Which force is believed to dominate the universe's overall mass-energy content?

Dark energy is believed to dominate the universe's overall mass-energy content, and its significance lies in its role in the accelerated expansion of the universe. Observations, particularly those from distant supernovae and the cosmic microwave background radiation, suggest that about 68% of the universe's total energy density is attributed to dark energy.

Unlike other forces such as gravitational or electromagnetic forces, which act in a manner that can be observed locally (e.g., the gravitational pull of planets or the electromagnetic interactions between charged particles), dark energy appears to exert a uniform pressure throughout the universe. This leads to the observed phenomenon where galaxies are moving away from each other at an accelerating rate.

In contrast, while gravitational force plays a critical role in the formation and cohesion of structures like galaxies and galaxy clusters, its effects are more local and dependent on the mass present. The strong nuclear force governs interactions at the atomic level within atomic nuclei, and the electromagnetic force is responsible for interactions between charged particles. However, neither of these forces is significant on a cosmic scale compared to the pervasive influence of dark energy, which shapes the universe's destiny and overall structure.