The evolution of the Universe spans nearly 14 billion years, starting from the Big Bang and progressing through various epochs. Initially, the Universe existed in a state known as the Cosmic Dark Ages, containing a hot soup of subatomic particles that formed ionized atoms. As it cooled, electrons joined protons and neutrons to create neutral atoms, allowing light to travel freely. This era transitioned into the epoch of reionization (500 million to 1 billion years after the Big Bang), where ultraviolet light is believed to have re-ionized these atoms, clearing the cosmic fog. The sources of this UV light remain uncertain, potentially originating from the first stars, galaxies, or quasars.
Pioneering research has allowed astronomers to observe early stars and galaxies, revealing that the first stars were massive and bright, emitting significant UV radiation that contributed to reionization. Recent discoveries include the identification of galaxies exhibiting unexpectedly advanced features, suggesting rapid evolution within very early cosmic structures. Despite significant strides in understanding the Universe’s early stages, many questions remain regarding the timeline of reionization and galaxy formation. Emerging technologies, such as the Extremely Large Telescope (ELT), promise to enhance our observational capabilities, shedding light on these mysteries.
