Science

Ho hum. I don’t know how many times this question has flashed into the minds of worrywarts in elevators, or how many times it has been asked of every friendly neighborhood physicist. It is easy to answer in one word (No), but thinking about it does raise a whole bunch of fun questions. First, here’s […]

No, but it sure would create a windfall for Chinese podiatrists. I suppose that everybody picks on China when they ask this question because China is the most populous country on Earth, containing 2.5 billion potentially sore feet. There are really two questions here, aside from the question of why people who ask this question […]

Ramps and loops on freeways enhance the traffic flow, from construction companies to politicians’ campaign chests. Sorry. They allow us to make left turns without getting killed by oncoming traffic. It’s a matter of simple geometry. When freeways and superhighways began to be built, engineers had to figure out how to allow traffic to make […]

There’s no such thing as a dumb question. Actually, yours is perhaps the most profound question in all of science. Nevertheless, it does have a fairly simple answer,  ever since a genius by the name of Josiah Willard Gibbs figured it all out in the late nineteenth century. The answer is that everywhere in nature […]

If by recycling you mean transforming something into a more useful form. We do it all the time. Power plants transform water, coal, or nuclear energy into electricity. In our kitchen toasters we transform electrical energy into heat energy. In our automobile engines we transform chemical energy into motion (kinetic energy). The different forms of […]

Those ladders of fuzzy black dashes used as evidence in court are just a way of making DNA visible to jurors and other ardent scholars of biochemical science certain things that are too small to see, even with a microscope. They’re the end result of a number of laboratory manipulations that never get explained in […]

Everything is made of particles: atoms and molecules. But it’s not simply that some particles are lighter than others, although that’s a big part of it. It’s also that some particles are packed more tightly together than others. Lead is denser than, i.e., heavier than the same volume of, water, mostly because lead atoms are […]

Yes, there is a much simpler way, and it’s a shame they don’t teach it in school. Once those complicated formulas with all their parentheses and 32s got into a textbook somewhere, they seem to have taken on a life of their own. Here’s the simple method: To convert a Celsius temperature to Fahrenheit, just […]

Among all the nations of the world, only four great powers, Brunei, Myanmar (Burma), Yemen, and the United States of America, have not yet adopted the metric system of measurement. Is it possible that the rest of the world is onto something that has thus far eluded these four? Let’s see how our creaky and […]

Suppose that the Rockettes came on stage one at a time and did solos. You would agree that the intended effect would be lost, would you not? But that’s exactly how school science curricula are designed: the chemistry and physics teachers do solo acts on separate stages, and there’s no course in school called Putting […]

Pedestrians in the vicinity of Chicago’s 1454-foot Sears Tower need not fear. Hatted or not, they are in little danger from purely scientific experiments such as yours. (We won’t deign to discuss water balloons.) What you undoubtedly have in mind is the acceleration due to gravity, the fact that a falling object will fall faster […]

Magnets are attracted only to other magnets. A piece of iron contains billions of tiny magnets, but copper and aluminum don’t. The only thing that the pole of a magnet will attract is the opposite pole of another magnet. It’s exactly the same as with electric charges: The only thing that a positive electric charge […]

All atomic nuclei are made up of particles called nucleons. A big nucleus like uranium’s is a conglomeration of more than a couple of hundred of these particles, all crowded together into an incredibly tiny space. That’s such a large number of objects to hold together that the nucleus’s average grip on each one is […]

Uranium doesn’t burn like in a combustion, a chemical reaction with the oxygen in the air. But the uranium atoms do get used up. Coal, oil, and uranium contain energy. Actually, every substance contains a certain amount of energy. It is inherent in the unique arrangement of its atoms and how they are held together. […]

Frankly, E = mc2 doesn’t mean a hell of a lot. But that’s not to say that it isn’t one of the most momentous realizations ever to dawn upon the human mind. Although it has to do with things that are happening right under our noses every day, they are much too small to notice except […]

Twenty degrees, eh? Well, let’s just see about that. (We’ll assume that we’re dealing with Fahrenheit cucumbers, rather than Celsius.) If cucumbers are always twenty degrees cooler than their surroundings, let’s put a cucumber into a barrel with a whole bunch of other cucumbers and wait to see what happens. Will they fight it out, […]

Strictly speaking, infrared radiation is neither light nor heat. It’s not light because we can’t see it, and it’s not heat because it contains no substance that is capable of being hot. I like to call it “heat in transit.” We’ll see why. Infrared radiation is nothing more than a certain segment of the broad […]

If you listen with a linguist’s ear, you’ll find that the ice in your drink isn’t actually popping, which implies a certain hollowness. But it certainly does snap and, on occasion, crackle. First, the snap. When you plunge a cold ice cube into a warmer liquid, the water warms up parts of the ice cube, […]

As we were saying, water is a champion heat absorber, without getting very hot in the process. When you put a flame; to something that’s wet, the water soaks up the heat like a sponge, preventing the object itself from ever getting hot! enough to ignite. This one will astound you. Put a little water […]

Before we get any further, note well: Water must never be used on an electrical fire or on an oil or grease fire. Reasons: Water conducts electricity and can lead it elsewhere, perhaps to your very own feet. And because water won’t mix with oil or grease, it just scrambles it around and spreads the […]

