On the largest scales in the Universe, dark energy causes the Universe’s expansion to accelerate. It not only drives distant galaxies farther and farther apart over time, it causes them to speed up relative to one another’s perspective. But on the other hand, gravitation causes matter to clump together, like our own galaxy and local group have, and can defeat this expansion if you get a large enough amount of matter together in one location. But galaxies and groups aren’t the biggest structures we know of. The Universe also has clusters and superclusters of galaxies, and we have some right in our own backyard! Will one of those defeat dark energy in the end?To read more, click here.