As we have seen, testability is crucial for any scientific theory. However, as crucial as it might be, it is not enough to test a theory against the observations that led to its creation. A scientific theory must also be able to predict unknown facts that can only be confirmed by fresh observations. If any of the predictions are proven wrong, the theory must be deemed incorrect. This potential refutability is a powerful criterion that can help distinguish scientific from most non-scientific theories, as can be demonstrated by comparing astronomy with astrology.

For thousands of years astrologers had been using the apparent movement of the sun, moon, and the five known extraterrestrial planets (Mercury, Venus, Mars, Jupiter and Saturn) to foretell earthly events. Once the sixth planet, Uranus, was discovered in 1781, astrologers adjusted their charts to include the new planet and continued with their forecasting as before.

Astronomers, on the other hand, were fervidly striving to calculate the orbit of the new planet. Their calculations, however, did not match the actual path of Uranus. The discrepancy could be explained by assuming that either Newton’s theory of gravity was wrong, or that the gravity of an unknown heavenly object, farther from Uranus, was responsible for the deviation. Using the law of gravitation, astronomers calculated the assumed celestial position of the undiscovered planet. They confirmed their calculations in 1846 when, by means of a telescope, they managed to view Neptune at the predicted location.

Just as discrepancies in the orbit of Uranus had led to the search for Neptune, irregularities in the orbit of Neptune, and to a lesser extent in the orbits of Uranus and Saturn, had led scientists to suspect the existence of a ninth planet. Again, it was theoretical calculations that led to the discovery of Pluto in 1930. The theory of Gravity is therefore a scientific theory.

To demonstrate how established scientific theories can be refuted, let’s look at the theory of ether, which was the established theory for an entire generation of scientists.

Since Maxwell (1831–1879) formulated the electromagnetic theory in 1865, 19th century scientists had puzzled how electromagnetic waves, such as light, traveled through vacuum and the emptiness of space. Just like waves in water or sound in air, the argument went, electromagnetic waves needed a physical medium to travel through. For this reason alone, a new substance, ether, was proposed. (Although the term ‘ether’ was borrowed from Aristotle, the 19th century’s ether was a different concept altogether.)

According to the theory, ether filled in the entire universe, including vacuum and the inside of material bodies. As such, it had to be a weightless, transparent, frictionless matter that did not take part in any physical or chemical interaction, and was, therefore, impossible to test or verify.

Yet, the theory of ether could predict that light emanating from a moving object in the direction of its movement would travel faster than light emanating from the same object in any other direction. (To illustrate, imagine an item thrown from a moving car. Clearly, if we threw it in the direction of the travel it would travel faster than if we threw it in the opposite direction.)

Michelson and Morley relied on this hypothesis in 1887, when they attempted to determine the speed of earth relative to ether by measuring the difference between the speed of a beam of light traveling with the movement of earth, and that of a beam of light traveling perpendicular to earth’s movement. (The importance of this experiment was that according to Galilean/Newtonian physics, motion is always relative, and there is no way to distinguish a body at rest from a body moving at a constant velocity. Ether could have offered a reference point and define absolute movement.)

Had Michelson and Morley detected the difference as expected, it would have put their names, in a side note, as the first scientists to measure the absolute speed of earth. As it turned out, the experiment failed and no difference could be detected. Even though Michelson and Morley could not explain their result, it was sufficient to inflict a death sentence on the theory of ether, and to win Michelson the 1907 Nobel Prize for physics. This was the experiment that subsequently it led Einstein to develop the theory of special relativity.

As strange as it may sound, modern science is not directly concerned with reality, but rather with models of it. Reality is the realm of philosophy. The essence of science is the scientific theory, whose purpose is to provide coherent explanations to observations; an objective aptly summed up by the physics Nobel laureate, Richard Feynman (1918–1988):

No one has ever seen the inside of a brick. Every time you break the brick, you only see the surface. That the brick has an inside is a simple theory which helps us understand things better. The theory of electrons is analogous … The electron is a theory that we use; it is so useful in understanding the way nature works that we can almost call it real.

Although theory is at the heart of science, not every theory is scientific. For a theory to be scientific it must first be internally consistent, that is, it should lead to no logical or mathematical paradoxes. If, for instance, a theory could lead to a conclusion that an object may simultaneously exist in two different places, the theory would not be consistent and cannot be deemed scientific. (This example is a paradox that contradicts the principle of space and time: a physical object exists separately in space and time in such a way that they are localizable and countable.)

