The expansion of the universe from the Big Bang is a fascinating topic in cosmology. It's important to clarify that the Big Bang was not an explosion that occurred within a pre-existing space, but rather the event marking the beginning of both space and time. The universe, as we know it, started expanding from an extremely hot and dense state.
The concept of the expansion of the universe is based on observations such as the redshift of light from distant galaxies. These observations indicate that galaxies are moving away from each other, and the farther apart they are, the faster they appear to be receding. This implies that the fabric of space itself is stretching, causing the observed expansion.
The reason the universe didn't collapse into a supermassive black hole after the Big Bang is due to the initial conditions and the distribution of matter and energy. In the early universe, matter and energy were uniformly distributed on large scales, and there were small density fluctuations. These density fluctuations eventually led to the formation of structures like galaxies and galaxy clusters over billions of years.
The expansion of the universe is driven by the energy content of the universe, particularly by dark energy, which is a hypothetical form of energy that is thought to be responsible for the acceleration of the expansion. As the universe expands, the effect of gravity is counteracted by the expansion itself, preventing the collapse of the universe into a black hole.
It's worth noting that black holes are formed from the gravitational collapse of massive objects, such as the remnants of massive stars. While there are supermassive black holes at the centers of galaxies, the expansion of the universe and the formation of black holes are distinct processes governed by different mechanisms.
Our current understanding, based on the prevailing cosmological model, suggests that the expansion of the universe will continue indefinitely. However, it's important to acknowledge that cosmology is an active field of research, and our understanding continues to evolve as new observations and theories emerge.