Scientists found similarities in the workings of two systems completely different in scale – the network of neuronal cells in the human brain and the cosmic web of galaxies.
Researchers studied the two systems from a variety of angles, looking at structure, morphology, memory capacity, and other properties. Their quantitative analysis revealed that very dissimilar physical processes can create structures sharing levels of complexity and organization, even if they are varied in size by 27 orders of magnitude.
The unusual study was itself carried out by Italian specialists in two very different fields – astrophysicist Franco Vazza from the University of Bologna and neurosurgeon Alberto Feletti from the University of Verona.
"The tantalizing degree of similarity that our analysis exposes seems to suggest that the self-organization of both complex systems is likely being shaped by similar principles of network dynamics, despite the radically different scales and processes at play," wrote the scientists in their new paper.
One of the most compelling insights of the study involved looking at the brain's neuronal network as a universe in itself. This network contains about 69 billion neurons. If you're keeping score, the observable universe has a web of at least 100 billion galaxies.
Another similarity is the defined nature of their networks–neurons and galaxies–that have nodes connected by filaments. By studying the average number of connections in each node and the clustering of connections in nodes, the researchers concluded that there were definite "agreement levels" in connectivity, suggesting the two networks grew as a result of similar physical principles, according to Feletti.
Section of the human brain (left) and a simulated section of the cosmos (right).
Credit: University of Bologna
There are also interesting comparisons when it comes to the composition of each structure. About 77 percent of the brain is water, while about 70 percent of the Universe is filled with dark energy. These are both passive materials that have indirect roles in their respective structures.
On the flip side of that, about 30 percent of the masses of each system is comprised of galaxies or neurons.
The scientists also found an uncanny similarity between matter density fluctuations in brains and the cosmic web.
"We calculated the spectral density of both systems. This is a technique often employed in cosmology for studying the spatial distribution of galaxies," Vazza said in a press release. "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."
Check out the new study "The Quantitative Comparison Between the Neuronal Network and the Cosmic Web", published in Frontiers in Physics.
Michio Kaku: Consciousness Can be Quantified | Big Think
"Believe it or not, sitting on our shoulders is the most complex object that Mother Nature has created in the known universe. You have to go at least 24 trillion miles to the nearest star to find a planet that may have life and may have intelligence. And yet our brain only consumes about 20-30 watts of power and yet it performs calculations better than any large supercomputer." - Michio Kaku
The Milky Way, the galaxy that contains our Solar System, is estimated to be about 13.6 billion years old. But what was there before? A loaded question that scientists are getting closer to answering. A team of astrophysicists reconstructed the cosmic ancestry of our galaxy. They figured out its family tree by using artificial intelligence to analyze globular clusters that orbit the Milky Way.
Globular clusters are collections of up to a million stars, almost as old as the Universe itself. Over 150 clusters of this kind are present in the Milky Way. Scientists believe that many of them were created in smaller galaxies that merged to form our galaxy. Astronomers treat them as "fossils" for reverse engineering the history of our home in space. The latest study allowed the research team to do exactly that.
The group led by Dr. Diederik Kruijssen from the University of Heidelberg (ZAH) and Dr. Joel Pfeffer from Liverpool John Moores University modeled the merger story of the Milky Way. They designed sophisticated computer simulations called E-MOSAICS to represent a complete model of the creation, evolution and demise of globular clusters. The researchers linked ages, the chemistry, and orbital motions of these clusters to the composition of the preceding galaxies that formed them, over 10 billion years ago. The analysis allowed the scientists to pinpoint how many stars the progenitor galaxies had as well as when their merger forming the Milky Way took place.
"The main challenge of connecting the properties of globular clusters to the merger history of their host galaxy has always been that galaxy assembly is an extremely messy process, during which the orbits of the globular clusters are completely reshuffled," Kruijssen pointed out.
Check out how E-MOSAICS simulations shows the formation of a galaxy like the Milky Way:
Once they trained their artificial neural network to investigate the galactic merger history, the researchers "tested the algorithm tens of thousands of times on the simulations and were amazed at how accurately it was able to reconstruct the merger histories of the simulated galaxies, using only their globular cluster populations," according to Kruijssen.
