Singapore and interstellar gas clouds

Sitting at a country pub on the banks of the canal, basking in the Sun beside a weeping willow, the barges chugging languorously past, Singapore seems more than a world away. Swatting away an over-ambitious wasp, the skyline of this extraterrestrial plutopolis rises in the imagination like numerous glass, steel and concrete stalagmites, slowly precipitating from the steady drip of money over economic aeons.

Four and a half billion years ago, a cloud of interstellar gas and 'dust' (tiny grains of solid matter) contracted under the force of its own gravity, started to spin, and formed a rotating disk. The ball of material at the centre of the disk reached ever higher temperatures and pressures, until nuclear fusion ignited inside, and a star, our Sun, was born. The residual material in the surrounding disk then coalesced into an array of planets, our solar system.

The most abundant elements in the contracting cloud were hydrogen H, helium He, oxygen O, carbon C, nitrogen N, neon Ne, magnesium Mg, silicon Si, iron F and sulphur S. The silicon combined with oxygen to make silicates, and further combined with iron and magnesium to make what is colloquially known as rock. The remaining oxygen combined with hydrogen to make water. Within the outer reaches of the protoplanetary disk, the water was frozen, and the accretion of such icy masses gave the more distant planetesimals a head-start over the rocky masses which formed closer to the Sun. The more distant objects acquired sufficient mass to attract hydrogen, helium, and compounds such as methane CH₄ and ammonia NH₃, thereby creating the gas giants: Jupiter, Saturn, Uranus and Neptune.

On the surface of the third planet from the Sun, a rocky planet, oceans of liquid water formed. The oceans were populated by countless microscopic photosynthesizing organisms. Many had shells or skeletons made of calcium carbonate, and these shells and skeletons were continuously returned to the ocean floor, where they accumulated over the ages as layers of chalk or limestone. Over those same timespans, grains of silica SiO₂, or sand, were created from the weathering of silicate rock on the surface of the planetary crust. Then, eventually, an intelligent species emerged from the biosphere of the planet, delved into the planetary crust, and devised construction materials such as glass (silicon oxide which has been cooled sufficiently rapidly that the molecules are unable to form a regular crystal lattice), steel (iron judiciously doped with carbon atoms), and concrete (a coarse aggregate of limestone or gravel, combined with cement, water and sand, the cement itself a product of the heating and grinding of limestone and clay).

Four and a half billion years after the contraction of that cloud of interstellar gas and dust, Singapore rose as a glass, steel and concrete monument to the growth of complexity.