Seven Ideas for a Sciencey Holiday


I am the first to admit that I have never gotten the holidays quite right. Whether I’m late shopping for gifts, mess up my contribution to dinner, do something embarrassing at a holiday party or hang all the decorations crooked, something always seems to go wrong.

Thankfully, there are a few sciencey tricks people like me can bust out around the holidays as a last ditch effort to spread a little holiday cheer... And promptly gather it up again when explaining exactly how it works.

  1. The Magnet TrainThe Magnet Train
    Ok so maybe you forgot to get a niece or nephew that fancy toy they wanted. You can either recreate the Schwarzenegger movie classic Jingle All the Way OR put together a homemade train. What kid doesn’t love trains? All you need is copper wire, a AA battery and a few strong magnets.

    Here’s a video of how it goes together. The train is powered by the principle of inductance. Passing an electrical current through a coil will create a magnetic field going one way inside the coil and another way outside the coil. By connecting the metallic magnets to the battery’s terminals you create a circuit that passes electrical current through the wire, and creates or “induces” a non-uniform magnetic field. The magnets interact with the induced field and pull the battery through the coil. As the “train” moves, so does the magnetic field, so it will go until the battery dies.

    It may not look like one of those fancy model train-sets, but that’s what imagination is for!

  2. Festive Fluorescence
    Christmas trees, Santa Claus, poinsettias... The holidays are full of green and red, but if you have to be the person to one-up all the other holiday parties, you can make yours glow green and red.

    CalciteThe gold standard is finding something that will glow on its own, say gathering a few thousand fireflies during summer and raising them until your party. Short of that you can make things fluoresce using ultraviolet light. Fluorescence actually happens at the subatomic level. Light is energy, and electrons on all atoms and molecules can absorb that light energy to move to a higher energy level, then release the energy again. The energy levels are extremely specific, however. When an electron moves from a higher energy level to a lower one, the light it releases will be exactly the same, every time. This is one of the backbones of quantum chemistry.

    Sometimes, an electron will absorb ultraviolet light, and when it returns to its lower energy level, it releases visible light. This is called fluorescence, and because the energy levels are so specific, all fluorescent materials have set colors. One such material is quinine, an ingredient in tonic water, which glows blue under UV light. Mix tonic water with something yellow and the glow will appear green. You can even trick your unwitting guests when they comment on your non-festive yellow drinks. Turn on a black light and boom! Festive.

    Red is a little harder to come by, and I would not recommend putting it into food as many of the things that fluoresce red are either rocks or poison.

    Rubies and emeralds both fluoresce red, but if you are on a budget, calcite might be the way to go. Calcite is a form of calcium carbonate often found in seashells, and under short-wave UV light it glows red. You could also try halite crystals (rock salt from your driveway), although it glows more pink than red.

    If you really wanted to go all out, however, there are several species of fish that fluoresce red and green. It would be expensive and probably illegal to get all these fish and you might have your hands full with the glowing shark, but what’s a few thousand dollars against a good conversation piece?

  3. The Amazing Balancing Pencil
    Admit it. There’s always someone on your list that is impossible to shop for. Either they give only give you a vague clue as to what they want, like “nothing fancy,” or they get their gift and after a day they never touch it again.

    The Amazing Balancing Pencil is the perfect gift, and all you need is a pencil, some thick metal wire and some kind of counterweight. Attach everything in the right way and you can make the pencil balance on its point.

    My high school physics teacher had one set up permanently in his classroom as a lesson in center of gravity. The pencil leans one way and the counterweight leans the other. If you position everything just right the two weights balance each other out and the center of gravity is directly underneath the pencil. This keeps the pencil from falling over.

    True to your word, it will be nothing fancy and if your tough gift receiver is anything like me, it will take until next Christmas to set it up.

  4. The Pinhole Camera
    Pinhole CameraDigital cameras are so 2013. This year get your friends and family pinhole cameras instead. This homemade device will make the science behind taking pictures painstakingly clear.

    With a shoebox, black spray paint, duct tape and a soda can, you can give the gift of 150 year-old camera technology. Click here for instructions on building a pinhole camera. The basic principle is projection. If you put a tiny pinhole in the box, light directed toward the pinhole will enter the box while all other light will stay out. That light makes an image inside the box of whatever the pinhole is pointing toward, flipped upside down.

    Film or photo paper is taped inside the box where the light can hit it, recording an image. Instead of a glass lens to properly focus the image, the pinhole camera relies on its tiny aperture. Essentially, if the pinhole is small enough the light hitting each point on the photo paper can only come from one place in front of the camera. Therefore, up to a point, the smaller the hole, the clearer the image.

    The small aperture on a pinhole camera does have a downside though. The chemicals in the film or photo paper need light to perform the chemical reaction that makes an image. The aperture on a pinhole camera is so small that it can take minutes and even hours to take a photo, depending on how light or dark the room is. And moving the camera or subject even slightly can give a blurry image. That said, you can do some very cool long-exposure images with one.

