We yearn for certainty.
As a species, we humans want to know things for sure. We want to have things spelled out in black and white.
I want to be able to look at the weather forecast for tomorrow (Victoria Day) and know if it’s going to rain or not.
Instead, I look at the weather forecast on my phone and it tells me there is a forty percent chance of rain tomorrow.
But wait, last time I looked, earlier this morning, it said there was a sixty percent chance of rain.
And we think to ourselves, “Those weatherpeople. They don’t know what they’re talking about.”
And tomorrow, if it rains, I’ll curse them for being wrong, even though they said there was a chance of rain.
We want to hear them make definitive statements.
And yet…
And yet 30 years ago, when they did make those sort of statements, they were wrong half the time anyway.
Because weather is not something that is deterministic. It does not operate based on a simple, easy to understand formula. It does not operate on the principle that “if it was sunny today, it will be sunny tomorrow.”
There are three main things that influence what the weather will be in an hour, in a day, in a week. Those are air pressure, density and temperature.
Each one influences the others, and when one changes, it causes the others to change, too.
This is a classic three body problem. In science, when you have two bodies interacting, it is fairly easy to predict. But when you have three bodies—say, three planets orbiting each other—the model of how they will move breaks down fairly quickly. As planet A affects the movement of planet B, it will affect planet C, which in turn affects planet A. After a few minutes or hours or days, it becomes impossible to predict how planet A will be moving. The third body introduces a level of chaos into the pattern. While this is not completely random, it is so unpredictable as to appear to be.
In meteorology, this is sometimes referred to as the Butterfly effect. The idea is from meteorologist Philip Merilees, who wrote a paper called “Does the flap of a butterfly’s wings in Brazil set of a tornado in Texas?”
Merilees was cagey about answering that question, noting that, if it did, there was an equal likelihood that a tornado that was going to form in Texas would not be able to form, due to the next flap of the butterfly’s wings.
His point is that, at some point in time, it becomes nearly impossible to understand the knock-on effects that will be created.
Because while I mentioned the three main factors that influence the weather, there are many others. The humidity, for instance. Or precipitation. Or humidity. Or the amount of radiation (sunlight) entering the system.
And tiny changes can make a big difference. Edward Lorenz, who in addition to being a meteorologist was also a mathematician (and one of the pioneers of the idea of chaos theory), says that the present determines the future, but the approximate present doesn’t not approximately determine the future.
He tells the story about entering data into a computer model. Instead of entering a precise value (0.506172), he entered a simplified version of the figure (0.506).
His results were completely different, based on a variation of 0.000172. A small variation can mean the difference between a rainy day and a tornado wiping out your house.
If everything is known, then everything is knowable, but “everything” is a really tricky word to parse. In our discussion of the weather, would knowing the exact temperature, air pressure and air density of every square kilometre allow meteorologists the ability to predict the weather accurately ten days out? Twelve? What if they had accurate measurements for every square metre? In order to predict the weather with complete accuracy for a year out, would they need to know the rotational state of every molecule of air?
The closer we look, the bigger the gaps appear. But let’s step back a bit. Because while meteorologists don’t have every bot of data, they have more than they did fifty years ago. Science changes. New discoveries are made and more detail is able to be made out, like a picture with greater resolution.
And yet because the experts are not know-it-alls, because they tell us that there is now a forty percent chance of rain as opposed to sixty, because they updated their model as new information became available, rather than slavishly sticking to their previous predictions, they are somehow less reliable, not more.
If it rains tomorrow, they were wrong, because there was a sixty percent chance of no rain. If it doesn’t rain, they were wrong, because there was a forty percent chance it would. Because they offer us probabilistic, not deterministic, visions of the future, we reject everything they say.
Recently, mathamaticians have come closer to solving the three body problem than ever before. Is it a perfect solution? No. But it’s better than before.
One more weather example. Down in the so called tornado alley in the states, weather forecasters have a ten to 15 minute lead time to predict if a tornado is going to form, and they generally predict where it is going to strike within a few hundred metre radius.
Thirty years ago, they had at most a one or two minute warning, and could predict where it was going to strike within a few kilometres.
Yet dozens of people die each year, because they ignore the experts. They don’t see the fact that the information is becoming more accurate, more nuanced. All they see is the fact that the weatherman is speaking in terms of probabilities.
We live in a world full of chance and chaos and probabilities, but we want certainty and determinism. We can fight against that, or we can accept that we can only predict with 60 percent accuracy what tomorrow will bring. Your choice.
Trent is the publisher of Tumbler RidgeLines.
