“To know that we know what we know, and to know that we do not know what we do not know, that is true knowledge.” -Nicolaus Copernicus
As we peel back the layers of information deeper and deeper into the Universe’s history, we uncover progressively more knowledge about how everything we know today came to be. The discovery of distant galaxies and their redshifts led to expanding Universe, which led to the Big Bang and the discovery of very early phases like the cosmic microwave background and big bang nucleosynthesis.
The history of the Universe, as far back as we can see using a variety of tools and telescopes. Image credit: Sloan Digital Sky Survey (SDSS), including the current depth of the survey.
But before that, there was a period of cosmic inflation that left its mark on the Universe. What came before inflation, then? Did it always exist? Did it have a beginning? Or did it mark the rebirth of a cosmic cycle? Maddeningly, this information may forever be inaccessible to us, as the nature of inflation wipes all this information clean from our visible Universe.
How cosmic inflation gave rise to our observable Universe, which has evolved into stars and galaxies and other complex structure by the present. Image credit: E. Siegel, with images derived from ESA/Planck and the DoE/NASA/ NSF interagency task force on CMB research. From his book, Beyond The Galaxy.