The entire cosmos is filled with light that has never been seen. Every star in every galaxy that’s ever existed in our universe has emitted starlight. Curious as it may sound, almost all of that light is still traveling through the cosmos. Yet remarkably enough, a group of researchers has managed to get a glimpse of this starlight as it’s still traveling. This sea of photons, some newly created, some fantastically ancient, which surrounds everything is known as Extragalactic Background Light (or EBL for short). In a similar way to the Cosmic Microwave Background (CMB) - the leftover radiation from the big bang - measuring the EBL is rather important in cosmology. Most recently, new research published by Alberto Dominguez, together with six co-authors, gives the best measurement ever made of this background light, showing how the EBL has varied over the past 5 billion years! By looking at the EBL over the past 5 billion years, cosmologists can learn about how galaxies change as the Universe ages. Whether or not ancient galaxies work the same way as modern ones is very important to our understanding of the Universe. As it happens, the kinds of galaxies observed in the Universe today are responsible for most of the extragalactic background light over all time. Because there’s still a lot out there in the Universe which we don’t fully understand, it also sets a limit on any other light sources which we may not yet know about. Observations like these do wonders for our understanding of the Universe and the way in which it works. It’s exciting to know that no matter how much we learn, there’s seemingly always more to be discovered out there. And perhaps most of all, we can learn all of this from the humble photons which are all around us. Though it’s not exactly light reading, the research paper for this work is available to read online at arXiv, in case you’d like to know more about the technical details.
matter becomes Spirit through evolution
