The Dark Energy Drive
When travelling through normal space rather than “folding”, the Spirit of London uses something called a dark energy drive. It’s not as sinister as it sounds, but what exactly is dark energy?
A difficult area of astronomy is the accurate measurement of distance. There are, though, different astronomical bodies we call “standard candles” that are always the same brightness. If we determine how much light we receive from them here on Earth, it gives us a very accurate measure of how far away they are. We can also measure something called the red shift (or blue shift), which provides bonus information on how fast these bodies are travelling away from (or towards) us.
A supernova is a cataclysmic explosion that will happen when a star of a certain size (it needs to be bigger than our Sun) reaches the end of its life. The great physicist Subramanian Chandrasekhar calculated that a certain type of supernova (called Type 1a) will always give out the same amount of light (roughly 5 billion times brighter than the sun) so we can use these occurrences as standard candles to measure distance and relative velocity.
Most people reading these pages will have heard of the Big Bang. It’s the prevailing cosmological wisdom that the universe (including time as well as space) was creating in a single, astonishing explosion around 15 billion years ago. Some astronomers are beginning to question this idea, but there is strong evidence in its favour: especially something called the cosmic microwave background radiation and the observational evidence that almost all the galaxies in the universe are receding from each other at great speed, as though flung apart from a single point in space and time.
The force that we’ve always thought determined the large-scale structure of the universe is gravity. Although galaxies are receding in every direction, it seemed logical to believe that the gravitational pull of all these galaxies would be slowing this expansion. In 1998, two teams of astronomers were investigating (very) distant supernovas to measure by how much gravity was decelerating the universe. They made a surprising discovery – it wasn’t. To general incredulity, they came to the conclusion that the rate of expansion of the universe is actually increasing. This has been confirmed by subsequent, different types of measurements.
For a long time now physicists have thought there are four fundamental forces: gravity, electromagnetism and two nuclear forces that work in different ways to hold atoms together. It’s been a dream of scientists from Albert Einstein to Stephen Hawking to unify these forces into one grand theory, but so far no one’s succeeded. But what if there’s a fifth force that works on an even larger scale than gravity, but is repulsive?
Current theories describing the makeup of the universe suggest it’s split between 4% normal everyday matter, 23% something called “dark matter” (which we can’t see) and the remaining 73% “dark energy”. It’s this dark energy that’s apparently responsible for this new fifth, anti-gravity force or quintessence. And, as it can repel whole galaxies, the Spirit of London is also able to use the minor fluctuations in the distribution of dark energy in the galaxy to travel at great speed through normal space.
I am quite pleased to have given Johnny’s ship such a novel propulsion system that I’ve not seen elsewhere. Even if, when I entered it into a recent New Scientist competition called Visions of the Future, the idea fell upon deaf ears…