How does big bang theory work?
The Big Bang theory does not have energy converted into matter at a single point. The Big Bang literally happens everywhere. Also, strictly speaking, the theories we have usually only talk about what happens after the Big Bang, not at at or before it (some quantum theories of gravity do attempt to deal with the singularity at the Big Bang, but they are not well grounded in other ways). The expansion of the universe (regarded as a uniform fluid of matter and energy) was predicted by Einstein’s theory of gravity (the theory of general relativity). However, Einstein did not like the conclusion that the universe would change over time and added another term to his equations (called the cosmological constant). Later, Edwin Hubble verified that galaxies are moving away from each other in a way consistent with what general relativity predicted. These initial observations have been extended and verified over the past 80 years. We know that the universe is currently expanding. We also know that
