Author Archives: Attention to the Unseen

The inflated debate over cosmic inflation

Amanda Gefter writes: On the morning of Dec. 7, 1979, a 32-year-old Alan Guth woke up with an idea. It had come into his head the previous night, but now, in the light of a California day, he could see the shape of the thing, and was itching to work through the math. He hopped on his bike and rode to his office at the Stanford Linear Accelerator Center. His excitement got him there in record time: 9 minutes, 32 seconds. At his desk, Guth neatly carried out the calculations in his notebook, forming the numbers and symbols in tight, careful lines. Then, at the top of a fresh page, he wrote in all caps: SPECTACULAR REALIZATION.

A year later and some 6,000 miles away, in Moscow, in the middle of the night, Andrei Linde, having read Guth’s paper, had his own spectacular realization. He had been working on his own idea and now he saw how to bring it to life by fixing the difficulties that plagued Guth’s theory. He woke his sleeping wife. “I think I know how the universe was created.”

Guth and Linde had worked out the beginnings of the theory of cosmic inflation. The theory would go through several incarnations over the next few decades, as kinks were worked out and details honed. But the core idea was spectacularly simple: In the earliest fraction of a second of time, a small patch of universe expanded faster than the speed of light, doubling its size again and again, growing a million trillion trillion times bigger in the blink of an eye. A little patch of world, about the size of a dime, grew into our entire observable universe.

What began as a radical notion has now become standard wisdom among physicists—except, notably, Paul Steinhardt, Anna Ijjas, and Avi Loeb. The three physicists recently wrote a scathing article in Scientific American arguing that it’s time to abandon inflation and look for a competing idea. (What idea, you ask? Steinhardt, conveniently, has one that he’s been pushing for decades.) Inflation is too unlikely to occur, too flexible to be confirmed or rejected experimentally, and too messy in its implications, the threesome argued. It “cannot be evaluated using the scientific method.”

It’s not surprising, then, that Guth and Linde—along with physicists David Kaiser and Yasunori Nomura—published a terse response in Scientific American earlier this month defending their theory. What is more surprising, perhaps, is that 29 more of the world’s leading physicists signed it—including four Nobel laureates and a Field’s medalist.

In the media flurry that followed, the disagreement between these groups of physicists was presented as a straight debate, of the kind that often occurs in science when there are multiple interpretations of data. But describing an equivalence between the opinions of Steinhardt, Ijjas, and Loeb on the one hand, and nearly the entirely cosmology community on the other, is a mistake.

The long list of signatories to the recent rebuttal letter in Scientific American puts the lie to the claim that the community is divided. When Ed Witten, Steven Weinberg, Leonard Susskind, Frank Wilczek, Juan Maldacena, Eva Silverstein, Sir Martin Rees, and Stephen Hawking (to name a few) write a letter saying you’ve gotten something wrong … well it’s probably worth considering.

The rebuttal letter also challenges us to understand more clearly why so many scientists are passionate about inflation. What is it about this theory that has the greatest minds in the known universe leaping to its defense? [Continue reading…]

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What hyenas can tell us about the origins of intelligence

David Z. Hambrick writes: Physical similarities aside, we share a lot in common with our primate relatives. For example, as Jane Goodall famously documented, chimpanzees form lifelong bonds and show affection in much the same way as humans. Chimps can also solve novel problems, use objects as tools, and may possess “theory of mind”—an understanding that others may have different perspectives than oneself. They can even outperform humans in certain types of cognitive tasks.

These commonalities may not seem all that surprising given what we now know from the field of comparative genomics: We share nearly all of our DNA with chimpanzees and other primates. However, social and cognitive complexity is not unique to our closest evolutionary cousins. In fact, it is abundant in species with which we would seem to have very little in common—like the spotted hyena.

For more than three decades, the Michigan State University zoologist Kay Holekamp has studied the habits of the spotted hyena in Kenya’s Masai Mara National Reserve, once spending five years straight living in a tent among her oft-maligned subjects. One of the world’s longest-running studies of a wild mammal, this landmark project has revealed that spotted hyenas not only have social groups as complex as those of many primates, but are also capable of some of the same types of problem solving.

This research sheds light on one of science’s greatest mysteries—how intelligence has evolved across the animal kingdom. [Continue reading…]

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Jumping genes play a big role in what makes us human

Science News reports: Face-to-face, a human and a chimpanzee are easy to tell apart. The two species share a common primate ancestor, but over millions of years, their characteristics have morphed into easily distinguishable features. Chimps developed prominent brow ridges, flat noses, low-crowned heads and protruding muzzles. Human noses jut from relatively flat faces under high-domed crowns.

Those facial features diverged with the help of genetic parasites, mobile bits of genetic material that insert themselves into their hosts’ DNA. These parasites go by many names, including “jumping genes,” “transposable elements” and “transposons.” Some are relics of former viruses assimilated into a host’s genome, or genetic instruction book. Others are self-perpetuating pieces of genetic material whose origins are shrouded in the mists of time.

“Transposable elements have been with us since the beginning of evolution. Bacteria have transposable elements,” says evolutionary biologist Josefa González. She doesn’t think of transposons as foreign DNA. They are parts of our genomes — like genes.

“You cannot understand the genome without understanding what transposable elements are doing,” says González, of the Institute of Evolutionary Biology in Barcelona. She studies how jumping genes have influenced fruit fly evolution.

