However, scientists say the journey to that point will be marked by a long, gradual fading rather than a sudden conclusion.
Right now, we live in the Stelliferous Era, a time of star formation that began around a million years after the Big Bang and will last for about 100 trillion years.
During this period, stars continuously form by fusing hydrogen, lighting up the cosmos. However, the universe has a limited amount of hydrogen, and as stars burn through this supply, new star formation will gradually slow until it ceases altogether. Massive stars will go supernova first, leaving behind stellar remnants such as neutron stars, white dwarfs, and black holes.
Eventually, even the smallest stars, like red dwarfs, will fade away after trillions of years, and the universe as we know it—bright with starlight—will cease to exist. However, that doesn’t mean the universe will be devoid of activity.
Stellar remnants will still shine faintly, and some planets will likely continue orbiting dead stars, while rogue planets that have no stars will continue to drift through the dark, empty cosmos.
Galaxies will also be pushed so far apart by the accelerating expansion of the universe, driven by dark energy, that even neighboring galaxies will become unreachable and invisible, passing beyond the cosmic horizon.
Though the universe’s current age of 13.8 billion years seems long, in comparison to its future, we are still living in the cosmic dawn, with an unimaginable stretch of time yet to unfold before the final darkness
Peoplesmind