and you are exposed to way too much of it. In addition, you can do things to avoid too much exposure. If you are out in the sun, for example, you can put on sunscreen, which absorbs the ultraviolet radiation so that it doesn’t kill your skin cells. If you are near a radioactive substance, you can either just move away from it or put a shield between you and the substance that will absorb a lot of the radiation coming from the substance. Of course, that can be hard, because one form of radiation coming from a lot of radioactive substances (called “gamma rays”) can require a thick wall of lead to absorb most of the radiation.
Even the “bad” radiation, however, can be used for good in some circumstances. One popular treatment for hyperthyroidism is for the patient to drink radioactive iodine. The iodine preferentially gets stored in the thyroid, and the radiation it emits kills some of the thyroid, reducing its activity. The same kind of treatment is also used for thyroid cancer. In addition, when a cancer patient has a tumor removed, he or she is often treated with radiation to kill whatever parts of the tumor the surgery could not remove. Sometimes, beams of radiation are used to kill tumors when surgery is too dangerous.
So radiation is not necessarily “bad.” Certain kinds can be bad, but even those kinds can be used for good.