Uncle John’s Impossible Questions & Astounding Answers (26 page)

A
lot
longer than it would take to get to the sun. The second-closest star to Earth is Proxima Centauri. A red dwarf too small to be seen by the naked eye, it’s 4.2 light years away. Light travels nearly 5.9 trillion miles per year, so if you were able to reach a velocity of 1 million mph, your journey would take 2,828 Earth years. You’d better bring along something to read. (For suggestions, go to
www.bathroomreader.com
.)

What type of work you dabble in determines the duration of your jiffy:

• Quantum physicists define a jiffy as the time it takes for light to travel the radius of an electron.

• Astrophysicists define it as the time it takes light to travel one
fermi
(about the diameter of a proton).

• Computer programmers assign it the duration of one tick of the system timer interrupt (between 1 and 10 milliseconds).

• Electricians define a jiffy as 1/50 or 1/60 of a second.

Much about this word is a mystery, even the origin: It was most likely coined in 18th-century England by thieves who used it as a slang term for “lightning.” Most dictionaries define a jiffy as 1) 1/100 of a second, and 2) a moment.

You’re in a pitch-black room. All you have is a cat and a fluorescent tube. But you can find your way out. How?

In July 1945, Enrico Fermi set up a $1 betting pool at his job. What were he and his workmates betting on?

Create a light source by rubbing the cat with the fluorescent tube. This would also work with your own hair (unless, like Uncle John, you don’t have any), but a cat is furrier and therefore more effective. How does this work? Rubbing the kitty scrapes electrons off its fur. Set loose as electricity, they strike the mercury vapor inside the tube, causing it to emit ultraviolet “black” light, which normally falls outside the visible spectrum. However, the inside of the tube is filled with phosphors that—like the special paints used inside fun houses—glow when excited by ultraviolet light. Now you can find a light switch.

Fermi and his co-workers at the Manhattan Project labs were betting on the size of the blast made by the first atomic bomb test, scheduled for July 16, 1945, in a remote part of New Mexico. Fermi bet that the air itself would ignite and destroy New Mexico. Physicist Norman Ramsey bet the opposite—that the bomb would be a dud. The winner was a physicist named Isidor Isaac Rabi, who bet that the blast would equal 18,000 tons of dynamite. He was only 2,000 tons short. (Rabi didn’t make his guess based on any scientific principle; he was late to the pool and chose the only square left.)

What’s the difference between a dirigible and a blimp? And which one was the
Hindenburg
? And what the heck is a Zeppelin? And why is it made of Led?

A blimp has a soft fabric shell that holds its elliptical shape because of the pressure of the gases inside. A dirigible has a strong frame that maintains its shape no matter what the gas pressure is inside.

The most famous dirigible was the
Hindenburg
, which went down in flames over a New Jersey airfield on May 6, 1937. It killed 35 people onboard and one on the ground. (“Oh, the humanity.”) But it wasn’t the gases
inside
the dirigible that caught fire; it was most likely caused by a buildup of static electricity from a recent thunderstorm. When a mooring line hit the ground, it sent up a spark that ignited the
Hindenburg
’s paint. (That’s one theory—the jury’s still out as to exactly what caused the disaster.)

The
Hindenburg
dirigible was also called a zeppelin, named after Count Ferdinand von Zeppelin, who invented the craft in Germany in 1874. For a time, it seemed as if zeppelins could be the future of air travel (as evidenced by the zeppelin dock that was built on top of New York City’s Empire State Building), but the
Hindenburg
disaster in 1937 ended that dream.

In 1968 guitarist Jimmy Page played a tape of his new band’s songs to the Who’s bass player, John Entwistle (or to drummer Keith Moon, depending on who’s telling the story). Entwistle joked, “That’ll go over like a lead zeppelin!” And that’s how Led Zeppelin got its name.

Air is constantly pushing against you, and your body is constantly pushing back. How much pressure are you and the air around you exerting on each other? And what about a soccer ball? How much is it pushing back?

Clouds are heavy, but they float. Why?

If you’re at sea level, there are 14.7 pounds per square inch of air pressing against you. You don’t feel it because your body is pushing outward at about the same pressure. Then, you may ask, why does a soccer ball that’s inflated to “5 psi” not collapse in on itself? Isn’t 5 psi a lot less than 14.7 psi? It’s because the numbers on a pressure gauge don’t indicate
absolute pressure
, but
overpressure
—the amount of pressure above 14.7 psi, for a total of 19.7 psi. If you placed that same inflated soccer ball in a vacuum where there’s no air pressure, it would expand outward and explode. The same thing would happen to
you
in a vacuum, only it would be a lot messier.

Even a small cloud covers more than half a cubic mile and weighs upward of two million pounds. And yet it floats. Why? Because there’s more than just water inside the cloud—there’s air as well. And even though the air is about 1,000 times heavier than the combined weight of all the water molecules, a cloud appears to float because it forms in warm, humid air that’s being pushed upward by air currents, and the tiny droplets of water in the cloud take a ride on top of those currents. When the air cools dramatically, the droplets combine into larger drops, and the pull of gravity trumps the upward-moving air. Then it rains.

In the 20th century, two volcanoes erupted in the continental U.S.—Mt. St. Helens in Washington, and…do you know the other one? Why isn’t it common knowledge?

Why do houses creak more at night than they do in the daytime?

In May 1915, California’s Mt. Lassen erupted, spewing ash several miles into the atmosphere, some of it landing more than 200 miles away. The eruption caused massive avalanches and hot ash flows that wiped out entire forests and devastated nearby homesteaders.

So why isn’t an eruption of such magnitude more commonly known in the United States? Two reasons: 1) It happened in central northern California, which was, and still is, fairly remote; 2) the volcano was overshadowed by current events—World War I had recently broken out in Europe. Americans were more concerned about whether the war would reach their shores than they were about a volcanic eruption in the middle of nowhere.