In 1591, Giordano Bruno, an Italian philosopher and priest, published a book on cosmology titled De Monade. This was not the book that originally outlined the astronomical ideas that saw Bruno burned at the stake nine years later, but it was the sentiments expressed therein which made that burning inevitable:
Bruno had a lot of time to reconsider this piece of prescience. When he was imprisoned and brought to trial by the Inquisition, it was for eight years – a period that ended with his gruesome execution in 1600. The General Inquisitors who pronounced his guilt were damning in their denunciation of him: “…Giordano Bruno, the accused, examined, brought to trial and found guilty, impenitent, obstinate and pertinacious…”
On Saturday the 19th of February, in the Square of Flowers in Rome, Bruno was stripped naked, and bound to the stake. An iron spike had been hammered through his tongue, and another through his soft palate, and his jaw was further bound in iron. It is impossible not to assume that this was to prevent him from speaking further – Bruno had received his sentence from the judges with threatening words. “Perchance you who pronounce my sentence are in greater fear than I who receive it.” After eight years in prison, eight years of questioning from the Roman Inquisitors, Bruno could not have been without fear. Perhaps it was his own words in De Monade that gave him the courage to face his eventual death when recantation might have saved him. He did not recant, and was burnt alive. There is a disgustingly gloating letter surviving from a lackey named Gaspar Schopp, who was witness to the whole affair:
For his bravery, Bruno has often been hailed as the first martyr to science and freethought. Despite his pantheism, he has been traditionally seen as an atheist (both by his contemporaries as a means of vilification, and by the modern atheist movement, which often co-opts him for his stance against organised religion). His execution has long been an embarrassment to the Church.
If De Monade emphasised the strength of Bruno’s convictions, it was De l’Infinito Universo et Mundi (published in 1584) that was the root of the problem. Arrested for many doctrinal errors, Bruno was particularly tasked with recanting his belief in the infinity of the universe, the plurality of worlds, and the possibility of extraterrestrial life. An extract from a dialogue in l’Infinito shows the explosive nature of his arguments:
Not all of Bruno’s astronomical ideas were correct – for instance he also believed that matter was distributed evenly throughout the universe, when modern astrophysics tells us that it is not. Correctness aside, these beliefs were inimical to the Church. They defied scripture, and in the explosion of intellectualism that was the Renaissance, that defiance was another weapon in the increasing conflict between science and religion, rationalism and faith. This conflict was to result in the detention and trial of other scientists, including Galileo. Many scientific books were placed on the Index Librorum Prohibitorum.
Where did Bruno’s idea come from? It did not originate with him, but its history stretched back to ancient Greece. Interestingly, the concepts of the plurality of worlds, the infinite universe, and extraterrestrial life have consistently been at the forefront of the debate between freethought and religion.
Random moves versus the Prime Mover.
The conflict between Bruno and the Church is not dissimilar to that which took place in classical Athens, where the Atomists were pitted against the Geocentrists. Atomists were not necessarily atheists, but they were often accused of being so.
The argument for the plurality of worlds began with Leucippus, a Greek philosopher who lived in the fifth century BC. Leucippus was the first to postulate the existence of atoms, hence his position as founder of the Atomists. What little is known of his life and beliefs can be found in the work of his student, Democritus. The Atomists thought that the universe was made up of innumerable tiny and indivisible objects – the atoms – which were indestructible and therefore eternal. These atoms moved at random throughout the universe, and spent a great deal of time bumping into each other. Sometimes they would deflect after a collision and bounce away in another direction, but sometimes the collision would be so strong that the atoms would stick together. As these clusters of stuck atoms increased, they formed the substances found in the universe. These substances were not confined to physical matter only – Democritus posited that the soul was made out of atoms, as were the senses.
Given an infinite number of atoms, however, the Atomists postulated that their random motions and accretions could form an unlimited number of worlds throughout the universe, some of which could even be populated. As Democritus comments in one of his surviving fragments:
(The basis of the idea was correct, although the Atomists got the details wrong. Today we know that atoms are not indestructible, and they are not indivisible. Nor is there any evidence that atoms make up a human soul. The fact that the Atomists believed it did, however, is enough to show that they were not really atheists after all – merely labelled as such because their argument was inconvenient to the religious ideals of the time.)
