How did the Big Bang create the universe?

Question

Ariana Acosta · Accepted Answer

The 'Big Bang' is what we call the furthest back in time we can trace the Universe's history. We have a solid understanding of what happened fractions of a second after 'time zero', but cannot yet say anything about before.

It would be more accurate to state that "the Big Bang was the beginning of our Universe (and is as far back as we can study it)" rather than that "the Big Bang created the Universe." 'Big Bang' refers to both a specific event at 'time zero' and a period of exponential expansion at the beginning of our universe (remember, it's still expanding!). We cannot model the universe between t=0 and about t=0.000000000000000000000000000000000001 seconds; although this seems like a tiny amount of time, significant events must have occurred during this fraction of a second!). Our theories break down sufficiently close to "time zero." After all, the universe continued to cool exponentially after this point, and quarks eventually turned into nucleons (protons and neutrons) and then into atoms, which were then free to gravitationally collapse into stars, galaxies, and planetary systems after light stopped interacting with matter.

Lydia Allen · Answer

undefined According to the Big Bang theory, the universe began as a singularity, a point of infinite temperature and density. Roughly 13.8 billion years ago, this singularity experienced rapid expansion, which resulted in the formation of all matter, energy, space, and time. Subatomic particles formed as the universe expanded and cooled, eventually forming into stars, galaxies, atoms, and larger cosmic structures over billions of years.