Firstly, I want this to be a very layman/simple level. According to Sean Carroll, we have certain possibilities for where dark-energy comes from:
- A modification of general relativity
- Vacuum energy
- A modification of vacuum energy
And he goes on to say that if vacuum energy is the right answer the universe will continue to expand.
What would be the implications if the right answer is a modification of general relativity? Are there any other theories that explain dark energy that make predictions about the future like this?