In 1665, Isaac Newton left Cambridge University and returned to his hometown of
Woolsthorpe to escape the worst ravages of the Black Plague. Safely back among
familiar surroundings, he made landmark discoveries that have provided us
with precisely the keys we needed to conquer space.
Although the young Newton had reportedly been a mediocre student in the early grades,
his powerful intelligence asserted itself even before he reached his teenage years.
When he was still a tow-headed youngster, for instance, he managed to construct a
charming little windmill backed up by one mouse-power so it could go on turning when
the wind refused to blow. Later, he made a paper kite rigged to carry a small lantern
high above the British countryside. The people of Woolsthorpe had never before seen
flickering lights floating across the nighttime sky, so the young Isaac may have been
responsible for some of the earliest sightings of UFOs.
At the age of 23, while relaxing on his mother's farm, Isaac Newton, by his own account,
saw an apple falling from a tree. That simple incident caused him to wonder why
apples always tumble down. That apple tumbled down toward the ground while the
pale August moon continued to sail contentedly overhead. Soon he theorized that the
force of gravity tugged on apple and moon falls off systematically with increasing
altitude in the same way a light beam dissipates as we move farther away from its
source. Double the distance and its intensity falls of by a factor of 4.
Thus, by Newton's reckoning, the force of gravity pulling on the moon should be
about 1/3000th as strong as the gravity we experience at the surface of the earth. In 1
minute, he soon calculated a falling apple would be pulled downward about 10 miles,
but the moon would fall toward the earth only about 16 ft. During that same 1-minute
interval, the moon's orbital velocity also carried it sideways 38 miles. Consequently, its
horizontal and vertical motion combine to bring it back onto the same gently curving
circular path over and over again.
Isaac Newton figured out how gravity works because of a fortunate encounter with his
mother's favorite apple tree. Armed with only his inverse square law of gravitation,
three deceptively simple laws of motion, and one of the most powerful intellects that
ever pondered anything, Newton quietly set about to unravel the hidden secrets of