Posted: Thu Jul 05, 2012 12:05 pm Post subject: Articles of Interest in Science
July 4, 2012
Physicists Find Elusive Particle Seen as Key to Universe
By DENNIS OVERBYE
ASPEN, Colo. — Signaling a likely end to one of the longest, most expensive searches in the history of science, physicists said Wednesday that they had discovered a new subatomic particle that looks for all the world like the Higgs boson, a key to understanding why there is diversity and life in the universe.
Like Omar Sharif materializing out of the shimmering desert as a man on a camel in “Lawrence of Arabia,” the elusive boson has been coming slowly into view since last winter, as the first signals of its existence grew until they practically jumped off the chart.
“I think we have it,” said Rolf-Dieter Heuer, the director general of CERN, the multinational research center headquartered in Geneva. The agency is home to the Large Hadron Collider, the immense particle accelerator that produced the new data by colliding protons. The findings were announced by two separate teams. Dr. Heuer called the discovery “a historic milestone.”
He and others said that it was too soon to know for sure, however, whether the new particle is the one predicted by the Standard Model, the theory that has ruled physics for the last half-century. The particle is predicted to imbue elementary particles with mass. It may be an impostor as yet unknown to physics, perhaps the first of many particles yet to be discovered.
That possibility is particularly exciting to physicists, as it could point the way to new, deeper ideas, beyond the Standard Model, about the nature of reality.
For now, some physicists are simply calling it a “Higgslike” particle.
“It’s something that may, in the end, be one of the biggest observations of any new phenomena in our field in the last 30 or 40 years,” said Joe Incandela, a physicist of the University of California, Santa Barbara, and a spokesman for one of the two groups reporting new data on Wednesday.
Here at the Aspen Center for Physics, a retreat for scientists, bleary-eyed physicists drank Champagne in the wee hours as word arrived via Webcast from CERN. It was a scene duplicated in Melbourne, Australia, where physicists had gathered for a major conference, as well as in Los Angeles, Chicago, Princeton, New York, London and beyond — everywhere that members of a curious species have dedicated their lives and fortunes to the search for their origins in a dark universe.
In Geneva, 1,000 people stood in line all night to get into an auditorium at CERN, where some attendees noted a rock-concert ambience. Peter Higgs, the University of Edinburgh theorist for whom the boson is named, entered the meeting to a sustained ovation.
Confirmation of the Higgs boson or something very much like it would constitute a rendezvous with destiny for a generation of physicists who have believed in the boson for half a century without ever seeing it. The finding affirms a grand view of a universe described by simple and elegant and symmetrical laws — but one in which everything interesting, like ourselves, results from flaws or breaks in that symmetry.
According to the Standard Model, the Higgs boson is the only manifestation of an invisible force field, a cosmic molasses that permeates space and imbues elementary particles with mass. Particles wading through the field gain heft the way a bill going through Congress attracts riders and amendments, becoming ever more ponderous.
Without the Higgs field, as it is known, or something like it, all elementary forms of matter would zoom around at the speed of light, flowing through our hands like moonlight. There would be neither atoms nor life.
Physicists said that they would probably be studying the new particle for years. Any deviations from the simplest version predicted by current theory — and there are hints of some already — could begin to answer questions left hanging by the Standard Model. For example, what is the dark matter that provides the gravitational scaffolding of galaxies?
And why is the universe made of matter instead of antimatter?
“If the boson really is not acting standard, then that will imply that there is more to the story — more particles, maybe more forces around the corner,” Neal Weiner, a theorist at New York University, wrote in an e-mail. “What that would be is anyone’s guess at the moment.”
Wednesday’s announcement was also an impressive opening act for the Large Hadron Collider, the world’s biggest physics machine, which cost $10 billion to build and began operating only two years ago. It is still running at only half-power.
Physicists had been icing the Champagne ever since last December. Two teams of about 3,000 physicists each — one named Atlas, led by Fabiola Gianotti, and the other CMS, led by Dr. Incandela — operate giant detectors in the collider, sorting the debris from the primordial fireballs left after proton collisions.
Last winter, they both reported hints of the same particle. They were not able, however, to rule out the possibility that it was a statistical fluke. Since then, the collider has more than doubled the number of collisions it has recorded.
The results announced Wednesday capped two weeks of feverish speculation and Internet buzz as the physicists, who had been sworn to secrecy, did a breakneck analysis of about 800 trillion proton-proton collisions over the last two years.
Up until last weekend, physicists at the agency were saying that they themselves did not know what the outcome would be. Expectations soared when it was learned that the five surviving originators of the Higgs boson theory had been invited to the CERN news conference.
The December signal was no fluke, the scientists said Wednesday. The new particle has a mass of about 125.3 billion electron volts, as measured by the CMS group, and 126 billion according to Atlas. Both groups said that the likelihood that their signal was a result of a chance fluctuation was less than one chance in 3.5 million, “five sigma,” which is the gold standard in physics for a discovery.
On that basis, Dr. Heuer said that he had decided only on Tuesday afternoon to call the Higgs result a “discovery.”
He said, “I know the science, and as director general I can stick out my neck.”
Dr. Incandela’s and Dr. Gianotti’s presentations were repeatedly interrupted by applause as they showed slide after slide of data presented in graphs with bumps rising like mountains from the sea.
Dr. Gianotti noted that the mass of the putative Higgs, apparently one of the heaviest subatomic particles, made it easy to study its many behaviors. “Thanks, nature,” she said.
Gerald Guralnik, one of the founders of the Higgs theory, said he was glad to be at a physics meeting “where there is applause, like a football game.”
Asked to comment after the announcements, Dr. Higgs seemed overwhelmed. “For me, it’s really an incredible thing that’s happened in my lifetime,” he said.
Dr. Higgs was one of six physicists, working in three independent groups, who in 1964 invented what came to be known as the Higgs field. The others were Tom Kibble of Imperial College, London; Carl Hagen of the University of Rochester; Dr. Guralnik of Brown University; and François Englert and Robert Brout, both of Université Libre de Bruxelles.
One implication of their theory was that this cosmic molasses, normally invisible, would produce its own quantum particle if hit hard enough with the right amount of energy. The particle would be fragile and fall apart within a millionth of a second in a dozen possible ways, depending upon its own mass.
Unfortunately, the theory did not describe how much this particle should weigh, which is what made it so hard to find, eluding researchers at a succession of particle accelerators, including the Large Electron Positron Collider at CERN, which closed down in 2000, and the Tevatron at the Fermi National Accelerator Laboratory, or Fermilab, in Batavia, Ill., which shut down last year.
Along the way the Higgs boson achieved a notoriety rare in abstract physics. To the eternal dismay of his colleagues, Leon Lederman, the former director of Fermilab, called it the “God particle,” in his book of the same name, written with Dick Teresi. (He later said that he had wanted to call it the “goddamn particle.”)
Finding the missing boson was one of the main goals of the Large Hadron Collider. Both Dr. Heuer and Dr. Gianotti said they had not expected the search to succeed so quickly.
So far, the physicists admit, they know little about their new boson. The CERN results are mostly based on measurements of two or three of the dozen different ways, or “channels,” by which a Higgs boson could be produced and then decay.
There are hints, but only hints so far, that some of the channels are overproducing the boson while others might be underproducing it, clues that maybe there is more at work here than the Standard Model would predict.
“This could be the first in a ring of discoveries,” said Guido Tonelli of CERN.
