In the early 1900s scientists in multiple labs were conducting studies which were trying to reproduce and expand on a study done by Thomas Young a century earlier. The results that concluded were so controversial that even Einstein, arguably one of the greatest physicists in history, had strong disagreements with it. And it’s no surprise why! This discovery changed everything. In fact, it was so profound that now, over a century later, it has revolutionized the way we think about not only physics, but biology, engineering, computing, and even philosophy. This discovery has fundamentally changed the way that we think of reality as a whole, and has given rise to an entirely new type of physics that has made possible the technological world we live in today. This was the beginning of what is currently called Quantum Physics.
The study being replicated was called the double slit experiment, and it is a relatively simple setup. A laser is positioned as to point at a metal plate with two thin slits cut into it in parallel. Behind this plate is a detector that can tell you where the photons of light traveling from the laser meet their final destination. The hypothesis behind this experiment is that if photons behave like particles, we expect to see two lines appear on the measuring device, indicating that they simply passed through the slits and hit the wall on the other side.
However when the test was performed they did not register two parallel lines. They registered several lines, fading outward from the middle. This was an interference pattern, showing that the photons of light were behaving like waves. Imagine that same metal plate with the double slits was partially submerged in water. As a single wave of energy travels through the water and hits the metal plate, it breaks into two separate waves on the other side. These waves then interfere with each other, creating an interference pattern as seen below. Seems simple enough. However, the experiment was just beginning.
The scientists then placed a detector next to the metal plate to observe which slit the photon was passing through. This is where things get weird. When they checked what pattern had appeared on the detector behind the plate, they simply found two parallel lines – exactly what you would expect if photons were behaving like particles. But how is this possible? Photons cant simultaneously be particles and waves, can they?
The answer is yes – and it doesn’t only apply to photons. This strange phenomenon is called wave/particle duality, and it has been found to apply to just about everything that is really small. Electrons, protons, neutrons, atoms, and even molecules! But what exactly is an electron wave? Aren’t electrons just tiny particles with a negative charge that orbit the nucleus of an atom? No. The truth is much more interesting. If you have never heard this information before, it might sound insane. But I promise, it’s the truth.
For every particle, there exists a field of energy that is the size of the universe. There is an electron field, a proton field, a quark field, and many more. Each field ripples with energy like water, and if enough energy is concentrated in a single area, there is a high probability that you will find a particle there. I say “probability” because, technically, until that particular area of space is observed, or interacted with, the particle is everywhere at once. A quantum field is a field of probability, and the more energy that exists within a certain area of the field, the higher your chance is of finding a particle when you look there.
For example, our understanding of an atom was that protons and neutrons are bonded in the nucleus, while electrons orbit around it like planets orbit the sun. However we now know that electrons don’t orbit the nucleus at all. Instead, they exist within probability fields that surround the nucleus called orbitals. It is the mathematics that describe these orbitals, or the energy within the system itself, that separates a carbon atom from a hydrogen atom.
Confused yet? You’re not alone. Quantum physics is one of the most insane yet revolutionary theories of the natural world that humans have discovered. But regardless, it is also very well understood. In fact, it is so well understood that we have used it to create entirely new fields of study such as quantum biology. It used to be believed that quantum effects could never be observed within a biological system. It’s just too warm and messy inside of a body. However recent studies have began to discover that the quantum world is much more all encompassing than we realized. Particles can perform something called “quantum tunneling”, in which they simply disappear from one location and miraculously reappear elsewhere. This happens within our DNA, and is one of the causes of mutation.
In addition, birds and some other animals seem to have evolved to use quantum physics to their advantage. One study found particles exhibiting quantum behaviors within the eyes of birds that allow them to detect and follow the magnetic field lines of the earth. When a specific liquid was removed from the eyes of birds, they were no longer able to migrate.
But perhaps the most thought provoking theories created because of quantum physics is string theory. It has yet to be proven, but the mathematics included in this theory seem to explain many aspects of our universe that we currently have no explanation for. There are many different interpretations of string theory, as well as a conglomerate called M-theory, but it basically describes how tiny one dimension strings form all of the natural world through their vibrations and interactions. String theory opens up the possibility of higher dimensions we are unable to perceive, as well as the possibility of a multiverse in which an infinite number of universes with infinite variation exists.
Some believe that quantum physics opens the possibility of creating a natural explanation of free will. Observing our universe through a framework of classical mechanics creates a domino universe, in which every action is simply the result of a previously predetermined action that chains all the way back to the big bang. But if everything is actually part of a field of probability as described in quantum mechanics, and if consciousness is intimately tied to quantum mechanics, it is possible that we are free will beings after all. However until this can be proven, all we can do it wait.
As I’m sure you’ve seen, the implications of quantum physics are profound. If every possible outcome exists in the quantum world, does that mean that every possible universe is actually real? Are there an infinite number of universes out there with infinite versions of ourselves? These are a few of the questions that scientists are still trying to answer. Until then, it is our duty as humans to absorb this information and apply it to the way we look at the world around us. This room, your clothes, your phone, and even your body is made of particles that exist in multiple states at once. You aren’t just you. At some level, you are everything.