Dark Energy Acceleration

In 1998, two teams of astronomers made a shocking discovery. By measuring the brightness of distant Type Ia supernovae, they found that the expansion of the universe is not just continuing — it is accelerating. Something is pushing galaxies apart faster and faster, counteracting gravity at the largest scales.

This mysterious force was named dark energy, and it makes up roughly 68% of the universe's total energy content. Its nature is completely unknown. The simplest explanation is Einstein's cosmological constant — a constant energy density inherent to empty space. But other theories propose dynamical dark energy fields that change over time.