Simple Science: Quantum Physics, Explained

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If your mind thinks it needs to start questioning everything it knows when you hear the phrase “quantum physics,” you’re not alone. For many of us, just a mention of quantum physics might bring up visions of incalculable math equations lining a vast chalkboard like wallpaper or tiny atoms performing an electrically charged ballet deep within, well, everything on Earth. We might imagine genius scientists poring over labwork or accidentally discovering the keys to teleportation during routine research. But you don’t have to be a genius to gain a working knowledge of what quantum physics is — it’s a lot more accessible than we’re led to believe in the media. Join us as we break it down in simple, easy-to-comprehend language. 

What Is Quantum Physics?

In the simplest terms possible, quantum physics, also known as quantum mechanics, is a branch of science that studies things that are very, very small — tiny particles that, together, make up everything around us. This branch of physics doesn’t just settle for studying how things work on the surface. Quantum physicists want to know how matter behaves at the level of atoms and molecules, which are about as small as things get. 

On the one hand, quantum physics deals with what’s happening all around us every day. The entire universe, ourselves included, is made up of tiny atoms and particles that are continually in motion and performing actions, whether we think about them or not. On the other hand, most of us don’t really tend to think of things on the quantum level, as atoms and particles require powerful scientific instruments to observe. This is part of why quantum physics can seem so mind-boggling.

It wasn’t until the development of high-tech scientific tools that quantum physics really began to emerge as a science itself. It was ushered in during the early 20th century with the work of scientists like Max Planck and Neils Bohr, who are considered the founding fathers of Quantum Theory. Albert Einstein doesn’t rank far behind, as he won a 1921 Nobel Prize for his theory of Photoelectric Effect, which greatly contributed to Quantum Theory as physicists understand it today. 

But why study it in the first place? There’s a reason that smartphones and computers didn’t exist before scientists really began to wrap their heads around quantum physics. Everything from modern computer chips to lasers, MRI machines, modern telecommunication devices and GPS signals simply could not exist without our modern understanding of quantum mechanics. 

The Trippy Nature of Quantum Physics

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Another reason why quantum physics can seem complicated, even to physicists, is that things can get confusing at a quantum level. Most of us understand reality as described by the laws of classical mechanics, which were pioneered by Issac Newton. These principles tell us that objects exist in a specific place and at a specific time.

The trick is that when you break things down to a quantum level, the laws of classical mechanics don’t apply. At this small level, some things exist in a state of probability — they might exist at either point A or point B. But what exactly does that mean?

Imagine, for instance, that someone brings you into a room where there are two identical boxes on a table. In one box, there’s a check for $1 million. In the other, there’s a check for $1. They then ask you to tell them the location of the $1 million check without opening either box.

While this situation would feel frustrating to the average person, on principle, it’s the kind of dilemma quantum physicists aim to work out. Often, at the quantum level, they have to understand tiny objects in terms of probability. Because the laws of what most people understand as reality are a bit different in quantum mechanics, they can be hard to picture in our heads. Sometimes, they’re best described using mathematical equations. 

What Are Some Common Principals of Quantum Physics?

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While it’s probably not surprising that it could take years of study to catch up with most quantum physicists, it is possible to get a broad overview of some of the core concepts of this branch of science. Let’s look at a few defining principles that have emerged from the study of quantum physics. 

Wave-Particle Duality

Wave-particle duality is a major concept in the world of quantum physics. It centers on the fact that some objects can appear to be both a particle and a wave at the same time. One way to imagine this concept is to picture a ball, which in this case represents an electron.

Say that you toss the ball into a lake and it disappears but creates a series of ripples, which represent waves in this metaphor. Maybe a second later, the ball pops back up to the surface, surrounded by the ripples. Are you looking at a particle or a wave? The simplest answer is both, which is the general idea behind wave-particle duality and the fact that sometimes you have to use both terms to fully describe what’s happening, even if they might sound conflicting. 

Quantum Superposition

Another interesting concept is the idea of quantum superposition, which focuses on the idea that an object like an electron can exist in two quantum states at the same time. To be more specific, let’s use the fact that electrons can have an “up spin,” which means they’re spinning upwards, or a “down spin,” which means they’re spinning downwards.

Until a particular electron is measured, there’s an infinite possibility it could be spinning in either direction. Think of it as a spinning quarter. Is the quarter heads or tails while it’s spinning? Technically both and neither until it stops and someone can measure the results. 

Quantum Entanglement

Quantum entanglement is a phenomenon that can happen when two particles interact in a certain way that causes them to become linked. From that point on, they’ll always oppose each other, so one will always have an up spin while the other will always have a down spin.

Once this linkage has occurred, these two particles will always maintain opposing states, no matter how far apart they are. To put this into perspective, think of it this way: It means that if you knew the spin of one electron on Earth, you could immediately discover the spin of the electron it was entangled with, even if it was in a distant galaxy light-years away. This information could be obtained faster than the speed of light — a concept that entertained Einstein to the point he nicknamed it “spooky action at a distance.”