Copernicus, Kepler, Galileo, Newton

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The Poinsot Solids

Slide 28

Strange Start - Good Finish

Kepler started off with mystical ideas, and ended up correctly describing the motions of the planets. How can this be?

Slide 29

Science often proceeds by a process of successive approximation Make an assumption

See how it fits reality,

Modify it (junk it if necessary) and try again.

After a few iterations of successive approximation you can be very far from your starting point,

Even fairly strange initial assumptions can lead to correct results.

Slide 30

Successive Approximation differs profoundly from circular reasoning, In circular reasoning, you start off with an assumption,

Accept, reject, or modify observations to fit the assumption,

Then use the results as proof of the assumption.

People who engage in circular reasoning almost never scrap or modify their initial hypothesis

The whole point of circular reasoning is to justify the initial hypothesis at all costs.

Slide 31

Kepler's Laws

Planets travel around the Sun in elliptical orbits with the Sun at one focus.

A line from the planet to the Sun sweeps out equal areas in equal times.

The square of a planet's period in years and its distance cubed are proportional.

Slide 32

How Did Kepler Do It? One Mars year (687 days) = 2 Earth years (730 days) minus 43 days

After 687 days, Mars is in the same place in its orbit, but Earth is not

Mars appears to be in a different location in the sky

Slide 33

How Did Kepler Do It?

Slide 34

Tycho Brahe 1546-1601 Tycho really did live the outrageous lifestyle shown in the video

Really did have a gold nosepiece.

He died the way he lived. He was hitting up some noble personage for patronage and support and, fearing that somebody else might upstage him, refused to leave to go to the bathroom. He developed a bladder infection and died.

Slide 35

A Neat Coincidence that’s Too Neat

Slide 36

Rosenkranz and Guldenstern are Dead

Slide 37

Hamlet

Hamlet’s Uncle has:

Murdered his father