The leader of the argument against the plurality of worlds was undoubtedly Aristotle. He ascribed the creation of the universe to a “perfect Prime Mover” who set in motion certain inalienable physical laws. One of these was the idea of the perfect circle. Another was the belief that Nature would not abide a void, or vacuum, and that because of this all matter within the universe collects in the centre of it. Aristotle believed that the Earth was the centre of the universe – a small universe with finite matter, shaped in a perfect circle, which revolved around the stationary Earth as water swirls around a plughole. The possibility of other worlds was horrifying to him, as that would have meant that there were two (or, Heaven forefend, even more!) centres, and two or more circumferences. With multiple central areas, the perfect circle and pattern of the universe would be disrupted, just as the circle of water swirling around a plughole is disrupted if several more plugholes appear near the first. No perfect Creator or Prime Mover would create something so aesthetically displeasing, and so contrary to order! (The problem with positing a Creator is that you are forced to posit his mental state as well.)
Aristotle found the perfect geocentricity of the solar system (as observed by the naked eye) to be proof of that Prime Mover. Denying that perfection meant denying the Prime Mover. Aristotle did not hold this position alone. As Democritus was supported by philosophers such as Thales, Epicurus, and Anaximander; Aristotle had the big guns of Plato and the Egyptian Ptolemy on his side. The influence of the Geocentrists was so pervasive that Ptolemy’s model of geocentrism as outlined in his Almagest was the prevailing idea for over 1500 years, until given the death blow by Copernicus in his 1543 book De Revolutionibus Orbium Coelestium.
This didn’t mean that the plurality position was left to dry on the vine, however. It was explored by several Roman philosophers, most especially Lucretius (99-55 BC), who supplemented the Atomist methodology of collision and accretion with his ideas on the “principle of plenitude”. In short form, this principle can be best described as the reflection of the imagination. If a person is capable of imagining something, then that thing exists in concrete form, and our imaginations reflect it like a great, unconscious mirror. We can imagine other worlds, therefore they exist. It has to be admitted that this argument can also be applied to God – the ontological proof of his existence. It’s probably equally reliable in both cases.
An example in point is the profusion of classical literature on the possibility of life (including intelligent life) on the Moon. Many classical philosophers wrote about the possibility, including Philolaus, Xenophanes, Plutarch, and Epicurus. By Lucretius’ reasoning, the Apollo spacecraft should have come across an entire menagerie of strange and amazing new life forms, and Neil Armstrong would have been the first to converse with intelligent life that was not of Earth. Wouldn’t it have been wonderful it he had? Alas, it was not to be. We are still alone – but it may not be forever. In his great poem De Rerum Naturae, Lucretius imagined life on other planets. Although his theory is defunct, perhaps one day his imagination will be proved correct.
The “noble and exalted” question.
Surprisingly, arguments about the possibility of other planets – including inhabited planets – carried on throughout the Middle Ages. On the cusp between the Classical and Middle Ages, St. Augustine of Hippo (354-430) disagreed with Epicurus on the plurality of worlds – his City of God pointed out the disconnection between the supposed random movement of the atoms and the Biblical concepts of creation and divine providence, and that was the end of that. However, in the latter half of the Middle Ages, discussion really began to start up again on the infinity of worlds and the possibility of extraterrestrial life. Not only did this occur despite the Church, which had an effective monopoly on the intellectual life of the time, but many of the debaters were churchmen. Although the plurality of worlds was a theologically iffy subject, it had gained a sort of intellectual cachet due to the rediscovery of Aristotle.
During the Middle Ages, Arabic science and technology were far more advanced than their Western counterparts, which had deteriorated from the high and heady times of the Classical era into not very much at all. In contrast, the Islamic Golden Age saw the invention of the decimal number system, algebra, optics, and Ptolemy’s Almagest. From the 11th century, Islamic scientists began to question Ptolemy’s model, but they mostly still worked within the traditional geocentric framework. A minority did posit possible heliocentric models – including Ibn al-Haytham (965-1039), who was particularly sceptical about the emphasis on the supposed “proof” of the perfect circle:
One of the first truly experimental scientists, al-Haytham’s scepticism extended to the idea of taking information on faith, especially when it came to scientific knowledge.