Unlike mathematical models – which being the creation of the human mind require internal consistency only -- scientific theories based on these models must also be testable: that is, it does not matter how elegant or internally consistent a theory may be, if it does not agree with observations external to the theory, it is wrong. This requirement means that a theory can be considered scientific only after test criteria can be defined. That is, every theory is potentially refutable. Contrary to the common belief, turning scientific does not necessarily improve a theory or make it more reliable, as it may often lead, inadvertently, to the refutation of the theory;

It was not surprising that evolution theory had evoked passionate antagonism. Its radical implications were far more reaching than the “we are not monkeys” emotional response. The theory eliminated the need for a designer or a creator, and it undermined what was probably the oldest and most frequently used proof for the existence of God, as first expressed by the ancient Roman Marcus Tullius Cicero (106– 43BC):

When you see a sundial or a water-clock, you see that it tells the time by design and not by chance. How then can you imagine that the universe as a whole is devoid of purpose and intelligence, when it embraces everything, including these artifacts themselves and their artificers?

Those who object to the evolution theory can be broadly classified into two camps: creationists, and the advocates of intelligent design, also known as design theorists. Creationists believe that the literal biblical narration provides a factual account of events, and reject any kind of evolutionary process. Intelligent design, on the other hand, accepts that organisms could evolve from other organisms, but rejects the randomness of the process and suggest that it was preordained and following a blueprint. To use an analogy, when dominos fall, although each piece falls because it is pushed by its predecessor, the pattern of the fall is predefined by the original setting of the dominos.

Intelligent design theorists claim that without such a blueprint, biological organs and systems that display irreducible complexity could not have evolved. That is, no random process could account for the development of an organ, like the eye, which is composed of several interacting parts, all required for its functioning. As evolvement of anything but the complete operating organ could not function at all, it would not have survived the process of natural selection.

It took Darwin many years and many attempts to find a theory that could answer the many questions that perplexed him during his voyage. His theory could explain why fossils of extinct animals carried a close resemblance to existing species, and clarified why each of the Galapagos Islands had its different but very similar species of animals. It also accounted for the existence of creatures that, in Darwin’s view, could never be designed by a benign entity, like the parasitic wasp, which stored caterpillars to be eaten alive by its grubs.

Modern evolution theory has evolved considerably since Darwin’s days. However, regardless of the major changes the theory has undergone, the new body of evidence, accumulated from otherwise unrelated fields of science, only strengthen its plausibility. While unlocking the secrets of DNA revealed the engine behind the random variations, microbiology gave empirical evidence that not only do such variations occur regularly, but that they directly impact on lives, as both the cause of new diseases (e.g. aids, bird-flu) and the means for their cure.

Further evidence has been derived by paleontologists and evolutionary molecular biologists, who have been able to fill many of the gaps in the history of species. Evolutionary molecular biology provides us with the tools to measure the amount of DNA change that differentiates one species from another. This has led to the surprise discovery that the difference in the DNA sequence between human and chimpanzee is no bigger than 2%. Humans were no longer the crown of the creation, but the result of random changes that happened to make them better adapted for survival – Aristotle’s scale of value had lost its meaning.

Unlike physics and astronomy, in which unbiased observation directly contradicted religious teachings, for a long time progress in biology did not challenge old wisdom. Throughout the 16th and 17th centuries biologists classified all known plants and animals into taxonomical groups, and were, therefore, well aware of the commonalities living organisms shared. Yet, the belief that all living organisms had been created in their current form was so well rooted that no serious alternative existed before 1859. This was the year that Charles Darwin shocked his contemporaries by implying that humans and animals shared a common ancestor.

In 1831, Charles Darwin (1809–1882) joined as a naturalist the survey ship HMS Beagle for an expedition around the world. When he returned home in 1836 with over 2000 pages of notes and thousands of skins, bones and fossils, his work had just begun. It took over 20 years before he finally formalized his findings and observations into a consistent theory, which he published in his book On the Origin of Species by Means of Natural Selection.

