Kepler vs Galileo

[danieldemol]

IIRC You were asking me if religious people have done bad things

Actually was asking you if religious teachings themselves (as opposed to the followers of the teachings) contain bad teachings and how can the teachings be rectified without undermining the concept of changeless religions?

In my opinion.

 

[Hop_David]

Actually was asking you if religious teachings themselves (as opposed to the followers of the teachings) contain bad teachings and how can the teachings be rectified without undermining the concept of changeless religions?

In my opinion.

The topic of this thread is Kepler vs Galileo

 

[danieldemol]

The topic of this thread is Kepler vs Galileo

So you have no answer to the question.
Gotcha.

In my opinion.

 

[Hop_David]

So you have no answer to the question.

This thread is about Kepler vs Galileo. You wish to derail with this thread with off-topic hot button questions? That is understandable.

But in spite of your efforts I will still talk about Kepler and Galileo.

The above is from my orbital mechanics coloring book. Kepler's 1st law is that planets follow elliptical paths with the sun at a focus of the ellipse.

Kepler's 2nd Law: A line from the planet to the sun sweeps out equal areas in equal times.

Kepler's 3rd law: Orbital period is proportional to length of semi-major axis raised to the 3/2 power.


Kepler's model fit empirical data from observations better than Copernicus' and Galileo's model.

Around 1673 Huygens derived an expression for centrifugal acceleration:
Centrifugal acceleration = ω^2r

Given Huygens' expression plus Kepler's 3rd law, it's almost trivial to demonstrate inverse square gravity for circular orbits:

But it's not so trivial to demonstrate the same is true for the elliptical orbits Kepler observed.

This was the back story when Edmund Halley, Christopher Wren and Robert Hooke met at a coffee house following a meeting of the Royal Society in January of 1684. Wren had offered a cash prize to whoever could derive the shape of planetary orbits assuming inverse square gravity. Wren also asked if inverse square gravity would imply Kepler's laws of planetary motion.

None of them could solve the problem. So Halley paid Newton a visit and asked him what sort of path would a planet follow if the sun's gravity fell off with inverse square of distance.

Newton replied an ellipse, that he had calculated it. Newton could not find his calculations at that time so he told Halley he would do them again and send it halley.

About a year and a half later Newton sent Halley a nine page manuscript de motu corporum in gyrum which was a rough draft for Principia which would be published some years later.

So it is my contention that it was Halley's heliocentric model that paved the way for Newton's Principia.

So why does Galileo's model get more attention? Well, flipping off powerful people makes for more drama and therefore a more interesting story. It also better fits a popular narrative used against religion.