Is our universe the only universe?
Category Archives: Attention to the Unseen
Resurrecting ancient proteins to illuminate the origins of life
Emily Singer writes: About 4 billion years ago, molecules began to make copies of themselves, an event that marked the beginning of life on Earth. A few hundred million years later, primitive organisms began to split into the different branches that make up the tree of life. In between those two seminal events, some of the greatest innovations in existence emerged: the cell, the genetic code and an energy system to fuel it all. All three of these are essential to life as we know it, yet scientists know disappointingly little about how any of these remarkable biological innovations came about.
“It’s very hard to infer even the relative ordering of evolutionary events before the last common ancestor,” said Greg Fournier, a geobiologist at the Massachusetts Institute of Technology. Cells may have appeared before energy metabolism, or perhaps it was the other way around. Without fossils or DNA preserved from organisms living during this period, scientists have had little data to work from.
Fournier is leading an attempt to reconstruct the history of life in those evolutionary dark ages — the hundreds of millions of years between the time when life first emerged and when it split into what would become the endless tangle of existence.
He is using genomic data from living organisms to infer the DNA sequence of ancient genes as part of a growing field known as paleogenomics. In research published online in March in the Journal of Molecular Evolution, Fournier showed that the last chemical letter added to the code was a molecule called tryptophan — an amino acid most famous for its presence in turkey dinners. The work supports the idea that the genetic code evolved gradually. [Continue reading…]
What ants can teach us about the operation of the human brain
Carrie Arnold writes: Deborah Gordon spent the morning of August 27 watching a group of harvester ants foraging for seeds outside the dusty town of Rodeo, N.M. Long before the first rays of sun hit the desert floor, a group of patroller ants was already on the move. Their task was to find out whether the area near the nest was free from flash floods, high winds, and predators. If they didn’t return to the nest, departing foragers would know it wasn’t safe to go search for food.
When the patrollers returned and the first foragers did leave, they scattered in all directions, hunting for the fat-laden, energy-rich seeds on which the colony depends. Other foragers waited in the entrance of the nest for the first wave to return. If lots of food were nearby, foragers would return and depart quickly, creating a massive chain reaction. If food was scarce, however, the second group of foragers might not leave the nest at all.
“It’s a brilliant system. The ants can take advantage of sudden windfalls of food but they don’t waste energy and resources if there’s nothing there,” said Gordon, who is an ecologist at Stanford University.
The behavior of each individual in the group is set by the rate at which it meets other ants and a set of basic rules. Its behavior alters that of its neighbors, which in turn affects the original ant, in a classic example of feedback. The result is astonishing, complex behavior. “Individually, an ant is dumb,” Gordon says. She gazes off into the distance and inhales sharply. “But the colony? That’s where the intelligence is.”
About 110 miles from Gordon’s offices in Palo Alto, Calif., Mark Goldman studies a different kind of complex, emergent behavior. Goldman is a neuroscientist at the University of California, Davis. For most of his life, he was never particularly interested in ants. But when he traveled to Stanford in 2012 to plan some experiments with a colleague who had recently attended one of Gordon’s talks, something clicked.
“As I watched films of these ant colonies, it looked like what was happening at the synapse of neurons. Both of these systems accumulate evidence about their inputs—returning ants or incoming voltage pulses—to make their decisions about whether to generate an output—an outgoing forager or a packet of neurotransmitter,” Goldman said. On his next trip to Stanford, he extended his stay. An unusual research collaboration had begun to coalesce: Ants would be used to study the brain, and the brain, to study ants. [Continue reading…]
The man who drank cholera and launched the yogurt craze
Lina Zeldovich writes: What do Jamie Lee Curtis, gut bacteria, and a long forgotten Russian scientist have in common? Why, yogurt, of course. But wait, the answer is not that easy. Behind it stretches a tale that shows you can never predict cultural influence. It wends its way through the Pasteur Institute, the Nobel Prize, one of the hottest fields of scientific research today, the microbiome, and one of the trendiest avenues in nutrition, probiotics. It all began in the 19th century with a hyperactive kid in Russia who had a preternatural ability to connect dots where nobody saw dots at all.
When Ilya Metchnikoff was 8 and running around on his parents’ Panassovka estate in Little Russia, now Ukraine, he was making notes on the local flora like a junior botanist. He gave science lectures to his older brothers and local kids whose attendance he assured by paying them from his pocket money. Metchnikoff earned the nickname “Quicksilver” because he was in constant motion, always wanting to see, taste, and try everything, from studying how his father played card games to learning to sew and embroider with the maids. His wife later wrote in The Life of Ellie Metchnikoff that Metchnikoff asked the “queerest” questions, often exasperating his caretakers. “He could only be kept quiet when his curiosity was awakened by observation of some natural objects such as an insect or a butterfly.”
