“What is it made of space-time?” asks physicist Aron wall from the Stanford Institute for theoretical physics. In the past there is no physics in different ways trying to make sense of the riddle of space-time, treating it not just as an empty background on which unfolds the history of the Universe, but rather as a stream of quantum information, flowing from one point to another. Wall and his colleagues are increasingly convinced that such a representation of space-time can be the key to developing theory that can explain gravity using quantum mechanics. About this dream of physicists since the days of albert Einstein.

Peter Zenczykowski from the Institute of nuclear physics, Polish Academy of Sciences asks the same question as the wall. Whether space-time is absolute, unchanging, eternal and always present an arena in which the unfolding events? Or perhaps it is the dynamic creation that occurs as if on a scale of distances, time, or energy? The mention of the absolute is not welcome in modern physics. It is believed that the space-time emergence, that is, occurs somewhere. It is not clear where.

## What is space-time?

Most physicists believed that the structure of space-time is generated mysteriously within the Planck scale, i.e. at scales close to one trillion from a trillionth of a meter. However, there are some beliefs, which question the certainty of this interpretation. There are many arguments in favor of the fact that the origin of space-time may occur as a result of processes that are much closer to our reality: at the level of quarks and their conglomerates.

“Math is the one related with the real world — other”, says Zenczykowski. “For example, the magnitude of the Planck mass seems suspicious. One would expect that it will have a value more characteristic of the world of quanta. Meanwhile, it corresponds to about 1/10 of the mass of the fleas, which definitely is a classic object.”

Most physicists tend to assume that space-time is created at the Planck scale, at distances close to one trillion trillionth of a meter (~10^{-35} m). In his article in Foundations of Science Zenczykowski sistematizirovat observations of different authors regarding the formation of space-time and argues that the hypothesis of its formation at the scale of quarks and hadrons (quark or aggregates) is quite reasonable for a number of reasons.

Questions about the nature of space and time has puzzled mankind since ancient times. Can time be separate from matter, creating a “container” for the movements and events that take place with the participation of particles, as suggested by Democritus in the 5th century BC? Or, perhaps, all the attributes of matter and cannot exist without it, as suggested by Aristotle a century later?

Despite the fact that it’s been a thousand years since then, these issues are still not resolved. Moreover, both approaches — despite their obvious difference is deeply rooted in the pillars of modern physics. In quantum mechanics, events occur on the hard arena with evenly current time.

Meanwhile, in the General theory of relativity, matter deforms the elastic space-time (stretches and twists it), and space-time tells particles how to move. In other words, one of the theories the actors take on the already prepared stage to play their roles, and in the other they create the stage during the performance, which in turn affects their behavior.

In 1899, German physicist Max Planck noticed that under certain combinations of certain constants in nature to the most fundamental units of measurement. Just three constant — the speed of light c, gravitational constant G and Planck’s constant h — and we get units of distance, time and mass are equal (respectively) of 1.62 x 10^{-35} m of 5.39 x 10^{-44} s and is 2.18 x 10^{-5} g. According to current belief, space-time is born at the Planck length. But there are no significant arguments in favor of the rationality of this hypothesis.

As our most complex experiments and theoretical descriptions of reach scale of quarks to the level of 10^{-18} m. we know that on the way to the Planck length — over a dozen consistent and even smaller orders of magnitude — space-time acquires its structure? We don’t even know rationally whether the concept of space-time at the level of hadrons! The division cannot take place forever, because at some stage the issue of the next smaller part simply ceases to have meaning. A perfect example would be temperature. This concept is well on macro scales, but successive divisions of matter, we reach the scale of individual particles and the concept of temperature loses its meaning.

“Currently, we first aim to build a discrete quantized space-time and then “inhabit” it a discrete matter. But if space-time is a product of quarks and hadrons, the dependence is reversed: the discrete property of matter should enhance the discreteness of space-time,” says Zenczykowski and adds: “Planck was based on math. He wanted to create a unit of the smallest possible constant. But math is one thing, but a relationship with the real world more. The value of the Planck mass seems suspicious. One would expect that it would be more suitable feature for world of quanta. But it corresponds to about 1/10 of the mass of the fleas, which definitely is a classic object.”

Since we want to describe the physical world, we have to rely on physical rather than mathematical arguments. And so, when we use the equations of Einstein, we describes the Universe on a large scale and there is a need to introduce additional gravitational constant, known as cosmological constant “lambda”. If, during the construction of the fundamental units, to extend our original set of three constant lambda, in the case of mass, we get not one, but three fundamental values of 1.39 x 10^{-65} grams of 2.14 x 10^{56} g and 0.35 x 10^{-24} g. the First can be interpreted as the quantum of mass, the second — level mass of the observable Universe, and the third is reminiscent of the mass of hadrons (for example, the mass of neutron is 1.67 x 10^{-24}. Similarly, whereas the lambda, there will be a unit of measurement of 6.37 x 10^{-15} m, very close to the size of hadrons.

“Games with constant can be risky, because a lot depends on which constants we choose. For example, if space-time really was a product of quarks and hadrons, the properties including the speed of light must also be emergent. This would mean that the speed of light may not be among the main constants,” said Sentowski.

Another factor in favor of the formation of the space-time scale of quarks and hadrons are themselves properties of elementary particles. The standard model, for example, does not explain why there are three generations of particles, where their masses or why there are so-called inner quantum numbers, which include the isospin, hypercharge and color. In the film, presented by Professor Zenczykowski, these values can be associated with a particular six-dimensional space created by the particle positions and their momenta. Thus constructed space equally respect the position of the particles (matter) and their movements (processes). It turns out that the properties of mass or internal quantum numbers, which can be a consequence of the algebraic properties of six-dimensional space. Moreover, these properties also explain the impossibility to observe free quarks.

“The emergence of space-time may be associated with changes in the organization of matter, occurring at the scale of quarks and hadrons in primary six-dimensional phase space. However, it is not clear what to do next with this picture. Each subsequent step will require going beyond what we know. And we don’t even know the rules of the game which Nature plays with us, we still have to guess them. However, it seems reasonable that all structures begin with the matter because it is physically and experimentally accessible. In this approach, space-time will only be our idealization of the relations between the elements of matter”, summarizes Professor Zenczykowski.

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