STRANGE BUT TRUE- Sea sounds: Wild underwater world of sound

Q. If you could stick an ear down deep in the ocean, what would you hear? –J. Irving

A. Undersea earthquakes and volcanic eruptions thunder throughout the ocean basin, says Oregon State marine scientist Christopher Fox. Over 80 percent of all volcanoes
are in the seas. Other sounds are of rainfall, lightning strikes, meteor impacts, beach waves.

Listen intently and you might pick up the popcorn-like sound of "snapping" shrimp, the odd humming and growling of the midshipman fish, the high-frequency echolocation clicks of dolphins and sperm whales, says Joseph Olson of Cetacean Research Technology in Seattle. "Vocalizations from a singing humpback whale will at times resemble a cat's meow, a cow's moo, a squeaky door, a bird and several others."

Add to these the din of humanity: "I was snorkeling in Bali a few years ago when a loud sound startled both me and all the fish around me," says Olson. "Someone a few miles away was fishing with dynamite!"

Q. Stop and think for a minute: How many two-person relationships are there in your family? If there are you and your spouse (A and B), plus three children (c, d and e), then you get: AB, Ac, Ad, Ae, Bc, Bd, Be, cd, ce, de, or 10 relationships among just five people. Now make this a class of 20, or a small company of 50, and how many do you get? We're talking here about nothing less than the wondrous multiplicity of the human community. –M. Mead

A. There's a general rule for figuring the number: Multiply N (the size of the group) by (N - 1), then divide the answer in half. In the example, 5 x 4 = 20; 20 divided by 2 = 10 relationships in the family. In a class of 20, there are 190 possible relationships; in a company of 50, 1225.

Now, if you consider a city, even a tiny one of 15,000, you get 15,000 x 14,999, divided by 2 = approximately 112 million 2-people relationships! And since each of these can be one of friendship, romance, cooperation, teaching, admiration... or all of these at once, the possibilities stagger the imagination.

Q. How can someone wearing a bulletproof vest be knocked over from the bullet's impact while an unprotected person usually isn't? –T. Longo

A. The first such vests in the 1940s were of nylon, supplemented with plates of fiberglass, ceramic or titanium, says Barry Parker in Death Rays, Jet Packs, Stunts & Supercars: The Fantastic Physics of Film's Most Celebrated Secret Agent (James Bond). Then came Kevlar, a liquid polymer that could be spun into fibers and made into cloth, and later Spectra. Their many layers (lamination) provided the bulletproofing.

Now, the force someone feels when hit is the "bullet's momentum divided by its stopping time," which means the faster the bullet stops, the more force will be applied. For a person not wearing a vest, the bullet usually travels far into the body, yielding a larger stopping time and so a smaller force, says Parker. But since the vest can stop a bullet a hundred times faster or more, the stopping time shrinks, the force goes way up–and knocked over is the wearer. But with a little luck... not for long!

Q. Imaging experts can't read someone's mind with a machine– yet!– but PET scans and others are certainly shedding light on the old question of whether dreams are deeply meaningful or just the random gibberings of the active mind at night. So which is it? –C. Jung

A. "When I'm facing a tough new project, I dream I'm climbing a mountain," said a famous chef. "Later once everything is going fine, I dream I'm going down the mountain." Who hasn't had dreams like these, leaving us feeling, "Wow! That had to mean something," says Michelle Brandt in The Meaning of Dreams: Still a Mystery After All These Years, in Stanford Medicine.

A century ago Freud argued dreams are "the royal road to the unconscious mind." In the 1950s, the discovery of REM sleep (rapid eye movements) allowed the tracking of dream time. Decades later "activation synthesis" pegged dreams as the ebb and flow of neurotransmitters, with the brain trying to make sense of random neurological impulses.

With the advent of PET scans (positron emission tomography) and other new imaging technologies, researchers can for the first time see which parts of the brain are active during dreams, says Brandt. Turns out to be the areas of emotions, senses and long-term memory. Even the skeptics now concede a link between dreams and feelings. One can almost hear Freud off somewhere intoning, "I told you so." But still Rush University's Rosalind Cartwright feels the mustery of dreams won't be unlocked in her lifetime.

Send Strange questions to brothers Bill and Rich at, coauthors of "Can a Guy Get Pregnant? Scientific Answers to Everyday (and Not-So- Everyday) Questions," from Pi Press.