ection 1
Sir Isaac Newton was born on Christmas day, 1642—the same year that Galileo Galilei
died. His life-long intolerance of contradiction and controversy is attributed to an early,
lengthy separation from his mother who was widowed shortly before Isaac’s birth. She
left Isaac in the care of his grandmother to remarry, live in the next town, and start a
new family consisting of another son and two daughters.
As a teenager, Isaac’s preoccupation with reading, experimentation, and observ a t i o n
was an irritant to his affluent, now twice-widowed mother who expected Isaac to
become a gentlemen farm e r. Apparently she was reluctant to have Isaac attend universi-
t y, perhaps concerned about both the farm he had inherited and the cost of additional
education. He entered Cambridge as a sizar (a student who waited on other students to
pay his way), a step down from his social class and his mother’s financial standing.
N e w t o n ’s university studies were interrupted in 1665 and 1666 by the closure of Cambridge
University because of bubonic plague. During this period, he left London and studied at
home, doing extensive work in optics, laying the foundation for calculus—and perhaps his
law of gravity. Experts disagree about the timing, some claiming another 13 years passed
b e f o re Newton’s ideas on gravity crystallized. In either case, Newton’s achievements at this
early age were substantial, although his undergraduate career was undistinguished.
Newton conducted research in theology and history with the same passion that he
pursued science and alchemy throughout his life. Some consider him the culminating
figure of the 17th century scientific revolution.
Newton’s intense dedication to his intellectual pursuits took a toll on his physical and
mental health, apparently causing at least two breakdowns during his life. He died in
1727 and is buried in the nave of Westminster Abbey.
ew ton’s Law of Universal Gravitation
The force of gravitational attraction between two point masses (m1 and m2) is pro p o r-
tional to the product of the masses divided by the square of the distance between them.
In this equation, G is a constant of pro p o rtionality called the gravitational constant.
The closer two bodies are to each other, the greater their mutual attraction. As a result,
to stay in orbit, a satellite needs more speed in lower orbit than in a higher orbit.
SI R IS A A C NEW TO N
S
N
Gm 1 m 2
F =
r^2
