Dark energy is a mysterious force that is causing the expansion of the universe to accelerate. It is not well understood, but it is thought to make up about 68% of the total energy in the universe.

The CMB is the leftover radiation from the Big Bang. It is a faint glow of light that fills the entire universe. The CMB contains valuable information about the early universe, such as its temperature and density.

Dark energy causes the expansion of the universe to accelerate. This means that the universe is expanding faster today than it was in the past. This causes the CMB to be colder than it would be if dark energy did not exist.

The evidence for dark energy comes from a variety of sources, including the accelerating expansion of the universe, the CMB, and supernovae. The accelerating expansion of the universe is the most direct evidence for dark energy. The CMB and supernovae provide additional evidence that supports the existence of dark energy.

The future of dark energy is unknown. It is possible that it will continue to cause the expansion of the universe to accelerate forever. It is also possible that it will eventually stop causing the expansion of the universe to accelerate, or that it will eventually cause the universe to collapse in on itself. We do not know enough about dark energy to say for sure what will happen in the future.