"Another explanation for how space acquires energy comes from the quantum theory of matter. In this theory, "empty space" is actually full of temporary ("virtual") particles that continually form and then disappear. But when physicists tried to calculate how much energy this would give empty space, the answer came out wrong - wrong by a lot. The number came out 10120 times too big. That's a 1 with 120 zeros after it. It's hard to get an answer that bad. So the mystery continues."

taken from: https://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy

"Another explanation for how space acquires energy comes from the quantum theory of matter. In this theory, "empty space" is actually full of temporary ("virtual") particles that continually form and then disappear. But when physicists tried to calculate how much energy this would give empty space, the answer came out wrong - wrong by a lot. The number came out $10^{120}$ times too big. That's a 1 with 120 zeros after it. It's hard to get an answer that bad. So the mystery continues."

taken from: https://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy