Nobody knows the fate of the universe, but there are many possibilities. For example, dark energy might become so strong that it overpowers all forces including gravity. If this happens, the expansion of the universe will grow faster and faster as it is pushed apart without any limit. This theory is called the “Big Rip.”
The “Big Rip” results in galaxies, stars, planets, and all life being torn apart, but it’s also possible that the universe just keeps expanding. If dark energy stays indefinitely the same force as it is today, space will keep growing and may never come to an end. Additionally, another possible end for our universe lies trillions of years in the future.
Eventually, after the universe expands too much, no heat will be able to be spread and the temperature could drop to its lowest possible point. This will be known as the “Big Chill,” meaning no life could survive.
Another theory is called the “Big Crunch”, where in a hundred billion years, the expansion of the whole universe could reverse and squeeze down to a single point, like an opposite Big Bang.
How and if the universe ends are among the many questions we have about the universe. As we expand our knowledge of space, we may have a better understanding of how things play out. There still is much to learn.