Seeing Is Believing, Sunburn Says Otherwise

The villagers, Science Village's happy residents, have had enough of this summer heat. When it's not muggy day after muggy day, it's when they work outside just a bit too long and get sunburned. Cursing the ultraviolet spectrum profusely, they congregate indoors somewhere with some nice cold water, comiserating about their scorch-skinned woes. Then, they get a brilliant idea! All this talk about invisible energy makes them want to go out and tell their occasional visitors all about it, as they each have something unique to say given their respective jobs.

Zookeeper's Infrared- and Ultraviolet-Seeing Friends

Zookeeper, the Village's happy keeper of the pets, approaches her waiting visitors with what is revealed to be a big terrarium containing a snake.

"You know what's special about this snake?" she says. "He can see infrared light." She points to the reptiles eyes. "He can see regular visible light like we can, but he's also got another little pair of eyes under those. It is with those eyes he can see infrared light. Can anyone guess why he and other snakes might like this feature?"

The crowd shrugged.

Zookeeper continued: "Night prey! Their animal prey gives off body heat, right? This body heat has a longer wavelength than red light, so it is infrared light, and we can't see it. But the snake can with his special extra eyes. So even at night when he otherwise couldn't see a tasty little creature, he can see the body heat, and go at it like normal, because his special infrared eyes make it visible to him!" She gazed out at the crowd, spotting a man who looked doubtful. "Why don't you come over here for a demonstration?"

Reluctantly, the man stepped forward next to the terrarium.

"Now," Zookeeper continued. "I haven't fed this snake in the past day or so, so he's pretty hungry right about now! Good thing I've kept that terrarium closed up nice, eh? Well, I'm going to get behind this little wall and shut off the lights. I advise the rest of you to step back a little." When the man by the terrarium started to move, she added "No, no. You stay put. It's part of the demonstration."

Zookeeper shut off the lights so the room was completely dark. She pressed a button which opened the top of the terrarium. All of a sudden, there was a vicious "HISS!!!" and the man began screaming for his life. The lights came back on to reveal the big snake biting the man, who flailed around yelling "Get it off me! Get it off me!". Laughing, Zookeeper coaxed the snake off him and got him back into the terrarium.

"You may want to go see Dr. Med," she advised. "But, as we can all see, even with the lights off, the snake could still see you and attack you. That's the amazing tale of snake eyes and infrared light."

She took the terrarium out of the room and returned with what she revealed to be a big honeycomb swarming with bees. "Now," she announced. "Bees can see ultraviolet light! That's the one on the spectrum just smaller than violet. A nice advantage to this is a cool flower signaling system! You see, bees get real testy when other bugs come over and start bogarting their flowers. The flowers don't like it either. Since those other insects cannot see UV light and bees can, they have a simple remedy. The flowers don't look all that inviting to the other bugs, but has UV markings to call the bees over. That way, flowers are for the bees!" The crowd muttered in amazement.

"For a demonstration," she went on. "I need two volunteers." Without waiting for anyone to step up, she randomly pointed to two people in the crowd and pulled them forward. "You two will do just fine. Now, I'll demonstrate this attraction to the UV light with this special ultraviolet dye. Hold still." She put hats on her two volunteers and then sprinkled a bit of dye on one hat. "Now watch."

She set the bees loose. The buzzed around a bit before swarming to the guy with the dye on his hat. "AAAAHHH!!!!" he screamed, running back and forth frantically. "Get them off! Get them off!"

Zookeeper hopped excitedly. "You see! They saw the UV markings on his hat and went right to him!" She beamed at him. "Oh, relax. They just think you're a flower. They like you!"

The crowd muttered as she took back the hats and collected the bees back into their confined honeycomb.

"And that's how our animal friends can see light that's invisible to us!" she concluded.

Dr. Med's Sunburn Session

"Welcome!" greeted stout old Dr. Med when the crowd of visitors came his way. "I am Dr. Med, the village's medical professional. I'm here to discuss a nasty annoyance. Sunburn! That's right. Most of us right here in SciVille have a case of it since we work outside a lot. Just an innocent redness and burning of the skin, right? Wrong! It transforms your innocent skin cells, messing them all up, and eventually may lead to skin cancer."

The crowd looked all worried.