Unfortunately, al-Haytham was not to become the pattern of Islamic science. From the tenth century internecine conflicts between the rational and the orthodox branches of Islam occurred, and the latter gained ascendancy. Islamic science and technology stagnated – but not before the innovations they had created and the copies of Classical literature that had been saved were passed back to Europe.
This occurred mainly in Andalusia. The Moorish conquest of part of the Iberian peninsula saw the spread of Islamic science and al-Haytham’s experimental and research methods into the European continent. Latin translations were made of the great Islamic and Classical texts, and this kick-started the European effort, just as Islamic science was beginning its decline. The influence of the Classical texts – especially those of Aristotle – was potent. Aristotle’s conception of the Prime Mover gave him greater standing than other pre-Christian philosophers in the eyes of the Catholic Church. It was one thing to dismiss one of the greatest acknowledged thinkers of all time as a pagan doomed to hellfire for the crime of being born before the Church could redeem him. It was quite another to spin him as having a glimpse of the one true God – it made Aristotle not so doomed after all, and it was more acceptable for people to believe in his ideas than it was for them to believe in the “atheism” of Democritus and Epicurus.
One of Aristotle’s biggest champions was the priest Thomas Aquinas (1225-1274). Aquinas’ teacher, the Dominican monk Albertus Magnus, stated in his De Caelo et Mundo: “Do there exist many worlds, or is there but a single world? This is one of the most noble and exalted questions in the study of Nature.” The apple didn’t fall far from the tree, and Aquinas explored this question in his Summa Theologica. Basically, he agreed with Aristotle’s idea of order. The perfect circle, and the orderly nature of the observable cosmos, indicated to Aquinas that the Atomists were mistaken. Both Aquinas and Albertus rejected the idea of the plurality of worlds, but there is a wonderful irony in Aquinas’ reasoning.
Being a firm believer in the omnipotence of God, Aquinas reasoned that as God could do anything, it is possible that he could have created other worlds (but that he simply didn’t). This is in lovely contrast to the earlier views of Augustine, who had similarly set views as to the limit of God’s power. Augustine argued that there were certain things that God could not do – for instance, he could not commit suicide. Whether (or if) Augustine considered the possibility of God creating other worlds as within his power is unexplored.
It is a shame that we don’t have a working time machine. I would pay good money to see a squabble between Augustine and Aquinas over the mess of couldn’t, wouldn’t, and didn’t in their respective assumptions. Luckily, Aquinas’ argument spread to other philosophers, such as the French Bishop of Lisieux Nicholas of Oresme (1323-1382) who spent many happy hours postulating about the other worlds God could have created (but didn’t).
The clause was a necessary one. In 1277 the Bishop of Paris, Etienne Temper – under the authority of Pope John XXI – issued a Condemnation of a grab-bag of heretical “errors” (219 of them, plus assorted offensive books). Amongst these was the idea of the plurality of worlds. It was permissible to speculate on other worlds – but only with a prominent caveat that they did not, of course, exist. Given that the possibility of plural worlds and extraterrestrial life was so inimical to the Church, this can be seen as one of the early footprints on the road to the burning of Giordano Bruno. In deference to the compassion of the Church, however, I must grant that they could have been more successful in repressing this doctrine by beginning the burning earlier (but didn’t).
“No right to question…”
This repression intensified in the Renaissance, just as the debate on the theological state of any theoretical worlds was gathering momentum. William Vorilong (d.1463) was the one to get the ball rolling, with two inflammatory arguments: that if other worlds existed, they might be un-Fallen (thus making their rational inhabitants better than us!), and that even if they had Fallen like humans did, Christ only had to make the sacrifice on the Cross here and it applied to all other worlds automatically (thus raising images of this not being the case, and putting an infinity of bloody deaths into the starved and slavering imaginations of the great unwashed).
Naturally something had to be done, to stop mad scientists stirring up the masses – and not only regarding other worlds, but also concerning the state of this one. It had become a hot topic, with strong opinions on either side. The German cardinal Nicholas of Cusa (1401-1464) had come out against the perfect circle theory, and he was supported by such intellectual heavyweights such as the astronomers Nicolaus Copernicus(1473-1543), Johann Kepler (1571-1630), and Christiaan Huygens (1629-1695). It is important to note that, in many cases, the supporters of heliocentrism were also the supporters of the infinite universe.
