“Science is not only compatible with spirituality; it is a deep source of spirituality. When we see our place in an infinity of light years and through the centuries, when we grasp the complexity, beauty, and subtlety of life, then that floating feeling, that sense of elation and humility together is certainly spiritual. “- Carl Sagan" The demon-haunted world ".
As I learned about the universe, I felt these spiritual moments as I understood my connection to everything else better. When I first learned that I was literally made out of the ashes of the stars – the atoms in my body spread through supernovae in the eternal ether. Another spiritual moment was seeing this picture for the first time:
Hippocampal mouse neuron with synaptic connections (yellow), courtesy of Lisa Boulanger, from https://www.eurekalert.org/multimedia/pub/81261.php. The green central cell body is? 10 µm in diameter. B. Cosmic Web (Springel et al., 2005). Scale bar = 31.25 Mpc / h or 1.4 × 1024 m. Contrast inspired by Lima (2009).
A neuron in the brain next to galaxy clusters and their interconnected filaments of matter and dark matter. The similarity is immediately clear. The implication? You may have a whole universe in your head. But the similarity between the images could simply be a case of apophenia – perceiving similarity where in fact there is none. Given the huge difference in size between them, how can these two things be similar? But what if an objective measurement beyond the visual similarity between the networks of neurons in the brain and the networks of galaxies in the cosmos could compare how similar they really are? Franco Vazza (astrophysicist at the University of Bologna) and Alberto Feletti (neurosurgeon at the University of Verona) wanted to find out, in order to combine both disciplines for a publication in "Frontiers of Physics".
An intergalactic connection
The human brain is literally one of the most complex structures in the universe – which is itself the greatest of all complexities. Your brain has approximately 80 billion neurons – the cells that process input from the senses and send signals to your body through the nervous system. Neurons are also networked and communicate with each other through connections called axions and dendrites. There are on the order of 100 trillion connections between neurons that make up the neural network that makes who you are.
NGC 6888, the "Crescent Nebula", is said to resemble a giant brain in space
– Patrick Hsieh CC BY-SA 4.0
The universe is also networked. While we can think of space as objects separated by large portions of … well … space, this is not entirely the case. The universe we see with our scientific equipment is known as the "observable universe," which is about 90 billion light years in diameter and on the order of hundreds of billions to a few trillion galaxies. These galaxies, like our Milky Way, collections of billions of stars, are themselves grouped into galaxy clusters. Our Milky Way is part of the "local group" that includes the neighboring galaxies Andromeda and Triangulum as well as 50 other galaxies. These galaxies, in turn, are part of a larger group called the Virgo Supercluster. The space between groups and clusters is not empty, but houses connecting filaments of ordinary and dark matter that span millions of light years. In this way, the universe can be viewed as a vast network of galaxy clusters, all of which are interconnected in a similar way to neural networks in the brain. This network is called the Cosmic Web.
A simulation of the creation of the cosmic web from the beginning of time to the present
One universe in one universe
The research to find quantifiable similarities between the two networks was born in a partnership between neuroscience and astrophysics. Using techniques and tools from both disciplines, Vazz and Feletti examined these two networks to find quantifiable similarities that go beyond perceived visual similarity. Were these networks comparable and if so, what does that mean?
The researchers used 4 micrometer thick slices of the human cortex – the outer layer of the brain responsible for processing language, sensory information, thoughts, memory and awareness. These were compared to 25 megaparsec (1 parsec = approx. 3.26 light years) thick "slices" of the universe, which were taken from a computer-simulated volume of 1 million cubic megaparsec of space. The slices of the brain and the universe are relatively comparable in thickness, provided they are both 27 orders of magnitude different in size from each other.
Cosmic Web and Brain samples with 4x, 10x and 40x magnification
– Vazza F and Feletti A (2020)Left: Section of the cerebellum with 40 times the magnification factor obtained with electron microscopy (Dr. E. Zunarelli, Modena University Hospital); right: Excerpt from a cosmological simulation with an extension of 300 million light years on each side (Vazza et al. 2019 A & A).
