Actually it's like this -- basically ' The Limit of Questions ' was an homage to American science fiction writer Greg Bear which is referenced by the series character 'Dr. Greg "Bear" Egan' or simply 'Dr. Bear'. The anime character even sort of looks like Greg Bear hehe. Anyway the concept was inspired by Greg Bear's novel Blood Music where the protagonist Vergil Ulam injects himself with intelligent one celled creatures called noocytes (very much like the scub corals).
Soon enough these individually intelligent noocytes multiply inside and make Ulam 'better', also other people become infected and spreads through a considerable population. Eventually the number of these intelligent one celled lifeforms surpasses the human race trillions of times over. So the Earth becomes home to enormous amount of sentient beings. So what is the relation to 'the limit of questions?'
In the Copenhagen interpretation of quantum mechanics, with the strong anthropic principle in mind (that of Barrow and Tipler), conscious observers can collapse a quantum wave function to a particular value of momentum or position. So the sci-fi premise in the novel is that with that humongous amount of conscious intelligent observers 'observing' (and 'questioning' so to speak) the environment and the earth around them, reality will have no room to 'breathe' because it will be pinned down to a particular value, that is, there will be an utter collapse of the quantum wave function everywhere. If reality becomes too 'frozen' or rigid because of too many observers, then reality will break down and the laws of physics will fail. The assumption in the sci-fi novel is that reality needs room to 'breathe' and move freely -- hence the quantum wave function of probability which is intrinsic in the fabric of reality. If the quantum wave function is collapsed on a massive scale because of too many observers then reality breaks down.
In Eureka 7, the 'Limit of Questions' precisely takes on this premise with the scubs in place of Bear's 'noocytes'. That is why the scubs should be in a state of sleep and dreaming to prevent the advent of full consciousness and observation which will trigger collapse. Of course Bear's premise is science fictional in nature, any possible relation to reality has not been proven in the laboratory yet hehe -- of course we don't want to speak hastily and discount anything outright
