Why did Robert Hooke and Newton become
rivals?
When Newton joined the Royal Society in 1672,
Robert Hooke was one of its most celebrated members, possessing
a brilliant if somewhat scattered mind, that leaped from discipline
to discipline and discovery to discovery. He and Newton had opposite
personal temperaments and approaches to scientific research, and
both craved the spotlight, so a rivalry may have been inevitable.
The rivalry began when Newton presented his first paper to the
Royal Society, detailing his work on the nature of light and advancing
his theory that white light was a composite of all the colors of
the spectrum. Hooke, who had his own ideas about the nature of
light, criticized Newton's work, and Newton took offense, claiming
huffily that his own discovery was "the oddest if not the most
considerable detection which hath hitherto beene made in the operations
of Nature," and threatening, in March of 1673, to withdraw from
the Society over the quarrel. He was dissuaded from this course,
but his rivalry with Hooke persisted, despite attempts to patch
things up in the late 1670s. In the 1680s, with the publication
of Newton's Principia, it flared anew; Hooke claimed
that he had worked out one of Newton's key mathematical formulae
a decade earlier. Thereafter, as Newton grew famous and Hooke
slid into obscurity, the older man became embittered, and developed
a loathing for his rival that endured until his death in 1703.
What was Descartes' theory of the universe?
How did it differ from Newton's?
The French philosopher and scientist René
Descartes declared that everything in nature, from the working
of the human brain to the weather over Europe, could be explained
by the motion and interaction of tiny, invisible particles that
filled the universe. He applied this to the solar system to explain
the motion of planets and moons: the swirling interaction of these
particles, he explained, created a whirlpool-like effect of "vortices"
that carried the planets around the sun. It was a logical system,
but it was entirely based on supposition, since Descartes could
not demonstrate the existence of his tiny particles. Newton, recognizing
that such an all-encompassing scheme was unverifiable, chose to
focus his energies upon what he could prove, using experiments and
the iron laws of mathematics. This led to his theory of gravity,
the force of attraction between objects that binds planets into
their orbits, and which he proved, mathematically, in the Principia.
Descartes' defenders objected that Newton had not shown how gravity
worked, and that his system thus lacked the explanatory power of
Descartes' vortices. Newton admitted that this was true: Descartes'
model explained the "why" and "how" of everything, whereas his
did not. But Descartes' vortices, however complete and philosophically
satisfying, did not make mathematical sense; only gravity could
be proven to be truly extant.
Name at least four phenomena that were
explained with Newton's law of universal gravitation.
The law of gravity, as propounded in the Principia, had
amazing explanatory power. Gravity explained why the planets orbit
the sun, as well as the orbit of our moon, and of Jupiter's moons.
Fifty years before, the astronomer Kepler had discovered all of
these orbits to follow elliptical paths; gravity now explained
why the paths took this particular shape. Gravity is also responsible
for the movement of comets, which, Newton revealed, transcribed
orbits around the sun just as planets did. He also discovered
that the force exerted on the earth by the sun's gravity is responsible
for the flattening of the earth at the poles and for the bulge
at the equator. Finally, gravity explains the tides: the weak
gravitational pull that the moon exerts on the earth combines with
the pull of the sun to form what Newton termed a "lunisolar" effect
and create the daily rhythm of the seas.
