You usually look at a map to know where you are going to go. But some maps can also reveal where you’ve been or how things have changed over time. That’s the case for a map of the universe put together by a team of astrophysicists, including researchers from the University of Chicago and the Department of Energy’s (DOE) Fermilab. It’s the most comprehensive map yet of how matter is distributed throughout the universe.

The map reveals how the universe looks today. By comparing it to data about the start of the universe, scientists can trace backwards and see how galaxies evolved over time.

One of the big discoveries is that the universe may not be as “clumpy” as our current best models predict it would be. Shortly after the Big Bang created all of the matter in the universe, that matter started spreading outward. Over time, gravity drew it together. Eventually, enough matter came together to form the planets, stars, and galaxies we know today. While the map mostly matches our models, it shows that the matter clusters slightly less in certain areas than our current physical laws predict. It suggests that something may be missing from our current model of how the universe evolved. While it’s not a definitive gap, it’s an area for future research to explore.

To create the map, scientists combined data from the South Pole Telescope and the Dark Energy Survey, projects that are both supported by the DOE’s Office of Science. Both of them collected years of data on galaxies and other astrophysical objects. Combining results from both makes it more likely that the data represents reality and isn’t thrown off by a measurement error. This work is also significant because it’s one of the first times that scientists have combined massive data sets from two different telescopes. It sets the stage for being able to merge similar data sets in the future.

From 13 billion years ago to now, our universe has changed radically. Every time astrophysicists collect more data about our universe today, they reveal a little more about our past.