One of the main tasks of theoretical physics today is to find the answer to the question of whether higher dimensions exist. Is space really only composed of length, width and height, or is it just the limitation of human perception? For millennia, scientists strongly rejected the idea of the existence of multidimensional space. However, the scientific and technological revolution has changed a lot, and today science is no longer so categorical in the matter of higher dimensions.
What is the essence of the concept of "multidimensional space"?
Man lives in a world that consists of three dimensions. The coordinates of any object can be expressed in three values. And sometimes two - if we are talking about what is on the surface of the Earth.
By means of length, width and height, it is possible to describe both earthly objects and celestial bodies - planets, stars and galaxies. They are also enough for the things that inhabit the microworld - molecules, atoms and elementary particles. The fourth dimension is considered time.
In multidimensional space there must be at least five dimensions. Modern theoretical physics has developed many theories for spaces with different dimensions - up to 26. There is also a theory that describes a space with an infinite number of dimensions.
From Euclid to Einstein
The physicists and mathematicians of Antiquity, the Middle Ages and the New Age categorically denied the possibility of the existence of higher dimensions. Some mathematicians even deduced the justification of the limitedness of space by three parameters. Euclidean geometry assumed only three dimensions.
Before the advent of the general theory of relativity, scientists generally considered multidimensional space to be an object unworthy of the study and advancement of theories. When Albert Einstein formulated the concepts of space-time, combining the three dimensions with the fourth, temporal, certainty in this matter immediately disappeared.
The theory of relativity proves that time and space are not separate and independent things. For example, if astronauts board a ship that will move at high speed for a long time, then upon returning to Earth, they will be younger than their peers. The reason is that less time will pass for them than for people on Earth.
The Kaluza-Klein Theory
In 1921, the German mathematician Theodor Kaluza, using the equations of the theory of relativity, created a theory that first combined gravity and electromagnetism. According to this theory, space has five dimensions (including time).
In 1926, the Swedish physicist Oscar Klein deduced the fifth-dimensional invisibility justification described by Kaluza. It consisted in the fact that the higher dimensions are compressed to an incredibly small value, which is called the Planck one and amounts to 10 -35 . Subsequently, this formed the basis of other theories of multidimensional space.
String theory
This direction of theoretical physics is by far the most promising. String theory claims to be the title of what physicists have been looking for since the advent of the general theory of relativity. This is the so-called theory of everything.
The fact is that two fundamental physical principles - the theory of relativity and quantum mechanics - are in unsolvable contradiction with each other. The theory of everything is a hypothetical concept that could explain this paradox. In turn, string theory is more suitable for this role than others.
Its essence is that at the subatomic level of the structure of the world, particles oscillate, similar to the vibration of ordinary strings, for example, violins. Hence the theory got its name. Moreover, the sizes of these strings are extremely small and fluctuate in the region of the Planck length - the same one that appears in the Kaluza-Klein theory. If you increase the atom to the size of a galaxy, then the string will reach only the size of an adult tree. String theory only works in multidimensional space. Moreover, there are several versions of it. Some require 10-dimensional, while others require 26-dimensional space.
At the time of its emergence, string theory was perceived by physicists with great skepticism. But today it is the most popular, and many theoretical physicists are engaged in its development. However, it is not yet possible to experimentally prove the theory.
Hilbert space
Another theory that describes higher dimensions is Hilbert space. He was described by the German mathematician David Hilbert while working on the theory of integral equations.
Hilbert space is a mathematical theory that describes the properties of Euclidean space in infinite dimension. That is, it is a multidimensional space with countless dimensions.
Hyperspace in Fiction
The idea of a multidimensional space resulted in many science fiction plots - both literary and cinematic.
So, in Dan Simmons’s tetralogy, “Songs of Hyperion,” mankind uses a network of hyperspace null portals capable of instantly transporting objects over long distances. In Robert Heinlein’s Star Troopers novel, soldiers also use hyperspace to move around.
The idea of hyperspace flights has been used in many films of the space opera, including the famous Star Wars saga and the Babylon 5 series.
The plot of the film "Interstellar" is almost completely tied to the idea of higher dimensions. In search of a suitable planet for colonization, the heroes travel in space through wormholes - a hyperspace tunnel leading to another system. And towards the end, the main character enters the world of multidimensional space, with the help of which he manages to convey information to the past. The film also clearly shows the relationship of space and time, deduced by Einstein: for astronauts, time goes slower than for characters on Earth.
In the movie Cube 2: Hypercube, the heroes find themselves inside a tesseract. So in the theory of higher dimensions is called a multidimensional cube. In search of a way out, they fall into parallel universes, where they meet their alternative versions.
The idea of multidimensional space is still fantastic and unproven. However, today it is much closer and more real than several decades ago. It is quite possible that in the next century, scientists will find a way to travel in higher dimensions and, therefore, travel in parallel worlds. Until then, people will fantasize a lot on this subject, making up amazing stories.