A couple years ago I read two novellas/novels set in the same universe. The outer galaxy is united in a largely digital civilization. Anyone that tries to enter the galactic core mysteriously finds themselves turned around.

In the first one, two travellers from different planets meet at a hot rock passing between their two solar systems. The main character, while she is on the trip, her whole planet slows down so that they will only experience a few years subjectively like her, as is there custom. On the planet/rock they find an aquatic species. The heat is caused by them figuring out how to turn themselves into little quantum strings or something that can run simulations and produce energy. Most people are in the circle faction but some are spiral in and others are spiral out.

In the second one, two travellers are invited to the galactic core as a planet is found that has DNA on it. The story alternates between their investigations and strange tale of weird alien life. It turns out the aliens are the source of the DNA and they evolved in the galactic core. Realizing how much the core sucks, they vowed to always push away others who try to enter the core. Thus they are revealed to be the mysterious keepers of the core.

  • 2
    This question could do with some spoiler markup, I think.
    – chepner
    Commented Sep 11, 2019 at 13:06
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    "Anyone that tries to enter the galactic core mysteriously finds themselves turned around." That can only mean one thing: Greg Egan. Commented Sep 11, 2019 at 14:26

1 Answer 1


The first story is the novella Hot Rock by Greg Egan. I read it in the 2010 anthology Godlike Machines.

It's set on the planet Tallulah. This is a rogue planet, i.e. a planet drifting alone through space, so it should have cooled to only a few degrees Kelvin but instead it is warm enough to have liquid water. The two travellers are Azaz and Shelma, who are sent to investigate the planet.

They find a sentient life form that look like lizards, and these have the three philosophies, Spiral In, Spiral Out and Circle:

The lizards had no apparent social hierarchies, and as hermaphrodites they exhibited no sexual dimorphism, but the scouts identified one curious form of division. Many of the lizards identified themselves as belonging to one of three groups, which were named for the actions of spiraling inward, spiraling outward, and, the clear majority, following a circle.

I would guess the second book is Incandescence by Greg Egan. The galaxy is controlled by two groups, the Amalagum and the Aloof. The Aloof control the galactic core and prevent all attempts by the Amalgum to enter the core. The story starts when an uncatalogued DNA world is found by the Amalgum.

  • Also in the Amalgam / Aloof universe and available for free on Greg Egan's site is the prequel story to Incandescence, Riding the Crocodile. Another story in that universe is Glory, but it has no connection to the other Amalgam / Aloof stories. It's available as a PDD linked on the page of Greg's works online. (I can't open that PDF on my phone, so it may no longer be available free at that site).
    – PM 2Ring
    Commented Sep 11, 2019 at 9:45
  • Cool, I'd read Incandescence but didn't know about Hot Rock.
    – chepner
    Commented Sep 11, 2019 at 13:05

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