Shortly after the Big Bang, the Universe entered a period astronomers refer to as the dark ages. During this time, the host of phenomena and processes that unfolded to set the Cosmos on its current evolutionary path remain hidden from astronomers, and experts are dying to know what happened.
Investigators say that the dark ages occurred between the time when the Universe first formed, and the time when the first stars and galaxies occurred. This period received this name because there were no lights in the Cosmos at that time.
Still, the fact remains that this specific period is critical to our very existence, since this is when the seeds of the first stars were produced. These massive fireballs would then go on to explode, and produce the heavy chemical elements we are made up of today.
In the words of Abraham Loeb, these cosmic dark ages represent our very origins or, better yet, the origins of life, stars, galaxies, and everything else there is today. Loeb is the chairman of the Harvard University Astronomy Department.
Since there was no light during those times, astronomers cannot use traditional observations methods to investigate what went on. As such, they are now trying to develop new technologies that would enable them to peer back farther in cosmic history than ever before.
“Our existence is a result of these first generation of stars, so when we investigate the dark ages, we're exploring our origins,” Loeb tells Space
. The expert authored a book on the subject, called “How Did The First Stars and Galaxies Form?” (Princeton University Press, 2010).
One of the most interesting and challenging mysteries relates to how the first black holes appeared. Such a dark behemoth is believed to lie at the core of every large galaxy, and even in some dwarf galaxies.
“The Milky Way has a black hole about 4 million times the mass of the sun, and some galaxies have black holes a billion solar masses large. […] How did these form? What are the seeds of these black holes?” Loeb asks.
Another puzzling aspect of the early evolution of the Universe is how dark matter came to play the role it does today in governing the interactions of gravity centers. Its influence must have become dominant at one point, and astronomers believe the answers lies within the blackest pits of the dark ages.
“If we assume dark matter is non-interacting, when people do simulations of the evolution of galaxies such as the Milky Way, there should be many satellite galaxies around it,” Loeb explains.
“However, when people look at the satellite galaxy population of the Milky Way, they find much fewer than the predicted number, and the inferred distribution of dark matter inside these dwarf galaxies is very different than what is predicted for them as well,” he concludes.