Technology of the Nexum
Spinnergates
Starflight is entirely possible through conventional, slower-than-light travel. It takes years, sometimes centuries. The alternative, so common across the Nexum that they are practically a token of their culture, are the spinnergates.
The Predecessors maintain concentrated tunnels within hyperspace between stars, funnelling energy and matter from place to place in real-time. One does require a capsule to travel through the spinnergates, but they are not unreasonably dangerous, beyond the always-present worry that your soul will be consumed.
One unique element of the spinnergates is that often one can access different systems by entering the gate at a different angle. Where, for example, passing through a spinnergate in orbit around Belenos in one way might get you to the star called Glycon, passing through it another way gets you to Typhon instead
Genometry
The study of genetics is an ancient science that by now has become more of an art form. The manipulation of genes for purposes from the mundane to the bizarre to the exploitative has become commonplace across the Nebula, and there is a history of such manipulation in every culture that has managed to achieve starflight. There is also a major trade in different genomes between systems, in infinite varieties derived from the genetic material of the planets where intelligent life has come to join the Nexum.
There are two major issues which, even nearly four hundred million years into the civilization of the Nexum, still boggle the minds of scientists.
The first is that, although often with substantial differences in the precise chemical composition preferred in biological compounds, almost all the life-bearing planets of the Crayfish Nebula use carbon-based nucleic acids to store information. Specific bases, amino acid structures, and additional elements aside (life on Parnassus makes much greater use of manganese, for example, while life on Lux Aeterna has significant quantities of sulphur in its cycles), the similarity is compelling—and perhaps worrying. Theories of panspermia and biogenesis have been propagated, and frequently new evidence is found which mostly denies this. But there remains a tantalizing possibility that somewhere in the distant past a species even more ancient than the Morphai spawned life on some distant world, or even in the Nebula itself, and that life seeded itself in some way across planets. The ability of phoenixes to travel through hyperspace, the occasional opening of portals on distant worlds, and indeed various terraforming efforts by dozens of species over hundreds of millions of years have both all contributed to this theory and muddied the waters when it comes to actual proof.
The second is whether or not the presence of certain elements is necessary for the formation and propagation of a soul. Souls exist on a separate plane of reality to the material one, and various methods have been used to determine what precisely the link appears to be. The suggestion that the presence of more complex souls might lead to more complex life and vice versa is once again a theory that is very popular in certain academic circles, but does not appear to have much in the way of hard evidence behind it. Another theory is that it is not individual life-forms but entire ecosystems which generate a sufficient "thaumic magnet" for souls, attracting more complex conglomerations as the world in which they live becomes self-aware. One thing is for certain: a soul requires the presence of a being which can both change reality and be changed by it without losing its "sense of self". Since this applies even to some microscopic single-celled life in the smallest quantities, the "conscience spectrum theory" (CST) is often dismissed by scientists, but there does appear to be hard proof of something related to even the smallest building blocks of life.
Citizens of the Nexum manipulate their forms in all sorts of ways. While the "classic profiles" are frequently the default, members of the species choosing forms closer to those of their ancestors during the pre-starflight or even pre-spaceflight days, there are infinite possibilities for changes to oneself and one's genome. Longevity treatments are the most common, although by now most of these have been written into the "classic profile". There are treatments allowing one to look similar to other species, for purposes from pleasure to business to immigration to comedy. (The last has been a subject of some controversy for about thirty million years and is unlikely to get any better any time soon.) There are treatments for surviving in specific environments, or for increased strength or intelligence or pleasure. Anything goes in the Nexum, goes the old saying, and not everyone comes around.
Bodybands
One of the more controversial inventions found in the Crayfish Nebula is the bodyband. While wearing it, a user is capable of transforming their physical form into that of another sapient species whose specifics have been copied into the machine via genetic samples. The process is instantaneous and painless, but does wear off after about half an hour if not renewed before that point. The other caveat is that, once put on, the bodyband cannot be removed. It fuses not only with the body but with the soul, from which it draws its energy, and that is unchangeable. In addition to not being able to take it off while still alive, the wearer can use no other kind of magic across their whole life.
