90s Sci Fi Book about Human tracking alien artifact ripples traveling through space, gets himself and team transported to alien space station

Question

I believe I read this in the late 90s. And like the title says, a human has this team, don't recall if it is all human or if there might be an alien or two mix in. Anyways, main protagonist discovers some kind of anomaly that is spreading out from multiple alien artifacts. Most people have forgotten that things move at the speed of light since faster than light travel is quite common. But, based on how these anomalies spread out from these alien artifacts, the ripples will hit a certain spot all at the same time.

The team travels to this spot, and then they get teleported or somehow otherwise travel to an alien space station. Same species that made the artifacts. This alien species has been collecting other species for some reason I don't remember. Eventually, the main protagonist's group has to fight an extremely dangerous alien race that was supposedly, and intentionally, wiped out by everyone else. Main protagonist's team is out gunned and outnumbered, but through some great old human ingenuity, wins the day.

Then everyone leaves, and main protagonist goes to warn everyone else that some of the very dangerous aliens were also able to leave.

Answer 1

This is the Heritage Universe series by Charles Sheffield. If you read a single book it was probably The Heritage Universe, which is an omnibus edition of the first three books.

The anomaly was discovered by Darya Lang, and the paragraph you remember is:

Humanity and its alien neighbors had become conditioned to think of space and distances in terms of the Bose Drive. Interstellar travel employed a precise network of Bose Nodes. The old measure of geodesic distance between two points no longer had much significance; it was the number of Bose Transitions that counted. Only the Ark dwellers, or perhaps the old colonists creeping along through Crawlspace, would see a change in a Builder artifact as generating a signal wavefront, expanding out from its point of origin and moving across the galaxy at the speed of light. And only someone like Lang, fascinated by everything to do with the Builders, might ask if there were single places and times where all those spherical wavefronts intersected.

The intersection is at the twin planets Opal and Quake, and the first book Summertide opens with Darya Lang on her way to Quake to study what happens at the moment the wavefronts meet at Quake.

The bad guys are the Zardalu:

Twelve thousand years earlier, long before humans had begun the Expansion, the land-cephalopods of Zardalu had tried to create something that neither humans nor Cecropians had ever been foolish enough to attempt: the Zardalu Communion, a genuine empire, a thousand planets ruled ruthlessly from Genizee, the homeworld of the Zardalu clade. It had failed disastrously. But that failure might have been the object lesson saving humans and Cecropians from the same mistake.

The books were written in the early 1990s, so they fit with the time you remember reading them, though stylistically they would have been right at home in the pulp era.