Genomes of most organisms are littered with the carcasses of transposons, says Cédric Feschotte, an evolutionary geneticist at the University of Utah in Salt Lake City. Fossils of the DNA parasites build up like the remains of ancient algae that formed the white cliffs of Dover. One strain of maize, the organism in which Nobel laureate Barbara McClintock first discovered transposable elements in the 1940s, is nearly 85 percent transposable elements (SN: 12/19/09, p. 9). Corn is an extreme example, but humans have plenty, too: Transposable elements make up nearly half of the human genome.

Most of the transposons in the genomes of humans and other creatures are now “dead,” meaning they are no longer able to jump. The majority are in bits and pieces scattered throughout the genome like so much confetti. Many researchers used to think these broken transposons were just genetic garbage.

Far from junk, however, jumping gene remnants have been an evolutionary treasure trove. Some of the control switches transposons once used for their own hopping have been recycled over time into useful tools that help species, including Homo sapiens, adapt to their environments or take on new characteristics. [Continue reading…]

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The thoughts of a spiderweb

Joshua Sokol writes: Millions of years ago, a few spiders abandoned the kind of round webs that the word “spiderweb” calls to mind and started to focus on a new strategy. Before, they would wait for prey to become ensnared in their webs and then walk out to retrieve it. Then they began building horizontal nets to use as a fishing platform. Now their modern descendants, the cobweb spiders, dangle sticky threads below, wait until insects walk by and get snagged, and reel their unlucky victims in.

In 2008, the researcher Hilton Japyassú prompted 12 species of orb spiders collected from all over Brazil to go through this transition again. He waited until the spiders wove an ordinary web. Then he snipped its threads so that the silk drooped to where crickets wandered below. When a cricket got hooked, not all the orb spiders could fully pull it up, as a cobweb spider does. But some could, and all at least began to reel it in with their two front legs.

Their ability to recapitulate the ancient spiders’ innovation got Japyassú, a biologist at the Federal University of Bahia in Brazil, thinking. When the spider was confronted with a problem to solve that it might not have seen before, how did it figure out what to do? “Where is this information?” he said. “Where is it? Is it in her head, or does this information emerge during the interaction with the altered web?”

In February, Japyassú and Kevin Laland, an evolutionary biologist at the University of Saint Andrews, proposed a bold answer to the question. They argued in a review paper, published in the journal Animal Cognition, that a spider’s web is at least an adjustable part of its sensory apparatus, and at most an extension of the spider’s cognitive system.

This would make the web a model example of extended cognition, an idea first proposed by the philosophers Andy Clark and David Chalmers in 1998 to apply to human thought. In accounts of extended cognition, processes like checking a grocery list or rearranging Scrabble tiles in a tray are close enough to memory-retrieval or problem-solving tasks that happen entirely inside the brain that proponents argue they are actually part of a single, larger, “extended” mind.

Among philosophers of mind, that idea has racked up citations, including supporters and critics. And by its very design, Japyassú’s paper, which aims to export extended cognition as a testable idea to the field of animal behavior, is already stirring up antibodies among scientists. “I got the impression that it was being very careful to check all the boxes for hot topics and controversial topics in animal cognition,” said Alex Jordan, a collective behaviorial scientist at the Max Planck Institute in Konstanz, Germany (who nonetheless supports the idea).

While many disagree with the paper’s interpretations, the study shouldn’t be confused for a piece of philosophy. Japyassú and Laland propose ways to test their ideas in concrete experiments that involve manipulating the spider’s web — tests that other researchers are excited about. “We can break that machine; we can snap strands; we can reduce the way that animal is able to perceive the system around it,” Jordan said. “And that generates some very direct and testable hypotheses.” [Continue reading…]

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Jupiter is much stranger than scientists thought

The Atlantic reports: About every eight weeks, hundreds of millions of miles away, a basketball court-sized spacecraft named Juno swoops toward Jupiter. For a few hours, Juno loops around the planet’s poles at high speed, sometimes getting within 2,100 miles of its atmosphere. It surveys Jupiter’s swirling, opaque cloud tops, and then gets flung out to the other edge of its orbit, beyond Callisto, the planet’s cratered moon.

Jupiter is surrounded by a massive magnetic field that produces belts of radiation capable of frying Juno if it wasn’t wearing 400 pounds of protective titanium. The poles are a haven from the strongest radiation, and it’s there that Juno can aim its various scientific instruments at Jupiter’s cloud cover and collect data.

These flybys, which began when Juno entered Jupiter’s orbit last summer, have produced some stunning photographs of the gas giant’s polar regions, unlike the typical views published in textbooks over the years. They have also provided plenty of useful observations for scientists around the world, the first of which were published Thursday, in multiple studies in the journals Science and Geophysical Research Letters.

At Jupiter’s poles, Juno has observed oval-shaped features, powerful cyclones which measure up to nearly 900 miles wide, according to one of the studies in Science. The finding isn’t surprising, given how good Jupiter is at producing storms. The planet is home to winds blowing at several hundred miles per hour, and storms the size of Earth. But scientists hadn’t observed storms like this at Jupiter’s poles until Juno showed up. They were surprised by the number of cyclonic storms they observed, as well as the differences in the weather patterns on the south and north poles. [Continue reading…]

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