In an e-mail, Maria Spiropulu, a professor at the California Institute of Technology who works with the CMS team of physicists, said: “I personally do not want it to be standard model anything — I don’t want it to be simple or symmetric or as predicted. I want us all to have been dealt a complex hand that will send me (and all of us) in a (good) loop for a long time.”
Nima Arkani-Hamed, a physicist at the Institute for Advanced Study in Princeton, said: “It’s a triumphant day for fundamental physics. Now some fun begins.”
ASPEN, Colo. — Last week, physicists around the world were glued to computers at very odd hours (I was at a 1 a.m. physics “party” here with a large projection screen and dozens of colleagues) to watch live as scientists at the Large Hadron Collider, outside Geneva, announced that they had apparently found one of the most important missing pieces of the jigsaw puzzle that is nature.
The “Higgs particle,” proposed almost 50 years ago to allow for consistency between theoretical predictions and experimental observations in elementary particle physics, appears to have been discovered — even as the detailed nature of the discovery allows room for even more exotic revelations that may be just around the corner.
It is natural for those not deeply involved in the half-century quest for the Higgs to ask why they should care about this seemingly esoteric discovery. There are three reasons.
First, it caps one of the most remarkable intellectual adventures in human history — one that anyone interested in the progress of knowledge should at least be aware of.
Second, it makes even more remarkable the precarious accident that allowed our existence to form from nothing — further proof that the universe of our senses is just the tip of a vast, largely hidden cosmic iceberg.
And finally, the effort to uncover this tiny particle represents the very best of what the process of science can offer to modern civilization.
If one is a theoretical physicist working on some idea late at night or at a blackboard with colleagues over coffee one afternoon, it is almost terrifying to imagine that something that you cook up in your mind might actually be real. It’s like staring at a large jar and being asked to guess the number of jelly beans inside; if you guess right, it seems too good to be true.
The prediction of the Higgs particle accompanied a remarkable revolution that completely changed our understanding of particle physics in the latter part of the 20th century.
Just 50 years ago, in spite of the great advances of physics in the previous half century, we understood only one of the four fundamental forces of nature — electromagnetism — as a fully consistent quantum theory. In just one subsequent decade, however, not only had three of the four known forces succumbed to our investigations, but a new elegant unity of nature had been uncovered.
It was found that all of the known forces could be described using a single mathematical framework — and that two of the forces, electromagnetism and the weak force (which governs the nuclear reactions that power the sun), were actually different manifestations of a single underlying theory.
How could two such different forces be related? After all, the photon, the particle that conveys electromagnetism, has no mass, while the particles that convey the weak force are very massive — almost 100 times as heavy as the particles that make up atomic nuclei, a fact that explains why the weak force is weak.
What the British physicist Peter Higgs and several others showed is that if there exists an otherwise invisible background field permeating all of space, then the particles that convey some force like electromagnetism can interact with this field and effectively encounter resistance to their motion and slow down, like a swimmer moving through molasses.
As a result, these particles can behave as if they are heavy, as if they have a mass. The physicist Steven Weinberg later applied this idea to a model of the weak and electromagnetic forces previously proposed by Sheldon L. Glashow, and everything fit together.
This idea can be extended to the rest of particles in nature, including the protons and neutrons and electrons that make up the atoms in our bodies. If some particle interacts more strongly with this background field, it ends up acting heavier. If it interacts more weakly, if acts lighter. If it doesn’t interact at all, like the photon, it remains massless.
If anything sounds too good to be true, this is it. The miracle of mass — indeed of our very existence, because if not for the Higgs, there would be no stars, no planets and no people — is possible because of some otherwise hidden background field whose only purpose seems to be to allow the world to look the way it does.
Dr. Glashow, who along with Dr. Weinberg won a Nobel Prize in Physics, later once referred to this “Higgs field” as the “toilet” of modern physics because that’s where all the ugly details that allow the marvelous beauty of the physical world are hidden.
But relying on invisible miracles is the stuff of religion, not science. To ascertain whether this remarkable accident was real, physicists relied on another facet of the quantum world.
Associated with every background field is a particle, and if you pick a point in space and hit it hard enough, you may whack out real particles. The trick is hitting it hard enough over a small enough volume.
And that’s the rub. After 50 years of trying, including a failed attempt in this country to build an accelerator to test these ideas, no sign of the Higgs had appeared. In fact, I was betting against it, since a career in theoretical physics has taught me that nature usually has a far richer imagination than we do.
Until last week.
Every second at the Large Hadron Collider, enough data is generated to fill more than 1,000 one-terabyte hard drives — more than the information in all the world’s libraries. The logistics of filtering and analyzing the data to find the Higgs particle peeking out under a mountain of noise, not to mention running the most complex machine humans have ever built, is itself a triumph of technology and computational wizardry of unprecedented magnitude.
The physicist Victor F. Weisskopf — the colorful first director of CERN, the European Center for Nuclear Research, which operates the collider — once described large particle accelerators as the gothic cathedrals of our time. Like those beautiful remnants of antiquity, accelerators require the cutting edge of technology, they take decades or more to build, and they require the concerted efforts of thousands of craftsmen and women. At CERN, each of the mammoth detectors used to study collisions requires the work of thousands of physicists, from scores of countries, speaking several dozen languages.
Most significantly perhaps, cathedrals and colliders are both works of incomparable grandeur that celebrate the beauty of being alive.
The apparent discovery of the Higgs may not result in a better toaster or a faster car. But it provides a remarkable celebration of the human mind’s capacity to uncover nature’s secrets, and of the technology we have built to control them. Hidden in what seems like empty space — indeed, like nothing, which is getting more interesting all the time — are the very elements that allow for our existence.
By demonstrating that, last week’s discovery will change our view of ourselves and our place in the universe. Surely that is the hallmark of great music, great literature, great art ...and great science.
Lawrence M. Krauss, the director of the Origins Project at Arizona State University, is the author, most recently, of “A Universe From Nothing.”
ISLAMABAD—The pioneering work of Abdus Salam, Pakistan’s only Nobel laureate, helped lead to the apparent discovery of the subatomic “God particle” last week. But the late physicist is no hero at home, where his name has been stricken from school textbooks.
Related: What is the Higgs-boson and why the hunt for the god particle matters
Praise within Pakistan for Salam, who also guided the early stages of the country’s nuclear program, faded decades ago as Muslim fundamentalists gained power. He belonged to the Ahmadi sect, which has been persecuted by the government and targeted by Taliban militants who view its members as heretics.
Their plight — along with that of Pakistan’s other religious minorities, such as Shiite Muslims, Christians and Hindus — has deepened in recent years as hardline interpretations of Islam have gained ground and militants have stepped up attacks against groups they oppose. Most Pakistanis are Sunni Muslims.
Salam, a child prodigy born in 1926 in what was to become Pakistan after the partition of British-controlled India, won more than a dozen international prizes and honours. In 1979, he was co-winner of the Nobel Prize for his work on the so-called Standard Model of particle physics, which theorizes how fundamental forces govern the overall dynamics of the universe. He died in 1996.
Salam and Steven Weinberg, with whom he shared the Nobel Prize, independently predicted the existence of a subatomic particle now called the Higgs boson, named after a British physicist who theorized that it endowed other particles with mass, said Pervez Hoodbhoy, a Pakistani physicist who once worked with Salam. It is also known as the “God particle” because its existence is vitally important toward understanding the early evolution of the universe.
Physicists in Switzerland stoked worldwide excitement Wednesday when they announced they have all but proven the particle’s existence. This was done using the world’s largest atom smasher at the European Organization for Nuclear Research, or CERN, near Geneva.