Dr. Med went on: "There are different kinds of ultraviolet light, which is what makes the skin burn, and why we're quite glad to have the ozone layer and not too happy to see it being depleted! You see, there is UVA and UVB. UVA is the longer one. UVB, the shorter of course, is the most common one that causes sunburns, since it is more easily absorbed. Your skin pigment melanin protects against ultraviolet radiation, but a sunburn occurs when there's more UV than your melanin can handle. Even though ultraviolet can be our friend when it urges production of vitamin D and kills bacteria on things that should not have bacteria, it is also very dangerous. DNA in skin cells absorbs it and gets damaged, and while cells have lots of safety and repair mechanisms against this, they can't hold off forever. Aside from skin cancers, which include squamous cell carcinoma, basal cell carcinoma, and the very nasty malignant melanoma, it can cause premature wrinkling, cataracts, and probably diminishes the immune system."

"What about sunscreen?" asked one frantic visitor. "Yeah, how about sunscreen?" asked another.

"Well," Dr. Med replied. "The kind with SPF 15 or higher is what to use, but even when used properly and often enough, sunscreen cannot protect against everything. It only protects against UVB. UVA still has a free run, and you're still prone to the immunity risks and whatnot. It takes a long time for it to built up, like a few decades, but the detrimental long-term effects of too much UV exposure can pop up as early as your teens, but usually later."

The crowd looked nervously at the sunny sky.

"Of course," Dr. Med went on. "No need to stay out of the sun all the time. Just keep it in moderation, you know."

"Hey," a visitor spoke up. "Isn't there a UVC? What's that?"

Dr. Med shuddered. "Ugh! That's even worse than the other two. It's why we should hope that ozone layer holds up. UVC gets blocked by it, and good thing it does. UVC gets to us, we're screwed! It's got the highest energy of the three."

Watchman's Waves

Aerial Watchman stood on his high perch as the visiting crowd gathered at the foot of the watchtower. He gazed far and wide through his telescope, which eventually pointed to the visitors below.

"Oh, hello!" he greeted them through a speaker connected to the top and bottom. "Didn't see you there at first. Just been trying to put up a nice canopy to block the sun for a bit. I'm sure Dr. Med told you all about that already. Anyway, while worrying with ultraviolet radiation, it got me thinking of all the other electromagnetic spectra hitting me and everyone else all the time."

The crowd muttered and gathered closer to the speaker, intrigued.

"Yup," Watchman went on. "I was just glancing at some of our village's towers. We've even got a satellite that we use on occasion. But anyway, it all uses the next thing up from infrared on the electomagnetic spectrum. Microwaves."

Ding! "Oh!" he reacted. "Well, that'd be an example of the microwave device we already know and love: the microwave oven. My burrito is finished now. I do get hungry up here." Some munching sounds came through the speaker. "Oh, man, that's a good burrito! Anyway, where was I? Oh, yes. Microwaves. Yes, the ones that just cooked my burrito are the middle frequency ones, ones that are small enough to go into the organic material of which food is made up, but just big enough so it doesn't just pass on through. They get in there, absorbed into the burrito, and start vibrating and vibrating. This generates heat, and heat cooks food." He took another bite of the burrito.

"Good stuff. Yeah, microwaves range from small enough to pass right through you or any organic tissue without notice, to a middle ground where it'll stay inside you and get absorbed into tissues depending on moisture, to too big to get into you or even try without you knowing. Microwaves are just part of the vast radio spectrum, ranging from about 3 Hertz to 300 gigahertz. The devices involved are everyday items."

The crowd muttered with intrigue.

Watchman continued: "I listen to the radio up here, and FM waves are very high frequency (VHF) band, as well as television. AM isn't quite so high. It's just medium frequency, MF. VHF ranges from 30 to 300 megahertz while MF ranges from 300 to 3000 kilohertz. Television reaches up into ultra-high frequency, UHF, as well, just above VHF, with a range of 300 to 3000 megahertz (0.3 to 3 gigahertz). Our little microwave oven is in the super high frequency (SHF) range, between 3 and 30 gigahertz (3000 to 30000 megahertz), along with cell phones and wireless internet connections." The crowd muttered with concern. "Oh, don't you folks worry about a thing," Aerial Watchman assured them. "Microwaves aren't that dangerous. Certainly no worse than ultraviolet. The only range you really need to worry about is the one that gets absorbed into tissues unnoticed, but so far there isn't much evidence that it causes cancer or any major damage."

Now the visitors seemed relieved.

"Well, I think I'll cook myself another burrito," he concluded. "Run along now. I think the rat wants to see you guys."

Rat's Rays

"Oh, yes! Oh, yes!" hissed Reactions Rat, who, the visitors were astonished to see, was simply a giant talking rat. "Reactions! So many delicious reactions!" Just when the crowd was thinking to get away from him, he spoke to them. "Don't go. I've been left to regale you with tales of the highest energy wavelengths of the electromagnetic spectrum. Shorter wavelengths past ultraviolet is the X-rays and then finally the gamma rays." He licked his lips. "Sweet. Such high energy. You know what that means?"

