STRANGE BUT TRUE- Topping off: Most of a mountain is under ground


Q. Earth analogy: The tip of an iceberg is to the whole iceberg as a mountain is to _________? –Z. Pike 

A. The whole mountain, which is much bigger than the "tip" you see aboveground, says Paul Hewitt in Conceptual Physics. Just as a floating iceberg is 90 percent submerged, 10 percent being the visible tip, a mountain floats on Earth's semi-liquid mantle with only its tip showing. Since the continental crust is about .85 times as dense as the mantle it floats upon, about 85 percent of a mountain extends beneath the Earth's surface. "So, like floating icebergs, mountains are appreciably deeper than they are high."

Another parallel: If you could shave off the top of an iceberg, the iceberg would now be lighter and float back up to around its original height. The same is true for the mountain. "That's why it takes so long for mountains to weather away."

Q. Has the "Googol" search engine performed a google search yet? Or should that be, Has the "Google" search engine performed a googol searches yet? And what are all these searches about anyway? –S. Brin

A. Googol is the fabulously Big number, 1 followed by 100 zeros, named by a youthful relative of mathematician Edward Kasner, says John Battelle in The Search. But at barely 5 billion Google searches daily, don't expect a googol googlings anytime soon: even at a billion every second since the birth of the universe 10 billion years ago, that would amount to only 10^26–i.e., not even a bite out of a googol's 10^100. Interestingly, the Google inventors confused the two words and thought they had chosen the name of the Big number for their new engine.

As to the world's Google profile, some 65 percent of searches are informational, 20 percent about entertainment, and 15 percent commercial. Nearly 100 percent of us have searched on our own names (vanity searches), 30-40 percent for old friends, some 20 percent for former flames. Google Inc. says that most word combos entered in are unique. In fact, the early popular game GoogleWhacking challenged users to find a query with exactly one result.

Q. Suddenly, on a calm, serene-looking sea, a massive wave rocks the ship, terrifying everyone. What's behind these all-too-common "rogue waves"? –S. Junger    

A. They've been part of nautical lore from Virgil's Aeneid 2,000 years ago to the recent film remake Poseidon. The highest ever observed was in 1933 when a 34-meter "monster wave" (about 110 feet) hit the Navy tanker USS Ramapo, says Sid Perkins in Science News. Most often encountered during storms, such waves can also appear on calm seas, bedeviling captains of oil tankers and cargo ships, or workers on oil platforms or on ships laying underwater cables.

Composite waves are often bigger than the total of individual waves of which they're made and travel in "trains," passing energy back and forth. At their crests, rogues can seem like "mountains of water," their troughs like "holes in the sea." Then they can disappear almost as quickly as they formed. Bad weather or passing trains can trigger them, as well as winds, seafloor shape, coastlines.

Yet better science and better predictions are on the way, Perkins says, and in some regions rogue-wave alerts are already being tested, a boon to industry and pleasure-boaters alike.

Q. Got a baby on the way? What's going on in its brain right now to get it ready for the wide-world-to-come? –L. Kelly

A. A singular event is REM sleep, for "rapid eye movements," a fascinating period later connected with dreaming, says Jim Horne in Sleepfaring: A Journey Through the Science of Sleep. In a fetus, this is customarily more than half of sleeptime just before birth, 8-10 hours per day, compared to only 100 minutes for a sleeping adult. This plunge in dream time after birth argues against the theory that REM sleep serves especially for processing memories, since a new baby is bombarded with new experiences and learning even as REM sleep declines. More likely REM in the pre-birth brain helps provide much-needed stimulation to aid brain development, "a level of stimulation not otherwise available within the muffled and dark confines of the womb," Horne says.

REM sleep remains with us throughout life, probably keeping the brain periodically "tweaked up" during sleep since the cortex dislikes long stretches of inactivity, says Horne. Without these periods, we wouldn't be able to detect dangers as we slept or stay ready to react as needed upon sudden awakening.

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