What is happening inside your Mystery Goo?

Mystery Goo is made from just cornflour and water, but mixing them creates a material with some very unusual properties.

Cornflour contains countless tiny solid particles. When water is added, these particles become suspended throughout the liquid rather than dissolving completely.

Together, the particles and water form a thick mixture called a suspension.

And this suspension doesn't always behave like an ordinary liquid.

Why does Mystery Goo flow when you move it slowly?

Move your fingers slowly through the Mystery Goo and it can ooze, drip and flow.

When the mixture is moved gently, the cornflour particles have enough time to move around one another. Water between the particles helps them slide past each other.

That's why you can slowly pour the goo or let it run between your fingers.

For a moment, it seems just like a very thick liquid.

Why does it suddenly feel solid when you hit it?

Now give the Mystery Goo a quick push, squeeze or tap. Everything changes!

When a sudden force is applied, the cornflour particles are pushed together so quickly that they cannot move out of the way easily. They crowd together and resist movement.

For that brief moment, the mixture becomes much firmer.

Stop applying the force and the particles can begin moving again — so your apparently solid lump turns back into flowing goo.

Is Mystery Goo a solid or a liquid?

This is where things get interesting.

Mystery Goo is known as a non-Newtonian fluid. That means its resistance to flowing — its viscosity — changes depending on the forces acting on it.

Move it slowly and it flows easily.

Apply a sudden force and it becomes much harder to move.

So rather than simply asking, “Is it a solid or a liquid?”, scientists investigate how the material behaves under different conditions.

Where is this strange science used?

Scientists and engineers study materials that can change their behaviour when forces are applied.

Similar ideas can be useful when developing impact-resistant materials, including protective equipment and other technologies designed to be flexible during normal movement but resist sudden impacts.

Studying unusual materials like Mystery Goo helps scientists understand how the microscopic structure of a material can affect the way it behaves on a much larger scale.

Scientists Say…

Mystery Goo is a shear-thickening non-Newtonian fluid.

That sounds complicated, but the big idea is simple:

Slow movement → it flows.

Sudden force → it resists movement.

You haven't changed the ingredients. You've changed how quickly force is applied — and the material responds differently.

Curiosity Spark

You can push your finger slowly into Mystery Goo…

…but what would happen if something moved across it really fast?