Just to repeat what others have said, the first two scenarios play to Forerunner's strengths.
They're long-lived beings, virtually immortal and part of a highly industrious society; when challenged by imposing technical hurdles and galactic scale threats, they can summon a vast sum of resources - so occupation by quintillions of drones is not a far-flung concept, especially if it allows them to mitigate potential damage to neighboring systems.
Although it would be funny if their reaction was to slather the exterior outcropping in smartmatter and let the self-replicating buggers just exponentially grow and prune the mass of the city to a more reasonable portion.
Madmanwithabox said:
Also, it's not my job to prove that they can scan the city. Prove that they can scan something an AU away, through thousands of miles of metal, through something with the density of a black hole, with a constant high energy field covering it.
The issue here is that FTL sensors that are designed for accurate real-time communications between distinct points over light years likely do not obey any kind of local causality unless they rely on some form of compressed warp field to transmit data through space as a compressed medium.
However, that's not the case with the Forerunners, who use a multitude of systems from remote quantum entanglement effective over light years to discern DNA molecules from any amount of present mass in a near-Earth biosphere to simply bypassing locality via extra dimensions as noted when the Didact uses the Glow to trace events that occurred decades prior.
Halo Cryptum; ch. 10-11.
The voyager's sensors scanned heat and other radiation signatures in the sky, latencies in cosmic ray patterns from the inner galaxy and outer reaches of the spiral arm.
"Our humans should feel right at home here," he said. "Once, they knew these worlds better than Forerunners. They fought and died here, surrounded by
Precursor ruins…" He slowly turned, the displays silently precessing with him. Then he pointed out a void in the system's magnetic flux. "There was recently a huge construct nearby, no more than three hundred million kilometers from here."
"Precursor?" I asked.
"No. Forerunner - but big enough. The size and mass were sufficient to create a persistent distortion in the system's field. See that - it even leaves a mark in the stellar winds."
"How recently?"
"Judging by the diffusion of its magnetic shadow, four or five decades ago. Portal technology has grown enormously more powerful, but to move such an object, they must be slowing other traffic throughout the galaxy."
He swept out his hands like a sculptor and tugged down virtual charts, diagrams, simulations based on the sensor's measurements. What they revealed was a circular gap in the interstellar medium, and a drawn-out loop in the star's vast, slowly wobbling magnetic field, its patterns smearing outward for hundreds of millions of kilometers....
That took me aback. I looked across the command center. The humans were clumsily adjusting to their outfits. Riser was much taller than he was used to, walking stiffly on long legs that put him on a level with Chakas.
The Didact was deep in study of the system's trace in the photonic realm of the Glow, which might reveal even more evidence of what had happened here.
What's interesting about this scene is that the density of the stellar medium is dictated by the aberration of light travelling through the magnetic field generated by the star itself (as you may or may not know stars persistently eject energy and mass), of course this is relative to the stellar activity of the star (being a blue star it's actually going to be incredibly violent), but assuming it's a docile star where the medium is a more conservative 100 km/s you end up with distances of billions of kilometers. Now detecting changes in the stellar medium is not exactly new to us as of now, the issue being that detecting said changes require high density gas formations to be observed in real-time over vastly lower distances, not decades apart when the particle charges and exchange have become chaotic through gravity or weak electromagnetic forces (the particles will disperse randomly over time), or even decayed. Even at a minimum the Didact is detecting variations in the magnetic field and stellar matter to trace back individual ions, protons and other charged particles back to a local point 300 million kilometers distant four or five decades before, just over roughly 4.5 light days distant (approximately 1/6th of the distance from the Sun to the Oort cloud) in a medium with a density of roughly 0.1 neutral hydrogen atoms (H) per cubic centimeter.
Of course the Halo is a massive structure with a massive volume, but the equivalent displacement of that much volume in the stellar medium would only amount to 1E+23 Hydrogen atoms, which is less than 20 milligrams of Hydrogen. At that range, thanks to the Inverse square law, the exact density of specific particles decreases to 1E-22 ions per cubic centimeter, or one hydrogen atom for every several thousand cubic kilometers - in a region of space where the electromagnetic and gravitational binding forces emitted by an atom over that range are worth 6.67E-69 Newtons, fifty-six orders of magnitude less than a small moon orbiting Proxima Centauri has on a person on Earth. Sensors are essentially determining the origin point of a shotgun blast fired from Earth's orbit nine thousand year prior based on the trajectory of the pellets that are a fraction of the way to the Oort cloud, while each pellet is drifting roughly twelve million kilometers apart.
If you can effectively reverse-engineer the motion of hydrogen particles in a vacuum through observing a weak system field that propagated over light years to a point fifty years in the past you're more than likely determining the difference between a near vacuum, atmospheric density and the solid wall of the megastructure.
Terran Imperium said:
For the exact same reasons people have pointed out that the density of the material is far beyond anything encountered in Halo?
I keep seeing this repeated in the thread, but where is the evidence that the density of the megastructure is greater than any known material?
Nihei makes reference to dimensional compression in the art book:
The computer chips of the megastructure are folded up into the Nth dimension like a virtual computer and can't be thought of as hardware.
Which treats it as a virtual computer which is folded into other dimensions, but where is this expressed as a higher density in effective "real-terms" such as those particles present in 3D space?
it is reasonable to question the efficacy of both FTL and subluminal sensors in penetrating megastructure. The density of the material would block if not disrupt the propagation of any known sensor particles or waves.
Subluminal to c, yes. However, Forerunners have expressly stated to have abandoned the EMS for communication purposes and evidently seem to regard it as archaic, given the elected sensor methods they employ.
As I mentioned above, the mode and means of transmission determine the efficacy of FTL sensors where intervening mass or strong fields can inhibit the transmission.
For example, if we look at the Mass Effect, signals can be sent at FTL velocities using carrier waveforms we are familiar with (LIDAR, etc.) but use some form of compressed space-time—similar to their drives—to propel the signal along zero-mass corridors of space. Once the beam hits the desired destination over many light years, the signal can be diffused by an intervening object.
For signals that arise through interactions with other dimensions layered over our own, that would depend on the accuracy and scale as to one could "telescope" their sensor systems through the intervening medium and back into realspace. If the object in real space has no means of inhibiting the signal propagating through a medium such as room temperature air, then it should be possible to observe events within the confines of the structure and determine if the void cavity can be teleported to.
For the Forerunners the latter is demonstrably proven to be the case on numerous occasions. In fact, they developed an entire weapons system composed of millions of planets and planetoids forming a thousands of light-years wide field capable of viewing vessels passing in close proximity in both real space and slip space and pulling them through.
Madmanwithabox said:
Caution, but I would give as much credence to Spacebattles memes as I would any other.
This site has a habit of propagating older, less adequately sourced statements and continuing to parrot them until sufficiently quelled. There are too many examples that come to mind.
I myself am guilty of this. I fell into thinking that BLAME! was set in a concentric series of Dyson shells layered out to Jupiter based on hearsay because A) I never fact-checked the setting at the time, B) I hadn't read the series yet, and C) because it's a fundamentally cool idea, therefore I was attracted to it.
