A Colorado reader wants to know why his IPOD STOPS WORKING when he climbs fourteeners. Two things can go wrong. Like all devices powered by a lithium-ion battery, an iPod will shut down when the temp is cold enough to neutralize the ion-transferring chemical reaction in the battery. Warmth will revive it. With a hard-disk-based music player like the iPod, thin air is a bigger threat. These units store data on a hard drive that spins at 4,200 rpm while a head floats nanometers above it, reading data. As air pressure drops, the air cushion has fewer molecules to sustain it; take it high enough and you risk a "head crash," in which head and disk collide, damaging your song library. Apple advises a ceiling of 10,000 feet for the 'Pod, but climbers on Everest have successfully busted out the...
Q) My son read an adventure book called Brian's Winter, in which it gets so cold that trees explode. Does that really happen?
Karyn Kay, New York, New York
A) In Gary Paulsen's 1996 novel about the harrowing exploits of 13-year-old Brian Robinsonwho survives a winter in the Canadian woods by overcoming a bear attack, a shortage of grub, and biting coldthe title character wakes up one morning to find trees cracking like rifles and sending foot-long splinters his way. Exciting though it is, that's a stretch. Oregon State University plant physiologist Les Fuchigami says trees do split open suddenly, but not in the morning, and not this dramatically. The phenomenon is called frost cracking, and it can happen to hardwoods that have wounds in their bark. It occurs late in the day, after the sun has warmed the tree and then recedes behind a cloud or sets, causing the air temperature to plunge and cooling the outside of the tree too quickly. The temperature shift creates mechanical stress inside the tree, leading to...well, not really a bang, but a loud whimper.
Q) Can earthquakes harm fish and marine mammals?
Jackie Rohrer, Montreal, Quebec
A) About 80 percent of earthquakes occur in oceans, mostly along the seismically volatile Pacific Rim. For sea critters, the worst thing they're likely to suffer is an earache. Brandon Southall, a marine biologist for the National Oceanic and Atmospheric Administration, says quakes create some of the loudest natural noises in the ocean, in the form of ultra-low-frequency rumbles that large whales can hear from thousands of miles away. Scientists don't know whether this causes pain, but confused cetaceans have been known to grumble back in unison, like dogs howling at a police siren. Shallow quakes can also cause tsunamis, which routinely wipe out fish swimming near the coast. Created by an uplifting of the ocean floor, these waves travel 500 miles per hour toward shore, but to animals in the deep ocean they're just a passing ripple.
Q) What's the oldest man-made object in space?
Stacey Yates, Sugar Land, Texas
A) The Methuselah of space stuff is Vanguard I, a three-pound aluminum sphere measuring six inches across. Launched by the U.S. Navy in 1958, it was the fourth satellite rocketed into space. (The Soviets' Sputnik I and II were first; the U.S. satellite Explorer I was third.) Dave Williams, a planetary scientist at NASA, says Vanguard I wasn't much to look atSoviet premier Nikita Khrushchev mocked it as the "grapefruit satellite"but it did have serious scientific aims, such as testing the viability of solar-cell batteries in space. Vanguard I went silent in 1964, but since it orbited much higher than its predecessorswell above the atmospheric drag that slowed the other satellites down and caused them to decay soonerthat little grapefruit won't burn up for at least 200 years.