At 16, Metchnikoff borrowed a microscope from a university professor to study the lower organisms. Darwin’s On the Origin of Species shaped his comparative approach to science during his university years — he viewed all organisms, and physiological processes that took place in them, as interconnected and related.
That ability led him to the discovery of a particular cell and enabled him to link digestive processes in primitive creatures to the human body’s immune defenses. In lower organisms, which lack the abdominal cavity and intestines, digestion is accomplished by a particular type of cells — mobile mesodermal cells — that move around engulfing and dissolving food particles. While staring at mesodermal cells inside transparent starfish larvae, Metchnikoff, 37 at the time, had a thought. “It struck me that similar cells might serve in the defense of the organisms against intruders,” he wrote. He fetched a few rose thorns from the garden and stuck them into the larvae. If his hypothesis was correct, the larva’s body would recognize thorns as intruders and mesodermal cells would aggregate around the thorns in an attempt to gobble them up. As Metchnikoff expected, the mesodermal cells surrounded the thorns, proving his theory. He named his cells phagocytes, which in Greek means “devouring cells,” and likened them to an “army hurling itself upon the enemy.” [Continue reading…]
Suicide crisis: The intergenerational trauma of Native Americans
Jason Coppola reports: Suicide arrives in waves on Pine Ridge Indian Reservation.
On Christmas Day, a 15-year-old Lakota girl took her own life. Soon afterward, a boy, just 14, took his.
Since then, a young man and six more girls, one as young as 12, have followed as this current wave continues to swell. There have been numerous additional attempts in the last few months on this South Dakota reservation of about 28,000 people.
The rate of suicide among Native youth in the United States is more than three times the national average. Very often that rate climbs even higher.
In March 2010, then president of the Oglala Sioux Tribe, Theresa Two Bulls declared a suicide state of emergency after a rise in the number of suicides. Current President John Yellow Bird Steele has now declared one yet again.
There are many difficult issues facing the Oglala Lakota people of Pine Ridge. Stories about alcohol and drug abuse, poverty and depression attract much attention. But to some, these are just parts of a much larger picture.
“I think of suicide in Native communities as an extension of the genocide that occurred against Indigenous peoples starting back in 1492,” said Ruth Hopkins, a chief tribal judge for the Spirit Lake Nation, and tribal judge for the Yankton Sioux and Crow Creek Sioux Tribe. “And I think there’s evidence to show that it’s still continuing to this day.” [Continue reading…]
Why too much Facebook can leave you feeling down
By Mai-Ly Nguyen Steers, University of Houston
“Comparison is the thief of joy”, said former US president Theodore Roosevelt. Spoken more than a century ago, Roosevelt’s words highlight a fundamental truth that is just as relevant today.
In the 1950s, the acclaimed social psychologist, Leon Festinger, devised the social comparison theory to help explain the psychological processes behind why we compare ourselves to others. Festinger proposed that individuals have an innate desire to see how they measure up with their peers on dimensions they deem personally important in order to evaluate how well they are doing.
This tendency hasn’t gone away, and in fact, through social media websites like Facebook we may be engaging in more social comparison than ever before. Such social comparisons can convey important information: are we measuring up in terms of our progress or achievements, or are we falling behind and need to put in the effort to catch up?
How the language you speak changes your view of the world
By Panos Athanasopoulos, Lancaster University
Bilinguals get all the perks. Better job prospects, a cognitive boost and even protection against dementia. Now new research shows that they can also view the world in different ways depending on the specific language they are operating in.
The past 15 years have witnessed an overwhelming amount of research on the bilingual mind, with the majority of the evidence pointing to the tangible advantages of using more than one language. Going back and forth between languages appears to be a kind of brain training, pushing your brain to be flexible.
Just as regular exercise gives your body some biological benefits, mentally controlling two or more languages gives your brain cognitive benefits. This mental flexibility pays big dividends especially later in life: the typical signs of cognitive ageing occur later in bilinguals – and the onset of age-related degenerative disorders such as dementia or Alzheimer’s are delayed in bilinguals by up to five years.
