Quantum: The 'spooky' world of the incredibly small

Monday 14 April is World Quantum Day, bested only by 2025 being the UN International Year of Quantum. Welcome to the realm of the phenomenally small where our every intuition is shattered at the tiniest level.

What is the Quantum World?

Most of us live our lives in the world of ‘big things’—think footballs and cars, skyscrapers and oceans.

We know these are made of tiny particles, but we never really experience that world.

Well, back in 1925, when scientists like Heisenberg and Schrödinger (with a nudge from Einstein) started exploring the realm of the very small, they uncovered weird behaviours—like a particle being in two places at once!

A century later, as the UN celebrates all things quantum in 2025, we’re still unravelling these mysteries.

What weirdness happens there?

The assumptions we make about the way things work in the big world do not hold in the quantum world.

In the big world, a ball will always bounce back off a wall, a dropped coin will follow a single path to the ground, and a ball and coin cannot be in the same place at once.

But in the quantum world, a particle may tunnel through a barrier rather than bouncing back, the particle can be on many paths at once (at least until we look at it), and two particles can seem to be in the same place at the same time.

How can we measure such weird and small stuff?

Our ability to peek into the quantum world relies on incredibly powerful and sensitive machines.

The Nanoscience Lab at the University of Sydney, for example, uses equipment that operates at the scale of billionths of a metre, with temperature controlled to within 0.025 degrees and specifications to block out the rumblings of trains over a kilometre away.

Here’s the kicker: measurement itself is a challenge because one of the peculiarities of quantum particles is that by just observing and measuring them, we change what we see.

Watching tiny particles actually precipitates their taking a single position. After observation, they can no longer appear in multiple places at once.

It’s mind-blowingly beautiful but difficult—and part of the quantum legacy the UN is celebrating in 2025.

Why is this stuff important?

Quantum weirdness isn’t just mind-bending—it’s world-changing!

Since 1925 quantum sciences have given us lasers and transistors, powering everything from phones to medical scans.

Today, it is the promise of super-fast computers for tackling big issues like climate change.

That’s why the UN declared 2025 the Year of Quantum—to celebrate this legacy, inspire new breakthroughs, and ensure everyone can share in the quantum future.

So how do Aussies go at quantum?

Given the challenges inherent in understanding the quantum world, you’d be forgiven thinking that research only takes place in the US and perhaps a couple of massive labs in Europe or China.

In fact, Australia’s output—championed by USyd’s Nanoscience Hub, former Australian of the Year Michelle Simmons at UNSW, and multiple other local institutions—is truly world class and something of which we can be immensely proud.

Where might it take us?

If we crack the secrets of the quantum universe, we could live in a world of staggeringly fast computers and ultra-precise medical sensors for early disease detection.

Let’s also not forget a possible darker side—Q-Day, when quantum machines might break our encryption, exposing our digital secrets.

It’s a thrilling yet daunting future, making the UN’s quantum focus in 2025 more crucial than ever.

And what was that bit about the cat?

You might have heard of ‘Schrödinger's Cat’?

In 1935, Schrödinger imagined a cat in a box with a quantum twist—depending on the state of a particle, a poison will or won’t be released into the box.

Since particles can be in two states at once, his thought experiment shows quantum weirdness on a big scale.

In theory the cat is alive AND dead at the same time!

And if all of this sounds a little overwhelming, don’t dismay.

One of the greatest physicists of all time, the enigmatic Richard Feynman, put it best when he once said, “If you think you understand quantum mechanics, you don’t understand quantum mechanics.”

Get involved

To find out more about plans in Australia for the Quantum Year, register events and get involved, visit quantum2025.org.au.

That’s all from me for now. If you'd like more geeky fun, please check out my other newsletters below, or connect with me on LinkedIn and/or X.

Yours at the tiniest of levels,

Adam