The human urge to understand the world is much like our quest to determine the origin of life. These deeper-than-survival considerations have been on our minds for at least a few millennia. What is the meaning of life? Where does life come from? What is life made of? Here we'll consider the sum of these questions.

Time to break down the “Theory of Everything”. You may wonder why we need such a unifying framework. Well, there’s not one that we all agree upon yet. So, here we’ll consider them all.

The human urge to understand the world is much like our quest to determine the origin of life. These deeper-than-survival considerations have been on our minds for at least a few millennia.

What is the meaning of life? Where does life come from? What is life made of? Here we’ll consider the sum of these questions. First, we’ll go way back and consider what the ancient Greeks thought.

The Four Fundamental Elements

According to Greek philosophers, life is eternal and the fundamental property of matter. To them, life has sprouted spontaneously wherever the conditions were conducive.

In ancient Greece, it was believed that all matter in the world was a combination of four elements. This is thanks to the work of Empedocles (490-435 BC). He was also a philosopher and poet and the creator of the first early “particle physics theory”.

According to Empedocles’ model of four elements, or, as he called, them “roots”, life is created from four primary elements: water, Earth, air, and fire.

Associating each of the elements with a deity (Nestis, Hera, Zeus, and Hades respectively), Empedocles also posited that two opposing forces, “Love” and “Strife”, influence the interaction between these elements.

Then, in his treatise “Timaeus”, Plato (428-348 BC) expanded on the concept of “four elements” that have become, since Empedocles, the starting point for any reflection on the nature of the world.

For Plato, like Pythagoras before him, God is a geometrician and mathematician who likes numbers.

Thus, Plato argued that there are five 3D geometric shapes or Platonic Solids. He associated these with these elements: Cube (Earth), Icosahedron (water), Octahedron (air), Tetrahedron (fire), and the Dodecahedron (the Universe).

Later, Aristotle added a fifth element. He posited the space-filling “Ether”, which he differentiated from Plato’s Dodecahedron, and believed it’s what heaven is made of.

Even if there’s no scientific basis to their underlying concept, the Platonic Solids left a big impression on scientists and artists afterwards. These geometric shapes, and particularly the mysterious dodecahedron, inspired many Renaissance artists like Leonardo da Vinci.

The Four Fundamental Forces

Today, we know that earth, air, water, and fire are far from being fundamental elements.

Nevertheless, the “four elements” model represents a good first try at figuring out life.

Since then, we’ve come to know that all matter is composed of molecules, atoms, and far smaller particles.

Still, we can’t consider any of these to be the fundamental building bricks of matter just yet. There might still be other elemental particles we have yet to discover.

If you asked a scientist today, particles we observe compose all of the world’s objects. “Love and Strife” have nothing to do with it–sorry Empedocles!

All the physical phenomena observed in nature, from the cohesion of atoms in our bodies to the motion of galaxies, are regulated by four fundamental forces. These are the electromagnetic force, the strong nuclear force, the weak nuclear force, and gravity.

The electromagnetic force is the force that holds together the atoms that make up the molecules of our body as well as cosmic objects. It was in 1864 that James Clerk Maxwell was able to demonstrate for the first time the combined effect of electricity and magnetism via his equations.

In the 20th century, the two nuclear forces were discovered: the weak interaction (responsible for radioactivity) and the strong one (the one that binds together the protons and the neutrons inside the atom, which makes the basis of nuclear bombs).

The first fundamental force to be discovered, the gravitational force, is still partly a mystery.

Theory of Everything: the Ultimate Goal of Physics

The electromagnetic and weak nuclear forces have already been unified to form the electroweak force. This discovery won the 1979 Nobel Prize in Physics for Sheldon Glashow, Abdus Salam, and Steven Weinberg.

Within the framework of the The Standard Model, we can explain the interactions of three forces. These include the electromagnetic force, the strong force, and the weak nuclear force, but not gravity.

Gravity still resists many “Theories of Everything”. This is because, while it has almost infinite range on the macroscopic level, it’s considerably weaker in the microscopic world than the three other forces.

That’s why most of scientific efforts geared towards unifying physics laws are focused on decoding the gravitational force mechanism.

Einstein’s Theory of Relativity describes gravity as the curvature in the fabric of space-time. Yet, attempts to understand how this curvature occurs have not been successful so far.

