Scientists have been trying for hundreds of years to understand what the universe really is. Recently, technologies have been developing, researchers are learning more about the world around them, and new theories are emerging about how everything works.
Some of them sound believable, while others sound insane. Today we will tell you about two of the strangest, but exciting, theories about the structure of the universe.
Why is the universe the way it is? Over the years, scientists have researched this issue and put forward many ideas that explain how the cosmos works and what awaits it in the future.
It is known that the Universe consists of clusters of galaxies. Each galaxy contains tens and hundreds of billions of stars with planets revolving around them, as well as huge gas and dust clouds.
There is also hypothetical dark matter and dark energy, which are responsible for the expansion of the universe. However, some scientists believe that everything is much more complicated.
According to the theory put forward in 1993, the universe is actually a huge holography. The concept is reminiscent of Plato’s cave allegory. According to the holographic principle, all matter contained in a certain area of space can be represented as a “hologram” – information that is located on the border of this area.
The principle was first proposed by the Dutch theoretical physicist Gerard’t Hooft, and the American professor of physics at Stanford Leonard Susskind combined his ideas with the previous ideas of Hooft and professor of physics at the University of Florida Charles Thorne, proposing string theory.
The holographic principle of the Universe itself was born from a discussion of the thermodynamics of black holes – Leonard Susskind wrote about this in detail in the book “The Black Hole War: My Battle with Stephen Hawking to Make the World Safe for Quantum Mechanics“.
The idea is that all information that once fell into a black hole (and there should be a lot of it there and, according to the law of conservation of energy, it cannot simply disappear) is duplicated on the event horizon.
When something falls into a black hole, it stays there forever and becomes distorted beyond recognition. As a result, all information is stored in an unreadable form.
This statement is based on a fundamental physical principle. It is thanks to Susskind that the holographic principle resolves the black hole information paradox (at least within the framework of string theory).
This is how the idea of a holographic black hole was born, which stores information about three-dimensional objects falling into it on a two-dimensional event horizon. Then the scientists went further – they suggested that in general any information in any volume can be recorded on the surface that limits this volume.
If we are talking about information from a black box, then it is written on the walls of a black box, if information about the solar system, then it can be written on an imaginary sphere around it, and data about everything that happens in the universe is recorded on its border.
This does not require any specific boundaries, because this is a theoretical principle. To summarize, it says that all information and processes that occur on a piece of space is equal to some kind of record on the border of this volume.
The theory of the holographic universe assumes that everything that a person sees hears. feels and observes, it can be both reality and a “holographic” 3D projection of 2D recordings on the “wall that surrounds the Universe.” Quotes are very important here – holography is not like the one we are used to, it is just a similar principle. And, of course, the world is not surrounded by a real wall, it is imaginary, like the equator on a globe.
While this idea sounds crazy, it is a scientifically testable theory. Scientists conducted the study in 2017. An international team of cosmologists from Canada, Great Britain and Italy has received evidence supporting the theory of the holographic universe.
Cosmologists used a two-dimensional model of the Universe, which, based on previously observed parameters, was able to accurately reproduce the picture of the microwave background – thermal radiation uniformly filling space. The results obtained testify in favor of the applicability of the holographic principle, although so far they do not refute the standard cosmological models.
The universe is a superfluid liquid
Even if space has only three dimensions, there is still a fourth dimension in the form of time. That is why it is theoretically possible to visualize the Universe that exists in four-dimensional space-time.
In 1905, Einstein, in his theory of relativity, was the first to suggest that space and time can be related. At the same time, the very term “space-time” was invented only three years later, its author – mathematician Herman Minkowski. “From now on, time in itself and space in itself become an empty fiction, and only their unity preserves the chance for reality,” he said at a colloquium in 1908.
According to some theories, such as those proposed by Italian physicists Stefano Liberati and Luca Macchione, spacetime is not just an abstract frame of reference containing physical objects such as stars and galaxies. Italian scientists believe that it is a physical substance in itself, analogous to an ocean full of water.
Just as water is made up of countless molecules, according to theory, spacetime is made up of microscopic particles at a deeper level of reality.
In general, the very idea that space-time behaves like a liquid, the newest – the theory of “superfluid vacuum” was proposed more than half a century ago. But Italian researchers were the first to question the viscosity of such a liquid.
How everything moves in the universe is one of the mysteries in physics. For example, a wave propagates through water, using it as a “medium” to move. Energy transfer requires a medium, but how do electromagnetic waves and, for example, photons move in space, where there seems to be nothing?
Liberati and Macchione proposed a solution to the problem – they developed a theory of superfluid space. According to her, the universe consists of a superfluid liquid with zero viscosity, which behaves as a whole. Superfluid is a liquid that can flow indefinitely without losing energy. This is not a fictional concept, such liquids actually exist.
Superfluidity is the phase of a substance into which liquids or gases pass when they cool down to temperatures near absolute zero. In this state, the atoms lose their individual properties and behave like a single super-atom. The most famous superfluid liquid is helium, but only cooled to 2 K (Kelvin) or –271.15 ℃.
Superfluids have several unique properties. They can, for example, climb the walls of an open vessel and “escape” from it. At the same time, they simply cannot be heated – they transfer heat perfectly. Superfluid liquid will simply evaporate when heated.
The theory visualizes space-time as a superfluid with zero viscosity. A strange property of such liquids is that they cannot be made to rotate “in bulk”, as an ordinary liquid “works” when stirred. They break up into tiny vortices. In 2014, scientists figured out that these quantum “tornadoes” in the early universe explain the origins of galaxies.
The future of the universe
Many scientists – physicists, mathematicians, astronomers – are working on the creation of such global and strange theories. All these disciplines are united by cosmology.
As a science, cosmology is only a hundred years old, but it already knows a lot about how our Universe works – how everything that surrounds us was formed, from atoms to galaxies, how it all began and how it will end.
Different theories explain the world in their own way. Perhaps one day scientists will come to a common answer.