The Earth’s underworld, where there is no life and nothing to live on
Stephen J Pyne writes: I had not intended to go to the end of nowhere. Even by Antarctic standards, Dome C was the back of beyond. But one afternoon, while fumbling with gear in a McMurdo warehouse, I overheard an allusion to ‘the source regions’. The technicians used the term casually, discussing what goods would be shipped to a remote camp well over the Transantarctic Mountains. But in my mind the phrase sparked an epiphany of symbolism. The source regions. Here was the geographic place at which the East Antarctic ice sheets gathered and then flowed outward. Here was a place that took nothing from elsewhere save fugitive water vapour and turned it into Ice. I had come here to understand Antarctica, by whatever means I could. Surely that quest demanded a journey to the source, for it must certainly contain the essence of the Ice. So after a trip to the National Science Foundation chalet where I pleaded my case, and then a layover at the Pole, adapting to high elevation, I stepped off an LC-130 (‘The Antarctic Queen’) on a dazzling 1981 New Year’s Eve at Dome C and found myself at the end of the world.
Antarctica is a place only an intellectual could love. The further one moves into the interior, away from the coast and storms and marine life that tenuously valence with the Earth, the more dominant the ice and the more extraterrestrial the surroundings. The commonsense perspective of ordinary people is that there is ‘nothing there’, and they are almost right. Even scientists in keen pursuit of data, precious by being rare — our age’s equivalent to the spice and bullion that inflamed early explorers — find Dome C extreme. The rumour soon spread on site, originating from a knot of geophysics graduate students from Wisconsin, that we were not in Antarctica at all but had been secretly drugged on the plane and taken to a prison camp in Minnesota.
Consider the geographic facts: Dome C is an infinitesimal rise in the East Antarctic plateau, atop 14,500 foot of ice that extends outward hundreds of miles. There is little else. This is the most singular environment on Earth, a synthesis of the huge with the simple. Space and time dissolve. The cycle of days and those of seasons collapse into a single spiral. The energy budget is always negative; none during the dark season, reflected away during the light. There is no life. There is nothing to live on. Here is Dante’s imagined innermost circle of hell as an inferno of ice. Here is the Earth’s underworld.
It is a scene of absences and abstractions. There are no mountains, valleys, rivers, shores; no forests, prairies, tide pools, corn and cotton fields, sun-baked deserts; no hurricanes, no floods, no earthquakes, no fires. The only contrast is between an ice-massed land and an ice-saturated sky. The descending ice that links them — the ultimate source of the dome — has the purity of triple-distilled water. Yet it too, as with everything else, simplifies into its most primordial elements, as snowflakes crumble and fall as an icy dust. There is no centre and no edge. There is no near or far; no east or west; no real here or there. Words, too, shrink and freeze, as language and ideas shrivel into monosyllables: ice, snow, dark, sky, blue, star, cloud, white, wind, moon, light, flake, cold. [Continue reading…]
Enormous hole in the universe may not be the only one
By Carole Mundell, University of Bath
Astronomers have found evidence of a giant void that could be the largest known structure in the universe. The “supervoid” solves a controversial cosmic puzzle: it explains the origin of a large and anomalously cold region of the sky. However, future observations are needed to confirm the discovery and determine whether the void is unique.
The so-called cold spot can be seen in maps of the Cosmic Microwave Background (CMB), which is the radiation left over from the birth of the universe. It was first discovered by NASA’s Wilkinson Microwave Anisotropy Probe (WMAP) in 2004 and confirmed by ESA’s Planck Satellite. For more than a decade, astronomers have failed to explain its existence. But there has been no shortage of suggestions, with unproven and controversial theories being put forward including imprints of parallel universes, called the multiverse theory, and exotic physics in the early universe.
Now an international team of astronomers led by Istvan Szapudi of the Institute for Astronomy at The University of Hawaii at Manoa have found evidence for one of the theories: a supervoid, in which the density of galaxies is much lower than usual in the known universe.
These are the memories you’re most likely to get wrong
Jennifer Talarico writes: It isn’t surprising that many Bostonians have vivid memories of the 2013 Marathon bombing, or that many New Yorkers have very clear memories about where they were and what they were doing on 9/11.
But many individuals who were not onsite for these attacks, or not even in Boston on Apr. 15, 2013 or in New York on Sept. 11, 2001, also have vivid memories of how they learned about these events. Why would people who were not immediately or directly affected have such a long-lasting sense of knowing exactly where they were and what they were doing when they heard the news?
These recollections are called flashbulb memories. In a flashbulb memory, we recall the experience of learning about an event, not the factual details of the event itself.
