There was a time when our Universe was nothing but an opaque, lightless sea of swirling gas.
The early Universe between 50 million and 1 billion years after theis another such case. This period is known as the Cosmic Dawn, the time at which the Universe as we know it today was just starting to come together out of the primordial plasma. Before the first stars came along, it was filled with a hot murky fog of ionized gas. Light was unable to travel freely through this fog; it simply scattered off free electrons.
"Most astronomers don't have labs to conduct experiments in. The scales of space and time are too large, so the only way we can do experiments is on computers,""We are able to take basic physics equations and governing theoretical models to simulate what happened in the early Universe." The resulting simulation is the most detailed view yet of the Epoch of Reionization, capturing physics on scales a million times smaller than the simulated regions, the researchers said. This gives an"unprecedented" look at the way early galaxies formed and interacted with the gas of the early Universe. It shows a gradual change as light begins to seep through the Universe.