Originally intended for interpreters in the diplomatic corps, bodybands have seen use in several different fields. Biological testing is one—seeing the effect of different planets on different bodies without needing to go to the expense of actually transporting members of the species here. Espionage is another. The pleasure industries, never far away, have been very interested in their potential. One or two have found their way to the planets of Ward species, those who have yet to achieve starflight, where they have often caused considerable chaos among the local sapients (and quite likely given them advanced warning of the weaknesses of the Nebula's inhabitants, so often special task forces are created to retrieve the wayward bodybands along with their users.) Still, it's not as though they're too common—the Nexum has a population in the hundreds of billions, and only something like four hundred thousand bodybands were ever made. And for good reason…
The Nadder who invented them, Eternal-Emptiness-of-the-Void, has long since vanished into history. Witnesses say that he (for the Nadder sired no children at all) was trying to find more species beyond the Nebula with which to update his own boyband—but there is nothing that lives beyond the Nebula. With no magic and no souls, how could other regions of space be anything but desolation?
Emolument Equations
Credits are technically used by the Nexum, but the genius of the Miser Crabs allowed for the creation of an entirely unique economic program. The Emolument Equations are part currency, part predictive index, functional across the entire Nebula and based on the projected value of the services of the purveyor in the local economy.
Psychic Computers
Computer technology has a great many forms across the Nexum. Quantum computers are a given, and are incredibly useful in many societies. But the height of Nexum computer technology is the psychic computer—a program written in the Deep as part of a self-regulating "soul", capable of possessing the object to which it is bound and magnifying its calculation and memory storage a millionfold. There are occasional issues with such computers, but most of these can be sorted out by giving them an emotional state to keep them docile. Some psychic computers can theoretically restructure one's entire mindscape, should they be granted access.
One unfortunate side effect of this technology is the emergence of "psychic viruses", which target not only computers but their organic users. To this end, one should never bond with a strange computer, lest it scramble your soul.
The Bai-Terek
Connection to the Nebula is actually relatively easy. Information travels only as fast as light, but the Bai-Terek takes advantage of the strange phenomenon that every particle of the Nebula itself contains within it a reference to the state and position of all other particles. In other words, what one sees in one oneirosphere is technically accessible, or at least stored, everywhere else in the Nebula.
The Bai-Terek is a separate layer of reality, slightly removed from the current one. It is not inherently magical; it has an "interface" of sorts, one maintained by non-psychic computer technologies, accessible to various beings for whom a template is provided. One can "plug in" using quantum allomizers, which allow the body to access various "worlds" within the Bai-Terek. There are quite literally quadrillions of smaller worlds within the space, accessible using various passcodes. Often these include "software add-ons" to make certain features of the world—be it a game-world, a retrohabitat, or what-have-you—function better. Designing these worlds, and the add-ons that go with them, is a very popular career choice among Patrons and Clients alike. There are also "call-spaces", where indivudals from across the Nebula can meet and converse even when their bodies are hundreds of light-years apart, and encrypted messages that can be sent to anywhere from fifty stars away to someone sitting right next to you.
Putting it in a nutshell? The Bai-Terek is a virtual reality simulator on an interstellar scale. With everything that that entails. Fortunately, the Bai-Terek, which remains under the control of the Predecessors, is a "locked world"—a pocket dimension of sorts designed for use by their Clients (and themselves occasionally). No similar fields around specific planets can be damaged in this way, nor does it contaminate souls. Some psychic computers do link to it, but this is by no means ubiquitous. Access to the Bai-Terek is monitored closely by the Predecessors for things they consider "misuse" of the space, although given the number of criminal activites that actively take place in the Bai-Terek it's unclear as to what "misuse" might constitute as for us lowly atom-based life-forms.