The Milky Way is just one of 100 billion galaxies in the universe, and each one is a bit of a time capsule. Thanks to their immense distance, we see them as they were milions or even billions of years ago, and keep pushing it back towards a time known as the Epoch of Reionization, when the first galaxies ignited hydrogen in the infant universe’s interstellar medium, making it possible to see the universe.
But what did these first galaxies look like? We’re still piecing it together. They were likely small, possibly containing a lot of dark matter. A handful of observatories are trying to draw out the smallest details to build a picture of this time when the universe was just 400 million years old.
While we don’t have answers, this video from Minute Physics gives a pretty good idea of what researchers are looking for. So in just three minutes, you can get a little insight into the early universe, even if some of the details are still a giant mystery.