There might be an advantage to recalling the elements of important events that happen to us or to those close to us, but there appears to be little benefit to recalling our experience hearing this kind of news. So why does learning about a big event create such vivid memories? And just how accurate are flashbulb memories? [Continue reading…]
How we know
In a review of The Information: A History, a Theory, a Flood, by James Gleick, Freeman Dyson writes: James Gleick’s first chapter has the title “Drums That Talk.” It explains the concept of information by looking at a simple example. The example is a drum language used in a part of the Democratic Republic of Congo where the human language is Kele. European explorers had been aware for a long time that the irregular rhythms of African drums were carrying mysterious messages through the jungle. Explorers would arrive at villages where no European had been before and find that the village elders were already prepared to meet them.
Sadly, the drum language was only understood and recorded by a single European before it started to disappear. The European was John Carrington, an English missionary who spent his life in Africa and became fluent in both Kele and drum language. He arrived in Africa in 1938 and published his findings in 1949 in a book, The Talking Drums of Africa. Before the arrival of the Europeans with their roads and radios, the Kele-speaking Africans had used the drum language for rapid communication from village to village in the rain forest. Every village had an expert drummer and every villager could understand what the drums were saying. By the time Carrington wrote his book, the use of drum language was already fading and schoolchildren were no longer learning it. In the sixty years since then, telephones made drum language obsolete and completed the process of extinction.
Carrington understood how the structure of the Kele language made drum language possible. Kele is a tonal language with two sharply distinct tones. Each syllable is either low or high. The drum language is spoken by a pair of drums with the same two tones. Each Kele word is spoken by the drums as a sequence of low and high beats. In passing from human Kele to drum language, all the information contained in vowels and consonants is lost. In a European language, the consonants and vowels contain all the information, and if this information were dropped there would be nothing left. But in a tonal language like Kele, some information is carried in the tones and survives the transition from human speaker to drums. The fraction of information that survives in a drum word is small, and the words spoken by the drums are correspondingly ambiguous. A single sequence of tones may have hundreds of meanings depending on the missing vowels and consonants. The drum language must resolve the ambiguity of the individual words by adding more words. When enough redundant words are added, the meaning of the message becomes unique.
In 1954 a visitor from the United States came to Carrington’s mission school. Carrington was taking a walk in the forest and his wife wished to call him home for lunch. She sent him a message in drum language and explained it to the visitor. To be intelligible to Carrington, the message needed to be expressed with redundant and repeated phrases: “White man spirit in forest come come to house of shingles high up above of white man spirit in forest. Woman with yam awaits. Come come.” Carrington heard the message and came home. On the average, about eight words of drum language were needed to transmit one word of human language unambiguously. Western mathematicians would say that about one eighth of the information in the human Kele language belongs to the tones that are transmitted by the drum language. The redundancy of the drum language phrases compensates for the loss of the information in vowels and consonants. The African drummers knew nothing of Western mathematics, but they found the right level of redundancy for their drum language by trial and error. Carrington’s wife had learned the language from the drummers and knew how to use it.
The story of the drum language illustrates the central dogma of information theory. The central dogma says, “Meaning is irrelevant.” Information is independent of the meaning that it expresses, and of the language used to express it. Information is an abstract concept, which can be embodied equally well in human speech or in writing or in drumbeats. All that is needed to transfer information from one language to another is a coding system. A coding system may be simple or complicated. If the code is simple, as it is for the drum language with its two tones, a given amount of information requires a longer message. If the code is complicated, as it is for spoken language, the same amount of information can be conveyed in a shorter message. [Continue reading…]
Learning a language? Sleep on it and you’ll get the grammar
By Kathy Rastle, Royal Holloway and Jakke Tamminen, Royal Holloway
In 2006, former US president George Bush supported his embattled defense secretary Donald Rumsfeld with the words: “But I’m the decider, and I decide what is best.” This quotation quickly entered the folklore of political humour. But to psychology researchers, it revealed something fundamental about human language.
At that time, most Americans had not encountered the word decider. While this is a common word in some parts of the world, it refers to the part of a game that determines the winner. So how did people understand what it meant? They understood it because across all of the words that people know, the suffix –er often transforms a verb into a person (as in teacher, builder, dancer). Thus, a decider must be someone who decides.
The ability to extract general principles from a small number of examples is fundamental to language and literacy. In teaching children how to read, teachers introduce sets of words like chin, church, chest, chess, chop, to convey information about how to pronounce particular letters. This general knowledge might then be applied to new words like chick. In later years of primary school, children develop general knowledge about the functions of affixes. Through exposure to relevant sets of words like uncertain, unknown, unhappy, children become able to use affixes like -un in new contexts.
