4 ideas
The galaxy is silent because ancient machine intelligences, the Inhibitors, wait for species to reach interstellar capability and then exterminate them before they can spread. Silence is enforced rather than natural, so a civilization's own expansion and conspicuous signals are what summon its destruction. The empty sky becomes evidence of a predator, not of rarity.
On the colony world Resurgam, archaeologist Dan Sylveste discovers that the bird-like Amarantin were wiped out about 900,000 years ago when their star flared, just as they began reaching into space. His drive to learn why brings the lighthugger Nostalgia for Infinity to Cerberus, an artificial world orbiting the neutron star Hades, which turns out to be a trap built to detect and report intelligent life. Sylveste has also been steered there by a surviving Amarantin intelligence, so his curiosity is the bait.
Without faster-than-light travel, a journey between stars takes years of ship time and more in planetary time, so every mission is committed to long before its conditions can be known. Information arrives outdated, the people who give an order may be dead or changed when it is carried out, and relativistic crews drift out of step with the worlds they visit. Strategy under this constraint means betting on futures you cannot observe.
A beta-level simulation reproduces a person's behavior from observation and has no inner experience. An alpha-level simulation is a destructive scan of an actual mind and may carry real consciousness. The distinction separates a convincing imitation from a continued self, and it forces the question of whether a copy that acts like the person is the person.