There are other worlds, many other worlds out there in the ether. All close enough to be touched, to be explored and to remain within your grasp and completely visible if you really want to see them. Depends how far you take things and how elastic your imagination is.
As a child I was amazed at how the nose cone of XL5 could detach from the main body of the spaceship and operate like an atmosphere craft or shuttle. The design still acts like some strange bridge between H G Wells and Star Trek in imagined technology. This was 1963 and I was getting my appendix removed.