Conservation and the rights of tribal people must go hand in hand
Jo Woodman writes: Evidence is growing that conservation – enforced by the creation of protected areas and policed by anti-poaching squads – leads to the eviction and abuse of vast numbers of people, especially tribal peoples, and is also failing to check the deepening environmental crisis. A new approach is urgently needed. Conservation should centre on protecting the land rights of the peoples to whom these vitally important areas are home.
Tribal peoples are better at looking after their environments than anyone else – their survival depends on it. When the Maasai were removed from Ngorongoro Crater in Tanzania in 1974 , poaching increased; the eviction of indigenous people from Yellowstone Park in the United States in the late 19th century led to overgrazing by elk and bison; Aborigines in Australia have used controlled burning to protect forests from devastating conflagrations… the list goes on.
South Asia’s tribal peoples have coexisted with the tiger for thousands of years, but now they are facing eviction in the name of protecting the animal. There is evidence, for example, from Chitwan national park in Nepal, that tiger densities can actually be higher in the areas where people live than in those from where they have been evicted. People provide a variety of different habitats and eyes and ears to detect and deter poachers. [Continue reading…]
‘We’re going to resist’: Brazil’s indigenous groups fight to keep their land in face of new law
Claire Rigby reports: From downtown São Paulo, the Pico do Jaraguá – the crest of a mountain ridge on the city’s north-western horizon – looks like a broken tooth, crowned by a towering TV antenna. Just beyond the rocky peak and down a steep, deeply rutted, unmade road, lies the nascent village of Tekoa Itakupe, one of the newest fronts in Brazil’s indigenous people’s struggle for land to call their own.
Once part of a coffee plantation, the idyllic 72-hectare plot is currently occupied by three families from the Guarani community who moved onto the land in July 2014 after it was recognised as traditional Guarani territory by Funai, the federal agency for Indian affairs.
The group had hoped that would be a first step on the road to its eventual official demarcation as indigenous territory, but they now face eviction after a judge granted a court order to the landowner, Antônio ‘Tito’ Costa, a lawyer and former local politician.
Ari Karai, the 74-year-old chief or cacique of Tekoa Ytu, one of two established Indian villages at the base of the peak, says the group intends to resist. “How can they evict us when this is recognised Indian land?” he asks.
The dispute comes at a crucial time for Brazil’s more than 300 indigenous peoples. Earlier this month, more than a thousand indigenous leaders met in Brasília to protest and organise against PEC 215, a proposed constitutional amendment that would shift the power to demarcate indigenous land from the executive to the legislature – that is, from Funai, the Ministry of Justice and the president, by decree, to Congress. [Continue reading…]
Explainer: The mysterious dark energy that speeds the universe’s rate of expansion
By Robert Scherrer, Vanderbilt University
The nature of dark energy is one of the most important unsolved problems in all of science. But what, exactly, is dark energy, and why do we even believe that it exists?
Step back a minute and consider a more familiar experience: what happens when you toss a ball straight up into the air? It gradually slows down as gravity tugs on it, finally stopping in mid-air and falling back to the ground. Of course, if you threw the ball hard enough (about 25,000 miles per hour) it would actually escape from the Earth entirely and shoot into space, never to return. But even in that case, gravity would continue to pull feebly on the ball, slowing its speed as it escaped the clutches of the Earth.
But now imagine something completely different. Suppose that you tossed a ball into the air, and instead of being attracted back to the ground, the ball was repelled by the Earth and blasted faster and faster into the sky. This would be an astonishing event, but it’s exactly what astronomers have observed happening to the entire universe!
Consumed: why more stuff does not mean more happiness
By Judith Stark, Seton Hall University
Consumption. By a strange shift of meaning, this 19th-century word describing a serious and often fatal disease is the same word used now for a way of life focused on material goods. Is it time to bring back its negative, and often deadly, associations into our public discourse?
Consumption as reality and metaphor operates on many levels – personal, communal and economic. Most importantly, it causes profound consequences for the planet and its resources.
The forty-fifth anniversary of Earth Day provides a fitting occasion to think more broadly and deeply about what these patterns of consumption mean for us, our communities, and for planet Earth.
Diminishing returns
We all want stuff, but in our overdeveloped, fast-paced culture we seldom challenge ourselves to ask ourselves the one important question: how much is enough?
