There are many differences between our world and alien worlds. In “Caves of Steel,” many aspects of differences between the spacer and humans appear. For instance, the spacers and humans live in divide sections within the city. The two divisions do not enter unless it’s for business situations. Spacers have a limited population as for humans there isn’t. The spacers provide better improved technology then the humans. An example of comparison shall be R Daneel; a spacer like robot with advance movement, speech, looks and etc. while man made robots are only capable of storing and non- fluent movements.

Besides the difference in technology, exterior influences are marked as well. Humans may worry about viruses such as a cold, fever or other diseases however; many of these symptoms can be handled in a well-cared situation. As for spacers, there are no such things as a common cold or diseases, they live in a specified atmosphere; cleaned and sanitized. To the spacer’s knowledge one touch or atom from a humanly bacteria may kill them instantly. Human bodies have grown an immune system to protect them from obtaining a disease while, spacer does not; due to never getting sick.

Human’s knowledge of the outer world is still brief; not knowing how many planets are out there, if any life forms and if any human like creatures are living amongst the planets. Spacers with their well-developed technology can travel through space; to planets and planets far across the galaxy. Their advance robots may receive outer world information as well, to better improve acceptance in various conditions.