Many people and scientists somehow came to the conclusion that the universe is roughly 13.8 billion years old, the reality is, nobody knows how old the universe really is. The Universe may be older than 14 Billion years. The big bang theory contradicts the laws of thermodynamics, that is energy cannot be created from nothing, it can only be transferred. The universe may be practically infinite, with all our advancements in science and understanding nobody knows for sure but what we do know from observation is the deepest any photograph anyone has taken in space shows a universe that just keeps going on to no end. I've noticed the farthest distances photographed in space keeps getting farther and older in age.
Stephen Hawking might say there was nothing before the big bang but that's his best guess and goes against the laws of thermodynamics. Scientists use the rate which they observe the universe expanding to determine the age of the universe, the Hubble constant is not a good way to figure out how old the universe is, that's based on theory and not observation or physical evidence, observation shows us a universe that keeps going farther to the point some parts of the universe are expanding away from us faster than the speed of light! We don't even know how consistent the universe has been expanding either, sounds good but just Don't be surprised if the age of the universe from big bang theorists gets pushed further back in time, older than the 13.8 billion years claimed today.
Our location in the universe is blocking the view of other parts of the universe! What if new telescopes in the future are able to see further and photograph parts of the universe older than 15 billion years old? Big bang theorists might say that's impossible, but they still haven't proven the universe was created from nothing. When you consider observations by scientists of the "distant universe" from really far distances, the light that took billions of years to travel to us has been though interference in some way. Scientists use wavelengths of light to determine how far a galaxy is to what elements are inside. Different wavelengths of colors of light may give us an idea what is there, it is not a perfect measuring method.
Many people believe in the big bang theory, it's taught in schools but it's still a theory and we don't have direct evidence to prove it. Scientists have mapped background radiation in space, but that's not proof it's from the big bang. Big bang theorists expect people to ignore observation and believe the laws of physics was created from nothing, explosions don't happen from nothing. Scientists may have found evidence of galaxies that have different conditions but those are not evidence of the big bang, our universe is almost infinitely unique, no two galaxies look exactly the same, there are many differences in every spiral galaxy, and galaxies in general.