How to live with regrets
Pacific Standard spoke to psychologist Edward Chang about the nature of regret and what our modern culture could learn from Nietzsche about living with our mistakes.
Is there anything new about the current philosophy of no regrets?
I have a young daughter who listens to music, and there’s a song out there by Kesha called “Die Young.” It’s about teenagers and living the night like it’s the last night of their lives. We find this theme everywhere in our history and culture. Think of Dead Poets Society, with its emphasis on the notion of carpe diem [“seize the day”]. There’s a tendency in human civilization to put an emphasis on living for that day, to its fullest. It extends back to ancient Greece, where citizens never had a notion of “human beings,” but of “mortals” and “immortals.” If you read any text from the ancient world, they all center on how a human being can live like the gods, forever. It’s this notion of mortality, embedded in us by religion, that drives not just aspiration, but also fuels a cycle of regret — a sense that no matter how hard you try, you’ll fail to live like the gods.
It was Nietzsche who really wanted to develop a coherent philosophy of “no regrets.” This starts, really, with Nietzsche’s “formula” for human greatness and the principle of amor fati, or “love of [one’s] fate.” Nietzsche wrote that “My formula for greatness in a human being is amor fati: that one wants nothing to be different, not forward, not backward, not in all eternity. Not merely bear what is necessary, still less conceal it — all idealism is mendaciousness in the face of what is necessary — but love it.”
Nietzsche was struggling with the question, driven by the specter of mortality, with how humans should live a good life. He had two extreme positions in front of him: the ancient ascetic position, which dictates that to live a good life you must forgo human desire, and the more hedonistic carpe diem philosophy that we see crop up in pop culture. But really, Nietzsche wasn’t arguing for either position. When he talks about amor fati, there’s a higher level of uber-morality going on there, that goes beyond carpe diem or asceticism, that’s really asking us to embrace our mortality rather than shy from it with regret.
So I guess Nietzsche was the originator of YOLO (“you only live once”), then?
Sort of. In a way, amor fati and the “will to power” aren’t just abstract philosophy; I’d argue that Nietzsche is actually one of the first and most powerful psychologists. Nietzsche asks: How am I going to get people to wake up from their day-to-day habits, the iron cage of daily life that makes us creatures of comfortable habit, and how should we be truly living our lives?
The vehicle for people to wake themselves up and change their lives, Nietzsche says, is regret. In reality, the YOLO and carpe diem culture is a misinterpretation of the “will to power” that made him famous. I’ve seen so many pop psychology books that suggest abandoning regret to live a good life; purging regret from your thought process. But none of these books have the backbone that Nietzsche did, to advocate that we face our mortality and the certainty of regret as a motivation for changing your life. [Continue reading…]
Dark matter discovery may open a new frontier in physics
Christian Science Monitor reports: A quartet of colliding galaxies in a vast cluster 1.4 billion light-years away may prompt scientists to rethink their notions about the nature of dark matter – a hidden form of matter that makes up some 85 percent of all the matter in the universe.
Dark matter forms cocoons in which galaxies and clusters of galaxies form. Its gravity holds galaxies together. It’s “dark” because, as currently conceived, it rarely, if ever, interacts with ordinary matter, or even itself, other than through gravity.
Out at the cluster, known as Abell 3827, hints have emerged that dark matter may be less reclusive than previously believed. Three of the four merging galaxies appear to be sitting in the middle of their own dark-matter halos, as theory predicts. The fourth halo, however, appears to be trailing its galaxy like a reluctant retriever tugging at the end of a 5,000-light-year-long leash.
Unless astrophysicists can come up with and verify a more prosaic reason for the offset, which still could happen, this could be the first hint that dark matter does interact with other dark matter and by a means other than gravity.
If dark matter turns out to interact with itself, the implications could be profound, researchers say.
It would provide confirmation at the cosmic level that a new physics frontier lies beyond the standard model of physics, which describes a zoo of subatomic particles and their interactions. The standard model has no candidates for dark-matter particles, explains Dan Hooper, an astrophysicist at the Fermi National Accelerator Laboratory (Fermilab) in Batavia, Ill.
Confronted with self-interacting dark matter, physics then would have to do more than identify the subatomic particle associated with dark matter itself. They also would have to propose particles that in effect govern the interactions.
“There is a huge difference between zero interactions and even teeny tiny interactions,” explains Richard Massey, an astrophysicist at the Institute for Computational Cosmology at Durham University in Britain and the lead author of a formal description of the Abell 3827 observation, published this week in the Monthly Notices of the Royal Astronomical Society. [Continue reading…]