To dive deep into the prehistory of our galaxy, the researchers directed their AI to study global clusters that they suspected were formed in the progenitor galaxies. The orbital motion of the clusters informed their predictions. The AI was able to pinpoint the masses of the stars and the details of the mergers with great precision. It also discovered a collision 11 billion years ago between the Milky Way and a mysterious galaxy the scientists evocatively dubbed "Kraken."
Credit: D. Kruijssen / Heidelberg University
Galaxy merger tree of the Milky Way. The main progenitor of the Milky Way is shown by the trunk of the tree, with color representing its stellar mass. Black lines show the five identified satellites. Grey dotted lines demonstrate other mergers that the Milky Way likely underwent, but could not be connected to a particular progenitor. From left to right, the six images at the top list the identified progenitor galaxies: Sagittarius, Sequoia, Kraken, the Milky Way's Main progenitor, the progenitor of the Helmi streams, and Gaia-Enceladus-Sausage.
Kruijssen called this collision with Kraken "the most significant merger the Milky Way ever experienced." This event would have superseded the collision with the Gaia-Enceladus-Sausage galaxy of 9 billion years ago and was likely much more transformative, since our galaxy at that time was four times less massive.
Overall, the researchers think the Milky Way consumed about five galaxies of over 100 million stars, as well as 15 galaxies with 10 million stars or more. The scientists hope their findings will be used to locate debris from all of our galactic ancestors.
Check out their study "Kraken reveals itself – the merger history of the Milky Way reconstructed with the E-MOSAICS simulations" published in Monthly Notices of the Royal Astronomical Society.
Dark matter is believed to be important stuff, the glue that holds together the dust, gas, and stars that make up galaxies. It's the organizing force for the universe's large-scale structure, the shape you'd see if you were able to zoom way, way out, and it comprises most of a galaxy's mass.
We don't know precisely what dark matter is, since it doesn't emit or reflect light, or absorb it for that matter, rendering it invisible to our instruments. However, we can see what dark matter does, insofar as light from objects behind dark matter warps and is magnified as it makes its way toward us. That visual distortion is referred to as dark matter's "lensing" effect, as it's similar to what you might see passing a magnifying glass over an object.
Now a new study of images from the Hubble Space Telescope combined with spectra from the European Southern Observatory's Very Large Telescope (VLT) in Chile finds that there's either a lot more dark matter than computer models predict, or there's a major puzzle piece missing from what we thought we knew about dark matter's behavior.
A trio of intriguing galaxy clusters
The three galaxy clusters imaged for the study
The discrepancy has to do with images of three galaxy clusters captured by Hubble's Wide Field Camera 3 and Advanced Camera for Surveys as part of two Hubble projects: The Frontier Fields and the Cluster Lensing And Supernova survey with Hubble (CLASH) programs. The three clusters are called MACS J1206.2-0847, MACS J0416.1-2403, and Abell S1063.
Such imagery can be used for authenticating — or exposing flaws in —predictive computer models of dark matter's behavior, locations, and concentrations.
Lead author Massimo Meneghetti of the INAF-Observatory of Astrophysics and Space Science of Bologna, Italy, says that "galaxy clusters are ideal laboratories in which to study whether the numerical simulations of the Universe that are currently available reproduce well what we can infer from gravitational lensing."
Mapping dark matter
The assumption has been that the greater the lensing effect, the higher the concentration of dark matter.
As scientists analyzed the clusters' large-scale lensing — the massive arc and elongation visual effects produced by dark matter — they noticed areas of smaller-scale lensing within that larger distortion. The scientists interpret these as concentrations of dark matter within individual galaxies inside the clusters.
The researchers used spectrographic data from the VLT to determine the mass of these smaller lenses. Pietro Bergamini of the INAF-Observatory of Astrophysics and Space Science in Bologna, Italy explains, "The speed of the stars gave us an estimate of each individual galaxy's mass, including the amount of dark matter." The leader of the spectrographic aspect of the study was Piero Rosati of the Università degli Studi di Ferrara, Italy who recalls, "the data from Hubble and the VLT provided excellent synergy. We were able to associate the galaxies with each cluster and estimate their distances."
This work allowed the team to develop a thoroughly calibrated, high-resolution map of dark matter concentrations throughout the three clusters.
But the models say...
