Tim Childers Tue, November 17, 2020, From Popular MechanicsAn astrophysicist and neuroscientist teamed up to compare similarities between the universe and networks of neurons in the brain.
Despite the substantial difference in scale, the two complex systems are strikingly alike.
The researchers used a combination of methods from cosmology, neuroscience, and network analysis to quantitatively compare the two.
Describing the human brain as a 3-pound universe may be closer to the truth than we thought. When scientists looked at two of the most complex and fascinating structures known to science—the human network of neurons in your brain and the cosmic web of galaxies—the resemblance seemed uncanny.
And when astrophysicist Franco Vazza and neuroscientist Alberto Feletti crunched the numbers and compared the two structures numerically, the similarities become even more astounding. It might just make you think we're all living in one big simulation after all.
Your brain is made up of a complex network of nearly 100 billion neurons that form 100 trillion neural connections. Neurons are clustered into a hierarchical network of nodes, filaments, and interconnected neural clusters that shape the complex thoughts, feelings, and emotions you experience. But these neurons make up less than 25 percent the mass of your brain, leaving the remaining 75 percent as water.
In a bizarre coincidence, the observable universe also contains an estimated 100 billion galaxies. The teetering balance between the pull of gravity and the accelerated expansion of the universe forms a cosmic web of string-like filaments composed of ordinary and dark matter.
Clusters of galaxies form at the intersections of the filaments, leaving desolate gaps of empty space between them. The resulting image looks strikingly similar to a network of neurons. Strangely, scientists estimate only around 25 percent of the matter in the universe is visible. The remaining 75 percent is dark matter.
“Although the relevant physical interactions in the above two systems are completely different, their observation through microscopic and telescopic techniques have captured a tantalizing similar morphology, to the point that it has often been noted that the cosmic web and the web of neurons look alike,” Vazza and Feletti write in their paper, published in Frontiers in Physics.
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Despite these immediate similarities, the scientists wanted to take a more quantitative look at the two systems. So they used a method called power spectrum analysis, a technique often deployed in astrophysics to study the large-scale distribution of galaxies. They measured the strength of tiny fluctuations throughout a range of spatial scales of both a simulation of galaxies and sections of the cerebellum and cerebral cortex of a brain.
"Our analysis showed that the distribution of the fluctuation within the cerebellum neuronal network on a scale from 1 micrometer to 0.1 millimeters follows the same progression of the distribution of matter in the cosmic web but, of course, on a larger scale that goes from 5 million to 500 million light-years," Vazza, from the University of Bologna in Italy, said in a press release.
The researchers also compared the power spectra of other complex systems, including images of tree branches, clouds, and water turbulence, but none came close to matching the neuron and universe duo. However, power spectra don't give any hints into the complexity of systems. To do that, the scientists surveyed the networks of both systems, comparing the average number of connections per node and how these nodes clustered together.
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"Once again, structural parameters have identified unexpected agreement levels. Probably, the connectivity within the two networks evolves following similar physical principles, despite the striking and obvious difference between the physical powers regulating galaxies and neurons," Feletti, from the University of Verona in Italy, said in the press release.
It's rather impressive that the cosmic web of our visible universe may have more in common with the network of neurons in your brain than its individual galaxies and stars—or that the complex network of neurons in your cranium make a better pair with the cosmic web than the individual cells of the brain. However, these similarities only arise when researchers compare a specific scale of each system.
This is particularly important when comparing something infinite like the universe (as far as science can tell), to your very finite brain. Given that everything in our universe is operating off the same rules of physics, it's not hard to imagine similarities will arise if you look hard enough.
