Galileo's contributions to scientific methodology and the heliocentric theory

Galileo and the Scientific Revolution: An Examination of Galileo's Progression And An Imagined Rebuttal

Galileo Galilei ranks among the greatest scientific minds ever to have lived. His contributions to numerous fields helped to lay the very foundations on which many modern scientific disciplines are built, as well as being entirely revolutionary in his own day. His political controversy and eventual house arrest are almost as well-known -- perhaps even more so -- than his many discoveries and inventions; though he appeared to grow meeker in his later years (or perhaps it was simply that the power structure had changed enough to demand his expediency overtake his integrity), he remained committed to the pursuit of scientific truth inasmuch as he was able until the end of his life. It was this commitment, and in a sense this controversy, that constituted what was perhaps a bigger gift to science than all of his discoveries.

Galileo did not just contribute to science, he almost invented it. He was among the first to bring a serious mathematical attention to issues in nature, observing, cataloging, and analyzing numerically rather than making assumptions based on perception alone. More than anything else, Galileo taught the world -- or at least the small portion of it that was really paying attention to him -- how scientific investigation was to be carried out if the results were to be reliable. The Scientific Revolution was a beast largely of Galileo's own making; one could say the he was martyred for or alternately became a traitor to this cause, and he wouldn't be the first or the last of either of these things. But attempts to come up with a single figure who had as much of an impact on the development of science at the time than Galileo Galieli are failed, and a small treatise called the Starry Messenger is a large part of the reason why.

The Starry Messenger

One of Galileo's biggest contributions, and the one that ultimately led to his own Scientific Revolution and eventual house arrest, was his verification of Copernican theory regarding the heliocentric universe. He lays out several pieces of evidence concerning his telescopic observations that support heliocentric theory in the Starry Messenger. One of the most convincing of these is his discovery of Jupiter's moons, which he terms "stars," and their orbiting of Jupiter rather than remaining fixed as stars were supposed to according to the traditional model of the cosmos. Specifically, his observation that what had been three stars was now two, "the third (as I supposed) being hidden behind Jupiter" shows the brilliance of Galileo's mind and his argument (Galilei 11). Though this conclusion seems obvious to us today, it was a startlingly astute inference at the time.

This explanation, however, could still be made to fit the awkward yet long-standing Ptolemaic conception of the cosmos, however, where the planets were fixed to epicycles that were themselves affixed to the larger crystalline spheres the revolved around the Earth. His subsequent discovery of the phases of Venus could not be explained away by this theoretical model no matter how many extra epicycles and sub-epicycles were added to it, though; no matter what, it was apparent that Venus traveled around the sun because it did not stay in a constant crescent phase, as it would if attached to an epicycle that kept it close to the sun (Drake 164-7). Galileo's telescope enabled him to be the first to observe the phases of Venus, and thus provide the first empirical evidence to test Copernicus' correct but unproven theory of a heliocentric universe.

The Math Behind the Revolution

Galileo was able to accomplish much of what he did because he recognized the importance of math in making observations about nature. This was perhaps nowhere as apparent as it was concerning the observations Galileo made involving motion, particularly falling bodies. Though Aristotle had drawn vaguely mathematical conclusions regarding the laws governing the speed of falling bodies, these conclusions were based on speculation and unempirical reasoning rather than careful observation and measurement. This is what made Galileo's use of mathematics in science so revolutionary; reasoning was still used, but it came after mathematical measurement.

Instead of leading to science built on assumptions -- even common sense assumptions -- this led to a science built on hard and indisputable (rationally indisputable, at least) facts. Galileo was certainly brilliant at deduction; as noted above, his "supposition" about Jupiter's moons appearing to have lost one of their number due to one of these "fixed" elements actually being hidden behind the planet is evidence of his reasoning abilities. But this reasoning was built on carefully recorded observations and an admirable objectivity that carefully rejected everything that was supposedly "known" about the world in order to allow a free conclusion to be drawn. Reasoning had been based on observations before, of course, but observation had occurred only at he most basic level, and the information thus obtained was then fit into the already accepted dogmas and/or theological structures of the time.

Galileo left his dogmas at the door when practicing science, and in a man with many less-than-noble qualities this is a character trait that renders him fully worthy of admiration. Tackling the motion of falling bodies, Galileo set up a system using a device similar to a water clock in order to measure the rate at which objects rolled down an inclined plane under the influence of gravity. Galielo showed that, contrary to Aristotle's conclusions, weight did not affect the force of gravity by dropping objects (possibly out of the Tower of Pisa), but the mathematical observations he made regarding rolling objects were far more astounding. Galileo discovered that for a given unit of distance traveled per unit of time, the total distance an object under the force of gravity is equal to the square of the time (Drake (62-5). For instance, if a ball rolls one foot in the first second, it would roll three during the next second 9 for a total of four feet in two seconds), five feet in the third (nine feet total) and so on. This held true no matter how steep the plane Galileo used was; absolute speed was changed but the mathematical relationship remained the same.

This was only one major example of how mathematics changed both Galileo's and science's way of observing the world. Mathematics also helped contribute to Galileo's success in proving Copernican theory. Galileo was able not only to observe and satisfactorily explain the existence of what eventually became four "stars" orbiting the planet Jupiter using his telescope, but the accuracy of his observations allowed him to calculate their cycles and predict their relative positions wit a remarkable degree of accuracy, presenting evidence that was compelling to other astronomical observers and mathematicians alike (Drake 151-4). Galileo's careful observation were key to his mathematical success, and his mathematics were key to his success as a scientist. Careful and repeated measurements allowed for an application of numbers to situations in a way that it simply hadn't even been thought truly necessary before.

To the Most Exalted Grand Duchess

I hope this finds you well and most unmoved on the point of Galileo Galilei's new conception of the motions of the heavenly bodies. Though his supposed observations, if indeed they have been confirmed by men of reputable science, do bear some further consideration and calculation, it is far too premature to cast out the model of the heavens that has accurately predicted the motions of the various celestial spheres for many thousands of years. Though the simplicity of the structure as it has traditionally been perceived was admittedly lacking in certain explanations, I have full confidence that careful considerations of the matter will result in a more satisfactory explanation.

It is entirely possible, for instance, that the point about which Venus' epicycle turns somehow distorts, reflects, and/or blocks the light emanating from the more distant Sun, causing the appearance of the phases that Galileo claims to have observed. A more complex system of layered epicycles quite neatly explains the existence of the stars noted orbiting Jupiter; doubtless these smaller luminaries revolve on their own spheres around Jupiter's planetary sphere. This conclusion neatly explains the existence and movements of these stars without necessitating the celebrity-seeking conclusion that thousand's of years worth of thinkers and observers were wrong.

Conclusion

The difficulties in composing this imaginary letter, and especially in coming up with a reasonable alternative explanation for the observations Galileo made, reflect the reasons that Galileo -- and through him Copernicus -- were ultimately proved correct regarding the theory of a heliocentric universe. This reason had nothing to do with politics, religion, or ultimately even with mathematics and observation. Galileo's theory won out against the Aristotelians because it was right, and all of the objective scientific minds at the time knew it just as we know it now. The Scientific Revolution that Galileo helped to foment if not carry out was built on a quest for truth, and would have been pointless if it had ended b accepting older dogmas simply because they used to work, and did so for so long. Galileo's careful observation and calculation led him to the right answer; unlike others of his era, Galileo made discoveries instead of facts.