Natural selection theory suggests that adaptation to the environment, through the survival of the fittest, is the main (though not the only) mechanism of evolution. Random variations continuously occur in species, which are constantly under struggle for resources. When “the surviving one of ten thousand trials” gives an organism an advantage in its environment, it would pass on this favorable change to its offspring. Accumulation of such variations within a population, particularly when major environmental changes occur, could eventually lead to the creation of new species.

The heated debate over the working of the universe, we have discusssed so far, had little relevance outside the scientific and theological communities. Whether it was the sun or the earth at the center of the universe, or what laws falling bodies obeyed, it made no difference to people’s faith. The new discoveries diminished neither the splendor of the creation nor the greatness of the creator. For most people, religious teachings were about how one goes to heaven, and not how heaven goes.

This attitude still prevails nowadays, when even the most religious of people do not expect their religious practices to explain nature, and are happy to leave these ponderings to science. In all areas, that is, but two: the age of the universe and evolution.

According to Genesis, the world was created in six days, and by counting the generations in the Bible since Adam and Eve, theologists concluded that the creation took place some 6000 years ago. This figure is supported by the Jewish calendar, which is believed to commence from the first day of the creation. Contemporary mainstream scientific theory, on the other hand, draws an entirely different picture. It estimates the age of the earth at about 4.6 billion years, and that of the universe at over 13 billion years.

Interpretations of the text in Genesis which aim to address this dichotomy have been around since the 19th century. A common explanation was that the Bible, speaking to the ancients who could not comprehend numbers like a million or a billion, did not speak of a ‘day’ (yom in Hebrew) as a period of 24 hours, but rather in a metaphorical way as an unspecified duration of events which could last thousands, millions or even billions of years. (By the way, such big numbers could not be written, let alone understood, before the introduction of ‘0’, which happened around the 7th century in the Arab world, and 13th century in Europe.) Alternative interpretation suggests that the six-days in Genesis do not represent the time of the creation itself, but a six-day period during which God revealed the truth of the creation to Moses on Mt. Sinai.

Despite the various interpretations, many are still adamant that the literal interpretation of the Bible is correct, and that the problem lies with science. They point out that unlike the previous conflicts mentioned, the age of the universe cannot be found by observation or any other direct method, but is deduced from a combination of complex theories with many underlying assumptions. They claim that as theories change frequently they cannot be trusted, and in the end, scientific theory will discover that the biblical age of the universe is correct.

Regardless of future scientific development, this dispute – just like those mentioned previously – threatens only human interpretation and not faith itself. Six days or 13 billion years, it leaves the magnificence of the creation intact, as it does the need for a creator. This, however, is not the case with the theory of evolution, which threatens not only the role of God, but also Her very existence.

While the new scientific way of thinking (as described in my previous posts) was partially responsible for the decline in the power of the Church, the resultant image of the world neither threatened the fundamentals of faith, nor replaced the need for a creator. For many scientists, revealing the nature of the world was the way to understanding the creation and the glory of God. Copernicus, Galileo, Kepler and Newton, were all devout believers who saw their scientific work as a religious undertaking. For example, Kepler wrote in his Harmony of the Worlds:

Geometry provided God with a model for the Creation and was implanted into man, together with God's own likeness. ... It is absolutely necessary that the work of such a Creator be of the greatest beauty.

Although these scientists were aware of the objections their work would provoke, they did not consider the new discoveries to contradict religious teachings. They held the view that the scriptures, written for everyone to understand, were not to be taken literally. Any contradiction between religious teachings and the scientific discoveries was due to human’s mistaken interpretation. They believed that correct knowledge of the cosmos would provide a better insight into the scriptures, and that it was our pious responsibility to reinterpret the texts to match the known facts, as there should be no inconsistency between science and the scriptures when they were rightly understood.

Standing upon the shoulders of giants, it was the British physicist Sir Isaac Newton (1642–1727) who finally replaced the Aristotelian model of the universe. His law of universal gravitation and the three laws of motion laid the cornerstone for modern physics, and provided a single set of laws that governed both earth and heaven. There was no need for two set of rules any longer, and the ‘corrupt’ transient earth and the perfect eternal heavens were now obeying the same laws of nature. The workings of the universe became the realm of science.

