Can People in Narnia Enter Our World?

Some people think that there might be multiple universes out there. Was he thinking about parallel universes, multiverses when he imagined the wood between the worlds and all these different worlds you could go to? Possibly, yes. He was quite interested in multi-dimensionality and the relation between time and space. That features a little bit in some of his own interplanetary novels, Perilandra for instance.