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Historical interlude--
more history--
not in the syllabus, with good
reason, but very interesting.
We've already met two of the
giants of mechanics, Galileo
and Newton.
Here are a few others who
made important contributions
to our understanding of
gravity and the motion
of the planets and the stars.
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Aristarchus of Samos,
310 to 230 BCE.
Aristarchus deduced that
the Earth orbited the sun,
but he did not observe parallax
in the view of the stars.
Normally, when we shift the
point of view of the observer,
the relative angles
of objects is changed.
Look at these two photos of
the Scientia building at UNSW.
And from a different
point of view.
Because we don't see this
effect in the relative angles
of stars, he deduced that
the distance to the stars
was vastly greater than
the distance to the sun.
Aristarchus did
not have a pet elk.
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Tycho Brahe, 1546 to 1601.
Tycho had an artificial nose,
because at the age of 20,
he lost his real nose
in a duel with swords
over a mathematical formula.
He set up an
astronomical observatory
on the island of Hven,
between Denmark and Sweden,
in spite of the climate not
being ideal for astronomy.
His detailed, precise data
gathered over many cold nights
in the observatory
later allowed Kepler
to make precise,
empirical models
of the orbits of planets.
Tycho had a pet elk--
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--which drank too much Swedish
beer, fell down the stairs,
and died.
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Johannes Kepler, 1571 to 1630.
At the age of six, Kepler
saw the great comet of 1577.
Later, he gave up a
job as a maths teacher
in Austria to become
Tycho's apprentice.
He inherited Tycho's
superb set of data
and, after much
complicated analysis,
fitted these data with his
three laws of planetary motion.
Kepler returned home to
defend his mother, who
was charged with witchcraft.
He got her off.
Kepler spent many
years trying to relate
the motions of the planets
to geometrical relations
and musical harmonies, which he
supposed a divine creator would
have done.
However, when the data didn't
fit his long-held theory,
he abandoned that theory
and many years of work.
Kepler wrote his own epitaph.
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[NON-ENGLISH SPEAKING]
I measured the skies, now
the shadows I measure.
Skybound was the mind,
earthbound the body rests.
There's no evidence that
Kepler ever owned an elk.
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Albert Einstein, 1879 to 1955.
Einstein was a
brilliant school student
who grew up to be an even
more brilliant researcher.
His father had a company making
mechanical-electrical-magnetic
equipment.
The company went broke because
it favoured DC supply over AC.
One of Einstein's several
outstanding contributions
to physics was reconciling
electromagnetism
with mechanics.
Einstein played the
violin and loved sailing.
The Nazis confiscated
Einstein's sailboat in Europe,
but acquired another
one in America.
Einstein never
needed to own an elk.
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