The Universe we reside in was born 13.7 billion years ago as a result of a Big Bang, and ever since it expands with galaxies “running away” from each other. Gravity interactions were a common explanation for these events, however, several years ago physicists showed that Universe expanded with some sort of acceleration.
Thus, there should exist some force, which pushes galaxies away from each other. Now physicists consider it to origin from a special kind of space energy, widely known as “dark matter”. This matter shows that a part of primary energy had never been converted into matter. All this gives a ground to suggest that at any moment highly unstable dark matter can turn into ordinary matter with a great explosion. In this case our Universe would be destroyed.
However, not all astrophysicists agree with this theory.
Source: Science News