What is Gravity?

We humans have had some odd ideas about what makes the world go 'round (literally) over the years. In the days of the ancient Greeks, gravity was perceived as a force that pulled all things toward the center of the universe (Earth, it was believed at the time). In the Renaissance, thinkers toyed with a number of different notions about what made things that went up come back down.

It was during that era that the first true modern theory of gravity was crafted, by the legendary astronomer-physicist Galileo. It had only been a few years before that Kepler had perfected Copernicus's model of the helio-centric solar system, replacing the Earth with the Sun at the center; before that, it wasn't really necessary to think about gravity - the center of the universe explanation seemed good enough, for the most part. But now that Earth was no longer the center of creation, things had changed.

Galileo suspected that gravity was actually a force that existed between massive bodies. The famous 'simultaneous drop' experiment, which supposedly involved the free-fall of two objects of different weights from the top of the Leaning Tower of Piza, was part of that research (actually, that story is an amalgamation of two separate accomplishments - Galileo conducted repairs to the Tower to prevent it from falling the rest of the way over, and the drop experiment actually used slopes, not a sheer drop, and took place in Venice). He found that (barring wind, friction, and other resistances) any object with mass will 'fall' toward another massive object at a constant rate dependant only on the mass of the heavier object. (Note: technically, the heavier object also falls toward the lighter one.)

Sir Isaac Newton went on to revise Galileo's ideas with precise formulas and figures. Yet, despite his gift with math, he too concluded that gravity was an attractive force between objects, much like a monopole version of magnetism that affects all matter. This is a thought that lingers to this day, despite the proving and acceptance of Einstein's ideas to the contrary.