One fascinating oddity of the universe is that shapes and patterns can be found in extremely different contexts: The Golden Spiral can be seen in human cochlea and the shape of a spiral galaxy; the fractal geometry of the veins echoed in the lightning branch.
In a bold new pilot study, an astrophysicist and a neurosurgeon came across it using quantitative analysis to compare two of nature’s most complex systems: the neural network in the human brain and the cosmic network of galaxies in the universe.
In fact, it’s not such a strange comparison. You may have seen an image shared from time to time, showing a human neuron and a simulated cluster of galaxies side by side; the two look strikingly similar.
But there is much more to the human brain – and the universe – than it looks.
So astrophysicist Franco Vazza of the University of Bologna in Italy and neurosurgeon Alberto Feleti of the University of Verona in Italy have spent the last few years investigating to see if the similarities are more than skin.
Writing in the Nautilus quarter of 2017, they explained:
“Galaxies can be grouped into huge structures (called clusters, super shelving, and filaments) that stretch for hundreds of millions of light-years. The boundary between these structures and adjacent areas of empty space called space cavities can be extremely complex.
Gravity accelerates matter at these limits to speeds of thousands of kilometers per second, creating shock waves and turbulence in intergalactic gases.
We predicted that the boundary between the cavity and the filament is one of the most complex volumes of the universe, measured by the number of bits of information needed to describe it.
This made us think: is it more complicated than the brain? “
The two types of structures differ in size by 27 orders of magnitude (this is a billion billion billion). But the team’s findings suggest that while the physical processes that drive the structure of the universe and the structure of the human brain are extremely different, they can lead to similar levels of complexity and self-organization, the researchers said.
The starting point was to develop similarities between the two. The human brain has about 69 billion neurons; the observed space network contains over 100 billion galaxies. This is one.
Both systems are arranged in well-defined networks, with nodes (neurons in the brain, galaxies in the universe) connected by threads.
Both neurons and galaxies have a typical scale radius, which is only part of the length of the strands. And the flow of information and energy between nodes is only about 25 percent of the mass and energy content of each system.
In addition, there are similarities between the composition of the brain and the composition of the universe. The brain is about 77 percent water. The universe is about 72 percent dark energy.
Both are obviously passive materials that penetrate their respective system and play only an indirect role in their internal structures.
With these defined similarities, the team undertook a quantitative comparison of the two based on images. They obtained slices of the human brain and cortex at various magnifications and compared them to space network simulations.
What they were looking for were similarities in the fluctuations in the density of matter between the brains and the cosmic network. And they found that the relative distribution of oscillations in the two systems was remarkably similar – albeit on very different scales.
“We calculated the spectral density of the two systems. This is a technique often used in cosmology to study the spatial distribution of galaxies,” Vase said.
“Our analysis showed that the distribution of oscillations in the neural network of the cerebellum at a scale of 1 micrometer to 0.1 millimeter follows the same progression of the distribution of matter in the cosmic network, but, of course, on a larger scale, which varies from 5 million to 500 million light-years. “
But that was not all.
The team examined other morphological characteristics, such as the number of threads attached to each node. The space network, based on a sample of 3,800 to 4,700 nodes, had an average of 3.8 to 4.1 connections per node. The human bark for a sample of 1,800 to 2,000 knots had an average of 4.6 to 5.4 knots per node.
In addition, both systems show a tendency to cluster connections around central nodes. Both seem to have similar information capacity.
A recent study suggests that the memory of the human brain is about 2.5 petabytes. Another recent Vazza study suggests that the memory capacity needed to store the complexity of the universe is about 4.3 petabytes.
“Roughly speaking,” researchers wrote in 2017, “this similarity in memory capacity means that the whole body of information stored in the human brain (such as a person’s entire life experience) can also be encoded in the distribution of galaxies in our universe. “
This does not mean that the universe is a brain or a capacity for consciousness. But it hints that the laws that govern the growth of the structures of both may be the same.
According to a 2012 simulation-based report, the causal network representing the large-scale structure of space-time in our accelerating universe is a degree graph very similar to the human brain.
Research such as that of Vaca and Feleti could pave the way for a better understanding of these laws.
“Once again, the structural parameters identify unexpected levels of agreement. The connection in the two networks is likely to follow similar physical principles, despite the striking and obvious difference between the physical forces governing galaxies and neurons,” Feleti said.
“These two complex networks show more similarities than those shared between the space network and the galaxy or neural network and the interior of a neuronal body.”
The study was published in Limits in physics.