Fermilab Discovery Science Resources: Nine Questions

2. How can we solve the mystery of dark energy?

Recent measurements with telescopes and space probes have shown that a mysterious force—a dark energy—fills the vacuum of empty space, accelerating the universe's expansion. We don't know what dark energy is, or why it exists. Particle theory tells us that, at the microscopic level, even a perfect vacuum bubbles with quantum particles that are a natural source of dark energy. But a naïve calculation of the dark energy generated from the vacuum yields a value 10120 times larger than the amount we observe. Some unknown physical process is required to eliminate most, but not all, of the vacuum energy, leaving enough left to drive the accelerating expansion of the universe. A new theory of particle physics is required to explain this physical process. Review.