What evidence supports the theory that the universe began with a big bang?

The theory that the universe began with the Big Bang is supported by the idea that everything was compacted into a small space before it rapidly expanded. This concept aligns with observations made in astrophysics, particularly the discovery of cosmic microwave background radiation and the observable redshift of distant galaxies. The redshift indicates that galaxies are moving away from us, suggesting that the universe is expanding from an initial singular state where all matter and energy were densely concentrated.

The notion of everything being compressed into a small area is fundamental to the Big Bang model, as it describes the conditions that would have existed at the very beginning of time. This initial singularity is theorized to have exploded, leading to the expansion and evolution of the universe as we know it today.

The other options do not provide direct support for the Big Bang theory. For instance, stationary galaxies would contradict the expansion observed in the universe, losing energy over time does not specifically correlate with the Big Bang, and while stars forming in vast quantities is an exciting aspect of cosmic evolution, it doesn’t directly indicate a singular starting event like the Big Bang.