Image source: Mike Rosecope/procy/Shutterstock/Big Think
- New findings in astronomy are making some astronomers doubt our basic model of the universe.
- Alignments of celestial objects suggest that they may be embedded in large-scale structures.
- Galaxies too far apart to be influencing each other are moving through space together.
Solidity is a function of magnification. We know that anything we experience as solid is actually a structure of atoms packed closely enough that to our eyes they appear to be a single solid thing. If we were small enough, we'd see the spaces between them; if we were even smaller, those spaces might seem vast. Likewise, in 1989 Margaret Geller and John Huchra, analyzing redraft survey data, discovered the immense "Great Wall," a "sheet" formed from galaxies many light years apart. That first large-scale structure is 500 million light-years long, 200 million light years wide, and with a thickness of 15 million light years.
Other gigantic large-scale structures been discovered since — sheets, filaments, and knots, with bubble-like voids intersperse among them. They appear to be connected by clouds and filaments of hydrogen gas and dark matter. Though the bodies that comprise the structures are not gravitationally bound to each other — the distances between them are too great — evidence is piling up that they are linked by something.
Recent observations indicate that galaxies far, far apart are somehow synchronously moving. Something appears to be binding large-scale structures, many light years apart, together after all. Is the currently accepted view of the universe as various clumps of material simply expanding outward from the Big Bang and gravitationally pulling on each other wrong?
Large-scale structures
The existence and mechanics of large-scale structures are a tantalizing puzzle with obviously major implications for our understanding of the universe. As Noam Libeskind, of the Leibniz-Institut for Astrophysics (AIP) in Germany tells VICE, "That's actually the reason why everybody is always studying these large-scale structures. It's a way of probing and constraining the laws of gravity and the nature of matter, dark matter, dark energy, and the universe."
The identification and study of large-scale structures is a product of analyzing and modeling simulations of redshift survey for specific regions of the sky that visually reveal these immense structures.
The large-scale structures revealed in one segment of sky
Image source: National Center for Supercomputer Applications by Andrey Kravtsov (The University of Chicago) and Anatoly Klypin (New Mexico State University). Visualizations by Andrey Kravtsov.
Billions of light years apart
Several pieces of research are causing interest in these large-scale structures to heat up. The most mind-blowingly distant synchronized motion was reported in 2014, when the rotation axes of 19 super-massive black holes at the centers of quasars — out of 100 quasars studied — were found to be in alignment, billions of light years apart. According to the study's lead author, astronomer Damien Hutsemékers of the University of Liège in Belgium, "Galaxy spin axes are known to align with large-scale structures such as cosmic filaments but this occurs on smaller scales. However, there is currently no explanation why the axes of quasars are aligned with the axis of the large group in which they are embedded."
The first word of the research paper's title, "Spooky Alignment of Quasars Across Billions of Light-years," invokes cosmic-scale quantum entanglement as a possible explanation.
Image source: orin/Shutterstock/Big Think
Galaxies of a feather
Astronomer Joon Hyeop Lee of the Korea Astronomy and Space Institute is the lead author of "Mysterious Coherence in Several-megaparsec Scales between Galaxy Rotation and Neighbor Motion," published in October of this year in Astrophysical Journal. Comparing data from two catalogs of redshift survey data — the Calar Alto Legacy Integral Field Area (CALIFA) and NASA-Sloan Atlas (NSA) catalogs — the researchers' analysis of 445 galaxies revealed, surprisingly, that galaxies six meparsecs, or 20 million light years, apart were moving in the same way. Those observed, for example, a galaxy moving toward the Earth was mirrored by other distant galaxies moving in the same direction.
"This discovery is quite new and unexpected," according to Lee, "I have never seen any previous report of observations or any prediction from numerical simulations, exactly related to this phenomenon."
Since the galaxies are too distant for their gravitational fields to be influencing each other, Lee poses another explanation: That the linked galaxies are both embedded within the same, large-scale structure.
Image source: sripfoto/Shutterstock/Big Think
Flatness
Another puzzle suggesting the influence of large-scale structures has become clear over recent years. It's been observed that galaxies surrounding our own Milky Way are weirdly arranged in a single, flat plane. Big-Bang thinking would suggest that they should be circling us at all different sorts of angles. Obviously, for adherents of that way of viewing the galaxy — known as the ΛCDM model — this at the very least a troubling anomaly.
The hope that it was an anomaly weakened with the discovery of the same thing occurring around the Andromeda galaxy, and then again around Centaurus A in 2015. By the time "A whirling plane of satellite galaxies around Centaurus A challenges cold dark matter cosmology" was published in 2018, the phenomenon was starting to seem quite common, and possibly universal. The idea that the satellite galaxies might part of a large-scale structure had become even worthier of serious consideration.
Just the beginning
As more astronomers embrace the notion of large-scale structures and related research accelerates, we can only hope that these perplexingly oddball movements and associations are eventually made clear. Certainly, imagining a vast arrangement of utterly gigantic structures in which galaxies are embedded paints a very different picture of the universe, and one that makes one wonder if these structures are themselves embedded in something even larger. In this mid-boggling case, we are indeed small enough to see only the space between objects — in this case galaxies. We've been no more aware of them than whatever it is that may be living between our own atoms.
