No, the current scientific consensus is that the universe is approximately 13.8 billion years old, not 15 billion years old. This age is based on extensive observational evidence, including measurements of the cosmic microwave background radiation, the expansion of the universe, and the ages of the oldest known objects within it.
The age of the universe is determined through a variety of methods, primarily using the principles of cosmology and astrophysics. Scientists study the properties and behavior of galaxies, the distribution of matter and energy, and the rate of cosmic expansion to estimate the age of the universe.
One of the key pieces of evidence supporting the age of 13.8 billion years is the data from the Planck satellite, which has provided precise measurements of the cosmic microwave background radiation. This radiation is a remnant of the early universe, and by analyzing its properties, scientists have been able to estimate the age of the universe.
It's important to note that scientific understanding is constantly evolving as new evidence and observations are made. While the age of the universe is currently estimated at approximately 13.8 billion years, future research may refine this estimate further.