As humans, we tend to think that we have a reasonably good idea of what the universe is all about. We live on a small blue planet orbiting a star on the fringes of a thoroughly unremarkable galaxy in a universe that extends basically forever. No matter how far out you go, you’ll always feel at home, because the universe is pretty much the same in every possible location. Because of this, it’s suggested that the laws of physics don’t change and that what we find in our galactic neighborhood we’d also find billions of light years away. This homogeneous theory is called the Copernican principle, and it’s an axiom on which much of our scientific knowledge about the universe is built. It is also, very possibly, wrong.
In recent years, scientists began noticing something a little bit off about the structure of the universe. By analyzing the light from distant galaxies, they were able to tell the relative speed and direction in which these objects were moving. The strange thing is that, rather than flying apart like most things in the universe, some of these distant galactic clusters appear to be caught up in a sort of current, speeding at unimaginable velocities (about two million miles per hour) along a specific path. Scientists have coined this phenomenon “dark flow” because, honestly, they really don’t know what’s causing it.