The Condemnation and Rehabilitation of Galileo Galilei by the Catholic Church

Abstract

The journey from the geocentric conception of the solar system as well as the total ignorance of the gigantic size and grandeur of the universe to today’s immense wealth of knowledge about the universe has been a long and perilous one.  The extent of knowledge we have today about the visible universe is amazing, and the picture emerging is truly mind-boggling.  Today we know that the universe consists of billions of galaxies, each comprising billions of stars.  We also know that the stars produce their intense heat and light by thermonuclear reactions.  Our Sun is one of some 100 billion stars that constitute our galaxy, the Milky Way.  We further know that the Sun’s mean distance from the Earth is approximately 150 million kilometres, the diameter of the Sun is about 1,392,000 kilometres, its mass is about 2x10³⁰ kilograms, and its average density is 1.4 grams per cubic centimetre.  The temperature at the visible surface of the Sun is about 6,000⁰C and at the core of the Sun it is about 13,000,000⁰c.  At such a high internal temperature thermonuclear reactions occur in which hydrogen is converted into helium.  The distance from the Sun to the nearest star is over four light-years or some 40 trillion kilometres.  The galaxy nearest to ours is some 1.6 million light-years away.  Today we know that in these galaxies some stars become supernovae while a few others become black holes with enormous density.  When a star uses up all its hydrogen it becomes a white dwarf star.  A white dwarf star that is about 1.4 times the mass of the Sun implodes under its own gravitational pull.  This super-collision produces a thermonuclear explosion, producing a supernova whose brightness could be as high as 100 million times the brightness of the Sun.  The planets of the solar system are believed to be matter thrown into space by a supernova.  The Sun’s gravitational field collected this matter, ultimately converting it into planets orbiting round the Sun.  Speaking about the black-holes, it has been observed that the mass of some of the black-holes is billions of times the mass of the Sun, and that not even light can escape from them.  For instance, the mass of a recently discovered black-hole, just a few kilometres in diameter and 13 billion light years away from the earth, is estimated to be more than three billion times the mass of our Sun.  The universe itself, born in a cataclysmic explosion of super-condensed matter – the event itself is known as the Big Bang – is calculated to be about 13.7 billion years old, and is still expanding at the speed of light the farthest ones expanding at the highest velocity.  Some scientists speak of the eternal expansion of the universe while others envisage a final implosion followed by yet another Big Bang explosion, and the subsequent repetition of the whole process, endlessly.  According to many scientists, space itself is infinite.  The string theory of the universe speaks of the possibility of a virtually infinite number of universes.  Some estimates point to at least 10⁵⁰⁰ possible universes, each operating on its own laws of physics and chemistry.  Scientists also speak of universes with five or six extra dimensions.  Today we have physicists accelerating particles to near light speed and astronomers measuring and studying celestial phenomena with the most sophisticated instruments and techniques.  Thus, for instance, through observations of the cosmic microwave background (CMB), which are residual radiation from the Big Bang, scientists have been successful in identifying the features of the early universe, namely, the universe at an age of about 400,000 years.  Scientists have sent space probes to Mars, Saturn, Mercury, and even beyond the solar system.  The space probe, “Genesis,” has recently brought back to earth a “piece” of the Sun, and it is hoped that its study would unravel the secrets of the origin of the solar system.