Kepler's contemporary, the Italian scientist and astronomer Galileo Galilei (1564-1642), in his most renowned experiment dropped two bodies of different weights from the Leaning Tower of Pisa, and clearly demonstrated that all bodies fall at the same speed regardless of their weight. This was indisputable proof that Aristotle's theory and the Church's dogma were fundamentally mistaken. Galileo also revolutionized astronomy when he was the first to apply the telescope to the study of the heavenly bodies. His observations led him to discover the moons of Jupiter and the phases of the planet Venus, and convinced him that Copernicus' heliocentric model was right. In 1633, Galileo was brought before the Inquisition for a grave suspicion of heresy. He was forced to formally renounce his beliefs, and was sentenced to life-long house arrest.

Claiming that the sun was at the centre of the universe, Copernicus directly challenged the Church's sacred worldview, which was based on the Aristotelian model. He was the first to challenge, but what he started was unstoppable, and many followed.

Johannes Kepler (1571-1630), a German astronomer, developed the Copernican model into his three major laws of planetary motion, which are still in use nowadays. These mathematical laws could accurately account for all planetary observations. However, by suggesting that the planets were moving in elliptical orbits around the sun, and not in the heavenly perfect circular motion, Kepler deviated even further from the Aristotelian model that was the base for the worldview of the Church. He was excommunicated from the Lutheran Church in 1612

As we have seen in our last posting in this blog Copernicus, who postulated a model in which the sun was at the centre of the universe. knew that the clear advantages of his model would not protect him from the hostile reaction of the orthodox authorities and the Inquisition, and it was not until 1543 – the year of his death – that he eventually published his complete work On the Revolutions of the Heavenly Spheres.

It is clear from the extent of the criticism of his work that Copernicus challenged not only the knowledge of the cosmos, as portrayed by the church, but he challenged knowledge itself: Should our impartial experience determine our understanding, or is it our knowledge that the world should conform to?

For example, Tolosani, a contemporary of Copernicus, wrote:

[Copernicus] seems to be unfamiliar with Holy Scripture since he contradicts some of its principles, not without the risk to himself and to the readers of his book of straying from the faith. ... in his imagination he changes the order of God's creatures in his system. ... he seeks to raise the Earth from its lower place to the sphere where everybody by common consent correctly locates the Sun's sphere, and to caste the sphere of the Sun down to the place of the Earth, contravening the rational order and Holy Writ, which declares that heaven is up, while the Earth is down.

It was most likely, therefore, that the Church would have condemned Copernicus’ work, had it not been for an introduction inserted by the publisher. The introduction stated that the book merely presented a simpler way to calculate the positions of heavenly bodies, and that “the hypotheses contained within made no pretense to truth that, in any case, astronomy was incapable of finding the causes of heavenly phenomena.” This unauthorized insertion, although appalling to many, ensured the book was not immediately condemned. In fact, it was publicly available for over 70 years before it was subject to censorship.

Although some were sentenced to death for their support of Copernicus’ heliocentric system (for example, Giordano Bruno was burnt alive in 1600) it was not until 1616 that the Church placed the work on the List of Prohibited Books (Index Librorum Prohibitorum) and decreed that “the propositions that the Sun is immobile and at the center of the universe and that the Earth moves around it, judging both to be ‘foolish and absurd in philosophy,’ and the first to be ‘formally heretical’ and the second ‘at least erroneous in faith’ in theology.” By then, however, Copernicus’ mathematics had already been widely in use, and although many still viewed it as a hypothetical calculation model, it was unavoidable that questions about the nature of the cosmos as derived from the model would arise.

The scientific revolution had begun.

So let's continue our exploration of the birth of modern science ...

Since early history, the scientists who studied the heavens were the only scholars to use mathematics, and the terms astronomer, astrologer and mathematician were virtually interchangeable. They calculated the dates of the holy days, developed methods to draw astrological charts, and forecast the position of the zodiac signs and the movement of the planets. However, despite their skillful observations, measurement and calculations, many questions remained unanswered. They could not account for the changes in the brightness of the planets, nor for their apparent retrograde movement. Their models did not explain why Venus and Mercury were never seen far from the sun, and they could not even agree on the order of the planets. However, it was not their role to ponder such theological matters. They were mathematicians, and calculation was what they did.

