Can we develop a theory in which space and time are not supposed to exist?

Over the past decade, a field of physics has developed that postulates the existence of mysterious algebraic entities called spinnets. These networks, proposed as constitutive elements of space and time, condensed to produce the Universe as we know it. That condensation resulted in the event we currently call Big Bang, giving the field its name: condensate cosmology.

It may sound like a strange idea, but we already know that the Universe works in very strange ways.

The idea, technically called “group field theory (GFT) condensate cosmology”, is a branch of quantum gravity, a field of physics that aims to lay the foundations of what is made of everything from light and matter up to space and time. It is an idea based entirely on theoretical calculations, and has not been tested for now. Condensate cosmology requires a great deal of abstract reasoning to even try to understand it.

Despite these challenges, quantum gravity has drawn the attention of some of the sharpest minds in all of physics. His ideas are daring and daring, highly creative and extraordinarily imaginative.

Why quantum gravity?

Quantum gravity has been formulated to tackle one of the biggest problems in all of physics: the need to unite the two great theories of the 20s^th century: general relativity and quantum mechanics.

The first presents a framework for understanding the world in terms of space and time, and covers behavior over long distances. General relativity introduces the notion that time is relative and that gravity itself exists due to a curved space-time. As Einstein first realized, a ball does not fall to Earth because it is attracted to its mass, as Newton told us; it falls due to the existence of a space-time field that permeates the Universe and curves around large objects.

Quantum mechanics is a mysterious but incredibly accurate theory that describes the world of the very small. It tells us that both particles and fields exist in discrete units that, due to uncertainty, can only be described probabilistically. The theory also describes entanglement, the puzzling phenomenon in which physical systems can become so intertwined with one another that they lose their individual and independent reality and begin to obey the rules that apply to a collective.

As far as we can see, these two theories are correct and in conflict. Its simultaneous existence generates a paradox, which means that physics is, in a certain sense, in disorder. Whereas quantum mechanics deals with reality in a discrete and granular way, relativity tells us that space-time, and therefore gravity, are continuous and not discrete.

One way to deal with this is to prioritize one of the theories. Since we know that the world is quantum, general relativity must be an approximation of an underlying quantum description of spacetime itself. And this suggests that any unification of theories requires that gravity become discrete.

LQG development

In recent decades, a branch of quantum gravity called Loop Quantum Gravity (LQG) has shown some potential to solve the challenge of making gravity discrete. LQG starts with Einstein’s field equations, but takes a closer look at what might be hidden beneath the surface of space-time. Mathematics produced countless discrete geometric objects, including loops, lattices, and polygons, arranged in various constructions called spin nets and spin foams. Together, they can describe the structure of reality itself: these LQG geometric oddities don’t exist. in space and time but are space and time and therefore the same components of gravity itself.

While recent progress has largely produced LQG, the idea has a long history. The dichotomy between general relativity and quantum mechanics became apparent during the 1920s.^th interwar period of the century. This generated approaches to quantum gravity that were developed by taking general relativity and using different methods to quantify it. But the focus of this problem changed during the 1970s and 1980s, when physicists began learning new things about semi-classical physics, according to Daniele Oriti, leader of the Heisenberg group at the Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-Universität in Munich.

Oriti told Ars that, at the time, emerging ideas about black holes focused on using quantum mechanics to describe the fields of matter around it. This work suggested that theorists might need a more radical approach to quantum gravity, rather than simply quantifying general relativity, a new way of understanding the nature of space-time at a microscopic level might be necessary.

These ideas derived from black holes suggested that the gravitational field itself is not really fundamental, regardless of whether it is classical or quantum. Instead, it became clear that the gravitational field could be a manifestation of something more fundamental, something that is not at all like a field and therefore cannot be described in a standard space-time manner.

New approaches to quantum gravity, like LQG, began to emerge during this period. In the 1990s through the 2000s, LQG gained a lot of credibility among a growing population of theoretical physicists. “One thing LQG accomplished was a precise suggestion of how space-time might look at a more fundamental level,” says Oriti. “It was discovered that, at least according to theory, the basic entities of space and time are nothing like the gravitational field as we know it. At LQG we call these basic entities spinnets, which are discrete and algebraic objects. “