“This would be a great vindication of Salam’s work and the Standard Model as a whole,” said Khurshid Hasanain, chairman of the physics department at Quaid-i-Azam University in Islamabad.
In the 1960s and early 1970s, Salam wielded significant influence in Pakistan as the chief scientific adviser to the president, helping to set up the country’s space agency and institute for nuclear science and technology. Salam also assisted in the early stages of Pakistan’s effort to build a nuclear bomb, which it eventually tested in 1998.
Salam’s life, along with the fate of the three million other Ahmadis in Pakistan, drastically changed in 1974 when parliament amended the constitution to declare that members of the sect were not considered Muslims under Pakistani law.
Ahmadis believe their spiritual leader, Hadhrat Mirza Ghulam Ahmad, who died in 1908, was the Promised Messiah — a position rejected by the government in response to a mass movement led by Pakistan’s major Islamic parties. Most Muslims consider Muhammad the last prophet and those who subsequently declared themselves prophets as heretics.
All Pakistani passport applicants must sign a section saying the Ahmadi faith’s founder was an “impostor” and his followers are “non-Muslims.” Ahmadis are prevented by law in Pakistan from “posing as Muslims,” declaring their faith publicly, calling their places of worship mosques or performing the Muslim call to prayer. They can be punished with prison and even death.
Salam resigned from his government post in protest following the 1974 constitutional amendment and eventually moved to Europe to pursue his work. In Italy, he created a centre for theoretical physics to help physicists from the developing world.
Although Pakistan’s then-president, general Zia ul-Haq, presented Salam with Pakistan’s highest civilian honour after he won the Nobel Prize, the general response in the country was muted. The physicist was celebrated more enthusiastically by other countries, including India.
Despite his achievements, Salam’s name appears in few textbooks and is rarely mentioned by Pakistani leaders or the media. By contrast, fellow Pakistani physicist A.Q. Khan, who played a key role in developing the country’s nuclear bomb and later confessed to spreading nuclear technology to Iran, North Korea and Libya, is considered a national hero.
Officials at Quaid-i-Azam University had to cancel plans for Salam to lecture about his Nobel-winning theory when Islamist student activists threatened to break the physicist’s legs, said his colleague Hoodbhoy.
“The way he has been treated is such a tragedy,” said Hoodbhoy. “He went from someone who was revered in Pakistan, a national celebrity, to someone who could not set foot in Pakistan. If he came, he would be insulted and could be hurt or even killed.”
The president who honoured Salam would later go on to intensify persecution of Ahmadis, for whom life in Pakistan has grown even more precarious. Taliban militants attacked two mosques packed with Ahmadis in Lahore in 2010, killing at least 80 people.
“Many Ahmadis have received letters from fundamentalists since the 2010 attacks threatening to target them again, and the government isn’t doing anything,” said Qamar Suleiman, a spokesman for the Ahmadi community.
For Salam, not even death saved him from being targeted.
Hoodbhoy said his body was returned to Pakistan in 1996 after he died in Oxford, England, and was buried under a gravestone that read “First Muslim Nobel Laureate.” A local magistrate ordered that the word “Muslim” be erased.
Large Hadron Collider restarts after two-year shutown
The world's largest particle collider has restarted after a two-year upgrade. Scientists are hoping the upgrade will provide still more energy to research so-called "dark matter."
Scientists at the European Organization for Nuclear Research, or CERN, on Sunday shot the first particle beams through the restarted Large Hadron Collider (LHC), after the particle accelerator underwent two years of work to increase its collision capacity.
The LHC - also known as the "Big Bang" collider -, which consists of a 27-kilometer-long (16.8-mile-long) tunnel beneath the Swiss-French border, is being used by researchers to study the "dark universe" - the subatomic particles that make up some 96 percent of matter in the known universe, along with the forces that hold them together.
The collider hit the headlines in 2012 with the discovery of the Higgs Boson, a subatomic particle that confers mass, whose existence had been theorized since 1968 but not confirmed.
The discovery earned the Nobel prize for two of the scientists who had proposed the existence of the particle.
The LHC uses powerful magnets to bend beams of protons coming from opposite directions, thus creating collisions that are monitored by sensors.
The subatomic debris is scanned for unknown kinds of particles and also provides information on coherent forces.
Scientists say the collider has nearly twice its previous energy following the upgrade, which will enable it to produce even more powerful collisions.
The restart was delayed last Saturday following a short-circuit in one of the LHC's magnet circuits.
DO physicists need empirical evidence to confirm their theories?
You may think that the answer is an obvious yes, experimental confirmation being the very heart of science. But a growing controversy at the frontiers of physics and cosmology suggests that the situation is not so simple.
A few months ago in the journal Nature, two leading researchers, George Ellis and Joseph Silk, published a controversial piece called “Scientific Method: Defend the Integrity of Physics.” They criticized a newfound willingness among some scientists to explicitly set aside the need for experimental confirmation of today’s most ambitious cosmic theories — so long as those theories are “sufficiently elegant and explanatory.” Despite working at the cutting edge of knowledge, such scientists are, for Professors Ellis and Silk, “breaking with centuries of philosophical tradition of defining scientific knowledge as empirical.”
Whether or not you agree with them, the professors have identified a mounting concern in fundamental physics: Today, our most ambitious science can seem at odds with the empirical methodology that has historically given the field its credibility.
How did we get to this impasse? In a way, the landmark detection three years ago of the elusive Higgs boson particle by researchers at the Large Hadron Collider marked the end of an era. Predicted about 50 years ago, the Higgs particle is the linchpin of what physicists call the “standard model” of particle physics, a powerful mathematical theory that accounts for all the fundamental entities in the quantum world (quarks and leptons) and all the known forces acting between them (gravity, electromagnetism and the strong and weak nuclear forces).
But the standard model, despite the glory of its vindication, is also a dead end. It offers no path forward to unite its vision of nature’s tiny building blocks with the other great edifice of 20th-century physics: Einstein’s cosmic-scale description of gravity. Without a unification of these two theories — a so-called theory of quantum gravity — we have no idea why our universe is made up of just these particles, forces and properties. (We also can’t know how to truly understand the Big Bang, the cosmic event that marked the beginning of time.)
This is where the specter of an evidence-independent science arises. For most of the last half-century, physicists have struggled to move beyond the standard model to reach the ultimate goal of uniting gravity and the quantum world. Many tantalizing possibilities (like the often-discussed string theory) have been explored, but so far with no concrete success in terms of experimental validation.
Today, the favored theory for the next step beyond the standard model is called supersymmetry (which is also the basis for string theory). Supersymmetry predicts the existence of a “partner” particle for every particle that we currently know. It doubles the number of elementary particles of matter in nature. The theory is elegant mathematically, and the particles whose existence it predicts might also explain the universe’s unaccounted-for “dark matter.” As a result, many researchers were confident that supersymmetry would be experimentally validated soon after the Large Hadron Collider became operational.
That’s not how things worked out, however. To date, no supersymmetric particles have been found. If the Large Hadron Collider cannot detect these particles, many physicists will declare supersymmetry — and, by extension, string theory — just another beautiful idea in physics that didn’t pan out.
But many won’t. Some may choose instead to simply retune their models to predict supersymmetric particles at masses beyond the reach of the Large Hadron Collider’s power of detection — and that of any foreseeable substitute.
