According to current scientific understanding, the universe is generally considered to be a closed system in terms of matter and energy. The principle of the conservation of energy suggests that energy cannot be created or destroyed within a closed system, but it can be transformed from one form to another.
In the context of the Big Bang theory, which is the prevailing cosmological model describing the origins and evolution of the universe, the initial singularity that led to the expansion of the universe is thought to have contained all the matter and energy that exist today. The subsequent processes, such as the formation of stars and galaxies, involve the rearrangement and transformation of this pre-existing matter and energy.
While new matter and energy cannot be added to the universe as a whole, it's worth noting that within specific regions or systems, localized increases in matter and energy can occur. For example, during processes such as star formation or in particle accelerators, new structures or particles can be created within the boundaries of those systems.
However, when considering the universe as a whole, the total amount of matter and energy remains constant. It can change forms and redistribute, but there is no net creation or destruction of matter and energy within the closed system of the universe, as far as our current scientific understanding suggests.