Cosmology might seem like a rarefied discipline, but in many indirect ways it touches everyone. We all have a need to know why the world is as it is and how we came to exist. Throughout history, societies have sought to address this need by producing creation myths: accounts which weren''t explanations in the scientific sense but stories intended to place human beings in the context of a grander scheme. When cosmology emerged as a scholarly discipline among the ancient Greek philosophers two and a half millennia ago, it was given a name that derived from the same root as ''cosmetic'', meaning beautiful, whole and complete; standing in opposition to chaos. The word implied that there was such a thing as ''a universe'', a coherent and organized entity that can be understood by human reason. Further progress, however, had to await the scientific age two thousand years later, which unleashed a stream of dazzling discoveries. When in 1543 Copernicus declared the Earth goes around the sun, he shattered the human-centric model of the cosmos that had prevailed for centuries. To be sure, the immediate effect on daily life was minor; there were no riots, no wars, no economic disruptions.

Yet, over time, the knowledge that we are not located at the centre of the universe fundamentally transformed the context of all human existence. The impact was felt not only in science, but in religion, sociology and economics too. Today we are poised to undergo a shift in perspective even more disruptive than that initiated by Copernicus. Future generations will look back at our era and envy those privileged to witness it first-hand. But beneath this triumph lies a profound mystery. For some reason, on an unexceptional planet orbiting a run-of-the-mill star, a species of organism evolved that managed to work out how the world is put together. That surely tells us something deeply significant about our place in the natural order. But what? It''s impossible to look up at the night sky and not be struck by the grandeur and beauty of the vista - the sweeping arc of the Milky Way, the myriad twinkling stars, the insistent, steadfast brightness of the planets.

The sheer vastness and complexity are overwhelming. For millennia after millennia, our ancestors observed the same sky, and struggled to make sense of what they saw. What was the key to understanding it? How did the cosmos come to exist? What was the place of human beings in the grand scheme of things? For many ancient societies, making sense of the heavens was not merely a philosophical or spiritual quest; it was also a practical necessity. Knowing the movement of heavenly objects was critical for human well-being: not just for navigation, but seasonal migration, crop growing and time keeping. Our distant ancestors'' preoccupation with the cycles of the sun, moon and planets is obvious from the megalithic structures they built, some deliberately designed to align with astronomical events - events often imbued with divine significance and marked by elaborate ceremonies. The sky was regarded as the realm of supernatural agents. In some cultures, the sun, moon and planets themselves were treated as gods. But the regularities evident in the movement of astronomical bodies suggested a very different concept of the heavens, not as the playground of the gods but a mechanism , an elaborate system of moving parts.

Once this notion became established, precision measurements were crucial to determine how the mechanism was organized and regulated. The mechanistic models of the universe were on the right track, but the theological dimension was never eliminated entirely. There was ever the vexatious issue of origins. How did the great cosmic contraption come to exist in the first place? Was there a Prime Mover who set the complex mechanism in motion? A supernatural Creator who conjured order out of chaos? A god who made the universe from nothing? No attempt was made in these early models to link the motion of astronomical objects with the motion of material bodies on Earth. Heaven and Earth, each filled with movement, remained separate domains. This view persisted through much of the Medieval period, until the seventeenth century. Then, suddenly, humankind''s understanding of the universe was transformed. A small band of visionary ''natural philosophers'' came to realize that the key to the universe was not to be found in divine agency, nor in the geometry of the cosmic architecture itself.

Rather, it resides in laws of nature that transcend the physical world and occupy an abstract plane, invisible to the senses but nevertheless within the grasp of human reason. Number and form, beloved of the ancient philosophers, are manifested not just in specific physical objects and systems, but interwoven into the very laws of nature themselves, forming a mosaic of subtle patterns encrypted in a kind of cosmic code. It was a stunning conceptual pivot, marking a transition from mere description of the world to explanation . Suddenly, humanity possessed a new window on the heavens. The swooping parabolas of comets, the graceful ellipses of planets, the scalloped gyrations of the moon - all the delicate tracery of celestial orbits - fell into place, linked to each other by the immutable logic of fixed mathematical relationships. Spectacular though such an advance was, Newton had a grander vision. Having explained the solar system, he set about applying his law of gravity to the entire cosmos. Since Galileo had turned his telescope on the Milky Way it was obvious that the universe is teeming with stars.

But how were they arranged? Were they clustered in a huge but finite cloud, or scattered endlessly through infinite space? Newton envisaged the cosmos as a gigantic clockwork, with gravity shaping its structure, literally holding it together, a universal force of attraction tugging tenaciously on every object in space. Where gravity is opposed by motion along a curved path, as it is for the Earth going around the sun, stability is attained: our planet is pulled by the sun but doesn''t fall into it. But what about the universe as a whole? With nothing to prop it up, why, wondered Newton, doesn''t the entire assemblage of stars fall together into one great mass? The solution he proposed was that the universe must be infinite. With no boundary and no centre of gravity, the cosmos lacks any privileged place to collapse towards. A given star would be pulled equally in all directions, the forces balancing out: ''by their contrary attractions destroy their mutual actions'' was how he quaintly expressed it. Clever though this dodge may have been, it was something of an intellectual sleight of hand. The delicate equilibrium isn''t in fact stable, as Newton himself acknowledged: ''For I reccon this as hard as to make not one needle only but an infinite number of them . stand accurately poised upon their points.

'' Newton''s infinite cosmos, it appeared, would teeter on the brink of collapse. Yet as a religious man (albeit in his own eccentric way), Newton did not baulk at invoking the hand of God to sustain His creation when necessary. And there the matter rested. It was to be another two centuries before the correct solution was found, but through the lens of history we can now see that the answer was hiding in plain sight--right above our heads.