However, when the researchers compared their map to the concentrations of dark matter computer models predicted for galaxies bearing the same general characteristics, something was way off. Some small-scale areas of the map had 10 times the amount of lensing — and presumably 10 times the amount of dark matter — than the model predicted.
"The results of these analyses further demonstrate how observations and numerical simulations go hand in hand," notes one team member, Elena Rasia of the INAF-Astronomical Observatory of Trieste, Italy. Another, Stefano Borgani of the Università degli Studi di Trieste, Italy, adds that "with advanced cosmological simulations, we can match the quality of observations analyzed in our paper, permitting detailed comparisons like never before."
"We have done a lot of testing of the data in this study," Meneghetti says, "and we are sure that this mismatch indicates that some physical ingredient is missing either from the simulations or from our understanding of the nature of dark matter." Priyamvada Natarajan of Yale University in Connecticut agrees: "There's a feature of the real Universe that we are simply not capturing in our current theoretical models."
Given that any theory in science lasts only until a better one comes along, Natarajan views the discrepancy as an opportunity, saying, "this could signal a gap in our current understanding of the nature of dark matter and its properties, as these exquisite data have permitted us to probe the detailed distribution of dark matter on the smallest scales."
At this point, it's unclear exactly what the conflict signifies. Do these smaller areas have unexpectedly high concentrations of dark matter? Or can dark matter, under certain currently unknown conditions, produce a tenfold increase in lensing beyond what we've been expecting, breaking the assumption that more lensing means more dark matter?
Obviously, the scientific community has barely begun to understand this mystery.
Given the mounting crises of 2020, wouldn't it be nice to just get on a giant spaceship and leave this troubled planet behind? While we don't yet have a surefire candidate for the new Earth, and our tech is probably still decades if not centuries behind, proposals and achievements in interstellar travel are stacking up. A new study makes the fascinating case that if a group of humans were to venture out on a space journey that lasted generations, their language would likely change. It could evolve into something the people of the original Earth would not understand.
Let's say a contingent of people boards a so-called "generation ship," a fully-stocked world-onto-itself spacecraft that can sustain generations of humans in space, slowly traversing the heavens towards another possibly inhabitable planet like Proxima b in the Proxima Centauri star system. We cannot yet build such a ship (which might have to fly for thousands of years) unless we invent some type of warp-drive or use antimatter as has been imagined in science fiction, but there have been some initial studies on the subject.
Cylindrical space colony
Credit: NASA Ames Research Center
Such a journey could be subject to a variety of dangers and unforeseen circumstances like viruses, asteroids, computer malfunctions, you name it. New research, carried out by linguistics professors Andrew McKenzie from the University of Kansas and Jeffrey Punske of Southern Illinois University, shows what might also happen is that the language of the travelers would mutate. The study highlights the fact that when communities become isolated from each other, conditions are ripe for language to transform. Over time, the spacefaring colonizers would not be able to understand their original language.
In the study, the linguists use examples of effects from long-distance voyages on Earth, like the changing languages of Polynesian island explorers, to show how much language can change, even within one's lifetime.
Professor McKenzie described a likely (and somewhat sad) scenario in a press release:
"If you're on this vessel for 10 generations, new concepts will emerge, new social issues will come up, and people will create ways of talking about them," McKenzie explained, "and these will become the vocabulary particular to the ship. People on Earth might never know about these words, unless there's a reason to tell them. And the further away you get, the less you're going to talk to people back home. Generations pass, and there's no one really back home to talk to. And there's not much you want to tell them, because they'll only find out years later, and then you'll hear back from them years after that."
What might also happen is that the language of people on Earth would change. So it's possible, given the distance, and the dwindling reasons to communicate, that both parties might simply not be able to speak to each other as time passes.
One way to prevent this issue – have a member of the crew trained in linguistics or make other accommodations to remember the language of Earth. Thinking even further ahead, the professors propose that each new ship of people coming over to a faraway space colony would essentially contain "linguistic immigrants" and an effort would have to be made to train them in the changed language to help them avoid discrimination.
In case you're deadset on going to Proxima b, recent research found that using currently imaginable tech, such a trip would take 6,300 years and would need to start out with a crew of at least 98 people.
Check out the study, "Language Development During Interstellar Travel" in Acta Futura, the journal of the European Space Agency's Advanced Concepts Team.