All this changed in 1514, when a Polish astronomer, Nicolaus Copernicus (1473-1543) circled amongst a few of his friends an unsigned hand-written book, Little Commentary. In his book, Copernicus introduced the heliocentric model, in which the sun, rather than the earth, was at the center of the universe, and all planets, including earth, were orbiting around it. With a single model, Copernicus could explain the apparent movement of the planets, the sun and the stars. His model could also account for the changes in the brightness of the planets, and offered a singular method of ordering them and calculating their relative distances from the sun with amazing accuracy (less than 10% difference from our current measurements.) Copernicus knew, however, that the clear advantages of his model would not protect him from the hostile reaction of the orthodox authorities and the Inquisition, and it was not until 1543 – the year of his death – that he eventually published his complete work On the Revolutions of the Heavenly Spheres.

Unlike most other studies, the study of alchemy did not challenge the Church’s view of the world and could, therefore, be practiced. For over 900 years, from about 500 to 1400, philosophers in Western Europe, surrounded by a cloak of secrecy, predominantly occupied themselves with the search for the mythical philosopher’s stone (the substance that could supposedly transform everyday material to gold and produce the elixir of immortality). During this Dark Age of European science, Arab philosophers cultivated an environment that encouraged the sharing of ideas, discussion and debate. The scientific framework they had developed – based on experiments to distinguish between competing scientific theories, citation, peer review and open inquiry – led to many invaluable breakthroughs in all areas of science: chemistry, physics, optics, astronomy and mathematics.

It was the fall of Constantinople (now Istanbul) that brought Arab science to the attention of the Western European philosophers. Constantinople, the capital of the Byzantine Empire, had been a major intellectual center. Its conquest by the Turks in 1453 led to an exodus of scientists and philosophers to Western Europe. Owing to the recent invention of printing by Gutenberg around 1450, the scientific knowledge these scholars brought with them (including Arab science) became widely available. The seeds for a new worldview were planted, and science of the stars – the oldest of all natural sciences – was the natural place for them to germinate.

We continue from the previous post to describe the world according to Aristotle

On earth, Aristotle suggested a hierarchical model he called The Great Chain of Being. It was not only a systematic method of classification, but also a scale of value – the higher an item was in the hierarchy the more it was worth. It gave organic items higher value than inorganic matter; living organisms were placed higher than planets; and within living organisms worms were at the bottom and men at the top. In Aristotle's view, the universe was ultimately perfect, which meant that the Great Chain was also perfect with no waste or duplication – each link contained exactly one species. This left no room for change or development and led to the doctrine of fixed species: if every link is occupied and none is occupied twice, no species can ever move from its original position. To do so would leave one level empty and put two species on another level.

It is easy to see why the Church adapted to Aristotle so willingly and why it eradicated any potential challenge. Aristotle’s philosophy separated the transient, corrupt earth from the perfection of the eternal heavens, and left room for the Divine and the angels beyond the outer spheres. (Some, for instance, speculated that the angels were pushing celestial bodies in their orbits.)

The Great Chain of Being was treated not only as a description of nature, but also as philosophical justification for social immobility; that is the futility of people attempting to change their status and position in society. Man, at the very center of the universe, was the crown of the creation. Christians were superior to every other man, and the Church was assigned to rule. This was a law of nature. This was the way the Church wanted it to remain.

So let's continue with Church’s favourite philosopher, Aristotle :

Aristotle supported the geocentric model in which the earth was the center of a finite spherical universe, and all celestial bodies: the sun, moon, planets and stars circled around it in an eternal, perfectly circular motion, driven by the force of a Prime Mover. According to Aristotle, there were two distinct sets of laws, one for the earth, and the other for heaven. He dismissed Democritus idea of the atom as worthless, and instead believed that everything was made of a combination of four elements: earth, water, air and fire. The combination of these elements in each object determined how fast it would strive to reach the center of the earth – the heavier an object was, the faster it would fall. Aristotle also postulated a fifth element, ether, which he believed to be the main constituent of all heavenly bodies.

When the Church assumed power, the interpretation of the Sacred Scriptures formed the foundation for the science of the Church. However, whenever a new philosophy was adopted, it became an inseparable part of the Holy Teachings, impossible to question or challenge.

