One effect of lockdown, for almost everyone, has been more time spent online — scrolling social media, reading articles, watching videos and listening to podcasts. There’s just so much out there to learn about, experience and enjoy; from inspiring illustrations to entertaining Twitter accounts, the internet has been a way to escape the everyday boredom of a life spent, for the most part, in our homes.
Back when the pandemic began, a well-known physicist called Sean Carroll launched a YouTube series called The Biggest Ideas in the Universe. I discovered the series having fallen down a YouTube rabbit hole on quantum physics — a fantastic way to spend a lockdown evening. What impressed me the most about the series was how accessible Carroll made what is usually inaccessible information.
I’ve always been interested in Quantum Mechanics — a branch of science that most people, including myself, know very little about (except perhaps what we’ve picked up from hearing bad jokes on the Big Bang Theory). It’s so fascinating to me because it goes so far beyond being ‘science’ as we might think of it in a school class. Like most people, I always just assumed that the classical theory of physics was the ‘way the world works’ — you know, all about particles, protons, neutrons and atoms; forces, fields and gravity. But that’s not really how it works.
Yes, we can use the classical theory of physics to describe all these incredible things about the universe. We can use it to launch rockets into space and build massive telescopes through which we can view black holes millions of light years away. But under the hood of things, there’s something else going on entirely. And there’s still a lot we don’t know or understand about it.
Here are some of the things I learned about Quantum Mechanics through watching this series.
Everything is made up of waves
The whole question around whether something is a particle or a wave is deeply complex — it goes back to the 1800s when over the course of a century, scientists debated on whether light is a particle or a wave. An English scientist by the name of Thomas Young began his experiment by shining light beams through two openings onto a screen behind them, creating a classic interference pattern whereby the stripes of light had varying intensity on the screen. This, he concluded, explained that light acts like a wave — an idea that was further supported several decades later when physicist James Clerk Maxwell discovered that light is waves of electricity and magnetism.
Things got confusing not long after when Albert Einstein came to the conclusion that light is made up of energy called photons and behaved like a particle under certain conditions. It gets even more complex from the 1920s, when a physicist named Louis de Brogile suggested that matter has a wavelength too. This was the basis for what is an incredibly important theory for quantum mechanics that, as Carroll explains, is best understood through the Copenhagen interpretation.
To boil it down, it says that a quantum particle doesn’t actually exist in one state or a different one but in every single state at once — and it’s our observation of this state that it’s forced to choose by our observation. All these possible places that the particle could be is the ‘wave’.
Entanglement is a really important concept for quantum mechanics. Essentially, it’s what happens when particles (whether a pair or a group) share spatial proximity in a way that means that none of them can be described independently of others — even when there’s a large distance between them.
Carroll does a really good job of explaining how this works.
(Warning! You may spend dozens of hours travelling down a YouTube rabbit hole on quantum mechanics from which you may find it impossible to escape… watch at your own risk!)
There’s a few ‘fields’ you may already be familiar with when it comes to science — magnetic fields, gravitational fields and electric fields, to name a few. According to physics, explains Carroll, the world is made of quantum fields. A field, in the context of physics, is something that has a value of some sort or another at each point in space. Quantum field theory is particularly hard to grasp because it contains all elements of physics. Fields are the basis for all matter — random fluctuations on top of which waves propagate.
If this all sounds confusing, that’s because quantum field theory is one of the most intimidating sets of ideas in theoretical physics. But our main man Sean Carroll breaks it down for you in the video below.
But why is this all so important?
It’s hard to imagine how quantum mechanics impacts our lives — it all sounds a little bit sci-fi and incomprehensible. But there’s a few good reasons to care about it; and many cool things that have come from it.
Computers & Smartphones
The foundations of the computer industry, including smartphones, is based on quantum phenomena. The computer chips that power so many of our iPhones, household appliances, laptops and smart electronics are built from our understanding of quantum mechanics. Because we can understand the wave nature we can we can manipulate the electrical properties of silicon — and stack up layers of these to make transistors on a tiny scale.
So when you’re scrolling through Instagram, remember that there’s some complex concepts around quantum theory that have led to the ability to tap likes on your screen.
Lasers & Telecommunications
Lasers are in fact quantum devices. And whether you’re using a laser indirectly by scanning a label on your groceries or indirectly by making a call on your phone, you’re using quantum mechanics to do so.
MRI machines use Nuclear Magnetic Resonance. When you undergo an MRI scan, an arrangement of magnetic fields allows doctors to measure how much hydrogen exists in different parts of the body; the basis of this is through quantum physics.
Look, I’m no expert on quantum mechanics. Heck, I’m barely an armchair novice! But I’m fairly certain that quantum mechanics is going to have a massively disruptive effect on a wide range of industries and applications in the years ahead, as our understanding continues to grow. It’ll be exciting to see what potential for impact this incredible, and mind-boggling, scientific concept can have on our lived realities.