Raiders of the lost dimension

Technorati Tags: BaCuSi2O6 or quantum mechanics and Dimensional Reduction at a Quantum Critical Point or Nanotechnology and nanoparticles or Nanotech and Xi'an terra cotta warriors or Qian Dynasty and nanoscale or Bose Einstein condensate and superconductors or physics and National High Magnetic Field Laboratory or Nuclear physicists and heavy fermions or Nanoscience

Discovery another step toward understanding the quantum mechanics of the universe

Ancient Chinese warriors are yet again helping scientists from the National High Magnetic Field Laboratory and their collaborators unravel some of the mysteries of the natural world.

It all starts with a pigment called Han purple that was used more than 2,000 years ago to color Xi’an terra cotta warriors of the Qian Dynasty. The pigment is known in the scientific world as BaCuSi206 — and when magnet lab scientists exposed it to very high magnetic fields and very low temperatures, it entered a state of matter that is rarely observed.

The most recent research, published in today's issue of the journal Nature, shows that at the lowest temperature point at which the change of state occurs — called the Quantum Critical Point — the Han purple pigment actually loses a dimension: it goes from 3D to 2D. Theoretical physicists have postulated that this kind of dimensional reduction might help explain some mysterious properties of other materials (high temperature superconductors and metallic magnets known as “heavy fermions” for example) near the absolute zero of temperature, but until now, a change in dimension had not been experimentally observed.

We live in three dimensions; up-down, front-back and left-right are the options. A sound wave, for example, “exists” in three dimensions and propagates in all of these directions simultaneously. If we could take a picture it would look like an expanding balloon. A wave in two dimensions looks like ripples on the surface of a pond. Ripples propagate on the surface only; they don’t propagate perpendicular to the surface, which is the third dimension.

“As often happens in science, we found something we weren’t looking for,” said Marcelo Jaime, an experimental physicist at the magnet lab’s Pulsed Field Facility in Los Alamos, N.M. “Much to our surprise, we found that when the temperature is low enough, the transition into the new magnetic state occurs in an unexpected way.”

The experiment was performed at the magnet lab’s DC Field Facility at Florida State University by Neil Harrison from the Pulsed Field Facility and Suchitra Sebastian from Stanford University, in collaboration with a team of scientists from these institutions. (To read more about the paper, "Dimensional Reduction at a Quantum Critical Point," visit the Nature Web site.)

They observed that at high magnetic fields (above 23 tesla) and temperatures between 1 and 3 degrees Kelvin (approximately -460 degrees Fahrenheit), the magnetic waves in three-dimensional crystals of Han purple "exist" in a three-dimensional world as per conventional wisdom. However, below those temperatures, near the quantum limit, one of the dimensions is no longer accessible, with the unexpected consequence that magnetic ripples propagate in only two dimensions. (Kelvin is the temperature scale used by scientists; zero degrees Kelvin is absolute zero, a temperature so low it is experimentally unreachable.)

The magnetic waves in the pigment exist in a unique state of matter called a Bose Einstein condensate (BEC), so named for its theoretical postulation by Satyendra Nath Bose and Albert Einstein. In the BEC state, the individual waves (associated with magnetism from pairs of copper atoms in BaCuSi2O6) lose their identities and condense into one giant wave of undulating magnetism. As the temperature is lowered, this magnetic wave becomes sensitive to vertical arrangement of individual copper layers, which are shifted relative to each other – a phenomenon known as "geometrical frustration." This makes it difficult for the magnetic wave to exist in the third up-down dimension any longer, and leads to a change to a two-dimensional wave, in very much the same way as ripples are confined to the surface of a pond. The theoretical framework that leads to this interpretation was provided by Cristian Batista at LANL.

Other members of the research team include Peter Sharma and Jaime of the National High Magnetic Field Laboratory at LANL, Luis Balicas from the NHMFL at FSU, Ian Fisher of Stanford, and Naoki Kawashima of the University of Tokyo.

