Time as a parameter
Raymond King Cummings [1887-1957] was a science fiction writer of the 1920s, regarded as a founding father of the literary genre known as Pulp Science Fiction. Such literature is characterized by a clear disregard for the laws of physics, typical stories being centred on conflicts between good and evil found in comparable genres such as Westerns, but dressed up in a pseudo-scientific cloth. However, on occasion, some interesting observations about the physical world can be found buried deep in otherwise completely forgettable and sometimes embarrassingly bad stories. In what is regarded as his best story, The Girl in the Golden Atom, Cummings has one of his characters make the useful and memorable observation:
Time ... is what keeps everything from happening at once. [Cummings, 1922]
From our point of view, this is another way of saying that time is one of the parameters used to label different physical states.
The inertia of reality
Isaac Asimov [1920-92] is widely regarded as one of the finest science-fiction writers of the twentieth century. He wrote the Foundation series of novels, based on the rise and fall of a human empire in the galaxy. Linked to these stories is one particular novel based on time travel, The End of Eternity [Asimov, 1955]. In that novel, Asimov discusses some thought-provoking concepts to do with time travel:
- 1. There are two flows of time: the usual time of Reality, equivalent to the time of the normal universe that we are living in, and physiotime, the time of Eternity, the realm of existence of the ‘Eternals’. In this two-component image of time, we may identify Asimov’s Reality with manifold time and his physiotime with process time.
- 2. The Eternals, humans living in Eternity, stand outside of the normal universe and have an exophysical view of it. They are able to see past and future in the ‘current reality’ of the normal universe. Their aim is to manipulate events in the current reality in order to improve life for the average person living in it.
- 3. The Eternals view Reality in a Block Universe form, that is, they are able to see Reality throughout a specific range of normal time. This starts in the twenty-third century (as we would know it), when Eternity was built, and goes ‘upwhen’ many billions of years. Power for the maintenance of Eternity outside the fabric of the normal universe is from ‘Nova Sol’, that is, the energy generated by the conjectured final supernova explosion of our Sun in several billion years’ time.
- 4. An Eternal can enter any point of Reality at will. From the perspective of normal individuals embedded in Reality, such an Eternal would appear to materialize from thin air.
- 5. An Eternal can change critical events in the current Reality. Ordinary causality within Reality then spreads out waves of change from a given critical event into the future of the current Reality (as seen by Eternals back in Eternity). Assuming the Eternals see the laws of Reality operating according to standard physics, such as special relativity, the reality changes done by the ‘Technicians’ of Eternity would all be located inside and on a retarded lightcone in the spacetime of Reality, with its vertex centred on the critical event. Lightcones are discussed in Chapter 17.
- 6. Asimov did not assume that induced Reality changes increased in an unbounded way. He developed the concept of the inertia of Reality: when a critical change is made by an Eternal in Reality, waves of change spread ever outwards, but get reduced in magnitude the further the Eternals look in the Block Universe view that they have.
Asimov was a trained research scientist and academic, and his discussion of time gives a strong impression that he thought carefully about the logical structure of the End of Eternity.