This article is taken from the last number of ENEL’s magazine, Oxygen
Our discourses must relate to the sensible world and not to one on paper.
(Galileo Galilei, Dialogue concerning the two chief world systems, second day)
In this day and age, is it possible to say that Galileo’s works reflect modernity? To do so we would have to pinpoint a facet that is still present and vivid in today’s culture. A difficult task. In fact, in modern-day science faculties, students following courses in mechanics or astronomy study neither the 1632 Dialogue nor Sidereus Nuncius, which was published in 1610. If anything, Galileo’s writings are remembered by historians. But research into the history of science, as it is usually conducted, is based on the requisite of contextuality, according to which a given theory must be interpreted without digressing from the historical context in which it was formulated. This precludes any knowledge which post-dates that particular context. If this requisite were strictly respected, disconcerting results would ensue.
An example might be of help in illustrating this point. In July 1610, Galileo described Saturn as formed by three spherical bodies that are motionless with respect to each other. During the three decades that followed, this strange conformation was represented by numerous, problematical variations. Only in 1675 was it established that Saturn is surrounded by rings and that the preceding images had been caused by the structure of the lenses that were available to Galileo and his fellow scholars at the time. But since Galileo died in 1642, in virtue of contextual coherence, a historian should sustain that because the notions of 1675 were not applicable to Galileo’s writings, in July 1610 it was discovered that Saturn is a three-bodied celestial formation. Similar results emerge, with great frequency, when historians contextually analyze Galileo’s theories of inertia, principles of relativity, rejection of the elliptical orbit of the planets or non-gravitational causes for tides.
In short, other paths must be followed in the search for Galileo’s modernity. I suggest the imperative need to abandon the historiographical models centered on the dogma of context in favor of evolutionistic models, according to which the growth of human culture has a tree structure of Darwinian memory. It is an evolution with many unexpected mutations and dead branches; it is not governed by a transcendent logic and it reveals discoveries that belie their discoverers’ expectations or predictions (Bellone 2009). From this alternative point of view, the pages written by Galileo present a number of characteristic traits. The first: sometimes Galileo strove to confirm, in a rigorous manner, various points of physical knowledge whose veracity he did not doubt yet he obtained disconcerting results that were extraneous to his expectations or his predictions (Drake 1979 and 1988).
The second: sometimes Galileo explored certain astronomical phenomena without cultivating any expectations at all and without trying to make any predictions. He was simply driven by curiosity and came upon revolutionary results (Righini 1978, Drake 1983). The third trait: as time passed, the development of Galilean science did not take place as a continuum but rather it was marked by abrupt twists (Bellone 2008). And finally: Galileo never wrote a treatise on true scientific method and his modernity does not lie in a presumed experimental method. In fact, as he conducted his research, Galileo consistently oscillated between acceptance of measurements that were not corroborated by theorems and praise of theorems lacking experimental confirmation (Bellone 2004).
A few concrete themes could help us reflect on the above-mentioned traits. At the beginning of the 17th century, after years of adherence to the centuries-old thesis of velocity as a constant in natural motion, Galileo accidentally discovered that the speed of descent of a small sphere on an inclined plane is not constant. Obviously, he could not measure this speed. He could only estimate the length of the space covered at equal intervals of time and discovered, in contrast to his expectations, that the sequence of these distances corresponds to the sequence of odd numbers. Thus, acceleration exists and suddenly both the pre-existing science of natural motion and Galileo’s own convictions crumbled.
In January 1610, he aimed his telescope at Jupiter and, over the course of just a few nights, he discovered the four Medicean stars. But we know from his manuscripts that he was not controlling any prediction regarding the possible number of satellites of this planet – all he did was see them. The same holds true for the stellar resolution of various nebulae or of the Milky Way: a few weeks of study that was not motivated by predictions but simply by curiosity, and a centuries-old image of the heavens fell by the wayside.
These two episodes, in their simplicity, highlight how a few events that are fundamental to the birth of modern science – the revolution of the telescope and overturning the theory of motion – are not the results of rigorous logic within the growth of knowledge; rather, they represent unexpected twists that were independent of expectations, intentions or predictions. Thus, a window is opened onto the structure of the growth of knowledge: to Galileo, the sequence of odd numbers began to connect to the unknown nature of gravity and the surprising images offered by his telescope demolished a millenary astronomical tradition, unifying the celestial world and the sub-lunar world into one physical framework, within which he came upon a prototype of inertia (Wisan 1974) and an archetype of the principle of relativity.
But, if we reconstruct Galileo’s legacy in these terms, we place it within a true evolution of knowledge. In short, we find, a posteriori, inertia and relativity. Newton and Einstein. A posteriori, and not as results that were governed by a transcendent logic; we find in Galileo the information which is needed to reshape the history of science as a sector of a cultural evolution that is typical of our species (Cavalli Sforza 2004, Bellone 2003 and 2006). In short, Galileo is modern because certain aspects of his theories, interpreted and reinterpreted from generation to generation, are still present in today’s culture. And at this point, two sets of questions arise.
The first regards the fact that these aspects have not been conserved in their original form but rather are present today after long sequences of variations. Long sequences which are often invalidated by theses that, always a posteriori, appear to be erroneous. In a famous passage of Galileo’s Dialogue, he presents us with the impossibility of distinguishing, from a mechanical point of view, between a system of reference at rest and one in constant rectilinear motion. The problem is represented in 1873 (Maxwell 1973) by no less a genius than Maxwell, who mathematically computed the invariance of equations in the electromagnetic field by Galilean transformations: an erroneous computation whose correction led to Einstein’s 1905 theory of the electrodynamics of bodies in motion (Einstein 2004). The history of science is full of similar situations, which is why the process is represented as a tree with many ramifications. Some branches remain arid stumps, others survive only because they produce new branches and acquire new meaning. I therefore suggest that the modernity of certain theoretical fragments coincides with this survival mode and that it is based on forms of cultural selection.
The second set of questions refers to the following fact: ever since the first written texts appeared – roughly 12,000 years ago – our species has always made use of elementary arithmetical and geometric structures in its attempts to adapt itself to its niche. Not by chance, in recent years discussions have involved true “embodied” mathematics with regard to both Homo sapiens and other living bodies (Lakoff and Nùnez 2005, Vallortigara 2005, Oliverio 2008). All this appears incomprehensible (or irritating) to those who do not subscribe to evolutionistic models of culture, on the basis of which culture is not regarded as a spiritual or Descartian mental world and ideas begin to be defined as material bodies and theories as physical-chemical variable states of neural networks.
In this way, an all-around evolutionistic framework proliferates regarding historical research, investing all of human culture (Moretti 2005, Bartocci and Odifreddi 2007). This research can be explored through typical themes of the naturalistic approach to knowledge (Van Orman Quine 1991, Valore, Giorello and Pettoello 2004), which lets us place Galileo’s modernity within a Renaissance framework that has already been well studied by Paolo Rossi (Rossi 2002). In this system, modern science develops as the public knowledge Galileo calls on in his Discourses, in which technique is praised as a high method of culture and the Arsenal of Venice is viewed as a place of true philosophizing.
Science historian, Enrico Bellone was the first to be asked to hold, in 1994, the Galileo Galilei Chair at the Università di Padova. In 2008 he received the Preti prize with George Lakoff of Berkeley University.
(Please refer to Italian version for recommended reading)
Translation by Gail McDowell