Final answer:
The estimated age of the universe is 13.8 billion years, based on current models and measurements such as the Hubble constant, which considers both the deceleration and acceleration of cosmic expansion.
Step-by-step explanation:
The current estimate for the age of the universe is approximately 13.8 billion years. This estimation is based on measurements such as the Hubble constant, which is roughly 67 kilometers per second per million parsecs, equivalating to about 20.65 kilometers per second per million light-years. When considering the expansion rate of the universe and other observations, the age of the universe must be at least as old as the oldest astronomical objects within it. The age we observe takes into account both the deceleration and acceleration phases that the universe has experienced, using models to adjust the age accordingly. Despite the variations in cosmic expansion and the Hubble constant, the estimated age of 13.8 billion years is consistent with current astronomical evidence.