Implicit in such a maneuver is a philosophical question: How are we to determine whether a theory is true if it cannot be validated experimentally? Should we abandon it just because, at a given level of technological capacity, empirical support might be impossible? If not, how long should we wait for such experimental machinery before moving on: ten years? Fifty years? Centuries?
Consider, likewise, the cutting-edge theory in physics that suggests that our universe is just one universe in a profusion of separate universes that make up the so-called multiverse. This theory could help solve some deep scientific conundrums about our own universe (such as the so-called fine-tuning problem), but at considerable cost: Namely, the additional universes of the multiverse would lie beyond our powers of observation and could never be directly investigated. Multiverse advocates argue nonetheless that we should keep exploring the idea — and search for indirect evidence of other universes.
The opposing camp, in response, has its own questions. If a theory successfully explains what we can detect but does so by positing entities that we can’t detect (like other universes or the hyperdimensional superstrings of string theory) then what is the status of these posited entities? Should we consider them as real as the verified particles of the standard model? How are scientific claims about them any different from any other untestable — but useful — explanations of reality?
Recall the epicycles, the imaginary circles that Ptolemy used and formalized around A.D. 150 to describe the motions of planets. Although Ptolemy had no evidence for their existence, epicycles successfully explained what the ancients could see in the night sky, so they were accepted as real. But they were eventually shown to be a fiction, more than 1,500 years later. Are superstrings and the multiverse, painstakingly theorized by hundreds of brilliant scientists, anything more than modern-day epicycles?
Just a few days ago, scientists restarted investigations with the Large Hadron Collider, after a two-year hiatus. Upgrades have made it even more powerful, and physicists are eager to explore the properties of the Higgs particle in greater detail. If the upgraded collider does discover supersymmetric particles, it will be an astonishing triumph of modern physics. But if nothing is found, our next steps may prove to be difficult and controversial, challenging not just how we do science but what it means to do science at all.
One of the main tenets of quantum physics is that particles, such as electrons and photons, can act like both a particle and a wave. In addition, a particle’s choice for which way it behaves depends upon how it is measured at the end of its journey.
Australian researchers recently confirmed this wave-particle duality by carrying out John Wheeler’s classic delayed-choice thought experiment. Their results confirm that, for quantum particles at least, reality doesn’t exist until it is measured, and that future events can affect the past.
“It proves that measurement is everything. At the quantum level, reality does not exist if you are not looking at it,” said study author Andrew Truscott, a professor of physics at Australian National University in a press release.
When Wheeler first proposed this thought experiment in 1978, he suggested using light beams, or photons, as the particles. The Australian team, though, used helium atoms instead. This added another layer of complexity to the experiment because, unlike photons, atoms have mass and can interact with electrical fields.
In this experiment, which was published May 25 in Nature Physics, the researchers sent a single atom down a path through a grating pattern formed by laser beams. This is similar to the solid grating used to scatter light. If the atom acted like a particle it would travel in a straight line. As a wave, though, the atom would produce the interference bands seen with light passing through double slits.
In addition, the researchers randomly added a second laser grating. They found that when this was present, the atoms created the wavelike interference pattern. When the second grating was not there, the atoms behaved like particles and traveled along a single path.
However, whether or not the second grating was added was determined only after the atom had made it through the first crossroads. The wave-like or particle-like behavior of the atom only came into existence when the researchers measured it after it had completed its journey.
This, says Truscott, shows that “a future event causes the photon to decide its past.” -
There was something wonderfully childlike in the delight of scientists and the public at the rendezvous of the New Horizons spacecraft with that most distant and mysterious of the planets, Pluto, even if it was reclassified a few years ago as merely a “dwarf” planet. But there was nothing childish in the extraordinary science and engineering required to send half a ton of highly sophisticated instruments hurtling through space at speeds of up to 47,000 miles an hour for three billion miles.
The whoops at the operations center at the Johns Hopkins Applied Physics Laboratory on Tuesday at the moment when the probe shot past Pluto, and the cheers when the spacecraft broke silence many hours later to confirm that it had survived the passage, spoke to an elemental curiosity in every human being, one awakened when a child first gazes out into a star-filled sky. That is ultimately what the mission was all about, as the celebrated British cosmologist Stephen Hawking declared in a message broadcast on NASA TV: “We explore because we are human and we want to know.”
For the scientists who launched New Horizons nine and a half years ago, there was a distinctly parental anxiety in the hours after it went silent on Monday so it could dedicate all its energies — a mere 200 watts — to taking pictures and measurements of the icy body. “We always talk about the spacecraft as being a child, maybe a teenager,” explained Alice Bowman, the operations manager.
There was a storybook quality to the entire mission. Perched at the edge of the solar system in a thicket of small frozen objects known as the Kuiper belt, Pluto was only discovered in 1930 by Clyde Tombaugh, a self-taught astronomer, a pinch of whose ashes were on board New Horizons, and named by an 11-year-old English girl, Venetia Burney, after the Roman god of the underworld. Once the spacecraft began sending clear pictures, scientists started naming various features on Pluto after fictional underworld characters ranging from the Balrog, a creature in J. R. R. Tolkien’s “Lord of the Rings” to Meng-Po, the goddess of forgetfulness in Chinese mythology.
The flyby is justifiably a source of great pride for the United States, which has now sent probes to all eight planets and the reclassified Pluto, fulfilling the ambitious challenge proclaimed by President John F. Kennedy on May 25, 1961, when he called on Congress to approve funding for a mission to the Moon and “perhaps to the very end of the solar system.”
The major motive then was to demonstrate the supremacy of Western freedoms over Soviet tyranny. The Cold War is over, and the end of the solar system has been reached. But that cannot be the end of space exploration.
What next? Scientists, of course, are full of ideas, from further probes into our solar system to a search for planets beyond (readers can vote their preferences here). Whatever the choice, there need not be any commercial or ideological justification. The human impulse to know is more than enough.
OUR senses appear to show us the world the way it truly is, but they are easily deceived. For example, if you listen to a recorded symphony through stereo speakers that are placed exactly right, the orchestra will sound like it’s inside your head. Obviously that isn’t the case.
But suppose you completely trusted your senses. You might find yourself asking well-meaning but preposterous scientific questions like “Where in the brain is the woodwinds section located?” A more reasonable approach is not to ask a where question but a how question: How does the brain construct this experience of hearing the orchestra in your head?
I have just set the stage to dispel a major misconception about emotions. Most people, including many scientists, believe that emotions are distinct, locatable entities inside us — but they’re not. Searching for emotions in this form is as misguided as looking for cerebral clarinets and oboes.
Of course, we experience anger, happiness, surprise and other emotions as clear and identifiable states of being. This seems to imply that each emotion has an underlying property or “essence” in the brain or body. Perhaps an annoying co-worker triggers your “anger neurons,” so your blood pressure rises; you scowl, yell and feel the heat of fury. Or the loss of a loved one triggers your “sadness neurons,” so your stomach aches; you pout, feel despair and cry. Or an alarming news story triggers your “fear neurons,” so your heart races; you freeze and feel a flash of dread.
Such characteristics are thought to be the unique biological “fingerprints” of each emotion. Scientists and technology companies spend enormous amounts of time and money trying to locate these fingerprints. They hope someday to identify your emotions from your facial muscle movements, your body changes and your brain’s electrical signals.
Some scientific studies seem to support that such fingerprints exist. But many of those studies disagree on what the fingerprints are, and a multitude of other studies indicate there are no such fingerprints.
