The big bang is often thought of as the beginning of everything, including time, making any questions about what happened beforehand nonsensical. Now exotic theories that suggest the existence of an era before the big bang are growing in number. They indicate that imprints of this era might exist and that an upcoming generation of telescopes could detect them.
According to conventional big bang thinking, the universe emerged from a point of infinite energy and density, a singularity where the laws of physics break down. The universe then underwent “inflation,” briefly expanding much faster than the speed of light. By smearing the cosmos out fairly evenly and smoothing out the early universe’s curves, inflation solved a number of puzzles, including why spacetime is “flat,” whereby light commonly travels in straight, not warped, lines. Ripples occurring during inflation could also explain the overall pattern, or structure, of galaxies seen now.