PBS Space Time Season 2019 Episode 16 The Cosmic Dark Ages

PBS Space Time is a YouTube show dedicated to exploring the mysteries of the cosmos. In season 2019, episode 16, the show delves into the concept of the Cosmic Dark Ages. This episode explores the period in the universe's history where light could not escape from clouds of gas and dust. This era began shortly after the Big Bang when atoms began forming for the first time.

Scientists believe that after the Big Bang, the universe was a bright, hot, and dense mixture of particles, including photons, the particles that make up light. However, as the universe expanded and cooled down, the photons "decoupled" from the matter, meaning they were free to travel on their own. This event is known as the cosmic microwave background radiation and is visible today as a faint glow of radiation that permeates the universe.

But before the cosmic microwave background radiation was released, significant events were occurring in the universe. The first of these events was the formation of atoms from protons, neutrons, and electrons. This process created a dense and opaque fog of gas and dust that permeated the universe. This fog blocked electromagnetic radiation, including light, and created the Cosmic Dark Ages.

During this period, the only light sources were massive stars that burned brightly and died quickly. But because the universe was in a state of low density, these sources were rare, and the Universe remained largely dark for millions of years. This episode explores how scientists study this period of cosmic history to better understand the early Universe and the fundamental forces that shape it.

The episode examines how scientists use telescopes and other tools to study the early Universe. By analyzing the cosmic microwave background radiation and studying the structures of galaxies and clusters of galaxies, scientists can piece together the timeline of the universe's history. The Cosmic Dark Ages is a particularly challenging period to study because it left few traces behind.

However, scientists have found a few signals from the Cosmic Dark Ages, which they have used to learn more about this mysterious and fascinating era. In particular, scientists are interested in studying the rare sources of light that existed during this time: massive stars. These were the only light sources that could shine through the fog of gas and dust and make their way to telescopes on Earth. By studying the light from these stars, scientists can learn more about their properties and how they may have influenced the Cosmic Dark Ages.

Overall, the Cosmic Dark Ages is a significant and fascinating period in the history of the universe. It was a time when the universe was still a mystery, and when the forces that shape it were just beginning to take shape. While it is difficult to study this era, scientists are making progress in understanding it, and this episode of PBS Space Time provides an excellent introduction to this mysterious period in cosmic history.