The age of the universe is estimated based on various observational data and theoretical models rather than solely relying on the distance to the farthest objects in the observable universe. While it is true that our ability to observe distant objects is limited by the speed of light and the age of the universe, scientists use a combination of methods to estimate its age.
One widely used method to determine the age of the universe is through measurements of the cosmic microwave background (CMB). The CMB is radiation that permeates the entire universe and is a remnant of the early stages of the Big Bang. By studying the properties of the CMB, such as its temperature and distribution, scientists can gain insights into the age and evolution of the universe.
Additionally, other astrophysical observations, such as the redshift of galaxies, the expansion rate of the universe, and the abundance of certain elements, provide valuable information for estimating the age of the universe.
It's important to note that the age of the universe is an estimate based on current scientific knowledge and understanding. As new observations and data become available, our understanding of the universe's age and its evolution may be refined or updated.
While our observations are limited to the observable universe, scientists use a range of techniques and data to arrive at an estimate for the age of the universe, taking into account the constraints imposed by the speed of light and the age of the universe itself.