The Hercules-Corona Borealis Great Wall was a massive filamentary structure made up of countless galaxies, galaxy clusters, and vast amounts of gas and dust. It was like an abnormally enormous fiber wall within the cosmic web of galactic structures, and it stretched fully ten billion light-years in length.
Of course, it was not a structure with length alone. In fact, its overall width and height also reached more than a billion light-years, making it a true, typical large-scale structure of the universe.
To the humans of the Earth Era, its scale was simply too vast, so vast that, back then, even Human Civilization's cosmological models struggled to perfectly explain the formation of such a gigantic structure. That was to say: it should not have been able to form within the 13.8 billion years since the birth of the universe.
Furthermore, according to Human Civilization's standard cosmological model at the time, the uneven distribution of matter in the universe would gradually be amplified through gravity, but the scale of the Hercules-Corona Borealis Great Wall had already taken into account the speed limit of gravity's effects under cosmic expansion. In other words, across a region as vast as the Hercules-Corona Borealis Great Wall, the expansion speed of the universe had long since exceeded the speed of light. Gravity, which acted at light speed, should not have been able to hold the galaxies within that range together, so logically, this kind of large-scale structure should not have existed.
The problem was, it did exist, and it had existed in the universe for more than ten billion years.
When theory could not explain an existing phenomenon, it meant the theory was incomplete, and the best way to perfect a theory was to go there and investigate it in person. In the past, Human Civilization