Could the Universe be a “donut”: New ways to measure the structure of space

As early as the 4th century B.C., Aristotle asked the question: is the universe infinite? The philosopher believed that the heavenly bodies moved in a circle around the Earth, which he thought was at the center of the universe. From this point of view, the Universe would have to be finite, as infinite space cannot have a center. Aristotle’s logic, though simplistic, posed a question that remains relevant even two millennia later.

Today, scientists still cannot say for sure whether the Universe is flat and boundless or whether its space has a finite shape, such as a sphere or a torus. However, modern research methods far surpass the insights of antiquity. Astrophysicists use space-based observations, mathematical models, and computer simulations to find the answer.

“Circles in the sky” technique

In 1998, scientists Neil Cornish, Glenn Starkman and David Spergel proposed the Circle in the Sky methodology. They hypothesized that if the universe had the topology of a three-dimensional torus, then light could travel along different routes and return to a single point. The detection of such “circles” in the cosmic microwave background (CMB), the remnants of the Big Bang, could confirm this hypothesis. However, studies using data from WMAP and Planck satellites have not detected such signals.

This may indicate that the Universe is either infinite or so large that our current observations only cover a small part of it. To overcome these limitations, the Compact research team, which includes scientists from seven countries, develops new approaches to the study of space topology.

Study of waves in the Universe

The idea forming the basis of the new methodology was proposed by mathematician Mark Kac back in 1966. It consists in using the analysis of the waves that left a trace in the structure of the Universe after the Big Bang. These waves were reflected in the variations of the CMB temperature. If the Universe has a specific topology, it can amplify certain frequencies and mute others.

Studying such frequencies will help determine the shape of the Universe. For example, the lack of temperature correlation in the CMB at large angular scales greater than 60 degrees may indicate that the Universe is finite in shape.

Further prospects

Compact researchers create models for different possible topologies, such as a 3D torus or sphere, and analyze the corresponding data. In addition to the CMB, they use information about the distribution of galaxies, which provides a more detailed three-dimensional picture of the Universe. The new maps, which will be obtained with the Euclid, Roman and Spherex telescopes, are expected to significantly improve the accuracy of the analysis.

While the likelihood of finding a definitive answer remains low, the researchers believe this work is important. If the topology of the Universe is found, it will be a breakthrough in our understanding of the cosmos.  If not, it could mean that the Universe is so large that its boundaries are beyond the reach of our observations.

Regardless of the outcome, such research will help us better understand the structure of space and solve a question that Aristotle called “extremely important to the search for truth.” 

Earlier we reported on the top 7 mysteries of the Universe.  

According to quantamagazine.org

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