Principia Mathematica Mathematical modeling Universal gravitation Commentary

Isaac Newton mathematics

Principia Mathematica

• By 1675, Isaac Newton had worked out the principles
• of planetary orbits—bodies moving freely through space
• subject to only gravity and their own inertia—
• how the planet must be balanced between centrifugal force
• and the gravity of the sun acting at a distance,
• and how its orbit must be elliptical with the sun at one focus—
• but Isaac hadn’t wanted to be brought down to earth—
• balanced between his sensitivity to criticism
• and his friend Edmond Halley coaxing him to publish.

Mathematical modeling

• Almost invariably, physics today is expressed using mathematical models,
• which Newton, in Principia Mathematica, first established as a model,
• going so far as to develop a new mathematical method—his infinitesimal calculus.
• Thus I claim M = I_e (meaning is explanation of interest)
• and I = Σ S_d + D_s (interest is the recognition
• of hidden differences between similar things
• and hidden similarities between different things).

Universal gravitation

• That all things in the universe
• great and small
• attract each other with force
• proportional to the product of their masses
• and inversely proportional to the square
• of their distance
• was irrefutably true and obvious
• until Einstein taught in his theory of general relativity
• that gravity was not mutual attraction
• but an attribute of the curvature of space and time
• leads to the theory that the distortion of the universe
• perceived while under the influence of LSD
• is no less valid than the distortion perceived
• while under the influence of mild tea
• so we are universally attracted
• to ideas great and small
• according to how far apart we are from them.