But even that initial state had its origins, with cosmic inflation as the leading candidate for where that all came from. The 20th century brought us General Relativity, quantum physics, and the Big Bang, all accompanied by spectacular observational and experimental successes. But — at least for the Big Bang — it left some unexplained problems that required us to go farther. And why, if we reached these ultra-high temperatures and densities early on, are there no leftover relic remnants from those times in our Universe today? But this means that the Big Bang wasn’t the very beginning of everything; it was only the beginning of the Universe as we’re familiar with it.

Source: Forbes August 18, 2020 06:00 UTC