What is the Big Bang Theory origin and age?

• A. The universe originated 13.8 billion years ago in an explosion from a single point of nearly infinite energy density, and has been expanding ever since.
• B. The universe has always existed in steady state.
• C. The universe formed from a collision of galaxies.
• D. The universe is contracting toward a final collapse.

Answer: (A)

The main idea tested is how scientists describe the origin and age of the universe according to the Big Bang model. The correct description says the universe began about 13.8 billion years ago from a very hot, dense state and has been expanding ever since. This matches the widely supported picture: the cosmic microwave background reveals the early hot conditions, distant galaxies are moving away from us as space itself expands, and the amounts of light elements fit with early nuclear processes in that hot era. It’s common to simplify this as an explosion from a single point, but the essential point is that space expanded from a hot, dense beginning and has been evolving over time.

The other ideas don’t fit what we observe. A steady-state view—where the universe has always existed with constant density—conflicts with evidence of expansion and the evolving structure of the cosmos. The notion that the universe formed from a collision of galaxies describes interactions that occur after formation, not the origin itself. The idea of a contracting universe toward a final collapse contradicts current measurements showing ongoing expansion, with the expansion rate still increasing due to dark energy.