Chaos theory in real life
It thrives across the universe – and also crops up in some everyday examples
Heart vs head
Parts of the human body may exhibit chaotic patterns. There’s some evidence that arrhythmia – when your heart beats out of rhythm – may occur in a chaotic way. It’s possible that our brain activity has chaotic tendencies, with some suggesting that electroencephalograms show it in action.
The natural world
Chaos is rife in the animal kingdom. Biologists studying the Canadian lynx have found that their population grows in a chaotic way. Small changes in food supplies, mating habits or the spread of diseases can become magnified into big differences in animal numbers.
Bless your cotton socks
In 1963, Polish mathematician Benoit Mandelbrot found recurring patterns in data on cotton prices from 1900 onwards that suggest they vary in line with chaos theory. They didn’t follow the famous ‘bell curve’ as a lot of data sets tend to.
In a jam
Often traffic jams can seem to clear suddenly and without any obvious cause. Tiny changes to the flow of cars can build into sizeable log-jams that vanish almost as soon as they arrive.
Make codes harder to crack
Cryptographers – those responsible for setting and deciphering codes – are big users of chaos theory. A message is scrambled and unlocked using a series of keys, and some computer-based encryption methods – including online image encryption – utilise chaos maps to construct those keys.
Up to the job?
Even the labour market hasn’t escaped the scrutiny of chaos theorists. The way we work, apply for jobs and move between companies could well follow chaotic patterns. Insights could lead to better decisions and a more streamlined workforce in the future.
Taking stock
The ups and downs of the stock market are notoriously hard to predict. That’s why the adage to success is “time in the market rather than timing the market”. It may be possible that chaos theory could reveal hidden patterns in the lightning-fast trades on the world’s exchanges.
Better understanding babies
The chaos in our lives starts early. Researchers have shown that they can better understand the warning signs of a condition called fetal hypoxia – where a developing fetus is starved of oxygen – if they model the situation using chaos theory.
and positions would have been amplified into considerable effects. Eventually they either crashed into other planets – just such an event is thought to have formed the Moon – or were jacked up onto such steep orbits that they were ejected from the Solar System entirely. “Only the ones born in good places at good times get to stick around,” Sutter summarises. Working out what constitutes a good place or good time is key in hunting out habitable worlds in other solar systems. Astronomers have spotted a whole host of weird-looking solar systems, including a planet that orbits its star in the opposite direction to its neighbours, probably because its orbit became so inclined that it flipped right over the poles of the star. This work is a shot in the arm for subscribers to the Rare Earth hypothesis – the notion that so many factors have to be just right for life that living planets like our own are few and very far between.
Yet even the chaos in our Solar System is still not complete. Over a human lifetime the path of the planets is predictable, but tiny interactions between worlds can build up to sizeable changes in the future. Just as the weather forecast begins to break down over timescales of more than a week, we can only predict the orbits of the planets for the next 40 million years or so – an astronomical heartbeat compared to the 4.6 billion years it has been around so far. It wouldn’t take much to upset the whole system, and one planet is particularly susceptible to the ensuing melee. “There’s a chance that Mercury could be ejected entirely,” says Sutter. The orbit of the Solar System’s smallest planet is constantly shifting round. The point at which it reaches its closest approach to the Sun – its perihelion – moves by 1.5 degrees every millennium. Jupiter’s perihelion is moving too, and if the two ever get into the same rhythm then that could spell the end of Mercury. There’s a one to two per cent chance its orbit will be seriously disrupted in the next few billion years. It could be ejected from the Solar System, or worse it could smash into the Earth. An inner Solar
System without its first planet would itself become unstable. That could lead to Mars and Earth nudged into a calamitous collision. It just shows how much chaos theory matters.
We already have some evidence that the astronomical furniture can be significantly rearranged. Nearly a decade ago, astronomers spotted the first ‘rogue’ planets – worlds jettisoned from their home systems to wander the emptiness of space alone. There could be one Jupitersized orphan for every four stars in a galaxy like our Milky Way. Five per cent of Earth-sized planets would be able to cling onto any moons as they exited their system. Ejected planets form a big part of our best model of the formation of our Solar System. Astronomers running computer simulations discovered that you end up with a solar system that looks more like ours if you start with five giant planets instead of four. Except we don’t have a fifth giant planet now. Either it went rogue or it is still languishing in the backwaters of the Solar System. That’s because astronomers increasingly suspect there is a ninth planet marooned far beyond Neptune. This ‘Planet Nine’ could well be a failed rogue planet that was unable to exit the Sun’s gravitational clutches entirely.
Even if the chaotic Solar System doesn’t set us on a collision course with our neighbours, it could still have telling consequences for our climate. In 2017 researchers studying layers of rock in the Niobrara Formation in Colorado found a key piece of evidence that Earth and Mars interacted in an unusual way nearly 90 million years ago. At the
“We suspect that a lot more planets formed around the Sun – some on chaotic orbits”
Paul Sutter
time there was a sea running through the middle of North America, and sediments falling to the sea floor were compressed into the rock seen there today. A team led by Professor Stephen Meyers of the University of Wisconsin-Madison found a difference in the clay levels between the layers of rock laid down over millions of years. A warmer, wetter climate leads to more clay being flushed into the sea from rivers than when the weather is drier. Alternating layers indicating wet and then dry climates were stacked up in a such a repetitive fashion that Meyer concluded there must be some cyclical phenomenon driving the changes. He points the finger at Mars and its ability to change the eccentricity of Earth’s orbit. Eccentricity is a measure of how much a planet’s orbit deviates from a circle. Any changes to this key value would change how much warmth the Earth receives from the Sun and provoke the knock-on climatic effects that come with that. It would also make our seasons unequal as the Earth would spend more of the year in one part of its orbit than another.
The Earth can be affected in other ways, too.
The tilt of our axis can vary under the gravitational influence of the other planets. Right now we lean at 23.4 degrees from vertical, but that varies between 22.1 degrees and 24.5 degrees over a 41,000-year cycle. This also changes the amount of sunlight we receive, particularly in summer and winter when we are leaning towards and away from the Sun. If small changes build up in a chaotic way, this cycle may get out of rhythm. Equally, the Earth’s axis moves around as our planet is wrenched by the Sun and Moon, tracing out a circle every 26,000 years or so. In the 1920s Serbian scientist Milutin Milankovitch combined all these effects and their regular effect on the Earth’s climate, suggesting we go through periodic changes called Milankovitch cycles. They too may be susceptible to chaos.
As we move into a future where human-made climate change is going to bite harder and harder, it has never been more important to understand the full range of factors that can influence the way our atmosphere receives, stores and transports energy. A better understanding of chaos theory goes hand in hand with more accurate climate models and a better picture of how tiny changes in the layout of the Solar System can translate into big effects on our already-warming planet.