The Big Bang happened as an event in which all the energy of the universe was concentrated into an extremely tiny, dense point. This point then underwent an explosive expansion, creating matter and propelling it outward to form the vast universe we observe today
. In the earliest moments, the universe was incredibly hot and dense. Around 10−4310^{-43}10−43 seconds after the Big Bang, during the Planck epoch, the four fundamental forces of physics were unified. Soon after, cosmic inflation occurred around 10−3710^{-37}10−37 seconds, causing the universe to expand exponentially faster than the speed of light. This rapid expansion smoothed out the universe and seeded the structures we see today
. As the universe expanded and cooled, particles like protons and neutrons formed within the first fractions of a second. Within minutes, these particles combined to form atomic nuclei, mostly hydrogen and helium. Hundreds of thousands of years later, electrons combined with nuclei to form neutral atoms, making the universe transparent and allowing light to travel freely- this is observed today as the cosmic microwave background radiation, a key piece of evidence supporting the Big Bang theory
. The Big Bang did not happen at a particular location in space; rather, space itself expanded everywhere simultaneously. The event marks the beginning of space, time, matter, and energy
. While the exact cause or "why" the Big Bang happened remains a subject of scientific investigation and philosophical debate, current models describe it as a transition from a high-energy, dense state to the expanding universe we see now, with cosmic inflation playing a crucial role in this process
. In summary, the Big Bang was an explosive expansion from an initial extremely hot and dense state, followed by rapid cooling and formation of matter, leading to the universe's ongoing expansion and evolution
