Hello again! On my continuing quest to spread the wonder of science throughout Bungie.net, I present this week’s [i]Science Friday[/i]. Last week, I covered the history and function of DNA—the molecule of life. To read it, you can check out the #sciencefriday tag on the site. This week, I thought I would give attention to the base of the science pyramid: physics (right after mathematics, of course). While an obvious start would be Newton, I will save him for another week. Today, let’s cover the important work of Galileo Galilei, the famous Italian astronomer and mathematician of the 17th century. I do not have an online source this week. Most information I present here is paraphrased from Leon Lederman’s fantastic book, [i]The God Particle: If the Universe is the Answer, What is the Question?[/i] which was published in 1993. Lederman won the Nobel Prize in the late 20th century for his work in particle physics. A bit of backstory... Galileo Galilei’s father, Vincenzo Galilei, was a musician/mathematician, and a good one at that. Despite this, he absolutely hated mathematics because, at the time, the Aristotelian view of the world was that everything could be determined from “Pure Reason,” or simply thinking. In fact, at the time, experimenters were often thought of as strange men with silly instruments attempting to verify what God’s creation—the mind—had already figured out. Vincenzo insisted that the music theory generally accepted by the Aristotelians be tested. This habit of “experimentation” was passed on to his son, Galileo. Galileo’s experiments hearkened the beginning of the scientific method as we see it today: that is, he formed hypotheses and tested them using precise experiments. This inverted the traditional approach, as hypotheses were tested with the same “Pure Reason” that conceived them. One of these Aristotelian notions was that heavier objects fall to the Earth faster than lighter objects. After all, this made sense considering a rock would fall to the Earth faster than a feather. Galileo, however, was not satisfied. In order to test whether heavier objects indeed fall faster than lighter ones, Galileo designed a rather ingenious experiment. Knowing that he would not be able to accurately time free-fall of objects (vertical drops), he instead used inclined planes, under the assumption that the mechanics of free-fall were still at work, but in “slow-motion,” and therefore measurable. This assumption can be verified by drawing a simple free-body diagram. He rolled polished balls down smoothed inclines, and, in order to time, used a series of strings arranged geometrically (i.e., the distance between each successive string decreasing) and his incredible sense of rhythm instilled by his father. (Remember, there were no stopwatches yet.) He came up with the following formula: [i]s[/i] = [i]At[/i]^2 where [i]s[/i] is the distance the ball traveled down the incline, [i]t[/i] is the time it took, and [i]A[/i] is some proportionality constant that depended on the angle of incline. Galileo noted that heavier balls did not have different values of [i]A[/i] for the same angle of incline, leading him to conclude that all objects do, in fact, fall to the Earth at the same rate. The example of the feather and the rock was misleading due to external forces not accounted for (i.e., air resistance). Galileo had discovered the solution to the differential equation defining the velocity of an object undergoing a constant acceleration with initial condition v(0) = 0, and yet, calculus had not been formally invented yet. Galileo, through reasoning and experiments, came up with what is now known as Newton’s First Law of Motion: an object in motion will stay in motion and an object at rest will stay at rest. Galileo also pioneered the idea of inertia, or resistance to acceleration, formalized by Newton in the same century. Galileo not only provided the foundation for Newton’s groundbreaking work (stay tuned), but for experimentation as a means of determination rather than sole reliance on the ability of the human mind to make accurate conclusions about the natural world. His influence in not only physics, but the entire realm of science and logical reasoning, is rivaled perhaps only by his spiritual successor—Newton—and Einstein. I hope this session of [i]Science Friday[/i] was informational. What were your thoughts? Too much to read? Not enough information? Please leave these thoughts below. I’d appreciate any feedback in terms of topics and format for upcoming weeks.