Let’s start with neuroscience. The Interdisciplinary Affective Science Laboratory (which I direct) collectively analyzed brain-imaging studies published from 1990 to 2011 that examined fear, sadness, anger, disgust and happiness. We divided the human brain virtually into tiny cubes, like 3-D pixels, and computed the probability that studies of each emotion found an increase in activation in each cube.
Overall, we found that no brain region was dedicated to any single emotion. We also found that every alleged “emotion” region of the brain increased its activity during nonemotional thoughts and perceptions as well.
The most well-known “emotion” region of the brain is the amygdala, a group of nuclei found deep within the temporal lobes. Since 2009, at least 30 articles in the popular press have claimed that fear is caused by neurons firing in the amygdala. Yet only a quarter of the experiments that we analyzed showed an increase in activity in the amygdala during the experience of fear. Indeed, it has long been known that certain “fear” behaviors, such as fleeing, don’t require the amygdala.
Other evidence against the amygdala-fear relationship comes from a pair of identical twins, known in the scientific literature as “BG” and “AM,” who both have a genetic disease that obliterates the amygdala. BG has difficulty feeling fear in all but the most extreme situations, but AM leads a normal emotional life.
Brain regions like the amygdala are certainly important to emotion, but they are neither necessary nor sufficient for it. In general, the workings of the brain are not one-to-one, whereby a given region has a distinct psychological purpose. Instead, a single brain area like the amygdala participates in many different mental events, and many different brain areas are capable of producing the same outcome. Emotions like fear and anger, my lab has found, are constructed by multipurpose brain networks that work together.
If emotions are not distinct neural entities, perhaps they have a distinct bodily pattern — heart rate, respiration, perspiration, temperature and so on?
Again, the answer is no. My lab analyzed over 200 published studies, covering nearly 22,000 test subjects, and found no consistent and specific fingerprints in the body for any emotion. Instead, the body acts in diverse ways that are tied to the situation. Even a rat facing a threat (say, the odor of a cat) will flee, freeze or fight depending on its surrounding context.
The same goes for the human face Many scientists assume that the face clearly and reliably broadcasts emotion (scowling in anger, pouting in sadness, widening the eyes in fear, wrinkling the nose in disgust). But a growing body of evidence suggests that this is not the case. When we place electrodes on a human face and actually measure muscle movements during anger, for example, we find that people make a wide variety of movements, not just the stereotypical scowl.
CHARLES DARWIN famously vanquished the notion of essences in biology. He observed that a species is not a single type of being with a fixed set of attributes, but rather a population of richly varied individuals, each of which is better or worse suited to its environment.
Analogously, emotion words like “anger,” “happiness” and “fear” each name a population of diverse biological states that vary depending on the context. When you’re angry with your co-worker, sometimes your heart rate will increase, other times it will decrease and still other times it will stay the same. You might scowl, or you might smile as you plot your revenge. You might shout or be silent. Variation is the norm.
This insight is not just academic. When medical researchers ask, “What is the link between anger and cancer?” as if there is a single thing called “anger” in the body, they are in the grip of this error. When airport security officers are trained on the assumption that facial and body movements are reliable indicators of innermost feelings, taxpayers’ money is wasted.
The ease with which we experience emotions, and the effortlessness with which we see emotions in others, doesn’t mean that each emotion has a distinct pattern in the face, body or brain. Instead of asking where emotions are or what bodily patterns define them, we would do better to abandon such essentialism and ask the more revealing question, “How does the brain construct these incredible experiences?”
Lisa Feldman Barrett is a professor of psychology at Northeastern University and the author of the forthcoming book “How Emotions Are Made: The New Science of the Mind and Brain.”
For the first time, a team of researchers have filmed a complete central nervous system firing as a more complex animal--in this case, a fruit fly larva--moved back and forth.
How Walking in Nature Changes the Brain
A walk in the park may soothe the mind and, in the process, change the workings of our brains in ways that improve our mental health, according to an interesting new study of the physical effects on the brain of visiting nature.
Most of us today live in cities and spend far less time outside in green, natural spaces than people did several generations ago.
City dwellers also have a higher risk for anxiety, depression and other mental illnesses than people living outside urban centers, studies show.
These developments seem to be linked to some extent, according to a growing body of research. Various studies have found that urban dwellers with little access to green spaces have a higher incidence of psychological problems than people living near parks and that city dwellers who visit natural environments have lower levels of stress hormones immediately afterward than people who have not recently been outside.
But just how a visit to a park or other green space might alter mood has been unclear. Does experiencing nature actually change our brains in some way that affects our emotional health?
That possibility intrigued Gregory Bratman, a graduate student at the Emmett Interdisciplinary Program in Environment and Resources at Stanford University, who has been studying the psychological effects of urban living. In an earlier study published last month, he and his colleagues found that volunteers who walked briefly through a lush, green portion of the Stanford campus were more attentive and happier afterward than volunteers who strolled for the same amount of time near heavy traffic.
But that study did not examine the neurological mechanisms that might underlie the effects of being outside in nature.
So for the new study, which was published last week in Proceedings of the National Academy of Sciences, Mr. Bratman and his collaborators decided to closely scrutinize what effect a walk might have on a person’s tendency to brood.
Brooding, which is known among cognitive scientists as morbid rumination, is a mental state familiar to most of us, in which we can’t seem to stop chewing over the ways in which things are wrong with ourselves and our lives. This broken-record fretting is not healthy or helpful. It can be a precursor to depression and is disproportionately common among city dwellers compared with people living outside urban areas, studies show.
Perhaps most interesting for the purposes of Mr. Bratman and his colleagues, however, such rumination also is strongly associated with increased activity in a portion of the brain known as the subgenual prefrontal cortex.
If the researchers could track activity in that part of the brain before and after people visited nature, Mr. Bratman realized, they would have a better idea about whether and to what extent nature changes people’s minds.
Mr. Bratman and his colleagues first gathered 38 healthy, adult city dwellers and asked them to complete a questionnaire to determine their normal level of morbid rumination.
The researchers also checked for brain activity in each volunteer’s subgenual prefrontal cortex, using scans that track blood flow through the brain. Greater blood flow to parts of the brain usually signals more activity in those areas.
Then the scientists randomly assigned half of the volunteers to walk for 90 minutes through a leafy, quiet, parklike portion of the Stanford campus or next to a loud, hectic, multi-lane highway in Palo Alto. The volunteers were not allowed to have companions or listen to music. They were allowed to walk at their own pace.
Immediately after completing their walks, the volunteers returned to the lab and repeated both the questionnaire and the brain scan.
As might have been expected, walking along the highway had not soothed people’s minds. Blood flow to their subgenual prefrontal cortex was still high and their broodiness scores were unchanged.
But the volunteers who had strolled along the quiet, tree-lined paths showed slight but meaningful improvements in their mental health, according to their scores on the questionnaire. They were not dwelling on the negative aspects of their lives as much as they had been before the walk.
They also had less blood flow to the subgenual prefrontal cortex. That portion of their brains were quieter.
These results “strongly suggest that getting out into natural environments” could be an easy and almost immediate way to improve moods for city dwellers, Mr. Bratman said.
But of course many questions remain, he said, including how much time in nature is sufficient or ideal for our mental health, as well as what aspects of the natural world are most soothing. Is it the greenery, quiet, sunniness, loamy smells, all of those, or something else that lifts our moods? Do we need to be walking or otherwise physically active outside to gain the fullest psychological benefits? Should we be alone or could companionship amplify mood enhancements?
