## Cosmology Begins

This is an important point in the history of physics. It’s the beginning of quantitative, predictive science of the universe. This subfield of physics and astrophysics is called **Cosmology**: the study of the whole universe. (*Cosmogony* is another similar word that describes the origin of the  universe. Formerly, thought to be outside of the province of science. Now...a regular part of physics. We tend to have expanded the word **Cosmology** to include origins.)

>**Cosmology**
>Cosmology is the scientific study of the large properties of the universe, including its origin, evolution, and future. Sometimes "Physical Cosmology" is used to distinguish it from religious or mythological origins stories. I prefer just plain Cosmology, where the descriptor "scientific" distinguishes it properly.

While Kepler came close, after all, he provided a formula that was descriptive of how the planets move. We understand Kepler’s law now as a logical (meaning: algebraic) consequence of Newton’s Gravitation...so it was eventually appreciated to be derivative.

Here we have Newton using an abstract (meaning: using a mathematical formula) explanation to describe the entire universe. The form of his equations insists that a gravitational force only goes to zero at infinity, so no matter how far away two objects with mass are situated, they will still attract one another. This presented a problem that needed explanation: his model was predictive, but not complete. His approach to this level of incompletion was to give up and require a deity. Our approach is to leave it open as a problem remaining to be solved. In that sense, we’re more Newtonian (“no hypothesis”) than he was!