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BDO of the Day: Solaria

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Today’s Big Dumb Object (BDO) is Solaria, a future series of nested Dyson shells encompassing our entire solar system, described in the Cageworld series by Colin Kapp. Solaria is a fairly well-executed BDO, with magic (mainly the Exis field) credited in all the right places. The series falls into much more mundane traps than any miscalculation or misunderstandings about the force of gravity.

Cageworld 1

In the first volume, Our Heroes leave their home shell, the Mars shell, on a mysterious Search for the Sun (1982/1983) as well as for Zeus, the artificial intelligence charged with creating and maintaining Solaria. The Mars shell is as vast as a Dyson shell should be, and a suitable number of people live on the outside of it, where the gravity is. (It seems thick enough to produce its own gravity.) Legend and dim memory report inner shells: an Earth shell at Earth’s orbit, a Venus shell, and even a Mercury shell.

Solaria has two additional features: the emigration spokes through which shuttles travel, carrying any excess population ever outward to unknown shells from which they can never return, and the cageworlds: entire planets trapped in vacuum bubbles within the shell material. Each shell has a generous helping of cageworlds evenly scattered about its equator, and there is speculation (never verified) that they predate the shells and were used in the building process somehow.

In order to pursue their journey inward, Our Heroes take an experimental ship through the small opening at the top of a Mars cageworld bubble. They land on the cageworld, have pulp-style adventures with their ever-varying isolated inhabitants, and continue out the other end of the bubble. This first shell-world is about 8,000 miles in diameter; the shells themselves tend to average in the neighborhood of 10,000 miles in diameter. Our Heroes quickly discover that Zeus is in no way excited to meet them, but they soldier on.

The surface area of Earth shell is reported to be a hundred quadrillion (1017) square miles, and Our Heroes approximate its population density as the same as that of Mars: 10,000 per square mile with only half of the surface habitable, or 500 quintillion (5020) people. It’s a steampunk shell on which Our Heroes have a brief adventure, and then continue on to the next cageworld, designated E12. Of course the cageworld turns out, purely accidentally, to be Earth herself, sadly neglected by Zeus. Still, Our Heroes pass through to the Venus shell, where they believe Zeus resides.

One important side-adventure is the discovery of a lab planet on which Zeus is trying to evolve new species, including, humans. Our Heroes fear, new, more packable, species of Man. Eventually they find and talk to Zeus. In the process of negotiating with Him, Our Heroes get to proceed farther to the Mercury shell and see the Sun from one of its cageworlds. Negotiations with Zeus end well enough, considering that he comes off as quite insane in this series, and the mission rolls back to Mars.

Cageworld 2

In The Lost Worlds of Cronos (1982/1983) Niklas Boxa, a student at the new-founded Centre for Solarian Studies on Mars shell, postulates an unknown shell between the Jupiter and Saturn shells. This shell is eventually found and explored by Boxa (for whom it is named) via emigration spoke, and by Our Heroes by ship. They have more fantastical adventures of the pulpy sort. Zeus, of course, interferes, because whatever d├ętente they have means little beside his inexplicable whims.

The contribution of the novel to the series is mainly the discovery of the overpopulated the Boxa shell, a layer-cake arrangement stuffed full of marsupialized, easily stacked human-like beings with night vision—more, Our Heroes estimate, than all of normal humanity on all the other shells. They fear Zeus intends to supplant humanity with marsupialanity in order to carry out the letter, if not the spirit, of its charge to support the ceaseless increase of Man.

Cageworld 3

The Tyrant of Hades (1982/1984) is a mystery on the vastly underpopulated Uranus shell that Zeus, having lost control over that distant region, allows Our Heroes to explore all the way out to that shell in their usual, pulpy way. Notable discoveries of this novel include the fact that Zeus must operate through semi-independent agents at distances where communication is delayed by hours. (There is no ansible here.)

Cageworld 4

Star Search (1983/1984) leads, inevitably, to the stars, by way of Neptune and Pluto shells, with the usual pulpy adventures along the way. Interestingly, Pluto shell shows the limits of the magic technology with which these shells are held together; bits of the Exis field poke up onto the shell surface, making travel challenging. Nevertheless, humanity is establishing itself there.

And yet, the expected sky and stars are not found over the Pluto shell, though clearly another habitable shell cannot be surrounding it. With more travel Our Heroes discover the barrier, a pure Exis shell meant to protect humanity from construction projects on the outside. Zeus objects, but local agents let Our Heroes through it to see the stars, and something else.

Here the series ends on a deus ex machina; it turns out crazy Zeus doesn’t seem to know that some of his split personalities/independent agents have been making more shellworlds surrounding new suns outside of Solaria, and positioning them to pick up the excess human population. So there is no Malthusian trap after all, and Zeus has been making marsupials to no end.


I read this series for the Big Dumb Object, and found myself far more entertained than I expected. The Cageworlds stuck into gaps within the Dyson shells are a great idea in their own right, and they also provide a new lost colony of humanity or weird project of Zeus’s with every shell crossing in the series. Along with some free-floating objects in intershellar space, they add up to a constant stream of new ideas and adventures.

This series was a fun read, if you can suspend your disbelief long enough for some short pulpy adventures in the fine old Barsoomian tradition. The cageworlds, shells, and other fragments of BDO are reasonably believable and entertaining, Zeus a bit less so. I haven’t gone into details about the characters because though their stories and skills are interesting, they get through the series without being deep or changing in any way.

The premise of the series is big and dumb: not even ten nested Dyson spheres can solve the Malthusian trap for long, and the crazed computer deals with the problem in the stupidest ways it can think of. In reality, people do not reproduce in a Malthusian way; crowding and prosperity cut birth rates, never mind disease and war happening well before you’ve packed a hundred thousand people into a square mile (on the overpopulated Jupiter shell).

Even if you accept the premise that people will reproduce exponentially if left to their own devices, the way to squelch that is not to force randomly selected humans to emigrate, but to force third children to emigrate. Humanity in Solaris lives in horror of emigration, so why not direct it in a way that keeps that third child from ever being born?


Minor edits to incorporate my brief Goodreads review.