I would argue that The Time Machine is one of the most influential works of science fiction ever written, but it is also a masterpiece of a particular genre of endof-the-world fiction – the dying earth. It came at a time when advances were being made towards understanding the nature of the universe, allowing scientists to finally develop more accurate theories regarding the workings and ultimate fate of our Sun – the very thing that brings light and life to our planet.
The Sun is a fire, so there will logically come a time when it burns itself out. That’s not a comforting thought: without a sun, the world will grow cold and dark and we will all die. People have been speculating about such end times for centuries. In the seventeenth century, the English naturalist and scientist John Ray argued that the sunspots, or ‘maculae’, we can see on the face of the Sun were symptoms that it was starting to die. His Miscellaneous Discourses Concerning the Dissolution and Changes of the World (1692) includes this prophesy:
After some vast Periods of Time, the Sun may be so inextricably enveloped by the Maculae, that he may quite lose his Light; and then you may easily guess what would become of the Inhabitants of the Earth.*
In the nineteenth century, scientists were particularly worried about the Sun going out. New discoveries about the actual age of the Earth combined with all the observations they had made told them the Sun should have burnt through its fuel long ago. In 1871, the British scientist William Mattieu Williams noted that even though the Sun’s ‘stupendous ocean of explosive gases’ constituted ‘an enormous stock of fuel’, it should have been used up over the millions of years the Earth had existed. Long before the present, he calculated, there should have been ‘a gradual diminution of the amount of solar radiation, and a slow and perpetually retarding progress towards solar extinction’.
The solution to this conundrum was not discovered until 1904, when the physicist Ernest Rutherford speculated that radioactive decay at the core of the Sun might provide it with its energy. Albert Einstein’s work provided the frame by which Rutherford’s insight could be theorised, and in 1920 Sir Arthur Eddington argued that the extreme pressures and temperatures at the Sun’s heart cause a nuclear fusion reaction, squeezing hydrogen atoms together with such force that they merge into helium nuclei, releasing considerable quantities of energy as a result. This is still our best understanding of why the Sun burns; nobody has travelled to the Sun to check, but we’re pretty sure.
But although this explains why the Sun has burnt for as long as it has, it only kicks the can down the road. For though the Sun’s fuel will last for billions of years, our star will eventually burn through all its fuel. And when that happens, the constitution of the Sun will alter and any life forms in the vicinity will die.
When the metaphorical fuel-tank indicator needle starts wobbling near zero, four things will happen, which we might regard as four apocalyptic horsemen. First, the Sun will swell hugely, becoming a red giant (let’s call this the red horse stage), which will gobble up the inner planets, assuming they are still in those orbits in five billion years’ time.* The red phase will last for 100 million years or so, until the Sun shrinks to a much smaller, dimmer version of its former self (the pale horse), which will last as long as 500 million years before eventually the outer layers of the Sun will blast away, leaving only the brilliant white core (the white horse). At this point, all of the fuel has run out, it burns only because its constitutive elements are very hot; over time, perhaps trillions of years, this heat will be radiated away and the Sun will reach its final state: a lightless black dwarf (the black horse).
It doesn’t stop there. If our Sun will die, then so too will all the stars in the universe. And while new stars are being born even as I write, it will not always be that way. Eventually all the stars will have used up their fuel, and will stop shining. Then, for unimaginable gulfs of time, the universe will be black, cold, inert, over and forever continuing to be over.
Almost all scientists agree that the universe began with the Big Bang, when a dimensionless point ‘exploded’, pouring out matter in all directions. This universal expansion is an ongoing, measurable phenomenon. As the matter continues to expand outwards, becoming less dense, new stars will no longer form. Eventually, over quadrillions of years, each and every existing star in the universe will use up its fuel. The unimaginably vast spaces of the expanding cosmos will be diluted to a temperature only slightly above absolute zero.
The technical term for this process is ‘entropy’, a word with a vulgar as well as a scientific meaning. The latter dates from 1865, but the former, which is much older, is that things run down. From ancient times, humans have understood this basic truth about the nature of things – that order slowly becomes disorder, as youth inevitably decays into age. Build your house, fit its windows and paint its walls, by all means; you know very well that unless you keep inputting your labour, it will fall away into crumbling, peeling, weed-clogged disorder. That’s the crude sense of what entropy means: disorder increases unless we put in the work to maintain order.
So this is the end that most