“There’s a tremendous amount of study that still needs to be done,” Mr. Bratman said.
But in the meantime, he pointed out, there is little downside to strolling through the nearest park, and some chance that you might beneficially muffle, at least for awhile, your subgenual prefrontal cortex.
Read the Lost Dream Journal of the Man Who Discovered Neurons
An exclusive look at the dreams Santiago Ramon y Cajal recorded to prove Freud was wrong.
Santiago Ramón y Cajal, a Spanish histologist and anatomist known today as the father of modern neuroscience, was also a committed psychologist who believed psychoanalysis and Freudian dream theory were “collective lies.” When Freud published The Interpretation of Dreams in 1900, the science world swooned over his theory of the unconscious. Dreams quickly became synonymous with repressed desire. Puzzling dream images could unlock buried conflicts, the psychoanalyst said, given the correct interpretation.
Cajal, who won the 1906 Nobel Prize for discovering neurons and, more remarkably, intuiting the form and function of synapses, set out to prove Freud wrong. To disprove the theory that every dream is the result of a repressed desire, Cajal began keeping a dream journal and collecting the dreams of others, analyzing them with logic and rigor.
[i]Translated here into English for the first time, the dreams of Santiago Ramón y Cajal offer insight into the mind of a great scientist.[/i]
Cajal eventually deemed the project unpublishable. But before his death in 1934, he gave his research, scribbled on stained loose papers and in the margins of books and newspapers, to his good friend and former student, the psychiatrist José Germain Cebrián. Germain typed the diary into a book, which was thought lost during the 1936 Spanish Civil War. In fact, Germain carried the manuscript with him as he traveled through Europe. Before his death, he gave it to José Rallo, a Spanish psychiatrist and dream researcher. To the delight of scholars and enthusiasts, Los sueños de Santiago Ramón y Cajal was published in Spanish in 2014, containing 103 of Cajal’s dreams, recorded between 1918 and his death in 1934.1 Translated here into English for the first time, these dreams, and Cajal’s notes on them, offer insight into the mind of a great scientist—insight that perhaps he himself did not always have.
Cajal exalted rational thinking and the conscious will. In his autobiography, the scientist described neurons as “mysterious butterflies of the soul, the beating of whose wings might one day, who knows, reveal the secrets of mental life.” He had a lifelong fascination with dreaming and dreams, despite, or perhaps because of, their tendency to resist all rational explanation. Early in his career, Cajal studied hypnosis and the power of suggestion, turning his home into a clinic for hysterics, neurasthenics, and spiritual mediums, and he planned to publish three psychological books before judging their content to be too speculative: Essays on Hypnotism, Spiritualism, and Metaphysics; Dreams: Critics of Their Explanatory Doctrines; and Dreams. He did, however, publish a scientific paper in 1908 on dreaming and visual hallucinations, which begins, “Dreaming is one of the most interesting and most wondrous phenomena of brain physiology.”2 He investigates visual hallucination in blind adults, concluding that the retina is not active during dreaming, instead studying the associative cortex, thalamus, and glial cells for evidence of activation.3
In 1902, in the preface to a contemporary poetry book, the normally reserved Cajal allowed himself to theorize a bit more freely about dreams. “The majority of dreams,” he writes, “consists of scraps of ideas, unconnected or weirdly assembled, somewhat like an absurd monster without proportions, harmony or reason.” He theorized that dreaming happens in unused areas of the cerebral cortex: “The fallow lands of the brain, that is, the cells in which unconscious images are recorded, stay awake and become excited, rejuvenating themselves with the exercise they did behind the back of the conscious mind.” At the end of the waking day, according to Cajal, certain groups of cells are tired out, leaving others to work during sleep. More than any theory, this persistent cellular focus is Cajal’s legacy to psychology, which indeed now favors a neurobiological approach.4 Some contemporary theories about the neuroscience of dreaming, namely the activation-synthesis hypothesis, would seem to support Cajal’s belief that dreams are a sequence of random images, unfiltered by the prefrontal cortex, which the brain then tries to interpret.
Cajal’s anatomical views on dreaming and his reluctance to speculate without physiological evidence stand in stark contrast to the dream theory made famous by Freud. In a letter to Juan Paulis, published in 1935, Cajal wrote, “Except in extremely rare cases it is impossible to verify the doctrine of the surly and somewhat egotistical Viennese author, who has always seemed more preoccupied with founding a sensational theory than with the desire to austerely serve the cause of scientific theory.”5
Devoted, like many mythologized geniuses, more to his work than his family, Cajal remained entranced at his microscope, failing to respond to his wife, Silveria Fañanás García, as she screamed through the night that their 6-year-old daughter was dying. In mourning, the light of the microscope was his only refuge. Thirty years after the death of his daughter, the father of contemporary neuroscience dreams that he is drowning off the coast of Spain, holding his little girl in his arms. This dream needs no further analysis.
THANKS to Caitlyn Jenner, and the military’s changing policies, transgender people are gaining acceptance — and living in a bigger, more understanding spotlight than at any previous time.
We’re learning to be more accepting of transgender individuals. And we’re learning more about gender identity, too.
The prevailing narrative seems to be that gender is a social construct and that people can move between genders to arrive at their true identity.
But if gender were nothing more than a social convention, why was it necessary for Caitlyn Jenner to undergo facial surgeries, take hormones and remove her body hair? The fact that some transgender individuals use hormone treatment and surgery to switch gender speaks to the inescapable biology at the heart of gender identity.
This is not to suggest that gender identity is simply binary — male or female — or that gender identity is inflexible for everyone. Nor does it mean that conventional gender roles always feel right; the sheer number of people who experience varying degrees of mismatch between their preferred gender and their body makes this very clear.
In fact, recent neuroscience research suggests that gender identity may exist on a spectrum and that gender dysphoria fits well within the range of human biological variation. For example, Georg S. Kranz at the Medical University of Vienna and colleagues elsewhere reported in a 2014 study in The Journal of Neuroscience that individuals who identified as transsexuals — those who wanted sex reassignment — had structural differences in their brains that were between their desired gender and their genetic sex.
Dr. Kranz studied four different groups: female-to-male transsexuals; male-to-female transsexuals; and controls who were born female or male and identify as such. Since hormones can have a direct effect on the brain, both transsexual groups were studied before they took any sex hormones, so observed differences in brain function and structure would not be affected by the treatment. He used a high-resolution technique called diffusion tensor imaging, a special type of M.R.I., to examine the white matter microstructure of subjects’ brains.
What Dr. Kranz found was intriguing: In several brain regions, people born female with a female gender identity had the highest level of something called mean diffusivity, followed by female-to-male transsexuals. Next came male-to-female transsexuals, and then the males with a male gender identity, who had the lowest levels.
In other words, it seems that Dr. Kranz may have found a neural signature of the transgender experience: a mismatch between one’s gender identity and physical sex. Transgender people have a brain that is structurally different than the brain of a nontransgender male or female — someplace in between men and women.
This gradient of structural brain differences, from females to males, with transgender people in between, suggests that gender identity has a neural basis and that it exists on a spectrum, like so much of human behavior.
Some theorize that the transgender experience might arise, in part, from a quirk of brain development. It turns out that the sexual differentiation of the brain happens during the second half of pregnancy, later than sexual differentiation of the genitals and body, which begins during the first two months of pregnancy. And since these two processes can be influenced independently of each other, it may be possible to have a mismatch between gender-specific brain development and that of the body.
