> When describing the gravitational dynamics in co-moving coordinates, by which the expansion of the Universe is factored out, underdensities repel and overdensities attract.

In an interested reader’s model of the universe at the cosmological scale, this would be described as the underdense region pulling less, and the overdense region pulling more.

I do understand that this is a useful way for researchers to model the problem, but I’m quite confident that many readers will come away from this summary of the article with a *worse* understanding of cosmology, as I just had a couple of colleagues do just that! I was unsure of what was going on until I found the section of the abstract that I quoted above.

I think it would be helpful for many readers to mention that this article is talking about relative levels of gravity rather than any kind of repelling force.