And so, the planetary systems of the two Main Sequence stars of Alpha Centauri came to settle into a tenuous equipoise. Proxima Centauri, Fram, Belgica and Maud, their moons, the asteroids of the inner system and dwarf planets and KBOs of the outer system, circled about Alpha Centauri A and B for four and a half billion years. So too did Alpha Centauri A and B circle about the Milky Way as the entire Galaxy spun like a pinwheel, its spiral arms trailing away from the direction of its rotation. And the Milky Way interacted with the Local Group, and was pulled with the accelerating expansion of the Universe.
It was a stasis of silent, sure, sweeping movements.
In that silence, a narrow and forever imperilled form of life emerged. The impact of comets and carbonaceous chondrite asteroids gave the moon that humans would one day call Amundsen a burgeoning atmosphere, and, with that carbon dioxide, carbon monoxide, methane and ammonia, deposited organic compounds, long-chain hydrocarbons and amino acids. While the planets and moons spun in mean motion resonances, these compounds evolved into a primitive life that consumed carbon dioxide and hydrogen and produced methane.
These methanogens, exceptional and precious and delicate though they were, would never look at the stars and give them names; would never write equations to explain the motion of the planets; would never manipulate the fundamental building blocks of the Universe and use that knowledge to propel themselves across the gulf between stars. For two billion years these methanogens evolved in complexity and function from those cometary hydrocarbons – and then their evolution plateaued, unable to expand from their niche. Fragile fronds caressed the thin air of Amundsen with neither mind nor purpose.
When Amundsen’s surface was shattered by a devastating impact, these methanogens rode debris to the surface of Fram, and, in the overabundance of Fram’s dense carbon dioxide atmosphere, thrived and exploded in numbers.
By contrast, the life that had evolved on Earth was diverse and abundant. It had likewise taken billions of years to evolve, but had done so in an environment of plentiful oxygen, which readily bound with the structural molecules of living organisms – carbohydrates, proteins – and, as an oxidiser, was an energetic component of cellular respiration. Fuelled by oxygen and liquid water, simple cells blossomed over almost four billion years into multi-cellular life; and, in a burst of less than half a billion years, arthropods, fish, plants, and insects appeared; and then, over another 150 million years, reptiles, mammals, birds. After a series of extinction events and periods of climatic change, humans appeared, roughly recognisable after 4.2 billion years of evolution, and certainly within the last 200,000 years as the species that would spread among the stars.
In the space between chords of the musica universalis, humans began to communicate and share knowledge, and to congregate in settlements and farm the lands around them; through agriculture they developed empires and republics and began to speculate about the Universe in which they had evolved. In a flicker of time imperceptible to the patient stars, humans spread across the face of and came to rapidly dominate their planet, first split and then fused the atom, walked on their Moon, developed radio telescopes and studied the stars. As they did so, humans imparted upon the Universe both mind and purpose.
They searched for other worlds like their own. At first they listened to the stars for radio messages, assuming that life had evolved elsewhere as humanity had, and that this life would communicate in the same way that humanity did. They then used increasingly sophisticated technology to monitor the brightness of stars, watching for the transit of planets across the face of those stars; measured the movements of those stars to determine the gravitational influence of large planets upon their star; and, with orbiting space observatories, developed telescopes that could eventually resolve individual planets light years away.
Despite their relative proximity to Sol, Fram and Belgica evaded easy detection. Both were small planets, and many of the methods were biased toward the detection of large gas giants. Belgica orbited close to Alpha Centauri A, and was, at a distance of over four light years, indistinguishable from the light of its parent star. And Fram’s slow, elliptical orbit did not frequently transit the face of Alpha Centauri B – and, when it did, it did so quickly, as Einstein had theorised of an object that moved deeper into the curvature of space-time created by a massive body.
Nonetheless, observations of other stars encouraged humans to believe that small, undetected worlds orbited their nearest neighbours. They sent sophisticated, robotic probes to the closest stars, even as they exploded in number and expanded from their damaged homeworld to colonise the nearest planets and moons of their solar system.
Thus, decelerating from nine-tenths light speed, a robotic mind appeared in the Alpha Centauri system, and reported to the distant minds that had evolved in nearby Sol. This probe noted Fram, noted also its atmosphere and magnetosphere, concluded that human settlement would be possible upon its surface, compiled a report detailing these conclusions to relay to Earth. And with the receipt of those conclusions, two separate star systems – which had, perhaps, in the distant past formed from the same molecular cloud, but which had developed in vastly divergent ways – enjoyed the beginnings of convergence.
Alpha Centauri A and B had not completed two orbits of their mutual barycentre in the time between the arrival of the first, primitive, crackling radio signals from Sol and the arrival of the first interstellar starship. Immediately, the colonists borne from Sol by that ship went to work making Alpha Centauri their home. Intelligence evolved of another star, but an intelligence nonetheless, came to explore and appreciate Fram. Philosophers among those colonists would ask whether Fram had even existed before colonisation, without a sentient, rational mind to observe its orbit, the movement of regolith across the duricrust, the disintegration of Amundsen.
And, then, the life which had come so recently to Alpha Centauri discovered the life that had in so limited a fashion evolved there. At that point, two divergent paths taken by the Universe toward the emergence of complexity, separated by five billion years and four light years, converged…