An attempt like a theory of everything could imply both metaphysics and physics. When we say the theory of everything (ToE) in the field of physics, it means the ultimate idea that integrates all the fundamental laws for the physical universe, especially for the gap between general relativity and quantum mechanics.
On the other hand, for metaphysics, ToE is the stand of the Integral Approach, which is supposed to embrace the spectrum from body, mind, soul, and spirit.
ToE in physics seems highly technical at a glance, and yet the effort is boldly philosophical. In our physical universe, there are four fundamental forces permeated as far as our physical observation is concerned.
- Weak nuclear force
- Strong nuclear force
- Electromagnetic force
Traditionally, the force of gravity caught the initial attention of physicists and mathematicians; well-known is Issac Newton.
He wondered why the moon did not fall, while an apple in front of him did. The truth is that the moon falls, even everything in the entire universe “falls” due to gravitation. They only look like mutual interactions among them in the way they fall with a shape of the movement. The moon falls along with the form of the earth; hence, both can avoid a collision. To understand such shapes and interactions, Newton discovered calculus and the law of universal gravitation with the respective equations.
While the force of gravity was the primary attention of many scientists, they were not able to figure out its mechanism.
The other three (weak nuclear, strong nuclear, and electromagnetic) forces are more on the realm of quantum mechanics. The individual particles act as the messenger to control these forces. Ironically, because of this knowledge, we know how to utilize these forces from electricity to nuclear power.
On the other hand, we still don’t know how to control the force of gravity. Some physicists proposed the existence of the particle called “graviton.” Despite the luxury effort of using a particle accelerator at CERN, the answer is still unclear.
Another proposal to understand the force of gravity is Albert Einstein’s theory of relativity, especially the theory called general relativity.
In this theory, the gravitation is more like the shape of space itself; moreover, spacetime as such. If we simulate the realm of spacetime as a two-dimensional model, then any objects on this surface can move around according to the respective slope. Just like a piece of paper can bend, our spacetime could also change its form. Thus, the stronger the gravitation, the more bending the spacetime may be. Astronomer, Arthur Eddington observed this fact by gazing the star behind the sun on May 29, 1919, during the total eclipse.
According to modern physicists, however, there is still the significant chasm of ignorance between the first three fundamental (weak nuclear, strong nuclear, and electromagnetic) forces and the fourth one, which is the force of gravity.
First, the theory of general relativity can’t explain and provide the equation to those three forces derived from the particle messengers, while the idea of quantum mechanics can, even though there are some enigmatic interpretation like quantum superposition and the like. Secondly, on the other hand, quantum mechanics can’t cover the force of gravity since there is no such particle as a graviton, at least for now.
Thus, the effort of ToE is primarily to fill the gap between these two theories:
- General Relativity – the force is spacetime shaped
- Quantum Mechanics – the force is particle/wave mediated
Modern physicists and mathematicians are proposing a few approaches to fill this gap:
- String theory or M-theory
- Quantum gravity
The former is to revisit the concept of a primary particle. In the realm of sub-atomic particles, we see them as such an infinitely small point, that is to say, a substance of one-dimensional entity, which would be the cause of the problem.
String theory is the effort to see them not as a particle, but a sort of string. Likewise, M-theory is the effort to see it as a sort of two-dimensional entity. Still, the appropriate mathematical equation is in the search. If the equation is found, which would contribute to explaining the mystery of multiverse, before Big Bang, and the infinite gravity of black holes. The latter, quantum gravity, is, as mentioned above, the effort of finding a particle called a graviton. Those quantum researchers who work on this investigation also think that graviton is the key to the same mystery of the universe.