The word “quantum” comes up in movies, marketing, and casual conversation far more often than any clear explanation of what it actually means. It’s a well-established field of physics, and understanding the basics doesn’t need any advanced maths or background knowledge beyond what you’ve already got.
The basic idea
Quantum science studies how matter and energy behave at extremely small scales, at the level of atoms and the particles that make them up. At this scale, the rules that describe how a ball rolls or a car accelerates stop applying, and a different set of rules takes over.
Just how small we’re talking about
An atom is roughly a hundred thousand times narrower than a strand of human hair. Quantum science studies particles smaller again, including electrons, which exist within atoms. At this scale, direct observation with the naked eye or a standard microscope isn’t possible, so behaviour is instead measured through specialised equipment and inferred using mathematical models built from decades of experimental data.
Where the confusion comes from
Quantum science shows up constantly in movies, video games, and marketing, usually attached to ideas like instant teleportation, parallel universes, or objects existing in two places at once. Most of this borrows the word “quantum” for its reputation rather than reflecting the actual science.
Quantum behaviour follows a different set of rules to the physics visible in daily life, largely because it only becomes measurable at a scale no one interacts with directly. That gap between what’s observable and what’s real gives fiction plenty of room to exaggerate. Real quantum science is grounded in decades of experiments and evidence, and it’s already responsible for technology you use every day, like the chips inside your phone and computer.
The two ideas behind most of it
Two concepts come up again and again when people talk about quantum science: superposition and entanglement.
Superposition means a particle can exist in more than one state at once, rather than being locked into a single definite state the way everyday objects are. Think of a coin spinning in the air. While it’s spinning, it isn’t simply heads or tails, it’s a mix of both possibilities until it lands and you check it. Particles behave a bit like that spinning coin until they’re measured. Entanglement happens when two particles become linked in a way that means the state of one instantly affects the state of the other, even if they’re far apart, without any signal passing between them in the usual sense. It’s still an active area of research today.
Where quantum science shows up in the real world
Quantum science already underpins plenty of technology you might not realise counts as “quantum.” The chips inside your phone and computer rely on quantum physics to work, since the behaviour of electrons in tiny transistors follows quantum rules rather than classical ones. Precision sensors used in navigation and medical imaging, like MRI machines, also depend on quantum effects to measure things with a level of accuracy classical technology can’t match.
Beyond what’s already in use, quantum computing is one of the most talked-about applications, using superposition and entanglement to process certain types of problems in ways traditional computers can’t. Secure communication is another growing area, using entanglement to detect if a message has been intercepted, which could make future data significantly harder to access without permission.
Why this field is growing right now
Quantum science has moved from mostly theoretical research to real-world application over the past couple of decades, which is part of why it comes up more often now than it would have a few years ago. Governments and companies are investing heavily in the field, particularly in computing, sensing, and secure communication, since the potential impact across industries like medicine, finance, and defence is considerable.
It’s still an emerging field, which means a lot of what’s possible hasn’t been figured out yet, rather than being an area where the groundwork is already fully established.
How it connects to what you’re already learning
You don’t need to already understand quantum physics to start building toward it. Senior physics covers the classical physics that quantum science builds on and eventually departs from, and maths subjects that cover probability and complex numbers give you tools that show up again in quantum theory later on.
If you’re curious about where physics and maths subjects could take you, our subject selection hub breaks down how different combinations connect to future pathways.
