QUESTION: Why is marble always so cold?
ANSWER: Do an experiment. Touch different objects around you. Metal is cold. Glass is cool. Plastic is warmer than glass. Styrofoam is "room temperature." Why doesn't everything feel the same? Isn't everything 72 degrees, whatever the ambient temperature is?While you're thinking about this, lie down on a marble floor. The heat gets sucked right from your body. This won't work as well on a wood floor. What's going on?
This: You've discovered conductivity. (How exciting! Get the confetti!) What you are feeling is the rate at which heat is being transferred from your finger (about 85 degrees Fahrenheit, probably) to these various objects, which are, indeed, at room temperature. Marble conducts heat better than, say, sandstone. Marble is very dense, and makes more contact with your skin than sandstone, which is a loose collection of sandy bits with lots of tiny air pockets in between. Air is a good insulator; it doesn't conduct the heat from one body to another. Styrofoam, which is mostly air, is therefore a great thing to put hot beverages in.
There's a second factor to consider: specific heat. This is the extent to which it is difficult to heat something up or cool it down. When you lie down on marble, it not only feels cold, it STAYS cold, rather than warming up the way a wood floor does. The Second Law of Thermodynamics dictates that heat will continue to flow from the warm body (you) to the cold one (the floor). Water has the highest specific heat of any common substance, which is why you can put your gas burner on high and it still takes several minutes to get a small pot to boil, even longer if you watch it (due to the First Law of Kitchen Proverbs).
QUESTION: Why aren't racehorses getting any faster, the way humans are, even though horses, not humans, are carefully bred for speed?
ANSWER: First, today's betting tip: Never put money on a horse with a name like "Dog Chow." Or, say, "The Glue Express."
You're welcome.
Now then, the real mystery is why horse breeding doesn't seem to work. Take the 1989 Breeders' Cup. It was a great race between two great horses, Sunday Silence and Easy Goer, but despite the heaving and huffing around the mile-and-a-quarter track, Sunday Silence's victory by a neck still took nearly three seconds longer than the record time for that distance, set in 1977 at Santa Anita Park, in Arcadia, Calif., by some creature called Double Discount.
The fastest a horse has ever run a quarter-mile is 20.8 seconds. That was Big Racket back in February 1945. The record for 21/2 miles was set by Miss Grillo in 1948. The three-mile best is still claimed by Farragut from 1941.
Compare that to human beings: Florence Griffith Joyner set the 100-meter and 200-meter speed records for women in 1988. The best mile ever by a man was by Steve Cram in 1985. Most of the track records have been set in the past decade.
Does that mean that thoroughbreds are not that thoroughly bred?
Neigh, say the experts. The top times haven't changed much, but speeds on the whole - including all those 90-to-1 long shots - have improved.
"The average horse these days runs very close to the speeds only the great horses used to run," says Jeff Seder of Equine Biomechanics, a Philadelphia company that gathers data and consults horse breeders.
What about the top speeds? Why haven't they changed much? There are several theories we might look at:
1. The ability to run fast is not genetically simple, as Colin Tudge noted in a 1989 article in New Scientist. Therefore the chance of being able to pass it on from one generation to another is slim. Speed is a "polymorphic trait" depending on such factors as muscle density, length of stride, efficiency of the blood to process oxygen, and intangibles like courage and pride. The more variables, the harder it is for them all to be inherited. This is also true of humans, which is why the children of great athletes are rarely great athletes themselves.
2. Breeders deliberately limit their effectiveness. Because racing is a sport - and a high-stakes business - horses aren't bred the same way that, say, bulls or pigs are. A good bull will have his semen dispersed by artificial insemination to innumerable cows, but horses are only allowed to breed in the old-fashioned, romantic way, to avoid flooding the market. (The owners charge a hefty price for such a fling.) This limited edition approach also limits the chances of a champion colt. Even a great horse like Secretariat needs a lot of chances: Of all his offspring only one, Risen Star, won numerous stakes.
3. Breeders are dumb, sometimes. We are told by breeding expert Paul Mostert, a professor of mathematics at the University of Kansas, that the horse community has suffered from some rather unscientific thoughts over the years, such as the idea that a little dose of these genes and a little dose of those genes will result in a genetically perfect horse. For instance, a breeder might try to combine the genes of a great sprinter with the genes of a great long-distance horse. The result: Alpo.
4. Horses are retiring before they're physically mature. A lot of the old speed records were set by 5-year-olds. But now horses race at a younger age, starting at age 2, and are more likely to get hurt (perhaps because physical soundness is not sufficiently emphasized in breeding). They're put out to stud while they're still adolescent.
5. Horses have hit their genetic peak already. Breeding has been around for centuries and they can't get faster indefinitely. At some point a species runs into a wall.
Why are humans more successful at improving their times? Because humans are more adaptable than horses. They're more easily trained, more clever, able to master complex new techniques. And such great new shoes!