Depending on the scale, the disks were examined – the similarity in structure was not always obvious. However, when the brain tissue was magnified 40 times, the researchers found similarities in structure. The 40-fold magnification corresponds to a scale of 0.01 to 1.6 mm in the brain and 1 to 100 megaparsec in the universe. Here the neural network appears like the galaxy clusters. In addition, the similarity of the networks can be measured objectively and compared using two techniques. The first is "network degree centrality" which measures the length of network links and the degree of connectivity in a given network. The nucleus or center of a neuron has a much smaller radius than the length of the connecting axes and dendrites. Similarly, galaxy clusters have a radius much smaller than the length of the connecting filaments. The second method for the objective comparison of both networks is the “clustering coefficient”, which quantifies the amount of structure next to each connection node (neuron or galaxy cluster) and compares this structure with a random point within the network. This comparison contrasts organization and randomness in both networks.
Vazza F and Feletti A (2020) Figure 3: “Upper fields: Enlarged details of the reconstructed connections between nodes for three examples of networks in our sample (blue lines, overlaid with the density contrast maps). Floor slabs: distributions of the cluster coefficient and degree centrality for all layers "
"How Big is the Universe" – Fraser Cain Universe Today
Using the techniques on these scales, Vazz and Feletti found "remarkable" similarities between the brain and the universe. They also found that the networks were more similar to each other than other biological and physical structures, including branches, the dynamics of cloud formation, or water turbulence. These other structures are fractal in nature. Fractal patterns repeat themselves and look the same regardless of the scale on which you observe them. In contrast, the universe looks completely different at smaller than at larger scales. Galaxies and solar systems do not resemble the cosmic web they create. The brain also no longer resembles the neural network when it is observed on different scales. The scaling itself could be important in creating these structures in terms of your organization.
The researchers conclude their results "suggest that similar network configurations can arise from the interaction of completely different physical processes, which leads to similar levels of complexity and self-organization despite the dramatic differences in the spatial scales of these two systems." In other words, networks like the brain and the universe can have a similar structure while being completely different in size and formed by different processes (gravity vs. biology). However, it is possible for something to develop and grow in a similar way.
This "Mandelbrot zoom" is a fractal pattern that looks similar regardless of the scale observed, in contrast to the brain and universe, which appear very different on different scales
The researchers found two other interesting similarities between the brain and the cosmic web. The first was composition ratios. The brain is 77% water, while the cosmic web is about 73% dark energy. Water and dark energy are not part of the network itself but are considered "passive material" or passive energy. The presence and ratio of passive material / energy could be important for the formation of these networks. A second fascinating similarity is that the amount of computer data required to map the simulated universe models is comparable to the theoretical memory limits of the human brain. Between 1 and 10 petabytes (1 petabyte = 1000 terabytes) of data are required to simulate the development of the observable universe on a scale in which the cosmic web becomes visible. The estimated total storage capacity of the human brain is around 2.5 petabytes. A person could then theoretically store a good part of the structure of the observable universe in his brain. What is even more amazing is that the cosmic web could theoretically store the dates of a lifetime of human experiences.
The Hubble image "eXtreme Deep Field" shows around 5,500 of the
most distant galaxies ever imaged. – NASA / ESA
In addition to similarities, there are differences between the cosmic web and the brain. While the brain samples used came from the cortex, the entire brain is not uniform. Different parts of the brain are structured for different purposes, while a key feature of the universe is its evenness in almost all directions. Connections between neurons in the brain are used to transmit sensory information, while connections in the universe transmit energy and matter alone. Vazz and Feletti hope their research will stimulate the development of more powerful algorithms to discover even more similarities between the brain and the universe. Perhaps we will get to know the conditions under which two networks that have emerged from completely different processes are so similar.
We've heard Carl Sagan describe how our body is literally made of stars. Now we are beginning to understand that our brain can also be structured like this. A whole universe of connections is in your head – a universe within a universe – and one is capable of reaching the other that made it. Billions of neurons touch billions of stars – certainly spiritually.
More to discover:
The actual simulated universe images used in the research: https://cosmosimfrazza.myfreesites.net/cosmic-web-and-brain-network-datasets
Is the human brain similar to the universe? | EurekAlert! Science news
Art exhibition above and below
Like your brain is like the cosmic web (nautil.us)
(2008.05942) Exploration of the connections between cosmos and spirit through six interactive art installations in "As above as below" (arxiv.org)
Ask Ethan: Does the universe live by itself? (forbes.com)
How big is the universe? – universe today
(astro-ph / 9512141) How filaments are woven into the cosmic web (arxiv.org)
Aquarius Dark Matter Simulation Video – ESO