Part 14 — How the Monkeys Measured the Speed of Light and Why the Parrot Has a Bad Temper

There was a time when monkeys played the gamelan. The concert would go on for weeks and the big drum which plays only when all the others have gone through their cycles — the Buddha drum — might boom out only once during a whole night, maybe not until moonrise and maybe not then. It has to wait, to surround and sum up the rhythms of all the others. In those days, before the monkeys got tired of the gamelan and turned it over to humans, all the animals were experts at rhythm — they could tell when a rhythm sped up by a hundredth of a percent and when it slowed down by a hundredth of a percent.

Now it written in the Holy Koran (or perhaps the National Geographic) that a falcon's eyesight is eight times sharper than yours and mine. Certainly falcons can see the Jovian moons without a telescope — there are even some sharp-eyed humans who can — and in those days all the birds could. So while the monkeys played, the birds would perch in a fig tree near the gamelan and watch Io and the other Jovian moons set and rise. After a while they mentioned this to the monkeys, who began to incorporate other moon rhythms in their playing — and the big Buddha drum would boom when Io emerged from Jupiter's shadow.

There are times, and not always at the same season of the year either, when the big planet rises at midnight and is overhead at dawn. It means the earth is approaching Jupiter, as it does for a while each year. That year this happened in summer, at the time of the monsoon rains, and it was then that the birds noticed the moons had sped up. They saw the moons' setting and rising had sped up by a hundredth of a percent, and they told the monkeys. The monkeys, who had moved the gamelan in under the dense foliage of the fig tree to keep the rain off the gongs, duly sped up their playing by a hundredth of a percent for the duration of the rains.

And later, in the dry winter months of that year, Jupiter was overhead at dusk and would set at midnight. This is a sign that the earth is in the part of its orbit where it flys away from Jupiter. Then the birds noticed that the Jovian moons were slower than usual, by a hundredth of a percent. They mentioned this to the monkeys, who slowed down their playing for the duration of the dry season. The birds would stay up all night listening to the gamelan, and that year they heard the big Buddha drum boom a little more slowly in the dry months than it did in during the monsoon.

Now it is well known that the parrot is the most irritable and suspicious of all birds. This is because he is wisest and most observant. So when the parrot heard that the moons of Jupiter were speeding up and slowing down he hired a Danish mathematician to look into it. The consultant was a young man with tight pants and shiny buckles on his shoes — his name was Olaus Römer and he had met Isaac Newton once and he knew that the earth goes a thousand miles a minute in its orbit around the sun. All humans knew this in those days, but they kept it secret from the animals.

The young consultant stood there calmly powdering his wig and explained to the parrot that the monkeys had just measured the speed of light. If the rhythm from somewhere speeds up a hundredth of a percent when the earth is going towards it, he said, then the earth is traveling a hundredth of a percent of the speed of light. That means light travels ten thousand times faster than the earth. Wonderful, said the parrot, now how many miles a minute does the earth go? — tell me this and I shall know the speed of light. I'm sorry, said the Dane, that is not in my contract. The birds and other animals drove the consultant out of the forest. And this is why, to this day, parrots take a sardonic view of human nature and treat the lot of us with raucous mockery.