The crowd held blank expressions.

"Reactions!" he answered fervently. "Beautiful, beautiful reactions. You see, the formation of X-rays is so tasty. Electrons speeding up so they run right into some yummy tungsten, and if they collide just right, one of tungsten's electrons just might break out and whoosh! X-rays!" He started drooling.

"You seem to like chemical reactions," one visitor noted.

"I do! I do!" the rat replied. "I am Reactions Rat." He snickered. "Anyway, where we were? Yes! High energy spectra. X-ray of course gets used for medical stuff, to look at bones or the occasional barium-containing blood. X-ray crystallography is a method used to map out DNA back in the day. Oh, how I just adore DNA! So many wonderful reactions there!" He cleared his throat. "Perhaps another time. Today we're on X-rays and gamma rays. Ah, Geiger counters, scintillators, photographic plates, and semiconductor detectors. X-rays have it all!"

The crowd muttered in fascination.

"These X-rays and gamma rays are forms of ionizing radiation, since they do what just happened to the tungsten I had just mentioned," Reactions Rat continued amid another saliva build-up. "That is also what makes them dangerous. Fie on those weak infrared spectrum and microwaves and such. Gamma radiation and X-rays are the thing to watch out for. They are what is referred to when you hear of radioactivity. Oh, there's so many kinds, too!"

The visitors looked worried.

"Alpha particles," the rodent mused on. "Are big and have lots of energy. They sure causes lots of yummy reactions! Trouble is, they are easily shielded. Even a piece of paper can block them. An alpha particle consists of two protons and two neutrons bound together, kind of like a helium atom. Can't get involved in too many reactions since they are shielded so easily, but never fear for them. They have ways of reacting quite nicely when they attach themselves to food and wreak havoc inside the body, causing cancer and cell mutations. Such fun!"

The crowd chuckled uneasily.

"For you see, they may not be able to pass through such weak barriers, but they can be absorbed into them, and so often get absorbed into what later on becomes food," Reactions Rat explained. "They spread forth due to alpha decay in uranium and radium, a process which, unlike in beta decay, involves what's called a strong nuclear force, meaning there is a fundamental force involving gluons, which are elementary particles, acting upon quarks, anti-quarks, and other gluons. But anyway, it is the most strongly ionizing kind of radiation and has been known to be involved with polonium-210, a radioactive polonium isotope, to get into tobacco and lodge itself in the bronchial tubes, causing eventual lung cancer. It does so much. It's so tasty!"

Reactions Rat snatched a huge block of cheese from a nearby table and devoured it in two chomps.

"Tasty like big cheese!" he remarked. "Now the beta particles are merely single electrons, and therefore can pass through barriers more easily than the alphas. They are mischievous! They enter bodies and such much the same way alphas must resort to, but they have their unique ways of messing up the place. Beta decay in strontium and iodine yield radioactive isotopes strontium-90 and iodine-131. Strontium-90 poses as calcium, and silly bones don't know the difference until it's too late. It sits there emitting the betas and the body thinks nothing of it. Brilliant! The iodine-131 lodges in the thyroid like normal iodine and does the same thing. Oh, my, these beta-emitters are something!"

"Where does ionizing radiation come from?" asked one visitor.

"It's natural, of course," the rodent replied with a vicious smile. "For the most part, anyway. Natural rays from the sun leave high altitudes especially vulnerable to cosmic radiation. Regions with lots of granite in the ground are rich with the infamous radon, a radioactive noble gas. It is the second leading cause of lung cancer, and likes to seep up through the ground and get into houses, where unsuspecting homeowners breathe it in all the time. Food items naturally have a little bit of these particles. So the naturally occurring you really can't do anything about, but there are other sources, too." "Well, if it's natural," said another visitor. "Why are we worried about it?"

"Accumulation, my dear," he responded. "Bioaccumulation. It is not a matter of presence versus absence. It is always present to some degree. The issue is how much of it. The untouched natural sources can't be altered. They'll give off the radiation like normal. What we do worry about is tampering with natural sources in a way that makes them generate more than they would otherwise. One example is uranium and phosphate mining. Aforementioned indoor radon contamination could fall under this category, since we are talking a man-made closed-in space, but, again, what can realistically be done about that? There's methods, but it's a bit outside of our scope at the moment. The thing we really need to work on is entirely human-generated radiation. Medical X-rays. Nuclear weapons. Nuclear power plants. Even products on the market. Working on these things could reduce radiation emissions around us a little bit, but until then, ionizing radiation spreads around, causing reactions, reactions, reactions!"

"What else can you tell us about gamma radiation itself?" asked a visitor.