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Image source: Christian Zimmerman/USGS/Big Think
Surprising Science
- A remote area visited by tourists and cruises, and home to fishing villages, is about to be visited by a devastating tsunami.
- A wall of rock exposed by a receding glacier is about crash into the waters below.
- Glaciers hold such areas together — and when they're gone, bad stuff can be left behind.
The Barry Glacier gives its name to Alaska's Barry Arm Fjord, and a new open letter forecasts trouble ahead.
Thanks to global warming, the glacier has been retreating, so far removing two-thirds of its support for a steep mile-long slope, or scarp, containing perhaps 500 million cubic meters of material. (Think the Hoover Dam times several hundred.) The slope has been moving slowly since 1957, but scientists say it's become an avalanche waiting to happen, maybe within the next year, and likely within 20. When it does come crashing down into the fjord, it could set in motion a frightening tsunami overwhelming the fjord's normally peaceful waters .
"It could happen anytime, but the risk just goes way up as this glacier recedes," says hydrologist Anna Liljedahl of Woods Hole, one of the signatories to the letter.
The Barry Arm Fjord
Camping on the fjord's Black Sand Beach
Image source: Matt Zimmerman
The Barry Arm Fjord is a stretch of water between the Harriman Fjord and the Port Wills Fjord, located at the northwest corner of the well-known Prince William Sound. It's a beautiful area, home to a few hundred people supporting the local fishing industry, and it's also a popular destination for tourists — its Black Sand Beach is one of Alaska's most scenic — and cruise ships.
Not Alaska’s first watery rodeo, but likely the biggest
Image source: whrc.org
There have been at least two similar events in the state's recent history, though not on such a massive scale. On July 9, 1958, an earthquake nearby caused 40 million cubic yards of rock to suddenly slide 2,000 feet down into Lituya Bay, producing a tsunami whose peak waves reportedly reached 1,720 feet in height. By the time the wall of water reached the mouth of the bay, it was still 75 feet high. At Taan Fjord in 2015, a landslide caused a tsunami that crested at 600 feet. Both of these events thankfully occurred in sparsely populated areas, so few fatalities occurred.
The Barry Arm event will be larger than either of these by far.
"This is an enormous slope — the mass that could fail weighs over a billion tonnes," said geologist Dave Petley, speaking to Earther. "The internal structure of that rock mass, which will determine whether it collapses, is very complex. At the moment we don't know enough about it to be able to forecast its future behavior."
Outside of Alaska, on the west coast of Greenland, a landslide-produced tsunami towered 300 feet high, obliterating a fishing village in its path.
What the letter predicts for Barry Arm Fjord
Moving slowly at first...
Image source: whrc.org
"The effects would be especially severe near where the landslide enters the water at the head of Barry Arm. Additionally, areas of shallow water, or low-lying land near the shore, would be in danger even further from the source. A minor failure may not produce significant impacts beyond the inner parts of the fiord, while a complete failure could be destructive throughout Barry Arm, Harriman Fiord, and parts of Port Wells. Our initial results show complex impacts further from the landslide than Barry Arm, with over 30 foot waves in some distant bays, including Whittier."
The discovery of the impeding landslide began with an observation by the sister of geologist Hig Higman of Ground Truth, an organization in Seldovia, Alaska. Artist Valisa Higman was vacationing in the area and sent her brother some photos of worrying fractures she noticed in the slope, taken while she was on a boat cruising the fjord.
Higman confirmed his sister's hunch via available satellite imagery and, digging deeper, found that between 2009 and 2015 the slope had moved 600 feet downhill, leaving a prominent scar.
Ohio State's Chunli Dai unearthed a connection between the movement and the receding of the Barry Glacier. Comparison of the Barry Arm slope with other similar areas, combined with computer modeling of the possible resulting tsunamis, led to the publication of the group's letter.
While the full group of signatories from 14 organizations and institutions has only been working on the situation for a month, the implications were immediately clear. The signers include experts from Ohio State University, the University of Southern California, and the Anchorage and Fairbanks campuses of the University of Alaska.
Once informed of the open letter's contents, the Alaska's Department of Natural Resources immediately released a warning that "an increasingly likely landslide could generate a wave with devastating effects on fishermen and recreationalists."
How do you prepare for something like this?
Image source: whrc.org
The obvious question is what can be done to prepare for the landslide and tsunami? For one thing, there's more to understand about the upcoming event, and the researchers lay out their plan in the letter:
"To inform and refine hazard mitigation efforts, we would like to pursue several lines of investigation: Detect changes in the slope that might forewarn of a landslide, better understand what could trigger a landslide, and refine tsunami model projections. By mapping the landslide and nearby terrain, both above and below sea level, we can more accurately determine the basic physical dimensions of the landslide. This can be paired with GPS and seismic measurements made over time to see how the slope responds to changes in the glacier and to events like rainstorms and earthquakes. Field and satellite data can support near-real time hazard monitoring, while computer models of landslide and tsunami scenarios can help identify specific places that are most at risk."
In the letter, the authors reached out to those living in and visiting the area, asking, "What specific questions are most important to you?" and "What could be done to reduce the danger to people who want to visit or work in Barry Arm?" They also invited locals to let them know about any changes, including even small rock-falls and landslides.
