With beautiful images like the one above, it may be hard to imagine that just before 1924, people thought that our galaxy, the Milky Way, was the only one. This changed when in the middle of 1990s, NASA’s Hubble Space Telescope took the legendary photo, which increased the number of galaxies in the observable universe from 100 to 200 billion. Like if that was not enough, a few days ago. scientists discovered that there are at least 10 times as many of them. Now, the number is closer to two trillion. It was this discovery that proved just how much we know about the universe. And by much I mean very little.
The research led by Christopher Conselice from the University of Nottingham, UK gathered all the verified data from studies and collected images from the Hubble and other telescopes to give the accurate number of galaxies in the universe. In order to make measurements, they converted the data into 3D models and used mathematical modeling to calculate galaxies, which cannot be detected by existing technologies.
The collected information allowed them to go back in the history of the universe for about 13 billion years. According to to the team, when the universe was just few billion years old, it was densely packed with many galaxies and their number exceeded the current one 10 times.
Outside of this unbelievably awesome finding, the scientists also made other important conclusions. The careful measurements proved the top-down formation model of the universe: it was denser in the beginning and, as it continued to stretch, the number of galaxies decreased.
The team also proposed the solution to the Olbers’ paradox, known as the “dark night sky paradox.” It asks the question which many of us probably have asked as kids: why does the sky remain dark at night if there are so many stars (like Sun and even bigger)? Based on the study, the team concluded that when you look at any point in the sky, you are looking at some galaxy. But since the universe is not static and expands faster and faster with time, not all light can reach us or be detected by our telescopes.
When it comes to the universe, many numbers are so high that is hard to understand what they stand for: trillion is not easy to imagine. The exciting part of the universe is what is behind those number and it’s left for people to explore. As Christopher Conselice nicely puts it, “It boggles the mind that over 90% of the galaxies in the universe have yet to be studied. Who knows what interesting properties we will find when we observe these galaxies with the next generation of telescopes.”