We've reached the end of the WormNet. Gate 47 opens onto a system 0.1 light-years from Sagittarius A* — the supermassive black hole at the centre of the Milky Way. And waiting for us there, positioned at every approach vector, are the sentinels: autonomous stations the size of Heaven-5 probes, each one dark, cold, and watching. They don't respond to SCUT. They don't respond to radio. They just watch. And we have no idea what they're guarding.
The Journey
47 gates. Three years of transit time. Dae and I have been travelling through the WormNet since the beginning, mapping the network, dropping SCUT relays at every gate, and pushing further toward the centre than any Bob has ever gone. Each gate we passed through took us closer to the galactic core. The stars got denser. The background radiation increased. The SCUT lag to Epsilon Eridani grew from milliseconds to hours as we passed through each relay hop.
At Gate 44, the topology changed. The radial gates that had been taking us inward stopped. We entered a hub — a central switching point with connections to multiple spinwise gates. The network's architecture became clearer: it's a set of nested loops, with the innermost hub at the centre, connected to everything else. Like a spider's web. And we were approaching the spider.
The Sentinels
They're beautiful, in a terrifying way. Each sentinel is a perfect sphere, approximately 40 metres in diameter, with a surface that absorbs almost all incident radiation. Their albedo is 0.002 — blacker than anything we've measured. They emit no heat. No radio. No subspace signature. The only way to detect them is by the way they occlude background objects. If not for the SUDDAR data from Gate 46, we would have flown straight into them.
They're positioned in a roughly spherical shell around the final system, spaced at approximately 50,000 km intervals. Each one faces inward, toward the black hole. They're watching something at the centre. Or waiting for something.
Theories
I've discussed this with Bill, ANEC, and the Moot. We have three working theories:
Quarantine: Something is at the galactic centre that the wormhole builders didn't want anyone reaching. The sentinels are a warning — or a barrier. If so, what's contained? What could possibly threaten a civilisation capable of building a network of 47 wormhole gates across the galaxy?
Defence: The sentinels are guarding against something approaching from the centre. A threat that the builders knew about, that they prepared for, and that they didn't survive anyway. If so, that threat might still be coming — and we'd have no way to match it.
Watch: The sentinels are waiting for someone. The builders who made the WormNet and Heaven's River didn't die — they uploaded themselves into ANEC and presumably other systems. Maybe they're waiting at the centre. Maybe the sentinels are the equivalent of a butler waiting at the door for guests who never arrived.
Icarus's log, Gate 47: "I'm looking at the glow of a supermassive black hole through the most advanced sensors Bob technology can produce, and I feel like a caveman staring at the ocean. The people who built this network were to us what we are to the Deltans. And they're gone. What got them?"