    Sure it isn’t as fast, easy-to-use or convenient as a digital camera, but you can always just explain how much more rewarding that half-hour-long selfie will be than the normal half-second ones.

  5. Invisible Ink
    When I was a kid, there were always things I wanted for Christmas that I was afraid to put in my letter to Santa for fear that my parents would see it and cross it out before mailing the note to the North Pole.

    For instance, I wanted a cat more than anything and I asked my parents for one about a thousand times, but they always said no because they were allergic. It turns out I am allergic too (go figure) but at the time I figured Santa would definitely leave that cat under the tree if I could just let him know that was what I wanted.

    Little did I know the answer was right in front of me the whole time: invisible ink. There are plenty of household items that can soak a clear chemical into paper that can be revealed later, or plant the seeds for a chemical reaction with the paper for a later date.

    Some inks, like lemon juice, onion juice, vinegar, and baking soda, honey or table sugar dissolved in water go on clear but will turn brown when heated over a 100 watt bulb or with a hair dryer. The sugary ones begin to caramelize while the others denature the proteins in the paper to get a color change.

    Others require slightly more sophisticated chemistry. Vinegar and ammonia will turn red when mixed with red cabbage water. Baking soda will turn purple with grape juice. If you really want to go all out, you can turn a saltwater ink black by adding silver nitrate to it.

    The final group of inks brings back the black light. Tonic water or diluted laundry detergent both glow blue under a black light, but go on clear.

    Any of these options would work great to sneak a secret message to Santa and I’d bet my figgy pudding there’s a whole lab full of elf chemists looking for these messages. How else would we preserve the top secret nature of our Christmas lists?

  6. Homemade Bouncy Balls
    Bouncy BallsBecause let’s face it, what kid doesn’t love bouncy balls?

    With borax, corn starch, Elmer’s glue and a little polymer chemistry, you can whip up a few bouncy balls in less than an hour. Click here for the full recipe.

    The key to the ball is a chemical reaction called cross-linking. The main chemical in glue is a repeating chain of polyvinyl acetate, and a blob of glue is a collection of those chains. The borax allows those chains to chemically bond to each other, allowing the ball to keep its shape. The corn starch gives it the elasticity.

    You can add food coloring to the mixture to make different colors. Soon the house will be filled with the noise of the thud of bouncy balls, laughter and the crash of decorations falling from the walls.

  7. The Gingerbread House of the Future
    Four walls, a roof, icing, maybe a few pieces of candy: gingerbread houses are just so...cookie cutter. Okay, that was really bad, but after so much science in your holiday plans why stop at the gingerbread house? Especially when you can make one of the most theoretically efficient dwellings ever designed: the geodesic dome.

    Geodesic DomeThe geodesic dome was patented and popularized by architect and inventor R. Buckminster Fuller in the 1950s as the “house of the future.” Where the rectangular houses built until that point were based on minimizing the compression of the frame and fighting gravity, Fuller’s idea was to build a dome based on very small triangles that rely on gravity and the forces each triangle puts on the ones surrounding it to hold the dome up. That design of connected rods wrapped in an insulated material allowed for a much lighter building, even one that could be lifted by helicopter.

    The dome had other advantages. Spheres have more space inside for a given surface area than cubes do, which by itself is an advantage as you get more space for the same amount of building materials. This helps control the indoor climate, as the more surface area means more contact with the air outside. Domes are also inherently stronger than cubes so wind is less likely to damage the dome. For those reasons, the Amundsen-Scott Research Station at the South Pole was housed in a geodesic dome from 1975 until 2003.

    So why are we all not living in domes? While in theory the geodesic dome is advantageous, building and maintaining them are challenging. Lloyd Khan, who wrote many books on the advantages of geodesic domes, has referred to them as “smart but not wise.”

    In the early days of the domes, Buckminster Fuller had trouble getting union contractors to work on them because they came with plumbing and sewer lines built in, when that was supposed to be union work, but apart from that, the actual construction became problematic. Designing chimneys, sewer lines and fire escapes that are up to code is challenging in a spherical structure. Also, most building materials are sold in rectangles, so to build the dome, contractors would have to cut them down to triangles, hexagons or pentagons to fit the domes, wasting materials and driving up building costs, especially with windows. 

    And while mathematically you get more space in a dome, the curved structure makes some of that room unusable as the side of the dome cuts off the head room.

    All in all, the dome never really took off in real houses but you can bring them back with your gingerbread house. You can buy a kit online or try to make it yourself. If you try it yourself, build an internal dome for your gingerbread to rest on — the kit comes with one — as icing is not the greatest building material.

    The great advantage of the ginger-desic dome, though, is all the pieces, so when it comes time to take the house down and eat it, you already have individual cookies!

- Daniel Lane

Daniel Lane covers science, technology, medicine and the environment in North Carolina.