Dolphins use their ultrasound to see surroundings

Question: How and what do dolphins see, and how do they tell their "friends" about the sights beheld?

Answer: Just as physicians use high-frequency sound (ultrasound) to "see" inside the body without X-rays, and bats emit ultrasonic squeaks to locate objects by their echoes, dolphins can do both of these tricks and a lot more, says Paul Hewitt in "Conceptual Physics." But whereas sound is a passive sense for us humans, for them it is the primary sense as they send out sounds and then perceive their surroundings on the basis of the echoes that come back.

Perceive what? The ultrasonic waves emitted enable dolphins to "see" through the bodies of other animals and people. Skin, muscle and fat are almost transparent, yielding only a thin outline of the body, though bones, teeth and gas-filled cavities are clearly apparent. "Physical evidence of cancers, tumors, heart attacks and even emotional states can all be 'seen' by the dolphin — as humans have only recently been able to do with ultrasound."

Amazingly, dolphins probably communicate their experience by transmitting the full acoustic image, placing it directly in the minds of other dolphins, speculates Hewitt. No need for a word or symbol for "fish," for example, but just the image of the real thing, just as we might communicate a musical concert via various means of sound reproduction. "Small wonder that the language of the dolphin is very unlike our own!"

Question: What's special about a number like 69,696?

Answer: This is an "undulating number," of the form ababababab . . ., says Clifford Pickover in "Keys to Infinity."

There are any number of such numbers, such as 171,717 and 28,282. A special feature of 69,696 is that it is also a square number — 264 squared — an "undulating square," in fact possibly the largest undulating square. This last point is far from certain, though one numbers hunter in Germany asserts that if there is a larger undulating square, it must have more than a million digits.

Says Pickover, 69,696 is "certainly my favorite of all the integers, a remarkable number" that is almost exactly equal to the average velocity in miles per hour of the Earth in orbit and to the surface temperature in degrees Fahrenheit of some of the hottest stars. And if that doesn't get you undulating with excitement or something . . ..

Question: When it comes to peak sports performance, what's relaxation got to do with it?