Remnant Energy produces "Reverberations" when it decays. It is the total of all frequencies a living being has ever encountered. However, under Newtonian Physics, energy would decay over time only if not in a medium. In the world of Solaris-3, everything is frequencies. And thus, everything functions as a medium. Even emotions, thoughts, dreams, etc.
With the continual existence of these energies, abnormal frequencies as a result of frequency overload can begin to collect. All these chaotic frequencies - born of humanity - begin distort the laws of physics -- everything except gravity.
Gravity then collects these informational frequencies into twisted spaces.
These can be understood as Sonoro Spheres. Parallel, chiral (non-superimposable) dimensions filled with facsimiles of the world of Solaris-3; worlds so very alike, yet unalike. They store events, memories, and then - given the energy they've absorbed - can reform that into whatever shows up inside.
With enough build-up of abnormal frequencies, these Sonoro will eventually form a nascent black hole, no longer able to release their information. Even further buildup of abnormal, chaotic frequencies here results in a "Lament."
An entropic explosion in an attempt to alleviate the "pressure."
Now scarred, the world continually manifests these chaotic frequencies as the Waveworn Phenomena — among them, Tacet Discords or Tacet Fields bear some of the most consistent danger to humanity as roving entities hungering to stabilize their own chaos by consumption.
What caused the First Lament though? What lead to this all happening in the first place? We can’t say for now, but what we do know is that someone has been diligently searching for a solution.
Rover, as Astral Modulator, has likely been using their Temporal powers, synchronized with Shorekeeper's Spatial powers (see: Document: Resolution K626) to use Sonoro spheres as wormholes in an attempt to find a solution to this problem - to stop the information overflow. How? Dimensional hopping using Sonoro frequencies to simulate close-time-loop universes. Tethys System will calculate the parameters, while Rover and the Shorekeeper go diving into a new realm. However, a constant in every single universe they may jump into is the existence of the Tethys System, so that they may return to their own timeline.
However, no matter how long they searched, they would never find a satisfactory answer. And, until they find a way to alleviate this pressure permanently, Solaris-3 is on a crash course to experience a "Final Lament."
It is a point of such entropic overload that results in everything reaching entropic equilibrium (see attached below snippet from Wikipedia) -- a state similar to that of Absolute Zero. No energy is transferred, and the world will slowly wither away, frozen in stasis until it becomes ice and dust.
A quiet end to the world shown at the end of the Patch 1.3 Questline: Act 8.
With no solution in sight, the Astral Modulator tries one last gambit. Undeterminism. Perhaps a new path comes with the freedom from the shackles of cursed knowledge. So they entrusted the truth of the matter to the Shorekeeper, erasing their memories and beginning anew, in search of a viable solution.
—-
Credits:
From both the Official Wuthering Waves Discord and the Solaris Archives Discord:
A snippet from Wikipedia, briefly describing the concepts behind the entropy of gravitational fields. The relevant information regards the loss of energy yielding a heterogenous system. However, as energy is continually generated by means of Remnant Energy, the opposite may hold true — the system moves towards a homogenous equilibrium.
A world, frozen in time. One possibility in a far-flung future where the Lament has consumed all.