HISTORY OF ASTRONOMY UP UNTIL THE BIG BANG THEORY
We intend to make a brief survey of the history of astronomy. It is our aim to remind our readers of the scientific process prior to the development of the Big Bang model; the place of the theory in historical perspective will thus be clearer.
DEVELOPMENTS ACHIEVED BY FORMER CIVILIZATIONS
Data easily accessible to a ten-year-old child today were enigmas for ancient people, and most often constituted the core of their mythologies and legends.
We know that the Sumerians acquired certain technical knowledge and made use of it, and that the Babylonians, who succeeded them, achieved considerable progress in mathematics and astronomy. The latter even contrived a useful calendar as a result of long and acute observations. They maintained that the sun entered through one gate of the heavens and exited from the other. The Babylonians were interested not only in astronomy, but also in astrology. They constantly watched the stars, attempting to read signs for the future.
In ancient Egypt, important developments took place both in mathematics and astronomy. Successful achievements in mathematics and astronomy were also observed in the Chinese and Indian civilizations. The immediate concern of these efforts was to find solutions to daily problems, rather than being scientific in the proper sense of the term.
These civilizations watched the movements of heavenly bodies, trying to read the future basing on their regular interrelationships; this, they believed, enabled them to benefit in the field of agriculture and prophesy the events likely to take place in the future through astrological findings. To the best of our knowledge, they failed to pry into the whys and wherefores of the results of their observations and to evaluate them on theoretical bases. This prevented them from marking any progress in astronomy in the sense of the scientific concepts of today. However, we must also add that recent discoveries have revealed that their progress had been more astounding than what has been conveyed to us in historical records, and formed the basis of the scientific achievements in Ancient Greece.
THE GEOCENTRIC UNIVERSE OF ARISTOTLE AND PTOLEMY
Aristotle believed that the earth was the center of the universe and that the sun and the moon revolved around it. According to him the prima materia of the stars was different from the material of which the world was made. The fire of the stars was inextinguishable. These materials had eternal existence. The earth, on the other hand, was not so perfect and was defective.
Ptolemy (85-165), benefiting from the heritage of Aristotle as well as of the views of Eudox and Hipparchus, postulated a geocentric model. He maintained that the five satellites discovered up until then, namely Mercury, Venus, Mars, Jupiter and Saturn, together with the moon and the sun, revolved around the earth. The stars occupied the outermost circle. The universe was described in terms of concentric circles and spheres.
THE GOLDEN AGE OF SCIENCE IN THE WORLD OF ISLAM
The period extending from the eighth to the thirteenth century was the summit of scientific achievement for Muslim civilization. While the majority of historians refer to the same period as the “Dark Ages” of the Christian civilization, the attribute used by historians corresponding to the era in question was the “Golden Age” for the world of Islam.
The Muslim world made use of Greek, Indian and Persian legacies. The works of these civilizations were translated into Arabic, while the Arabs themselves were also the authors of many scientific works based on their original discoveries. An observatory in the sense of the modern acceptance was established for the first time in 1259 in Meraga. Nasraddin Tusi found defects in the Ptolemaic model of the universe, while other scholars like Harazmi, Bitruji and Biruni made valuable contributions to astronomy.
The scientific lore of the Muslims was transmitted to the western world through translations from the Arabic. According to a great number of historians, the process of technological advances in the West from the Renaissance onward owes much to this erudition of the world of Islam. The western world came into contact with Ancient Greece, with Plato, Aristotle and Ptolemy through these translations.
THE CHURCH AND THE PROCESS INITIATED BY COPERNICUS
More than 1500 years after it emerged, the Ptolemaic system was widely accepted as the basis of astronomy by a large circle of believers, particularly by the Christian world. Given the fact that the Catholic Church was considered to be God’s representative on earth, any opposition to this creed meant opposition to God Himself. Thus the model of the universe of Aristotle and Ptolemy gained incredibly wide acceptance, more in fact than even its initiators would have dreamt possible. These early philosophers were sanctified, while their ideas became dogmas!
It was Copernicus (1473-1543) who initiated the process that rejected this system. He postulated and proved that if the geocentric system were supplanted by the heliocentric system, universal phenomena would be better explained. This idea was rejected, not only by the Catholic Church, but by Luther and Calvin as well. They just could not imagine any system other than the geocentric one.
Had the new postulate been proven, then the Church and the persons canonized by it would be involved in error. This first serious objection refuting the age-old conception of the Church became one of the heralds of secularism. Had the absolute authority of the Church not been questioned, secularization would never have taken place. The views of Aristotle espoused and sanctified by the Church were said to have a scientific foundation. The Church thus had exclusive authority over the curricula of schools. The control of curricula by the Church caused the western world to acquiesce to the erroneous data of Aristotle’s physics that it had sanctified as if revealed by God. The detriment caused by this became the groundwork of secularism.
