The understanding of time has also been impacted by modern science. Relativity not only changed how the fabric of space is viewed but also how time intersects with space: The fabric of spacetime is both weirder and vaster than originally thought possible. Even though the idea that the universe had a specific beginning was resisted by some scientists, it has always been embraced by various cultures throughout the world; creation stories are ubiquitous in myths and religions.

This discovery led to questions about the size and age of the universe. These measurements are made possible by calculating the luminosity of stars, thus determining their distance from Earth in light-years. After many decades of recalculations, the universe is estimated to be about 13.8 billion years old. The oldest signal detected in the universe—the cosmic microwave background (CMB)—also indicates the temperature of the universe, which again confirms that the cosmos had a definitive beginning. While the temperatures of stars and other matter fluctuate, the CMB remains constant, which confirms that at one moment in time, the universe “was all in the same place experiencing the same event at the same time” (246): the Big Bang.