Is it really so surprising that gender identity might, like sexual orientation, be on a spectrum? After all, one can be exclusively straight or exclusively gay — or anything in between. But variability in a behavior shouldn’t be confused with its malleability. There is little evidence, for example, that you really can change your sexual orientation. Sure, you can change your sexual behavior, but your inner sexual fantasies endure.
In fact, attempts to change a person’s sexual orientation, through so-called reparative therapy, have been debunked as quackery and rightly condemned by the psychiatric profession as potentially harmful.
Of course, people should have the freedom to assume whatever gender role makes them comfortable and refer to themselves with whatever pronoun they choose; we should encourage people to be who they really feel they are, not who or what society would like them to be. I wonder, if we were a more tolerant society that welcomed all types of gender identity, what the impact might be on gender dysphoria. How many transgender individuals would feel the need to physically change gender, if they truly felt accepted with whatever gender role they choose?
At the same time, we have to acknowledge that gender identity is a complex phenomenon, involving a mix of genes, hormones and social influence. And there is no getting around the fact that biology places constraints on our capacity to reimagine ourselves and to change, and it’s important to understand those limitations.
The critical question is not whether there is a range of gender identity — it seems clear that there is. Rather, it is to what extent and in which populations gender identity is malleable, and to what extent various strategies to change one’s body and behavior to match a preferred gender will give people the psychological satisfaction they seek.
Although transsexualism (defined as those who want to change or do change their body) is very rare — a recent meta-analysis estimated the prevalence at about 5 per 100,000 — it garners much media attention. What do we really know about how these individuals feel and function in their new role?
The data are all over the map. One meta-analysis published in 2010 of follow-up studies suggested that about 80 percent of transgender individuals reported subjective improvement in terms of gender dysphoria and quality of life. But the review emphasized that many of the studies were suboptimal: All of them were observational and most lacked controls.
Dr. Cecilia Dhejne and colleagues at the Karolinska Institute in Sweden have done one of the largest follow-up studies of transsexuals, published in PLOS One in 2011. They compared a group of 324 Swedish transsexuals for an average of more than 10 years after gender reassignment with controls and found that transsexuals had 19 times the rate of suicide and about three times the mortality rate compared with controls. When the researchers controlled for baseline rates of depression and suicide, which are known to be higher in transsexuals, they still found elevated rates of depression and suicide after sex reassignment.
This study doesn’t prove that gender reassignment per se was the cause of the excess morbidity and mortality in transsexual people; to answer that, you would have to compare transgender people who were randomly assigned to reassignment to those who were not. Still, even if hormone replacement and surgery relieve gender dysphoria, the overall outcome with gender reassignment doesn’t look so good — a fact that only underscores the need for better medical treatments in general for transgender individuals and better psychiatric care after reassignment.
Alarmingly, 41 percent of transgender and gender nonconforming individuals attempt suicide at some point in their lifetime compared with 4.6 percent of the general public, according to a joint study by the American Foundation for Suicide Prevention and the Williams Institute. The disturbingly high rate of suicide attempts among transgender people likely reflects a complex interaction of mental health factors and experiences of harassment, discrimination and violence. The study analyzed data from the National Transgender Discrimination Survey, which documents the bullying, harassment, rejection by family and other assorted horrors.
On a broader level, the outcome studies suggest that gender reassignment doesn’t necessarily give everyone what they really want or make them happier.
Nowhere is this issue more contentious than in children and adolescents who experience gender dysphoria or the sense that their desired gender mismatches their body. In fact, there are few areas of medicine or psychiatry where the debate has become so heated. I was surprised to discover how many professional colleagues in this area either warned me to be careful about what I wrote or were reluctant to talk with me on the record for fear of reprisal from the transgender community.
If gender identity were a fixed and stable phenomenon in all young people, there would be little to argue about. But we have learned over the past two decades that, like so much else in child and adolescent behavior, the experience of gender dysphoria is itself often characterized by flux.
Several studies have tracked the persistence of gender dysphoria in children as they grow. For example, Dr. Richard Green’s study of young boys with gender dysphoria in the 1980s found that only one of the 44 boys was gender dysphoric by adolescence or adulthood. And a 2008 study by Madeleine S. C. Wallein, at the VU University Medical Center in the Netherlands, reported that in a group of 77 young people, ages 5 to 12, who all had gender dysphoria at the start of the study, 70 percent of the boys and 36 percent of the girls were no longer gender dysphoric after an average of 10 years’ follow-up.
THIS strongly suggests that gender dysphoria in young children is highly unstable and likely to change. Whether the loss of gender dysphoria is spontaneous or the result of parental or social influence is anyone’s guess. Moreover, we can’t predict reliably which gender dysphoric children will be “persisters” and which will be “desisters.”
So if you were a parent of, say, an 8-year-old boy who said he really wanted to be a girl, you might not immediately accede to your child’s wish, knowing that there is a high probability — 80 percent, in some studies — that that desire will disappear with time.
The counterargument is that to delay treatment is to consign this child to psychological suffering of potentially unknown duration. This is a disturbing possibility, though much can be done to help alleviate depression or anxiety without necessarily embarking on gender change. But rather than managing these psychological symptoms and watchfully waiting, some groups recommend pharmacologically delaying the onset of puberty in gender dysphoric children until age 16, before proceeding to reassignment. Puberty suppression is presumed reversible, and can be stopped if the adolescent’s gender dysphoria desists. But the risks of this treatment are not fully understood. Even more troubling, some doctors appear to be starting reassignment earlier. Some argue that the medical and psychiatric professions have a responsibility to respond to the child as he or she really is.
But if anything marks what a child really is, it is experimentation and flux. Why, then, would one subject a child to hormones and gender reassignment if there is a high likelihood that the gender dysphoria will resolve?
With adolescents, the story is very different: About three quarters of gender dysphoric teens may be “persisters,” which makes decisions about gender reassignment at this age more secure.
Clinicians who take an agnostic watch-and-wait approach in children with gender dysphoria have been accused by some in the transgender community of imposing societal values — that boys should remain boys and girls remain girls — on their patients and have compared them to clinicians who practice reparative therapy for gays.
I think that criticism is misguided. First, there is abundant evidence that reparative therapy is both ineffective and often harmful, while there is no comparable data in the area of gender dysphoria. Second, unlike sexual orientation, which tends to be stable, gender dysphoria in many young people clearly isn’t. Finally, when it comes to gender dysphoria, the evidence for therapeutics are simply poor to start with: There are no randomized clinical trials and very few comparative studies examining different approaches for this population.
Given the absence of good treatment-outcome data, how can anyone — whether transgender activist, parent or clinician — be sure of the best course of action?
There is obviously a huge gap between rapidly shifting cultural attitudes about gender identity and our scientific understanding of them. Until we have better data, what’s wrong with a little skepticism? After all, medical and psychological treatments should be driven by the best available scientific evidence — not political pressure or cherished beliefs.
Richard A. Friedman is a professor of clinical psychiatry at Weill Cornell Medical College and a contributing opinion writer.
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A version of this op-ed appears in print on August 23, 2015, on page SR1 of the New York edition with the headline: How Changeable Is Gender? . Today's Paper|Subscribe
How a Volcanic Eruption in 1815 Darkened the World but Colored the Arts
In April 1815, the most powerful volcanic blast in recorded history shook the planet in a catastrophe so vast that 200 years later, investigators are still struggling to grasp its repercussions. It played a role, they now understand, in icy weather, agricultural collapse and global pandemics — and even gave rise to celebrated monsters.