No philosopher dominated the Holy Teachings more than the Greek philosopher Aristotle (BC 384–322): the most renowned student of Plato and the teacher of Alexander the Great. His collection of lectures, covering the entire field of knowledge known in the Mediterranean world of his day, spanned over 150 volumes. He developed the art of reasoning and logic, and his biological observations and classification of animals were far ahead of his time. For example, he classified dolphins as mammals, a classification that only in the 19th century was recognized.

Although at first the Church forbade his teachings whether public or private (Council of Paris in 1210) in 1366 he received the Church’s full recognition, and his views became regarded as possessing an almost divine authority. This was ironic as Aristotle himself had used logic and observation to draw his conclusions, and as an advocate of debate and freethinking, he did not believe in blind obedience to authority, but rather that science grew out of curiosity and wonder, to which religious myth gave only provisional satisfaction.

How did the rivalry between the Church and science begin?

It started when the persecuted Christian minority had gained enough power to persecute others.

Priscillian, a Christian theologist, won his place in history for being the first Christian executed by the Christian authorities. In the year 385, shortly after Constantine had changed Rome’s religion to Christianity, Priscillian, with six of his companions, was sentenced to death for heresy: that is, not following the official line of the Church. For centuries to come, his execution set the stage for how the Church would deal with any of those subjects who questioned its teachings.

By the early Middle Ages, the Church, which had continued to consolidate its power, had established itself as the spiritual leader of the “civilized world”, and often as the political and economical superpower, successfully challenging rulers and states.

To strengthen its authority further, the Church positioned itself as the custodian of all truth, which it alone was authorized to expound under the inspiration of the Holy Spirit. It eliminated any challenge to its teachings by giving explicit sanction to officially correct views of nature and scripture; and in 1231 it established the Inquisition to maintain and defend the integrity of the faith, and to examine and proscribe errors and false doctrines. Heretics became the enemy of society.

In the beginning, interpretation of the Sacred Scriptures formed the foundation for the science of the Church. However, whenever a new philosophy was adopted, it became an inseparable part of the Holy Teachings, impossible to question or challenge.

In the outer rim of a 200 billion stars galaxy, a blue planet, earth, is traveling at a staggering speed of over 100,000 kilometers an hour. It would have disappeared in the vastness of space, if it were not for a mysterious and invisible force that keeps it orbiting, for all eternities, round a medium-size yellow sun, 150 million kilometers away.

Every 176 years, four other planets: Jupiter, Saturn, Uranus and Neptune, are lined up on the same side of the sun. This was not known to the ancient astronomers and astrologers, whose picture of the universe did not include Uranus (discovered in 1781) and Neptune (discovered in 1846). This fact, however, inspired the farthest exploration in the history of humankind, when in 1977 two spacecrafts, Voyager 1 and Voyager 2, were launched to reach the aligned planets. The extraordinary photos they beamed back, and the new information they are still sending from the final frontier of our solar system, some 15 billion kilometers from home, have made this exploration a great triumph of science and our understanding of the laws of nature, without which none of this could have been achieved.

These laws of nature: the principles of motion, action and reaction and gravity, are the very laws that started the age of scientific exploration and changed our understanding of nature forever. Although this new worldview did not directly contradict the principles of faith, it did threaten the monopoly the religious authorities enjoyed as the guardians of all knowledge, as declared, for instance, in the Council of Trent (1546):

No one relying on his own judgment and distorting the Sacred Scriptures according to his own conception shall dare to interpret them contrary to that sense which Holy Mother Church, to whom it belongs to judge their true sense and meaning, has held or does hold, or even to interpret them contrary to the unanimous agreement of the Fathers.

This powerful position was not to be given away lightly; so rather than choosing to become the patrons of the sciences and embracing the new discoveries in order to strengthen faith and belief, the Church and its judicial institution, the Inquisition, chose to declare the new worldview heresy and its holders heretics.

The birth of science into this environment still influences our way of thinking nowadays, nearly 500 years later. While only esoteric minorities will not embrace the many improvements that only science could bring (medicine, transportation, communication, to name just a few) many still view the scientific worldview to be a threat to their beliefs. Is it a real threat? Must scientific and religious viewpoints collide, or can there be consistent description of the universe in which each is equally valid?

In this chapter, we will demonstrate that realities in which science and religion coexist are possible. This will position science as the functional model of the world as experienced by our senses, leaving questions about the nature of reality to philosophy, faith and belief. We will start our exploration with a brief introduction to the history of the conflict.