The lot of scientists and freethinkers (the tiny minority) throughout the Renaissance was a mixed one. On the one hand, the great flowering of science and technology (including the progression of optics and the invention of the telescope just about the time Bruno was having the stars taken out of his own eyes) meant that whole new worlds were (literally) opening up to them. On the other, the existence of a rationalist philosophy was rightly seen by the Catholic Church as an increasing source of danger to them, and steps were taken to negate the possibility of the scientific method being turned against the viability of the scriptures as the inspired and literal word of God.
Thus the conservative backlash against this disruptive position was based upon the inerrancy of the Bible, and the absolute authority of the Catholic Church to interpret it. Luiz Nuñez Coronel (an early physicist, and author of Physicae Perscrutationes) asserted in 1511 that because the Church had pronounced the position for the plurality of worlds as heretical, then members of the Church had no right to regard any of it as open to question. In effect, Nuñez was advocating a gag order – denying freedom of thought and speech in order to shore up the position of the Church.
This is a truly conservative viewpoint, but it was not one that was likely to last in the intellectual environment of the Renaissance. The essence of both science and freethought is the ability to question received wisdom – whether religious or scientific – and to replace it with new information if that information better explains the world around us. There are some who see this as a weakness of science: “Why should I believe what the scientists say, when tomorrow they’ll be telling me something different?” The answer to this question is that science does not provide certain results. It provides certain methodology. This methodology gives answers, but they are self-correcting ones. Hypotheses are made and tested – just as Ibn al-Haytham tested his optical theories – and the old ones are thrown out if the new are found to be even a little bit better. The new answers do not have to give the whole truth, but science corrects itself to give a more complete one. As new discoveries flooded the Renaissance, and technology slowly became more and more advanced, the means of testing and the entrenchment of both the scientific method and William of Ockham’s principle of parsimony gave a new impetus to rational inquiry. This has been reflected in the centuries since Bruno’s murder, with science and freethought continuing to gain momentum at the expense of those who would crush it; that which would advocate that we should wallow in ignorance like the proverbial pig in its sty, piously telling ourselves all the while that doing so is indicative of a humble nature, and illustrates a noble and trusting test of faith.
Giordano Bruno would have known how to answer that.
Bruno was unlucky. Arrested before the invention of the telescope or the many other fascinating and marvellous devices humanity has invented since, he had no means of producing verifiable and replicable proof against an institution determined not to face the fact that their viewpoint had become obsolete.
The universe today.
Blackened around the edges or not, Bruno’s idea of the infinite universe was correct. This has been a difficult idea to grasp – and not only by the religious – because of the apparent paradox inherent in the formation of an infinite universe from the Big Bang, where primordial material of extreme density and temperature exploded to form the expanding universe as we know it today. This paradox can be more easily understood by analogy. Imagine that the primordial, pre-Bang state is that of an egg. (This follows in the footsteps of the Hindu creation mythology of the cosmic egg, which was later picked up by the scientists of the 1930s to explain the Bang itself.) Within this egg, all matter is compressed, just as a hen’s egg has yolk and egg white compressed within it. That matter is finite. To use the hen’s egg example: we can hold it in our hand. Now if, shuffling around the kitchen in an early morning stupor, I was to drop my breakfast egg before I was able to put it in the frying pan, the egg would fall to the ground and shatter. There would be a very sticky mess – but it would be a finite mess. I could easily clean it up, which I would not be able to do if the finite yolk and egg white suddenly began to expand into infinity, spilling out of the house and eventually taking up all space in the universe.
Hence the paradox. The universe is expanding – that has been determined experimentally through the phenomenon of red shift. This universe is filled with matter. How can it be, if the universe is infinite and the matter is not? The answer is quite simple. The momentum from the initial explosion – from the moment when the egg shattered – is still driving the matter outwards. Galaxies are flying apart from each other, and the universe is expanding, but the matter itself is not, although it may be transformed. The only thing that is increasing is the space between the clumps. Imagine ten soap bubbles in an enclosed room, and compare it to ten soap bubbles outside during a windy day. Although the same number of bubbles are present each time, the space between the outside bubbles increases because of the wind. There are not any more of them, but they are becoming more spread out than the bubbles in the room. This is what is happening with the galaxies. Space itself continues to expand, and the matter is propelled into it. We are propelled through the infinite universe on the surface of our own planetary bubble – although please note that the analogy of the bubbles does not extend to the necessity of a bubble-blower!