Around the lush isles of the Dutch East Indies — modern-day Indonesia — the eruption of Mount Tambora killed tens of thousands of people. They were burned alive or killed by flying rocks, or they died later of starvation because the heavy ash smothered crops.
More surprising, investigators have found that the giant cloud of minuscule particles spread around the globe, blocked sunlight and produced three years of planetary cooling. In June 1816, a blizzard pummeled upstate New York. That July and August, killer frosts in New England ravaged farms. Hailstones pounded London all summer.
A recent history of the disaster, “Tambora: The Eruption that Changed the World,” by Gillen D’Arcy Wood, shows planetary effects so extreme that many nations and communities sustained waves of famine, disease, civil unrest and economic decline. Crops failed globally.
Most of us have come down from the highs of seeing Pluto up close for the first time. Ever since New Horizons beamed back those photos, the question has loomed: What's next?
We asked a few experts and Times readers what NASA’s exploratory priority should be in the years ahead. More than 1,600 readers shared their imaginative ideas. Some responses were serious and technical. Others were more whimsical, like that of Carter Read of Brooklyn, who proposed that we “send a record player bumping the sounds of Chuck Berry’s ‘golden decade’ into deep space,” because “he’s the best communicator the human race has.” (Mr. Berry already has one song in space, aboard the Voyager spacecraft.)
Below are some of the best responses, starting with the most popular. Perhaps NASA — and the members of Congress who appropriate its budget — will listen up.
Jacob Bekenstein, Physicist Who Revolutionized Theory of Black Holes, Dies at 68
Jacob Bekenstein, a physicist who prevailed in an argument with Stephen Hawking that revolutionized the study of black holes, and indeed the nature of space-time itself, died on Sunday in Helsinki, Finland, where he was to give a physics lecture. He was 68.
In the Haaretz.com interview, Dr. Bekenstein put it more modestly. “I look at the world as a product of God,” he said. His job as a scientist, he added, was to figure out how it works.
“I feel much more comfortable in the world because I understand how simple things work,” he said. “I get a sense of security that not everything is random, and that I can actually understand and not be surprised by things.”
Boston — IS psychology in the midst of a research crisis?
An initiative called the Reproducibility Project at the University of Virginia recently reran 100 psychology experiments and found that over 60 percent of them failed to replicate — that is, their findings did not hold up the second time around. The results, published last week in Science, have generated alarm (and in some cases, confirmed suspicions) that the field of psychology is in poor shape.
But the failure to replicate is not a cause for alarm; in fact, it is a normal part of how science works.
Suppose you have two well-designed, carefully run studies, A and B, that investigate the same phenomenon. They perform what appear to be identical experiments, and yet they reach opposite conclusions. Study A produces the predicted phenomenon, whereas Study B does not. We have a failure to replicate.
Does this mean that the phenomenon in question is necessarily illusory? Absolutely not. If the studies were well designed and executed, it is more likely that the phenomenon from Study A is true only under certain conditions. The scientist’s job now is to figure out what those conditions are, in order to form new and better hypotheses to test.
A number of years ago, for example, scientists conducted an experiment on fruit flies that appeared to identify the gene responsible for curly wings. The results looked solid in the tidy confines of the lab, but out in the messy reality of nature, where temperatures and humidity varied widely, the gene turned out not to reliably have this effect. In a simplistic sense, the experiment “failed to replicate.” But in a grander sense, as the evolutionary biologist Richard Lewontin has noted, “failures” like this helped teach biologists that a single gene produces different characteristics and behaviors, depending on the context.
Similarly, when physicists discovered that subatomic particles didn’t obey Newton’s laws of motion, they didn’t cry out that Newton’s laws had “failed to replicate.” Instead, they realized that Newton’s laws were valid only in certain contexts, rather than being universal, and thus the science of quantum mechanics was born.
In psychology, we find many phenomena that fail to replicate if we change the context. One of the most famous is called “fear learning,” which has been used to explain anxiety disorders like post-traumatic stress. Scientists place a rat into a small box with an electrical grid on the floor. They play a loud tone and then, a moment later, give the rat an electrical shock. The shock causes the rat to freeze and its heart rate and blood pressure to rise. The scientists repeat this process many times, pairing the tone and the shock, with the same results. Eventually, they play the tone without the shock, and the rat responds in the same way, as if expecting the shock.
Originally this “fear learning” was assumed to be a universal law, but then other scientists slightly varied the context and the rats stopped freezing. For example, if you restrain the rat during the tone (which shouldn’t matter if the rat is going to freeze anyway), its heart rate goes down instead of up. And if the cage design permits, the rat will run away rather than freeze.
These failures to replicate did not mean that the original experiments were worthless. Indeed, they led scientists to the crucial understanding that a freezing rat was actually responding to the uncertainty of threat, which happened to be engendered by particular combinations of tone, cage and shock.
Much of science still assumes that phenomena can be explained with universal laws and therefore context should not matter. But this is not how the world works. Even a simple statement like “the sky is blue” is true only at particular times of day, depending on the mix of molecules in the air as they reflect and scatter light, and on the viewer’s experience of color.
Psychologists are usually well attuned to the importance of context. In our experiments, we take great pains to avoid any irregularities or distractions that might affect the results. But when it comes to replication, psychologists and their critics often seem to forget the powerful and subtle effects of context. They ask simply, “Did the experiment work or not?” rather than considering a failure to replicate as a valuable scientific clue.
As with any scientific field, psychology has some published studies that were conducted sloppily, and a few bad eggs who have falsified their data. But contrary to the implication of the Reproducibility Project, there is no replication crisis in psychology. The “crisis” may simply be the result of a misunderstanding of what science is.
Science is not a body of facts that emerge, like an orderly string of light bulbs, to illuminate a linear path to universal truth. Rather, science (to paraphrase Henry Gee, an editor at Nature) is a method to quantify doubt about a hypothesis, and to find the contexts in which a phenomenon is likely. Failure to replicate is not a bug; it is a feature. It is what leads us along the path — the wonderfully twisty path — of scientific discovery.
Lisa Feldman Barrett, a professor of psychology at Northeastern University, is the author of the forthcoming book “How Emotions Are Made: The New Science of the Mind and Brain.”
Mendeleev’s Garden In honor of the late neurologist who charmed us with over a dozen books, a beloved essay from the archives.
By Oliver Sacks
"Even as a student in St. Petersburg, Mendeleev showed not only an insatiable curiosity but a hunger for organizing principles of all kinds. Linnaeus, in the eighteenth century, had classified animals and plants, and (much less successfully) minerals, too. Dana, in the 1830s, had replaced the old physical classification of minerals with a chemical classification of a dozen or so main categories (native elements, oxides, sulfides, and so on). But there was no such classification for the elements themselves, and there were now some sixty elements known. Some elements, indeed, seemed almost impossible to categorize. Where did uranium go, or that puzzling, ultralight metal, beryllium? Some of the most recently discovered elements were particularly difficult—thallium, for example, discovered in 1862, was in some ways similar to lead, in others to silver, in others to aluminum, and in yet others to potassium.
It was nearly twenty years from Mendeleev’s first interest in classification to the emergence of his periodic table in 1869. This long pondering and incubation (so similar, in a way, to Darwin’s before he published On the Origin of Species) was perhaps the reason why, when Mendeleev finally published his Principles, he could bring a vastness of knowledge and insight far beyond any of his contemporaries—some of them also had a clear vision of periodicity, but none of them could marshal the overwhelming detail he could."
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