Though they can’t prove it, scientists posit that the four forces merge into one underlying superforce. There’s no catchy name for this yet.

The ultimate goal of physics is to find a master theory that can describe the universe as a whole. Ideally, this theory would bring the four fundamental forces together. It would reconcile Relativity and Quantum theories all under the same unifying mathematical framework.

The 3 Best “Theory of Everything” Candidates

1. The String Theory

What if the universe we live in is built on vibrating strings in a 11-dimensional space?

In broader terms, String Theory basically takes us even deeper into the essence of matter and suggests that the Universe is not made of infinitely small particles, but of one-dimensional vibrating strings.

Vibrating like the strings of a guitar, these strings produce the different types of particles found in nature (a proton, an electron, a photon, etc.) according to the way of vibration.

If you think there’s no way to wrap your head around the concept of String Theory, here’s theoretical physicist Brian Greene explaining it in the simplest way possible.

Don’t let the word “Lagrangian” or the heady stuff he says in the first minute of the video put you off!

Fitting all elementary particles into open strings, and closed strings, or loops might seem nice and tidy. However, there is a catch.

String Theory is very hard to verify, for now, because it doesn’t work in a three-dimensional world. It would theoretically require ten dimensions for space and one for time.

The mathematical construction of String Theory remains incomplete and its physical ingredients have yet to be seen.

Nevertheless, it has already overcome several impediments. For example, the theory would incorporate all known forms of matter and leave little room for anomalies.

Despite the lack of proof, String Theory hasn’t been proven wrong either.

2. Loop Quantum Gravity

There’s just no way to detect gravity’s effect on particles using the theory of relativity. Meanwhile, relativity best explains the gravitational forces acting on big objects such as galaxies.

Some physicists took Einstein’s gravity principles and applied them to the world of the infinitesimally small, suggesting there’s a quantum nature for gravity.

In quantum physics, Quantum Gravity is a concept that tries to unify gravity with the three other fundamental forces. Within it, the quantum theory of electromagnetism predicted the existence of gravity in the form of photons.

We already have a name for this speculative particle: the graviton. Sadly, we haven’t been able to isolate and observe it even with our largest particle accelerators.

The hunt is still on for a gravity particle.

While the String Theory studies matter and its behavior in the fabric of space-time, the Loop Quantum Gravity (LQG) theory is dedicated to space-time itself. More specifically, LQG concerns the quantum properties of space-time.

The LQG theory focuses on the physics of the creation of the universe, its expansion, the behavior of black holes, and physical interactions on the very small scale.

LQG provides promising, although hypothetical, answers to the information paradox. It also considers black holes as so-called Planck stars.

Instead of the Big Bang, LQG speaks of a Big Bounce. Or, it hints that a contraction phase would have preceded the expansion of the universe.

A leading candidate theory after the String Theory, LQG has encouraging indications that suggest it as a viable unifying model. However, as is always the case in theoretical physics, many questions remain unanswered and predictions unverifiable.

3. Emergence Theory

Emergence Theory is currently under development by an LA team of scientists, led by Klee Irwin, at Quantum Gravity Research.

The newest developing theory on the list, Emergence theory, attempts to put Einstein’s Relativity, Quantum Physics, and the Standard Model under the same mathematical umbrella.

What sets Emergence theory apart is its inclusion of consciousness into the mix as it bases its intricate mathematics on the concept that reality is made of information.

Information requires an observer to make sense of it.

“Fundamentally, then, the existence of information must therefore imply a “chooser,” or some form of consciousness, in order for it to be actualized.”

Here’s a shout out to Plato and his geometric shapes as Emergence theory calls for geometry to explain reality.

“A central feature of reality behaving geometrically is that all fundamental particles and forces in nature, including gravity, can transform into one another, through a process called gauge symmetry transformation, in a manner that corresponds precisely to the vertices of the 8-dimensional polytope of a crystal called the E8 lattice. However, we do not appear to live in an 8-dimensional universe.”

But apparently, we live in a 3D universe. Developers of the Emergence theory think they can project the 8D crystal to 3D and 4D spacetime.

In other words, the Emergence theory posits that reality is a pixilated 3D projection from an 8D source (the E8 lattice).

Which Theory of Everything do you put stock in?