Cethente could not share these questions with anyone except the bathysphere’s log recorder, for the EM interference and the sheer intervening mass of water made communication with Titanimpossible. It logged its observations into the recorder, but soon it ran out of things to say. For long minutes, the realm outside was unchanging, save only for a steady increase in pressure and a gradual brightening of the magnetic field patterns emanating from below. There was nothing to do, nothing to perceive. So much of the universe is empty,the Syrath reflected. Life exists only in tiny portions of it. Even on planets whose surfaces seem so lush and rich with life, scratch below the surface and you find immense volumes of emptiness.Cethente knew the emptiness of space was unimaginably more vast, but it was more difficult to perceive that as one raced through it at high warp speeds, hurrying through it to avoid facing it. Especially on a ship with hundreds of other beings of numerous different types, surrounding one with life. And as an astrophysicist, he was able to think of the universe in terms of vast scales, abstract and removed from life. But down here, alone, drifting slowly through the emptiness, facing it on a scale that was smaller and more comprehensible, it was easier to appreciate how vast the cosmos actually was in proportion to living things. Is this why we so rarely visit ocean planets?Cethente mused. Not only because they are barren, but because their depths frighten us?Syrath had little fear of nonexistence, but to exist without input or companionship—that was terror.
Cethente’s time sense slowed in response to the sensory deprivation, and it entered the meditative state that was its species’ closest analog to sleep. An unknown time later, it was roused by several changes in its environment. One was that the magnetic field patterns dancing across its sensory nodes were resolving and growing brighter. Another was that the pod’s descent was beginning to slow. The third, related to the second, was that the readouts in the control cradle were registering an accelerating increase in water density. It was a myth that water was incompressible; it was merely difficult to compress, requiring hundreds of atmospheres of pressure to make a significant difference in its density. But that point had been reached at about the same depth where total darkness had fallen, and the density had been increasing at a slow but exponentially rising rate ever since; this comparatively sudden increase had to be from some other cause.
The other thing that affected water density, Cethente recalled from its daylong crash course in oceanography, was salinity, the ratio of minerals dissolved in the water. Checking its depth and taking a few more scans, Cethente confirmed that it was nearing the hypersaline layer, the saltwater dynamo whose contamination was altering the planet’s magnetic chorus. Cethente took a moment to “listen” to the magnetic field, although to the Syrath it was more like tasting; the field patterns did seem slightly dissonant, tinged with more exotic energies, though Cethente found it bracing rather than disquieting. Must be a flesh thing,it reflected.
The interface between the upper ocean and the hypersaline layer was not a sharp divide. The two layers had separate convection currents, keeping them from mixing too extensively, but there was a gradual transition from one to the other, more like the distinction between two layers of an atmosphere or a stellar interior than between two strata of rock, say. Nonetheless, the pod was slowing as the water around it grew denser and more buoyant, and once it was confident it had become sufficiently immersed in the dynamo layer, Cethente set the antigravs to give the pod neutral buoyancy, halting its descent. The Syrath set the sensors to maximum gain, and opened its own senses as well—the same senses that had allowed its species to develop an advanced knowledge of astrophysics while living on a perpetually clouded world.
Both sensory suites soon revealed the same thing: Cethente was not alone down here. It could sense smaller surges and pulsations in the magnetic field, isolated, seemingly random, yet oddly purposeful. It had the flavor of life to it. The sensors confirmed it: the dynamo layer was inhabited!
“Remarkable,”Cethente said into the log recorder after studying the scan results. “This is an order of high-pressure life—barophiles, the computer calls them—completely unlike what is found on the surface. They are evolved for pres sures that would destroy protein-based life. They are very dense, solid creatures, made of pressure-resistant shapes: spheres, toroids, cylinders with rounded ends. They have no internal voids, no pockets of lower density to give them buoyancy. They use hydrofoil surfaces, fins, to give themselves lift. They seem to ride the convection currents, which implies they can survive being swept down near to the deepest, highest-pressure regions of the dynamo layer.”
Cethente took the time to collect samples of a few small creatures, beaming them into the sample chamber, for the pressure-resistant design of the pod allowed for no hatches to draw them through. After a few minutes of analysis, it went on. “Instead of normal cell walls, they have microskeletons made of silicate spicules. Down here, the heavier elements are sufficiently concentrated to allow this. The spicules are intricately interlocked in a tight but flexible framework. It reminds me of plant biology on Syr.”“Plant” was a rough analogy, but it would do. “They appear to be magnetosynthetic, feeding on the field energy of the saltwater dynamo. Their biochemistry is based on molecules that are sturdy enough to withstand these pressures and temperatures, but would be inert under normal conditions. Intriguingly, this includes clathrates of carbon and heavier elements—ice-seven crystals actually serving as part of their biology.”This did not come as a complete surprise; Cethente was near a depth where it was possible for that allotrope of ice to form, though salinity, temperature, and other factors affected its formation and survival. At this depth, the water was fully liquid, but farther down it would grow increasingly slushy, a gradual transition from the liquid ocean to the hot-ice mantle below. Apparently when the creatures followed the convection currents down to the deeper levels, they fed upon the clathrates—ice-crystal lattices holding other types of atoms or molecules caged within them—and made use of the elements and compounds thus obtained, including the ice crystals themselves as a structural material. No doubt this was a major source of the silicates and other heavy elements constituting their biology; although the hypersaline layer was itself rich in these substances compared to the ocean above, the clathrate layer atop the mantle would be richer still, for that was where the infalling debris from space would eventually settle, accumulating more and more over billions of years.