A (Very) Brief History

In the matter concerning cosmology and theoretical physics, there are three books I'd like to discuss. One is The Elegant Universe by Brian Greene, another is A Brief History of Time by Stephen Hawking, and the third is The Hidden Reality also by Brian Greene. I've finished The Elegant Universe, but plan on going through it again, due to some things that I didn't quite understand. The best book to begin with would be A Brief History of Time by Stephen Hawking, I think. It lays the foundations for everything that ensues, including those beyond our wildest imaginations.

In the first chapter, Hawking begins with the earliest beliefs of the Universe, from ancient superstitions that say the Earth sits upon the back of a giant tortoise to various religious beliefs. Whatever belief holds for a particular age, one truth always remains: we as human beings constantly yearn to know our place in the Universe and to know how, when, and why things began. "Did the Universe have a beginning, and if so, what happened before then? What is the nature of time?" These questions have startling answers for those who haven't yet been exposed to the true nature of space and time. Many of us live our lives without any thought to exactly how our environment behaves and what it is made of. Many live and die without even glancing up at the cosmos and wondering how everything came to be.

Scientific revolutions allow us to leap forward towards the truth about nature. Once upon a time, man believed Earth to be flat (some still do...). But through simple observation, scientists of history were able to deduce simple truths that made all the difference. For example, Aristotle deduced that the Earth is round instead of flat by looking at the moon during a lunar eclipse. He saw that the shadow cast upon the moon during an eclipse was always round. If the Earth were a flat disk, the shadow would actually appear as an elongated ellipse with its shaped determined by the position of the sun behind the Earth. The only way a flat-disked Earth would consistently cast a round shadow on the moon is if the sun was positioned exactly behind the center of the Earth every time an eclipse occurred. Second, Greeks noticed that the North Star appeared in different locations in the sky depending on where they were on the planet. For example, viewed from the North Pole, the North Star would be located directly above the observer. But to someone observing from the Equator, the star would be closer to the horizon. Thus, the Earth could not be flat.

Aristotle, however, did believe that the Earth was the center of the Universe and that all observable planets moved in perfect circles around us. This model was shared by Ptolemy and this view, of course, has religious roots, as man did indeed believe that humans are divine creations. And because it held with the writings of Scripture, the church adopted the model, placing Earth at the center of the Universe. However, there were some questions that the model could not answer and that were left unanswered, such as why the moon sometimes appeared twice as big in the night sky. "Eh...let's not worry about that...moving on!"

Then came the Copernican Revolution. Nicolas Copernicus proposed (rather anonymously and for good reason) that instead the planets orbited the sun. It wasn't until later, when Kepler and Galileo came along, that he was taken seriously in 1609. Kepler went further to state that planets don't necessarily move in circles, but in ellipses. But the question of how this is even possible eluded him. Although Kepler wondered if planets were held through magnetic forces, he could not reconcile his observations of the planets' movements with this theory.

Then in 1687, Sir Isaac Newton published his work Philosophiae Naturalis Principia Mathematica in which he "postulated a law of universal gravitation according to which each body in the universe was attracted toward every other body by a force that was stronger the more massive the bodies and the closer they were to each other." This showed that "gravity causes the moon to move in an elliptical orbit around the earth and causes the earth and the planets to follow elliptical paths around the sun." Newton also devised a brand new complex branch of mathematics in order to analyze the motions of planets: calculus.

This will be the end of this post because after this, things get a little messy. Well, more like enlightening. But that was a very brief history of how man viewed the Universe. We now know that everything revolves around the Earth in perfect celestial circles and that Harold Camping will lead believers to salvation.

Wait...