“This is truly paramount work,” said Alex Lacerda, associate director for user operations for all three sites of the magnet lab and director of the Pulsed Field Facility. “It takes world-class magnets, instruments and people, all of which the mag lab has, to produce these kinds of landmark results.”

Research such as this could aid in the understanding of processes important for quantum computers. It is believed that this type of computer would operate based on quantum magnetism to perform many different computations at once. Theorists believe this capability could produce answers to mathematical problems much more quickly than is currently possible with conventional computers.

Scientists also think that someday, information gleaned from BEC will help make instruments for very sensitive measurement and tiny structures that are much smaller than computer chips.

The National High Magnetic Field Laboratory develops and operates state-of-the-art, high-magnetic-field facilities that faculty and visiting scientists and engineers use for interdisciplinary research. The laboratory – with branches in Tallahassee and Gainesville, Florida; and Los Alamos, New Mexico – is sponsored by the National Science Foundation and the state of Florida and is the only facility of its kind in the United States. To learn more, please visit magnet.fsu.edu

About Han Purple

Chinese chemists first synthesized the Han purple pigment from barium copper silicates more than 2,000 years ago and used the pigment in pottery, large imperial projects such as the terra cotta warriors, and as a trading coin. Scientists at the magnet lab did not initially know the historical significance of their sample, which precedes both paper and the navigational compass. Historians speculate that the basic know-how necessary to make BaCuSi2O6 was spread by word of mouth from Egypt to China along the legendary “Silk Road.” A similar pigment called Egyptian blue (SrCuSi4O10) was synthesized in Egypt more than 3,500 years ago.

For a photo illustration of the Xi’an terra cotta warriors, please e-mail Susan Ray: sray@magnet.fsu.edu)

Contact: Neil Harrisonnharrison@lanl.gov 505-665-3200 National High Magnetic Field Laboratory Contact: Cristian D. Batista, 505-667-5611, Marcelo Jaime, 505-667-7625

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Hope I die before I get old?

Technorati Tags: aging or Pete Townshend and My Generation or Medical and old age or youth and Mental Health or social sciences and Psychology or biology,

Study finds attitudes about aging contradict reality, U-M and VA team find young and old alike fail to anticipate late-life happiness.<

ANN ARBOR, MI – Back when he was 20 years old in 1965, rock star Pete Townshend wrote the line “I hope I die before I get old” into a song, “My Generation” that launched his band, the Who, onto the rock ‘n’ roll scene.

But a unique new study suggests that Townshend may have fallen victim to a common, and mistaken, belief: That the happiest days of people’s lives occur when they’re young.

In fact, the study finds, both young people and older people think that young people are happier than older people — when in fact research has shown the opposite. And while both older and younger adults tend to equate old age with unhappiness for other people, individuals tend to think they’ll be happier than most in their old age.

In other words, the young Pete Townshend may have thought others of his generation would be miserable in old age. And now that he’s 61, he might look back and think he himself was happier back then. But the opposite is likely to be true: Older people “mis-remember” how happy they were as youths, just as youths “mis-predict” how happy (or unhappy) they will be as they age.

The study, performed by VA Ann Arbor Healthcare System and University of Michigan researchers, involved more than 540 adults who were either between the ages of 21 and 40, or over age 60. All were asked to rate or predict their own individual happiness at their current age, at age 30 and at age 70, and also to judge how happy most people are at those ages. The results are published in the June issue of the Journal of Happiness Studies, a major research journal in the field of positive psychology.

“Overall, people got it wrong, believing that most people become less happy as they age, when in fact this study and others have shown that people tend to become happier over time,” says lead author Heather Lacey, Ph.D., a VA postdoctoral fellow and member of the U-M Medical School’s Center for Behavioral and Decision Sciences in Medicine. “Not only do younger people believe that older people are less happy, but older people believe they and others must have been happier ‘back then’. Neither belief is accurate.”

