Rapid expansion of the early Universe. We need to have Inflation in order for the Big Bang to work as a theory.
Without it, the Big Bang theory runs into major problems:
1. The Horizon Problem: The cosmic microwave background (CMB) has nearly identical temperature in all directions, suggesting the entire observable universe was once in contact. But without inflation, opposite sides of our universe would never have been able to “communicate” and reach this equilibrium.
2. The Flatness Problem: Our universe is remarkably “flat” (parallel lines stay parallel), which would require impossibly precise initial conditions without inflation.
3. The Origin of Structure: Inflation explains how quantum fluctuations during this expansion became the seeds for galaxies and cosmic structures we see today.
Without it, the Big Bang theory runs into major problems:
1. The Horizon Problem: The cosmic microwave background (CMB) has nearly identical temperature in all directions, suggesting the entire observable universe was once in contact. But without inflation, opposite sides of our universe would never have been able to “communicate” and reach this equilibrium.
2. The Flatness Problem: Our universe is remarkably “flat” (parallel lines stay parallel), which would require impossibly precise initial conditions without inflation.
3. The Origin of Structure: Inflation explains how quantum fluctuations during this expansion became the seeds for galaxies and cosmic structures we see today.