Most people remember Galileo, if they remember their schooldays at all, as the champion of the Copernican model of the solar system, with the sun at the center. Perhaps they might even remember the story that he dropped a heavy and a light weight together, from the top of the leaning tower of Pisa, to show that they would reach the ground at the same time. All Galileo’s valuable experimental work in the movement of objects on earth was recognized by Newton and incorporated into his monumental synthesis of laws of motion. It is now merely a part of the history of physics, with little relation to the present state of the science.
However, there is another side to Galileo’s work which was not only of immense importance in his own time but also to our present age. It was Galileo alone who was responsible for setting down the scientific methods to be followed by the new science of physics. He published three foundation concepts which underpinned and guided all thinking in physics until the modern age of relativity and quantum mechanics. In sciences other than physics, these concepts still form the axiomatic basis of all later developments.
Galileo’s three foundation concepts can be expressed as follows:
The first of these stated that if a theory is proved to be correct by repeated and careful observation or experiment, it ceases to be merely a theory and becomes an established fact, an expression of a law of nature, a truth that has been definitely established. He further stated that the philosopher had the duty to test all statements made about phenomena, especially those phenomena that were quantifiable and measurable, and not rely on unsupported traditions.
His second axiom was stated very simply: mathematics is the language of nature. Without it, we cannot understand a single word of it, in his opinion. Here, he implies that mathematics is not simply a construct of the human mind, something internal and subjective (no matter how abstract), but a reflection of natural law that exists outside the brain and is part of the fabric of the world.
Galileo really becomes audacious and radical in the last of his three axioms. He divides the world into two categories, the “primary qualities” and the “secondary qualities”. In his opinion, only the former are suitable for scientific consideration because they exist without the need of a human presence. They are therefore imbued with objective reality. They were very few in number and Rene Descartes later reduced them to just two, matter and motion. All the secondary qualities, that is everything we perceive through the senses of touch, taste, smell and hearing, needed the presence of a person and his sense organs and was thus hopelessly subjective and unsuited to science.
This reduction in the focus of physics to just two allowable “qualities” was accepted by later thinkers. Newton’s great synthesis of laws, for instance, is all about matter and motion only. It was thought that these alone could unlock all the mysteries of nature. The philosophical expression of Newton’s laws was given in the completely deterministic cause-and-effect formulation of scientific determinism, championed by Laplace and many others. It lasted until the 1920s, when physics had breached the atomic barrier and it was realized that subatomic particles could not be explained without including a degree of uncertainty.
However, as far as our awareness of the world is concerned, we still live in th age of Newton and Galileo. We still feel that the world of nature that surrounds us leads a completely separate existence from us and has a completely separate history. This means that we still feel that the reality of nature is objective, that is it does not depend on us and our presence.
This is no longer the position taken by modern physics, which argues that everything we know and can know about the world, on an experimental basis, comes through our sense structure and is therefore subjective, not objective. If we now take a second look at Galileo and his primary qualities, it will become clear that the human sense of sight has to be involved in investigating matter and motion, so that a person is still needed. Therefore, these qualities cannot be granted objective reality, that is a reality which does not include man.
Galileo’s other axioms similarly contained serious flaws. For instance, no serious modern physicist would ever claim that experimental proof, no matter how often repeated successfully, could ever turn a theory into a fact, or a truth about nature. To be properly scientific, a theory always has to remain open-ended, because you never know when some new facts might be found to upset it. Newtonian laws are a prime example of this. For hundereds of years, every experiment verified them, yet their absolute truth was overturned by relativity and quantum concepts, and they were found to be nothing but good, rough approximations.
Galileo is responsible in large part for the fact that today out consciousness of the world of nature is out of step with our latest science. We have to make a conscious effort to realize that nature is not objectively real, and this affects the way we ought to think about the ages of the world before the appearance of man.