The findings have implications for understanding young people’s decisions about habits — such as smoking or saving money — that might affect their health or finances later in life. They also may help explain the fear of aging that drives middle-aged people to “midlife crisis” behavior in a vain attempt to slow their own aging.

Stereotypes about aging abound in our society, Lacey says, and affect the way older people are treated as well as the public policies that affect them.

That’s why research on the beliefs that fuel those one-size-fits-all depictions of older people is important, she explains. The study is one of the first ever to examine the ability of individuals to remember or predict happiness over the lifespan. Most studies of happiness have focused on people with chronic illness, disabilities or other major life challenges, or have taken “snapshots” of current happiness among older people.

The senior author of the new paper, Peter Ubel, M.D., has conducted several of these studies, and has found that ill people are often surprisingly happy, sometimes just as happy as healthy people. This suggests an adaptability or resilience in the face of their medical problems. Ubel is the director of the Center for Behavioral and Decision Sciences in Medicine, an advisor to the RWJ Clinical Scholars Program, and author of You’re Stronger Than You Think: Tapping the Secrets of Emotionally Resilient People (McGraw-Hill, 2006).

“People often believe that happiness is a matter of circumstance, that if something good happens, they will experience long-lasting happiness, or if something bad happens, they will experience long-term misery,” he says. “But instead, people’s happiness results more from their underlying emotional resources — resources that appear to grow with age. People get better at managing life’s ups and downs, and the result is that as they age, they become happier — even though their objective circumstances, such as their health, decline.”

Lacey adds, “It’s not that people overestimate their happiness, but rather that they learn how to value life from adversities like being sick. What the sick learn from being sick, the rest of us come to over time.” The new study, she explains, sprang from a desire to see whether the experience that comes with advancing age affects attitudes and predictions about aging.

The study was done using an online survey with six questions, asked in four different orders to reduce bias. The participants were part of large group of individuals who had previously volunteered to take online surveys, and chose to respond to the U-M/VA inquiry. The two age groups were about equally divided between men and women. About 35 percent of the younger group’s members were from ethnic minority groups, compared with 24 percent of the older group’s members.

Each participant was asked to rate his or her own current level of happiness on a scale of 1 to 10, and also to rate on that same scale how happy an average person of their age would be. Each participant was also asked to remember or predict (depending on their age) their level of happiness at age 30 and at age 70, again on a scale of 1 to 10. They were also asked to guess the happiness of the average person at each of those ages.

To make sure that their online survey methodology didn’t skew the results by including an atypical group of older people, the researchers compare the older group’s happiness self-ratings with those from self-ratings collected in other ways from people of the same age range. They matched.

In all, a statistical analysis of the results show, people in the older group reported a current level of happiness for themselves that was significantly higher than the self-rating made by the younger group’s members. And yet, participants of all ages thought that the average 30-year-old would be happier than the average 70-year-old, and that happiness would decline with age.

Interestingly, the younger people in the study predicted that they themselves would be about as happy at age 70 as they were in younger years, though they said that others their own age would probably get less happy over time. And the older people in the study tended to think that they’d be happier at older ages than other people would be.

This tendency to think of oneself as “above average” has been seen in other studies of everything from driving ability to intelligence, Lacey says. This bias may combine with negative attitudes about aging to help explain the study’s findings, she notes.

Further analysis of the study data will examine the impact of individuals’ core beliefs on their predictions and memory of happiness.

Since completing the study, the researchers have gone back to study people between the ages of 40 and 60, and hope to present those data soon. They also plan to study how beliefs about happiness in young and old age influence people’s retirement planning and health care decision making.

In addition to Lacey and Ubel, the study was co-authored by Dylan Smith, Ph.D., a research investigator at the CDBSM. The center’s web site is www.cbdsm.org. The study was funded by the National Institute of Child Health and Human Development, and by the Department of Veterans Affairs. Reference: Journal of Happiness Studies, June 2006 Vol 7, Issue 2.

Written by Kara Gavin, Contact: Kara Gavin kegavin@umich.edu, 734-764-2220 University of Michigan Health System

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