TYCHO BRAHE AND KEPLER
It was Tycho Brahe (1546-1601) who made the most astute observations prior to the invention of the telescope. Brahe, under the auspices of the Danish king, drew a detailed map of the sky. In the West, Brache’s observations of great bearing met with Kepler’s (1571-1630) theoretical approach. Kepler, who was a very good mathematician, turned to good account Brache’s observations and corrected the deficiencies in the Copernican system. Copernicus believed that the sun was in the center, and the earth and other planets moved in perfectly circular orbits around it. Kepler, on the other hand, demonstrated that the planets did not move uniformly in circles, but in ellipses with the sun in focus. Kepler corrected the Copernican system, while confirming his heliocentric system.
Kepler’s mathematical laws heralded the future vital role of mathematics. These laws were not mere drab and abstract knowledge. The calculations related to travel in space, to the revolution of the earth around the sun, and to the distance to the farthest stars could not have been achieved were it not for this mathematical approach.
GIANT STRIDES OF GALILEO
Kepler was the first person to apply the physical laws of the earth to celestial bodies. He was also the first scientist to claim that astronomy was a branch of physics, and is accredited today as the first astrophysicist. It was Galileo (1564-1642)-the discoverer of the laws of motion-who contributed to the soaring of science to great heights. He used the telescope that led to his astronomical discoveries to put an end to Ptolemaic physics. This time the church was not as lenient as it had been with Copernicus and Kepler; Galileo was tried by the Inquisition for heresy.
This event is referred to as the most illustrative example of the controversy between religion and science. Yet, all those people who refuted the Ptolemaic system were devout people, faithful adherents of the church. Their unshakeable belief in God is apparent in many of their statements. None of them ever thought of attacking the church. However, the results they obtained through their scientific research could not help clashing with the heads of the Church. These scientists maintained that the results they had achieved did not conflict with God’s existence and omnipotence. Mathematics was the language in which God had written the universe, said Galileo. He believed that the universe was one of the books of God and that there could be no inconsistency between any of them.
The Church was to later acknowledge its unfair treatment of Galileo. This meant the acknowledgment of the fact that God’s will had been supplemented by the will of the Church. Galileo had shaken the traditional Aristotelian conception to its foundations. Quantitatively oriented physics superseded Aristotle’s qualitatively oriented physics. He argued that nature had to be interpreted by recourse to mathematical certainty and impartiality.
ARISTOTLE AND HORSE’S TEETH
Aristotelian logic had yielded its place to mathematics, and the sanctification of Aristotelianism by the church had thus run its course. The principles of Aristotelian physics had become a controversial issue and physics became an object of re-assessment, and was re-evaluated on mathematical and experimental bases. According to legend, in the Middle Ages someone asked the number of a horse’s teeth; the addressee was said to have consulted Aristotle’s opinion on the matter.
According to the new method, phenomena were observed carefully and mathematical laws were constructed through experiments and analyses. These laws permitted scientists to elucidate many secrets of nature and to make generalizations for future phenomena. The system that Copernicus, Kepler and Galileo advanced made clear the great benefit that one could draw from mathematics and the fact that cosmology should be approached not only theoretically, but through experiments and observations as well.
René Descartes (1596-1650) conceived a reconstruction of the entire body of knowledge into a unified system of certain truth based on mathematics. He had considerable understanding of spatial phenomena based on mathematics. Galileo’s physics was to constitute the foundations of the classical physics; while Descartes’s mathematical view of the universe would be seminal.
THE GREATEST GIANT NEWTON
The heliocentric system developed by Copernicus and Kepler, coupled with Galileo’s observations and physics, contributed to a better understanding of the universe. There were, however, mysteries still to be cleared up: What kept the planets in their orbits? What prevented those on the earth’s underside from falling? It was Newton’s (1642-1726) lot to shed light on these mysteries.
For many, Newton was the most important figure in the history of science; his only rival was to be Einstein. The fall of an apple induced the train of thought that led to the law of gravitation, according to which the moon was attracted by the earth. It was thanks to this law that the celestial bodies and the people on the earth’s underside did not fall out of place. The laws of motion maintained that the planets moved in their orbits. Newton reached these laws through mathematical equations. The magnitude of the gravitation was proportional to the masses of the two objects and was inversely proportional to the square of the distance between them.
Newton’s law of motions demonstrated that nothing in nature is static. The Ptolemaic system was henceforth set aside. The Church finally accepted that the earth was one of the planets revolving around the sun. Newton defined the law of gravity as the law that God created to have sway over the universe. His law of motions proved that physical laws were applicable all over the universe. Aristotle’s view of stars and the earth was thus repudiated.
Thanks to Newton, mankind had access for the first time to a detailed and systematic cosmology. But cosmogony, the branch of science concerned with the origin and development of the universe as a whole, was still missing. Basing their assertions on Newton’s laws, Kant (1724-1804) and Laplace (1749-1827) were later to describe the formation of planets out of clouds of gas. The studies of Kant and Laplace may be defined as the first attempts at building up a cosmogony in terms of science.
They maintained that the stars and the planets were the outcome of the condensation of gas and dust under the action of mutual gravitational forces. A purely scientific cosmology and cosmogony including every detail from subatomic particles, atoms and clouds of gas to the formation of stars would be the work of the Big Bang model that awaited the advent of Einstein, Hubble and Lemaitre.