The expanding universe theory is that the universe has been slowly expanding since it began with the Big Bang. According to this theory, all the galaxies that make up the universe are slowly moving away from each other, and they seem to be moving at an accelerated rate. Scientists have been aware that the universe has been expanding for several decades, and they were able to determine that the expansion is accelerating by observing the light of distant galaxies in relation to the light generated by supernovae.
The Fate of the Universe
Even though there is much that scientists have been able to observe, they do not know what the expanding universe theory means for the ultimate fate of the universe. There are some theories, however. It is possible that the universe will continue to expand for eternity and become infinitely large, but most scientists believe that the universe as we know it is finite. It will continue to expand seemingly forever, but that expansion will eventually overcome the gravitational pull that the galaxies have on each other. As the galaxies grow farther and farther apart, they will eventually be unable to sustain themselves. They will burn out, resulting in the universe essentially ceasing to exist sometime in the very distant future.
It is also possible that there is a limit to how far the universe will expand before the galaxies and other celestial bodies are eventually drawn to each other again. They could come together in a singularity that scientists refer to as the “big crunch.” Seeing as how the universe most likely started as a singularity that expanded into the universe, it is possible that this new singularity will begin to expand again, giving birth to a new universe. For all we know, this has happened countless times before.
In other words, our universe may not be the first to exist, and it will certainly not be the last.