You probably already know that our solar system is part of a much larger group of stars, the Milky Way Galaxy. And also that galaxies seem to be arranged in clusters. Some of these clusters are so large that they are called “super clusters.” The biggest single entity that scientists have identified in the universe is a super cluster of galaxies called the Hercules-Corona Borealis Great Wall. It is so wide that light takes about 10 billion years to move across the entire structure.
So, our galaxy, which light could traverse in about 100,000 years is puny compared to this super cluster. But what I do not understand is that galaxies move and their speeds have been measured at from 0.05% and 1% of the speed of light, at the maximum. But all of the Hercules-Corona Borealis Great Wall’s stars were cheek-by-jowl, right next to one another, according to the Big Bang Theory. In order for the farthest reaches of that super cluster to get that far apart, at the speed at which galaxies travel, would require one trillion years.
Now the universe is supposedly 13.8 billion years removed from the start of the Big Bang, according to that theory, so there hasn’t been enough time for those galaxies to get that far apart, traveling at the speeds galaxies do.
So, the solution? Obviously space-time is expanding. Bt there has never been any proposed explanation for why space-time would expand, much less that expansion accelerate as it is now claimed to be doing . . . well, none but the ad hoc, mysterious “dark energy.” To claim dark energy is the cause of that expansion is grotesquely misleading because it was hypothesized to explain that expansion, so its characteristics are being inferred from what it is supposed to explain, so it is tailor made to do just that. The only problem is no evidence of its existence has been found, so it is pure speculation. I might also note that dark energy has no behaviors it shares with any known phenomenon of the universe. In other words, you can’t use the “If it walks like a duck, quacks like a duck, waddles like a duck, it’s a duck argument” because no form of energy behaves at all like the proposed dark energy. In fact it is only being called an energy because it is proposed as the explanation of an action. But no known form of energy comes close to doing what is claimed dark energy does.
So, while those galaxies are tottering along at at most 1% of the sped of light, the universe is expanding to make up the difference, which means it was expanding faster than the speed of light. (I don’t know how one could measure the speed of expansion of space and I have no reason to believe that expansion is limited to the speed of light (in a vacuum), but everything else seems to be.)
I am ready to admit I am a bear with very little brain when it comes to this topic, but still I tend to cringe at the outlandish number of ad hoc bizarre concepts being offered up. And, like string theory, there may be some truth there but it is impossible to test.