0.15 light-orbits from Anniax (Imperial Core)
Beneath the heavy lead-perfused sapphiroid of the observation gallery, the opposite side of the station twisted, or rather the view of it did. The other galleries, the enormous magnetic coils that dominated the space at the station’s center, heat exchangers, feeder-stabilizers, and all kinds of equipment gantries wavered around the edges, as if in a heat haze, while in the center, the distortion was the product of a supra-fisheye lens, or particular exotic pharmaceuticals.
Galen Larynath blinked, rubbed his eyes, and tore his gaze away from the madness beneath his feet. “I’ll take your word that it’s in there.”
“Oh, it is. It’s not much bigger than an esteyn-piece itself, though, so you’d need better eyes than ours to see it from up here. We just get,” his companion shrugged, “the lensing.”
“That is a ridiculously big kernel.”
“The largest ever built. Planetary mass. But if you want to be heard across a galaxy, you need a big speaker.”
“What are you planning on sending?”
“The usual unknown-hailing protocols: hydrogen-frequency timing pulses, some simple mathematical representations, then sequence-chained Contact language, one through eleven, and an ident-and-response burst, then repeat twice more. The data transfer rate’s everything you’d expect from throwing a kernel this big around – we’ll consider it astonishing if we can get a Kb/sec out of it – so that’s all we have planned for Phase I. By the time we’re done with that, there’ll be plenty of better ideas to choose from.”
“I have some other thoughts you might want to consider.”
“My branch has been working on analysis of some of the data we’ve been picking up on the Super-Size Synthetic Aperture. We’ve been sitting on some targeted signals and possible responses that would seem worthwhile if we had had a transmitter big enough – which we don’t, EM-side, unless we knew that they had a triple-SA and would have it pointed the right way at the right moment. You, on the other hand –”
“Interesting. Let’s discuss it over in my office. The engineers have a test sequence to fire up, and we don’t want to be standing on this station when the jigglers go live.”
Well, that explains why our SETI hasn’t heard anything.
Advanced tech civilizations use gravity waves, not electrodynamics.
To an extent, anyway; as I suggest, part of the problem with transmitting over gravity waves is that, gravity being such a weak force, it takes inconveniently massy transmitting equipment to make yourself heard. (Not usually this massy if you aren’t trying to be heard all through the galaxy, in fairness.) That’s partially compensated for by interference sources being much less common, but still. It’s also probably going to be inconveniently omnidirectional.
My theory (which is true in the Eldraeverse, at least, and I’ll note in advance that it doesn’t cover intentional transmissions) for why SETI hasn’t heard anything is based on one quick observation: wireless bandwidth is finite; wired bandwidth is (functionally) infinite. Which is to say, with very few limitations, you can run an arbitrarily large number of network cables and optic fibers from A to B without them interfering, but try to do that with wireless signals, and you rapidly run out of frequency space, especially if C, D, E, and F through ZZ are also trying to talk. The more so the less strictly directional they get.
What that means in practice is that wireless bandwidth *there* remains subject to the ugly necessities of scarcity economics and externality pricing both, so people work extremely hard to avoid using anything loud, omnidirectional, or worst of all, both.
So long-range EM transmissions are hard to pick up because people have become extremely good at collimating and aiming their communications, the old “reliably pour an interplanetary beam into a two-foot dish” trick, accompanied by the use of relays and other very directional tech such as whisker lasers, and so forth. What omnidirectional wireless there is tends to be very short-ranged to avoid polluting the ether any more than absolutely necessary, and used as a last-step that gets the signal onto a wired network as soon as possible.
So, you’ve got an awful lot of EM communication going on on, its fair to say, on Eliéra, but it’s in the form of a billion or so wireless microcells all whispering at minimum necessary power. It works fine locally, but to listen to from a distance? It’s all, quite intentionally, blended and blurred into something barely distinguishable from noise…