Solid ice itself isn’t slippery. There’s a thin film of liquid water on its surface that the skaters are sliding on. Solids in general aren’t slippery because their surface molecules are tied tightly together and can’t roll around like ball bearings. The molecules of liquids, on the other hand, are free to move around, so […]

The weather has only a small effect on the boiling temperature of water. When people go around saying that water boils at 212 degrees Fahrenheit (100 degrees Celsius) at sea level, they’re speaking rather loosely. The standard definition of the boiling temperature of pure water says nothing about sea level. It is defined in terms […]

When it’s boiling, water in New York is a little hotter than water in Mexico City. And hotter water will get an egg to a given state of doneness in a shorter time. A little thought will show that the biggest difference between New York and Mexico City, apart from the relative difficulty of finding […]

“Water seeks its own level” is a catch phrase that was probably uttered by a Greek philosopher two thousand years ago, and people have been parroting it ever since. In plain language, it means that water will lie flat whenever it can. If a body of water, anywhere from a bucket to a bathtub to […]

Generally, yes. But water is an exception. As trivial as this question may sound, the answer is of life-and-death importance. If ice didn’t float on water, we might not even be here to wonder why. Let’s see what would happen if ice sank in liquid water. In prehistoric times, whenever the weather got cold enough […]

This controversy has been raging ever since the early seventeenth century, when Sir Francis Bacon became a charter member of the Betcha-the-hot-water-freezes-first camp. The only appropriate answer to this puzzle is, “It depends.” It depends on precisely how the freezing is being carried out. Freezing water may sound like the simplest of happenings, but there […]

No, all liquids are not wet. Even water is not always wet. It depends on who or what is the “wet-ee.” Make this inquiry of a linguist, however, and you’ll be told that it is a foolish question. The word wet is so intimately related to the word water in the roots of our language […]

In the strength of its inward-directed surface-tension force, water is the champion of all liquids. Its surface tension is so strong that water resists being stretched outward at all, even into the three-dimensional shape of smallest surface area: a sphere. Water knows that it can have an even smaller amount of surface area by simply […]

Let’s put it this way: You’d be pretty surprised if they were square, wouldn’t you? That’s because all of our experience since we were babies tells us that Mother Nature prefers smoothness. There just aren’t many natural objects that have! sharp points or jangling angles. The major exception is certain mineral crystals, which occur in […]

Fortunately, it isn’t necessary to answer that question, because divers, and fish,  don’t get the bends (more accurately known as decompression sickness) from staying down too long. Divers get the bends by coming up too fast, but fish can indeed get the bends from other causes. When the water pressure on a diver’s body is […]

Of course, it can always swish its tail and swim to wherever it wants to go, but that’s just a temporary solution. What it would really like to do is adapt its body to the pressure of the new depth, so that it can maintain its neutral buoyancy and rest there without constantly having to […]

In order to be at home suspended in seawater, in precisely neutral buoyancy without sinking or rising, a fish, or any other object, must have exactly the same overall density as the water. That is, it must weigh exactly the same as an equal volume of seawater. If it weighs more, it will sink to […]

If you doubt that the water exerts an upward pressure, try to submerge a balloon in the bathtub. You’ll feel a substantial upward push that resists your downward push. When we lowered the Admiral Nimitz into our giant bathtub, the water level rose; it got deeper. As every diver knows, deeper water means higher pressure. […]

Very simply. They change their amount of internal air space, thereby changing their density. You want to dive? You let water into your ballast tanks. You want to surface? You blow the water out with compressed air. It gets a bit tricky in reality, though, because the density of seawater actually varies a bit, depending […]

The pat answer to the everyday puzzle of why things float invariably goes like this: “According to Archimedes’ principle, a body immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced. And that’s why things float.” Perfectly correct, of course, but just about as illuminating as a […]

The answer is, “It does and it doesn’t.” Maybe that’s why people go around simply parroting the prefabricated, though hardly enlightening, answer, that “evaporation is a cooling process.” We notice that our sweat glands are exuding a liquid water containing a little salt and urea, onto our skin only at certain times, such as (a) […]

The cooling effect on your skin has little to do with the evaporation of perspiration, in case that’s what you were thinking. That effect peters out as soon as there is enough wind so that all the perspiration has already evaporated. A strong wind cools us because the moving stream of air molecules carries off […]

No, that would knock the sponsor’s neon signs off the sides, and that would never do because today’s blimps are nothing but flying billboards. Instead, they use a clever system of swapping helium and air back and forth. The blimp is, as you’ve noted, essentially a big rubber bag full of helium. The contraption floats […]

Antigravity? We don’t use that word. Science fiction is two shelves over to the left. Surprisingly, there is no upward-pushing force. It’s just that there is less downward-pulling force on the helium than there is on the air that surrounds it because helium gas is lighter than an equal volume of air. Gravity pulls less […]

The colors are actually glowing atoms, stimulated by electricity. It’s pretty much the same as making the colors in fireworks: Stimulate atoms with energy, and they’ll quickly get rid of the excess energy by emitting light of their own characteristic colors. There are a couple of differences (fortunately) between fireworks and neon signs. In neon […]

