Is the expansion of the universe just an illusion?

A new theoretical study suggests that the expansion of the universe could be a mirage, and that the universe is flat and static, as Einstein once believed. The effects we observe that point to expansion are instead explained by the evolution of the masses of particles over time. This rethinking of the cosmos also suggests solutions for the puzzles of dark energy and dark matter, which scientists believe account for around 95% of the total energy and matter in the universe but remain shrouded in mystery.