By Eleanor

Something I find bizarre and amazing about science is the juxtaposition of scales.

You can have a big problem, like “how did our planet form?” and attack it by understanding very small things, like how atoms arrange themselves in magma, or tiny differences in the amounts of elements present in different rocks. By understanding many small things, you can build a huge, yet rigorous and detailed picture of the world. Like a high-resolution panoramic photograph.

As a scientist, thinking about my research every day, I get desensitised sometimes to how cool it is. But sometimes I read something that blows my mind a little bit, and gives me a new appreciation for what it is I’m doing, and the achievements of the generations of scientists before us.

A moment like this happened last week. I was reading about a new technique that I will be using soon, which involves measuring something on the scale of ‘parts per million’.

What does a concentration of parts per million mean? Well, imagine a water tank that can hold ten thousand litres of water… like this one:


Now imagine that you fill it up with water, and then (assuming there’s a little more space in the top), pour in 100 mL (a bit under half a cup) of apple juice.


The concentration of apple juice in this water tank is ten parts per million.

Now imagine you have two water tanks, and an evil mastermind has put 100 mL apple juice into one, and 110 mL into the other. This evil mastermind will tell you all the secrets to the universe if you can figure out which one is which (and no guessing allowed; that’s not scientific!).

How would you do it? You could try to taste the difference, but I’d be willing to bet that you wouldn’t even be able to tell there was apple juice there at all, since it’s so dilute, let alone the difference between the tanks.

This is exactly the type of problem that earth scientists are confronted with on a regular basis. The evil mastermind is nature, who will share her secrets only if we try very very hard. The tank of water could be rock, and the apple juice is a certain element that we try to measure in the rock.

Fortunately, scientists have, over decades of work, developed techniques and machines that help us to make measurements like these. It’s something I often take for granted because these measurements can seem so routine, but it’s nice to remind myself every now and then that some of the simplest things I do are actually pretty cool. And that some of the smallest details that we discover are helping to complete that high resolution, panoramic photograph of the world.