8. PEOPLE FREEZING
Arthur C Clarke's pre-occupation with interplanetary space travel led him to consider how humans could survive for the long periods needed to cross vast tracts of space.
One of the answers he came up with, outlined in the story The Songs of Distant Earth, was cryogenic suspension.
The plot sees the human race having to leave Earth in a convoy of spaceships as the Sun is about to explode.
Currently, cryogenic preservation of living people is impossible, and in many countries it is illegal to attempt it.
More than 150 people, mainly in the US, have been frozen in liquid nitrogen after their death.
But even the companies running these projects admit that freezing cannot be reversed and there is no proof that it would preserves peoples' identities, even though there is evidence that brain structure can survive the process.
In medicine, very cold conditions are used to store organs before transplantation and to store eggs and sperm, and as a way of removing warts.