As I continue my study of the universe as a physicist, I find myself facing invisible walls. I have the arbitrary feeling that I have begun to scratch the first layer of the knowledge of the cosmic onion with my microscopic nails, yet already my nails are breaking, and I cannot easily dig deeper... Unfortunately, I lack the tools or even a companion capable of peeling off this onion together. On the other hand, we come into this world alone and we also leave alone, so perhaps only ourselves are the best company to solve the mystery of the universe.
Yet I have already encountered dead ends; I am not exactly the best at advanced mathematics, I have a specific mind with specific abilities, and solving quantum equations was never exciting for me, not even interesting. It was necessary. Fortunately, I do not deal with the mathematical part in what I analyze and think. I make simple physical considerations following a logical flow and nothing else.
Now, about the "quantum." What is it and how does it help us? In reality, it comes from the Latin "quantum," which means package and essentially describes how matter and energy can be divided into very small packages. For example, a very small package of light is the photon, a small package of electrical energy is the electron, and so on. They are mathematically statistical models that have emerged more through experiments in particle accelerators and less through answers to crucial questions of physics. That's why it's called quantum mechanics and not quantum physics, as many would like it to be called.
It has many positives; one of its basic features is that it tolerates the form of particles, and there's no terrible problem in considering them as spheres and imagining them that way. However, it also has some imperfections that need to be somehow covered up. Many imperfections are covered with improbable terminologies, such as why did particle X go from there when it should have gone from the other side? - Well, it's obvious: because it's purple and sad. Personally, such 'explanations' do not satisfy me (may God make them)...
The universe is made up of particles that interact by exchanging other particles. These particles describe the quantum world (if we can call it that). They are divided into 2 categories: fermions, which generally are responsible for matter, and bosons, which are responsible for interactions. However, what does this model not describe? Well, of course, my sorrow, the woman who is responsible for everything being in its place: gravity. On a large scale, macroscopically, curvature of spacetime is observed in bodies of large mass (see gravitational lenses in a previous article), but in the microcosm, since the theory states that gravity is a force, the particle responsible for it, the graviton, should exist. A particle we have been searching for a long time now. A particle that poses problems in the quantum mathematical model.
This is what string theory aims to solve. It suggests that particles are not tiny balls but rather small strings, threads, vibrating and divided into 2 categories: open strings and closed strings, like the 1 (open) and 0 (closed) of computers. Depending on their shape and vibration, they correspond to another particle. The remarkable thing is that some strings behave like the graviton particle.
In quantum mechanics, there is the possibility of finding a particle in a specific region/state. In the classical model, a particle is a point, so its trace in space is a line. However, in string theory, each string, as it travels, leaves a surface trace instead.
In the classical model, a particle traveling can interact with another particle by exchanging a third particle. This would leave behind 3 lines as traces, and of course, we would have to predict this. In string theory, however, it suffices to predict the geometric shapes of the surface traces that the string will cover during its motion, and we automatically have all possible interactions! Additionally, in classical theory, the emission of a photon, for example, is considered instantaneous, without the passage of even the slightest time (!), whereas in string theory, this doesn't exist. Every interaction has at least an infinitesimally small duration, allowing the theory to include the graviton in the string vibrations.
So why don't we use this theory then? It sounds very promising.
However, it has some flaws. All strings behave like bosons, and there are no strings predicted to behave like fermions. Additionally, the "tachyon" emerges. A separate particle with a mass square of -1... This implies imaginary mass! Finally, this theory works correctly in a universe of 26 dimensions. Ours, as far as we understand, only has 4 (3 spatial and 1 temporal).
f we add spin (rotation) to the strings, the existence of tachyons is not predicted, and the existence of fermions is predicted. How cool is that? Thus, we have the theory of superstrings! Which has another advantage: symmetry! It predicts an equal number of bosons and fermions (supersymmetry), and in general, we like a balanced, symmetric universe... Also, we've saved 16 dimensions, as the mathematics only predicts 10 dimensions 😅 in a universe of superstrings!
That's it for now... Because I like symmetry and prefer geometry over statistical models, I'm particularly drawn to the theory of superstrings. In the next article, I'll write down my thoughts on the "extra" 6 dimensions and how the universe we live in could indeed contain them.
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