They add chemicals to the explosive mixtures that emit specific colors of light when subjected to heat. You could throw some of these same chemicals into your fireplace if you thought that a green fire, for example, might be more romantic. When you throw an atom into a fire, it can pick up some of […]

It’s a nice idea, because snowflakes certainly do have beautifully complex shapes, with spikes, lacy edges, and all the rest. But interlocking hooks and loops are a bit too much to expect. Besides, they’re much too fragile and brittle; when you pack them together they suffer a crushing experience. The answer lies in the fact […]

Just pumping a spray of water into the air wouldn’t work very well, except perhaps in extremely cold weather. And by the way, the machines don’t produce actual snowflakes; they make tiny beads of ice, each one around ten thousandths of an inch in diameter. The simple spraying of water wouldn’t work because when water […]

It really does get warmer when the snow begins to fall. Think of it this way: In order to melt a lot of ice or snow, you have to add heat to it. So when a lot of water freezes into ice or snow, which is the reverse process, that same amount of heat has […]

Freeze dried coffee is made by the sublimation of ice. Freeze-dried coffee differs from ordinary instant coffee in an important way. To make either kind of fast-beverage powder, they first brew two-thousand-pound batches of incredibly strong coffee. If they are making instant coffee, they then quick-dry this thick brew by dropping it down through a […]

The snow in winter isn’t melting if it’s below freezing; it is actually going straight off into the air as water vapor, without having to melt into liquid water first. We might be tempted to say that the snow is evaporating, but scientists prefer to reserve the word “evaporation” for liquids only. So when a […]

The Greenhouse Effect is the effect of infrared radiation-trapping by the Earth’s atmosphere, which can raise the average temperature at the surface of the entire globe, just as the trapping of infrared radiation within a greenhouse raises the temperature inside. The overall temperature of the Earth’s surface, averaged over all seasons and climates, depends on […]

Greenhouses, sometimes called hothouses or glasshouses, are always naturally warmer, without any artificial heating. But believe it or not, the main reason is not what everybody refers to as “the greenhouse effect.” A greenhouse is just a closed, glass container for plants. The glass lets in sunlight, which the plants need for growth, while keeping […]

You can tell the temperature by counting the chirps crickets make. All cold-blooded animals perform their functions faster at higher temperatures. Just compare how fast the ants run around in cool and hot weather. Crickets are no exception. They chirp at a rate that is geared directly to the temperature. To understand their message, all […]

It’s all a matter of how big the water droplets are. That’s what clouds are: collections of tiny droplets of water. The droplets are so small that under the continual bombardment of air molecules they are kept suspended in the air and do not settle out by gravity, until it rains, of course. The droplets […]

First of all, please don’t call air pressure “barometric pressure.” The air around us has a temperature that is measured by a thermometer, a humidity that is measured by a hygrometer, and a pressure that is measured by a barometer. Television weather reporters wouldn’t dream of talking about the air’s “thermometric temperature” or its “hygroscopic […]

It’s very simple. The molecules in air are so far apart that we’re actually looking through empty space. To notice anything at all, we would have to be able to see the individual molecules, but air molecules are about a thousand times smaller than anything we can observe, even with a microscope. We’re talking about […]

Those copper roofs on old churches and city halls have been out in the weather longer than a borrowed lawn mower, all those years that have passed since people could afford to cover roofs with that durable and beautiful red metal. Today copper is too expensive to use to shelter even the heads of politicians […]

While the temperature “in the shade” is a fairly reproducible figure, the temperature “in the sun” depends too much on whose temperature you’re talking about. Different objects, including different people in differed clothing, will experience different temperatures in the sun because they will absorb different amounts of different portions of the sunlight’s spectrum. Light-colored clothing, […]

Right on. When it is winter on the part of the Earth where you live (northern or southern hemisphere), your hemisphere is leaning away from the sun a bit. That is, the axis of the Earth wobbles, so that during winter in the northern hemisphere the North Pole is farther from the sun than the […]

The ninety-three-million-mile separation between the sun and the Earth pays little attention to our lunchtime or recreational schedule. The sun is essentially the same distance from your rapidly reddening nose at all times of day. But the strength of the sunshine varies, for two reasons: one atmospheric and one geometric. Picture the Earth as a […]

Waves can tell when they’re approaching a shore and actually turn to line up with it. What makes waves, of course, is wind blowing across the water’s surface. But it can’t be that the wind is always blowing the waves straight in to shore. Out in the ocean, the wind may be blowing every which […]

“Sea Breeze” isn’t just the name of a thousand beach motels. The breeze coming in from the sea is a real phenomenon that makes the shore cooler than it is inland at least in the afternoon, which is when people most want to cool off anyway. In the daytime, cool breezes almost invariably blow in […]

The term proof was coined in the seventeenth century when people proved, or tested, the alcohol content of whiskey by moistening gunpowder with it and setting it afire. (Honest.) A slow, even burn indicated the desired 50-percent-or-so of alcohol. If the booze was watered down, the flame would sputter. Today in the United States, 50 […]