To only reject that the physical world exists is not solipsism. Solipsism also rejects or doubts that other people exist. As an epistemological position, it is the concept that nothing but one's own mind can be "certain" to exist. The existence of other minds, in this position, is considered a possibility, but not a certainty. Including time, which does not stop just because there would be nobody being to experience it (which is probably going to happen in the end of the universe when there would be simply nothing)