"Ah, gamma," Reactions Rat sighed. "Bitter end of the electromagnetic spectrum, it is, smallest wavelengths of them all. Gamma cannot be shielded nearly as easily as alpha or beta. You need lead or several feet of concrete to block this one. Alpha and beta are not electromagnetic radiation, but gamma is. They are the rays in a nuclear blast, so an all-out bomb shelter is needed with concrete and all. They are not as ionizing as alpha or beta, but they can still cause the same sort of damage as its X-ray and ultraviolet friends, meaning more, you guessed it! Reactions!" He laughed joyously. "Oh, the effects of gamma! The photoelectric effect is when a gamma photon steals an electron right out of an unsuspecting atom's orbit, yielding a photoelectron with same kinetic energy as the gamma photon it used to be without the binding energy. It is a dominant energy transfer mechanism in gamma and X-rays. Compton Scattering and Pair Production are a couple of others. Gamma gets used for medical sterility sometimes and to irradiate food, both to kill bacteria. Gamma is also useful for cancer treatments. Good stuff!"

Extra Notes

As the visitors prepared to leave, ending what would no doubt be a memorable visit to Science Village, they were certain to receive a little more information. Here it is.

-Gamma radiation runs from 1 to 10 picometers on the electromagnetic spectrum. Hard X-rays range 10 to 100 picometers while soft X-rays are 100 to 10000 picometers (0.1 to 10 nanometers). Extreme UV ranges 10 to 200 nanometers, and Near UV ranges 200 to 380 nanometers. Violet goes 380 to 430 nanometers, then blue with 430 to 500 nanometers, next cyan with 500 to 520 nanometers, and green with 520 to 565 nanometers, yellow with 565 to 590 nanometers, to orange ranging 590 to 625 nanometers, and finally red going from 625 to around 740 nanometers. Next up is Near Infrared running around 740 to 2500 nanometers (0.74 to 2.5 micrometers), Mid Infrared going 2.5 to 10 micrometers, and Far Infrared ranging 10 to 1000 micrometers (0.01 to 1 millimeters). The rest is the radio waves and microwaves, with a very wide range of 1 millimeter to 10 megameters!

-Ultraviolet light is present in black lights, flow hood lamps for sterility, and is used also for reading thin layer chromatography plates. It is wise to turn off UV lights before entering a room or working under them, and to use gloves or other protections in cases where they must be on. Black lights do not emit enough to be dangerous. UV light is also present in bug zappers, so it attracts the insects to their fiery death. It is present in a lot of other stuff, too.

-Infrared has many applications, too. In chemistry, infrared spectroscopy is useful in determining organic chemical structure. It is also the active ingredient to night-vision goggles. It comes in near infrared and far infrared. Heat is expressed as far infrared waves, explaining how the snake's infrared eyes are so useful. Infrared lamps are useful for keeping food heated, like in fast food restaurants and other places.

So just as the visitors are leaving, the villagers who spoke to them stop with a realization that they may have forgotten something. Just as they remember it and start rushing after the departing crowd, they see their accidental omission was not completely overlooked. High in the sky stood a magnificent, vivid rainbow. "Visible light!" Aerial Watchman announced from his tower through a megaphone to the awestruck crowd. "Of course! The one we can actually see. Why, that pretty rainbow there is the result of white light getting scattered by a prism. White light is all the colors meshed together, and the prism separates them out, as you can see."

"Cones!" declared Dr. Med. "You have special cones in your eyes to see the visible spectrum. They take it in."

"Right!" contributed Reactions Rat. "Visible lights gets all absorbed into stuff, except when a color might get reflected, and therefore be the color of said object. For example, chlorophyll in plants reflects green light, so plants look green."

At this, the visitors became fascinated with the colors of their surroundings, such as their own clothes and skin colors, the grass, and even the big vivid rainbow high above them. Satisfied, the Villagers nodded to each other, calling it a good day and going back inside to get some aloe for their sunburns.

Sources and More Info

Nadakavukaren, Anne. 2000. "Our Global Environment, A Health Perspective." 5th Edition. Waveland Press, Inc.

The Electromagnetic Spectrum - http://imagers.gsfc.nasa.gov/ems/ems.html

The Visible Light Spectrum - http://www.ski.org/Vision/Basics/visualspectrum.html

Biological effects on human health due to radiofrequency/microwave exposure: a synopsis of cohort studies. - http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids==14508584

International Ultraviolet Association - http://www.iuva.org

Infrared Photography - http://www.dpreview.com/learn/?/Photography_Techniques/Infrared_Photography_01.htm

Toxic effects of ultraviolet radiation on the skin. - http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15020192

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