Saturday, November 20, 2010

77 Arguments

John Duns Scotus (not Giovanni Riccioli)

In a recent paper published in the Physics ArXiv, Christopher Graney presents a translation from the Latin of a section of Jesuit astronomer Giovanni Battista Riccioli's Almagestum Novum (1651) in which Riccioli presents 77 arguments against the motions of the Earth that the new Copernican (1473-1543) system required. Riccioli (1598-1691) was a Jesuit priest who is still remembered for mapping and naming the main features on the Moon's surface (including ironically the giant Copernicus crater) and for being the first to measure the Earth's gravitational acceleration.

In Riccioli's day, questions about the true motions of the Earth and planetary system were as topical and exciting as today's speculations about the results from the Large Hadron Collider with the additional spice (not present in today's frontier physics) that certain answers could get you locked up or burned at the stake as was the case with Galileo (1564-1642) and Bruno (1548-1600).

Graney presents Riccioli's arguments plus the Copernican counter argument which in many cases was non-existent. In particular Riccioli cites many physical effects (the Coriolis force, for instance) which should be observable if the Earth is really rotating. None of Riccioli's effects had been observed in his day so the experimental facts did indeed seem to support a stationary Earth just as the Catholic Church's doctrines required.

One amusing use of Riccioli's arguments is to test your own knowledge of physics. Of course "everybody knows" that the Earth is rotating but can you defend today's common knowledge against the arguments of an educated seventeenth-century Jesuit? Why, for instance, do we not witness powerful winds blowing from East to West as the Earth rotates (at a supersonic equatorial velocity of 1000 miles/hour)? When NASA launches its rockets eastward it utilizes the Earth's eastward rotation as an additional boost. Why does this work in space but not on Earth? Why--if the Earth is really rotating so rapidly--doesn't a ball thrown to the East travel further than a ball thrown to the West? asks Father Riccioli in Argument #20. A very instructive physics course could be designed using Riccioli's arguments as a basis for teaching Newtonian mechanics.

Reading Riccioli is also a excellent exercise in the realization that Today's Obvious Truth is forever in danger of suddenly being demoted to Tomorrow's Naked Absurdity. Pay special attention to areas where acquiring and publishing knowledge has been declared illegal or is being actively suppressed.

Graney points out that the Copernican System was accepted not because its supporters refuted all of Riccioli's arguments--some of his predicted rotational effects remained unobserved well into the 19th century--but because of the persuasive power of Newton's new laws of motion which provided a firm theoretical foundation for the Copernican moving-Earth model against the fixed-Earth picture of Tycho Brahe.

In preparing this post I accidentally discovered that riccioli is a type of pasta. But it was not named after the Italian Jesuit who published these 77 arguments against the Copernican motion of the Earth.

1 comment:

Robert said...

You give fascinating historical tidbits! I wish I had stayed in school when I was younger and learned all this. I feel at my age (57), I am getting a little slow.
Love you.