The Time Traveler's Almanac

Luna still floats in Terrestrial orbit – it is a useful tool to stir Earth’s liquid core. Prone to a rocky sclerosis, the Earth’s heart is a major problem for the Stasis. They can’t let it harden, lest the subduction cycle and the deep carbon cycle on which the biosphere depends grind to a halt. But there are ways to stir it up again. They can afford to wait half a billion years for the Earth to cool, then reseed the reborn planet with archaea and algae. After the first fraught experiment in reterraforming, the Stasis find it sufficient to reboot the mantle and outer core once every ten billion years or so.

The universe changes around them, slowly but surely.

At the end of a hundred billion years, uranium no longer exists in useful quantities in the Earth’s crust. Even uranium 238 decays eventually, and twenty one half-lives is more than enough to render it an exotic memory, like the bright and early dawn of the universe. Other isotopes will follow suit, leaving only the most stable behind.

(The Stasis have sufficient for their needs, and might even manufacture more – were it necessary – using the necrostar’s ergosphere as a forge. But the Stasis don’t particularly want their clients to possess the raw materials for nuclear weapons. Better by far to leave those tools by the wayside.)

The sky is dark. The epoch of star formation has drawn to a close in the galaxies the Earth has left. No bright new stellar nurseries glitter in the void. All the bright, fast-burning suns have exploded and faded. All the smaller main-sequence stars have bloated into dyspeptic ruddy giants, then exhausted their fuel and collapsed. Nothing bright remains save a scattering of dim red and white dwarf stars.

Smaller bodies – planets, moons, and comets – are slowly abandoning their galaxies, shed from stars as their orbits become chaotic, then ejecting at high speed from the galaxy itself in the wake of near encounters with neighboring stars. Like gas molecules in the upper atmosphere of a planet warmed by a star, the lightest leave first. But the process is inexorable. The average number of planets per star is falling slowly.

(About those gas molecules: the Stasis have, after some deliberation, taken remedial action. Water vapor is split by ultraviolet light in the upper atmosphere, and the Earth can ill afford to lose its hydrogen. A soletta now orbits between Earth and the necrosun, filtering out the short-wavelength radiation, and when they periodically remelt the planet to churn the magma, they are at pains to season their new-made hell with a thousand cometary hydrogen carriers. But eventually more extreme measures will be necessary.)

The sky is quiet and deathly cold. The universe is expanding, and the wavelength of the cosmic microwave background radiation has stretched. The temperature of space itself is now only thousandths of a degree above absolute zero. The ripples in the background are no longer detectable, and the distant quasars have reddened into invisibility. Galactic clusters that were once at the far edge of detection are now beyond the cosmic event horizon, and though Earth has only traveled two hundred million light-years from the Local Group, the gulf behind it is nearly a billion light-years wide. This is no longer a suitable epoch for Science Empires, for the dynamic universe they were called upon to study is slipping out of sight.

SLIDE 12.

A trillion years will pass.

The universe beyond the necrosun’s reach is black. Far behind it, the final stars of the Local Group have burned out. White dwarfs have cooled to the temperature of liquid water; red dwarfs have guttered into chilly darkness. Occasionally stellar remnants collide, then the void is illuminated by flashes of lightning, titanic blasts of radiation as the supernovae and gamma-ray bursters flare.

But the explosions are becoming rare. Now it isn’t just planets that are migrating away from the chilly corpses of the galaxies. Stellar remnants are ejected into the void as the galaxies themselves fall apart with age.

Space is empty and cold, barely above absolute zero. The necrostar’s course has passed through what was once the Bootes Void, but there is no end to the emptiness in sight: there are voids in all directions now. The Stasis and their clients have abandoned the practice of astronomy. They maintain a simple radar watch in the direction of travel, sending out a gigawatt ping every year against the tiny risk of a rogue asteroid, but they haven’t encountered an extrasolar body larger than a grain of sand for billions of years.

As for the necrosun’s planetary attendants …