The Relatable World of Quantum Mechanics

A diagram showing some of the possible ways for a particle to get from A to B. In reality it will simultaneously travel all of these routes

For most people, quantum mechanics seems counterintuitive and paradoxical. Whether it’s Schrödinger’s famous cat which is simultaneously alive and dead, or strange entities that behave both like particles and like waves, quantum mechanics is full of strange results that seem nothing like the world around us. But if you’ve ever been busy or lazy, been uncertain or unreliable, perhaps you can relate to the weird and wonderful quantum universe. Imagine placing a tiny particle such as an electron on the table in front of you. If you then looked away and did not interact with this particle you might expect it to stay perfectly still. However, according to quantum mechanics, if you look back the particle may not be exactly where you left it. It could be a few nanometres to the right, or on the other side of the room, or even on the other side of the universe! This is because quantum theory states that a particle can be in a superposition of states, meaning that while you’re looking away from your particle and not interacting with it, it is simultaneously in infinitely many different places. On looking back at your new pet particle, it ‘decides’ on a place to be. Feynman’s Principle of Least Action states that all the possible paths a particle can take, no matter how bizarre or unlikely, can be added together and a resultant probability can be found. By far the highest probability is for the particle to have barely moved, if at all, but there is a small but non-zero chance of it having moved much further. So, if you’ve ever felt so busy that you feel like you’re everywhere simultaneously, or wished you could be in two places at once, maybe you and your strange particle have more in common than you think. But there’s also no need to feel bad about being lazy, quantum particles usually are too, so by staying on the sofa all day, you’re technically just obeying the Least Action Principle!

A diagram illustrating how a quibit is a mixure of both states

This principle of superposition also applies to states, and this is the basis of quantum computing. In a classical computer, a signal is either 1 or 0, but in a quantum computer, a particle can act as a qubit that’s a mixture of both states. This provides far greater computing power, which makes quantum computing very useful for handling and analysing vast amounts of data, giving it exciting applications in drug development, climate science, and energy storage. So perhaps being confused or undecided isn’t such a bad thing!

And if you’ve got a particularly unreliable friend, perhaps they’re just behaving like a quantum particle. Heisenberg’s Uncertainty Principle states that the more accurately you know a particle’s position, the less accurately you know its momentum or velocity. Therefore, if you take an electron and confine it to a small space using an electric or magnetic field, you can accurately determine its position, but there is a high uncertainty in its velocity. In other words, you know where this particle is, but you have no idea where it’s going, much like that one friend at a party who was definitely in the kitchen a few seconds ago, but could now be headed anywhere!

An illustration of quantum tunnelling

If you like to feel in control of your life, all this talk of inherent randomness and uncertainty in the universe can be quite unnerving. But instead, try to think of it as liberating. Take quantum tunnelling for example. In classical mechanics, if a particle doesn’t have enough energy, there is no way for it to overcome a barrier without gaining any more. However, quantum particles have wave-like properties, and this means there is a chance for them to bypass the barrier completely!

So, while quantum mechanics is random and confusing, maybe it can be relatable when you feel uncertain, busy, or even lazy. Perhaps we should all behave a bit more like quantum particles and try to overcome some otherwise impossible barriers, because after all, in the quantum world, nothing is set in stone.