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When you hear the name Star Wars, (possibly) the most popular saga in history, one of the first things that may come to mind is The Force. For those, however, who are guilty of not having seen the saga, The Force is an energy field created by all life that connects everything in the universe. Cool, right? What if I told you that there is actually a theory for our universe which states that all the known forces can be explained away with only four fundamental ones? The Standard Model is going to surprise you!
Unlike our four forces, in the Star Wars universe, The Force existed in only two forms: The Cosmic Force and The Living Force. The Cosmic Force was responsible for keeping the galaxy together, while – as the reader may have already guessed – the Living Force represented the energy of all life in the universe. However, not all individuals were Force-sensitive – only a few, like Leia or Luke, were able to notice major perturbations in The Force.
In order to understand how our universe works, we have to broaden our understanding of fundamental particles. In the Star Wars universe, all existing “stuff” is classified based on its spin, the intrinsic angular momentum of a particle. What a coincidence! We do the same, too! Our fundamental particles with integer spin are called bosons. These particles are responsible for force transmission. If, instead, they have half integer spin, they are called fermions, those being matter constituents instead. By arranging fermions together, protons and neutrons are created, leading to atoms and subsequently all matter.
The Standard Model states that the known universe is ruled by four forces, ordered by decreasing strength: the strong interaction, the electromagnetic force, the weak interaction and gravity. Mathematically, all these forces can be described using what we call fields: quantum fields for the first three and the curvature of space-time itself for gravity.
The strong interaction is carried by the gluon boson. It unifies quarks (fermions) in order to form hadrons, such as neutrons and protons. It is also responsible for the nuclear force that brings all the latter particles together to form atomic nuclei.
The weak interaction also acts at a nuclear level by the regulation of radioactive decay. The particles responsible for these interactions are W and Z bosons.
The electromagnetic force is regulated by photons, which you may know as the particles of light. It is responsible for the existence of both electric and magnetic fields, which makes it the source of the attraction between atomic nuclei and their electrons, of visible light, since it too is an electromagnetic wave, of chemical bonding and much more. As stated previously, this interaction is stronger than gravity, but it also has the tendency to cancel itself at astronomical distances, where gravity is the dominant force.
As we said, three of the four fundamental forces result from the exchange of force-carrier particles, or bosons. Matter particles interact with each other by transferring energy in discrete entities, the bosons, which are different for each fundamental force.
In Star Wars, the existence of the so-called midi-chlorians works similarly to how bosons work in our universe. Midi-chlorians were intelligent microscopic lifeforms that lived symbiotically inside cells. If they were sufficiently numerous, the being composed of those cells would become Force-sensitive, like the Jedi were. In the same way that bosons are essential for particles to communicate via forces, midi-chlorians are the connection between The Force and the living being who wields it.
We still have not mentioned the last fundamental force: gravity, experienced by all particles due to their mass (although photons, though massless, experience it too). It is the weakest of the four forces, but it has an infinite range. This force, despite being the most well known by the general population, is still keeping one secret from the most curious physicists: its boson. Gravity’s boson, called the “graviton” has been hypothesized but not discovered – yet.
The Standard Model is able to explain the behavior of electromagnetic, strong and weak interactions by the exchange of their respective bosons between matter particles. However, even though the scientific community has made an effort to change this, gravity cannot be included in this model yet. Quantum physics, which is used to describe the other three forces, and general relativity, which is used to describe gravity, are difficult to fit in one single framework. Luckily, when it comes to the smallest of scales the effect of gravity is negligible – it is only relevant in matter in bulk, at much larger scales. This makes the Standard Model work exceptionally well despite its reluctant exclusion of one of the fundamental forces.
Although our universe is maybe not as cool as Star Wars in some ways and does not possess one unique way to unify all the forces, the Standard Model is working on it. We may not be able to have the same superpowers as Master Yoda, but we are definitely getting closer in our understanding of the forces than ever before, approaching mastery too, in a way.
In a nutshell, in order to achieve the unification of the four fundamental forces in the Standard Model, particle scientists are working as the Jedi – or, perhaps, still just the Padawan – of our universe by learning how to wield the four fundamental forces.
May the four fundamental forces be with you! Did you enjoy this post? Let us know in the comments!