But if the universe is infinite, how can it expand? How can it become more infinite, or “infinity squared!” as children tiresomely shriek when getting into a “Bags one!” “Bags two!” “Bags infinity!” contest as to who gets to sit in the front seat. Wonderfully, the noisy brat who squares infinity is in the wrong. Infinity squared is still infinity, and is no more or less infinite than the square root – this can be proved by a relatively simple one-to-one correspondence in series mathematics, a subject available in any undergraduate university mathematics department.
There is also no longer any doubt as to the existence of other planets. To date, 254 extrasolar planets have been found, with the aid of radio arrays and orbiting telescopes such as Hubble. Many of these planets are very different from Earth – some are gas giants such as Jupiter, others are rocky ice giants. An example of one of the exoplanets found this year is the Neptune-sized ice giant GJ436b, which orbits the M-class star Gliese 436, located 30 light years from Earth. From density measurements, GJ436b is thought to be half rock, half compressed and frozen water.
Bruno’s assertions on the infinity of the universe and the plurality of worlds have been proven. Not so his speculations about the existence of extraterrestrial life. The search goes on, however. National space organisations such as NASA and the ESA, and non-governmental projects like SETI (the Search for Extra-Terrestrial Intelligence) continue to capture the funding and imagination necessary for their work to continue.
In his 1881 book, Colonel Robert Ingersoll – an American state attorney, political orator, and strong supporter of humanism and freethought – had this to say about the death of Giordano Bruno.
This harks back to Diderot’s even more bloody religious condemnation of the previous century: “Man will never be free until the last king is strangled with the entrails of the last priest”. Sympathetic as I am to these sentiments, one really has to ask if they are at bottom any different from the mindset that murdered Bruno.
Giordano Bruno was not killed by the priests of today – or even the priests of the nineteenth century, despite Ingersoll’s attempt to smear them all with the same bloody brush. Nor does demolishing every trace of that institution – including some of the great world treasures of art – provide any sort of useful revenge. The man is dead, after all. Satisfying as bellowing hyperbole may be, there is always someone stupid enough to take it seriously, and wanton destruction won’t bring Bruno back.
The most that can be done for Bruno is to vindicate his astronomical ideas. Not all of them had any lasting merit, but his beliefs on the expansion of the universe and the possibility of extraterrestrial life have attracted such a weight of proof that even the Catholic Church, the same institution that silenced him for holding these views in the first place, is slowly coming around. In 2000, Pope John Paul II formally apologised for his murder, although Bruno is never likely to be rehabilitated. According to Cardinal Paul Poupard, who is Chair of the Vatican Cultural Council, Bruno’s teachings are “incompatible” with those of the Church.
What good is an apology now? One might ask. It’s several hundred years too late, and Bruno’s not around to benefit from it.
Many religious institutions around the world hold various beliefs which are irreconcilable with scientific evidence. Worse, they put forward these beliefs under the umbrella of science in a misguided attempt at legitimacy. An example of this is the attempt to shoehorn Creationism into public school science classes by tarting it up as “Intelligent Design”. Worse still, those who dissent are still subject to religious sanction. For Catholics, this no longer means recanting or being burnt at the stake. Other religions are not so lenient. That does not mean that the atheists, the agnostics, the scientists, and other freethinkers should descend to that level, and Ingersoll and Diderot do their cause a disservice by suggesting otherwise.
Those of us who want the freedom to question entrenched dogma of any kind live in a fortunate time. In the centuries long collision between science and religion, the former is finally winning out. It may be slow, and there may be setbacks. We may even be wrong, and some of our theories proved impossible. No matter. Let us be slow, and thwarted, and wrong, but let us also remember the value of curiosity, and of questioning. Let us maintain that value to the end. Let us be Bruno – and let us hope that his statue, which now presides in Rome’s Campo di Fiori, outlasts the institution that burnt him alive at that same spot so many centuries ago.