PRESS-NEWS.org - Press Release Distribution
PRESS RELEASES DISTRIBUTION

Experimental quest to test Einstein's speed limit

Physicists use dysprosium to put bounds on maximum speed of electrons

2013-07-29
(Press-News.org) Albert Einstein's assertion that there's an ultimate speed limit – the speed of light – has withstood countless tests over the past 100 years, but that didn't stop University of California, Berkeley, postdoc Michael Hohensee and graduate student Nathan Leefer from checking whether some particles break this law.

The team's first attempt to test this fundamental tenet of the special theory of relativity demonstrated once again that Einstein was right, but Leefer and Hohensee are improving the experiment to push the theory's limits even farther – and perhaps turn up a discrepancy that could help physicists fix holes in today's main theories of the universe.

"As a physicist, I want to know how the world works, and right now our best models of how the world works – the Standard Model of particle physics and Einstein's theory of general relativity – don't fit together at high energies," said Hohensee of the Department of Physics. "By finding points of breakage in the models, we can start to improve these theories."

Hohensee, Leefer and Dmitry Budker, a UC Berkeley professor of physics, conducted the test using a new technique involving two isotopes of the element dysprosium. By measuring the energy required to change the velocity of electrons as they jumped from one atomic orbital to another while Earth rotated over a 12-hour period, they determined that the maximum speed of an electron – in theory, the speed of light, about 300 million meters per second – is the same in all directions to within 17 nanometers per second. Their measurements were 10 times more precise than previous attempts to measure the maximum speed of electrons.

Using the two isotopes of dysprosium as "clocks," they also showed that as the Earth moved closer to or farther from the sun over the course of two years, the relative frequency of these "clocks" remained constant, as Einstein predicted in his general theory of relativity. Their limits on anomalies in the physics of electrons that produce deviations from Einstein's gravitational redshift are 160 times better than previous experimental limits.

The UC Berkeley physicists and colleagues at the University of New South Wales in Sydney, Australia, who provided crucial theoretical calculations, published their results this week in the journal Physical Review Letters.

Hohensee noted that similar tests of Einstein's theories can be conducted in huge accelerators like the Large Hadron Collider (LHC) in Switzerland, but such experiments are expensive, the colliders take a long time to build and still don't reach energies high enough to where the theories could break down.

"You can try to probe these theories using big accelerators, but you would need to produce electrons with seven times the energy of the protons at the LHC. Or you can look at high energy phenomena in distant stars or black holes, but those are not in the lab and not fully understood," he said. "Instead, We can look for evidence that the standard model or general relativity break at low energy scales in small ways in a tabletop experiment."

Compared with existing tests, the revamped experiment by UC Berkeley physicists will potentially be a thousand times more sensitive, the level at which some theorists predict special relativity might break down.

"This technique will open the door to studying a whole other set of parameters that could be even more interesting and important," said Budker, who was among the first to use dysprosium's unusual electronic structure to test fundamental aspects of particle physics.

Budker and his team also report in a newly accepted paper in Physical Review Letters that they used the same experimental apparatus to show that a fundamental constant of nature, the fine structure constant, does not vary over time or in different gravitational fields.

Hohensee is part of a group led by UC Berkeley physics professor Holger Müller that focuses on precision measurements to test aspects of Einstein's theories, including gravitational redshift. The new results complement findings from one of Müller's 2010 experiments, which put the tightest limits yet on the gravitational redshift for matter waves.

"This experiment introduces a new technology using dysprosium to the field of testing Einstein. That is the major new trick. That makes it especially interesting to me," Müller said.

### The work was supported by the Australian Research Council, National Science Foundation, Foundational Questions Institute and Miller Institute for Basic Research in Science at UC Berkeley.


ELSE PRESS RELEASES FROM THIS DATE:

Examination of lymph nodes provides more accurate breast cancer prognosis

2013-07-29
After a breast cancer operation, the removed tumour is always examined, as its subtype can provide an indication of how aggressive the disease is. The patient's lymph nodes are not analysed in the same way. Yet the breast tumour can sometimes appear to be of a less aggressive type while the subtype in the lymph nodes gives a different and more worrying picture. In these cases, it is the lymph nodes that provide the correct prognosis, according to new research at Lund University in Sweden. An analysis of the proliferation, hormone receptor status and HER2 status of the ...

Young cannabis-smokers aware of the health risks

2013-07-29
91 percent of on average 20-year-old Swiss men drink alcohol, almost half of whom drink six beverages or more in a row and are thus at-risk consumers. 44 percent of Swiss men smoke tobacco, the majority of whom are at-risk consumers – they smoke at least once a day. 36 percent of young adults smoke cannabis, whereby over half are at-risk consumers, using the drug at least twice a week. Researchers from the University of Zurich's Institute of Social and Preventive Medicine investigated whether these young Swiss men read up on addictive substances such as alcohol, tobacco, ...

Borneo's orangutans are coming down from the trees

2013-07-29
Orangutans might be the king of the swingers, but primatologists in Borneo have found that the great apes spend a surprising amount of time walking on the ground. The research, published in the American Journal of Primatology found that it is common for orangutans to come down from the trees to forage or to travel, a discovery which may have implications for conservation efforts. An expedition led by Brent Loken from Simon Fraser University and Dr. Stephanie Spehar from the University of Wisconsin Oshkosh, travelled to the East Kalimantan region of Borneo. The region's ...

The best of 2 worlds: Solar hydrogen production breakthrough

2013-07-29
This news release is available in German. The photo anode, which is made from the metal oxide bismuth vanadate (BiVO4) to which a small amount of tungsten atoms was added, was sprayed onto a piece of conducting glass and coated with an inexpensive cobalt phosphate catalyst. "Basically, we combined the best of both worlds," explains Prof. Dr. Roel van de Krol, head of the HZB Institute for Solar Fuels: "We start with a chemically stable, low cost metal oxide, add a really good but simple silicon-based thin film solar cell, and – voilà – we've just created a cost-effective, ...

Cockatoos know what is going on behind barriers

2013-07-29
This news release is available in German. VIDEO: How do you know that the cookies are still there although they have been placed out of your sight into the drawer? Alice Auersperg and her team from the University... Click here for more information. How do you know that the cookies are still there although they have been placed out of your sight into the drawer? How do you know ...

Researchers identify genetic mutation linked to congenital heart disease

2013-07-29
A mutation in a gene crucial to normal heart development could play a role in some types of congenital heart disease—the most common birth defect in the U.S. The finding, from a team in The Research Institute at Nationwide Children's Hospital, could help narrow the search for genes that contribute to this defect, which affects as many as 40,000 newborns a year. The findings were published in a recent issue of in Human Mutation. Several hundred genes have been implicated in the formation of the heart, and a mutation in any of them could potentially contribute to a cardiac ...

Danes contract Salmonella infections abroad

2013-07-29
These are some of the findings presented in the annual report on the occurrence of diseases that can be transmitted to humans from animal and food. The report is prepared by the Danish Zoonosis Centre at the National Food Institute, Technical University of Denmark in collaboration with Statens Serum Institut and the Danish Veterinary and Food Administration. In 2012, 1,198 Danes were registered with a Salmonella infection, which corresponds to 21 cases per 100,000 citizens. It is a little more than the record-low incidence in 2011. Nearly half (45 percent) of all Salmonella ...

When fluid dynamics mimic quantum mechanics

2013-07-29
CAMBRIDGE, Mass- In the early days of quantum physics, in an attempt to explain the wavelike behavior of quantum particles, the French physicist Louis de Broglie proposed what he called a "pilot wave" theory. According to de Broglie, moving particles — such as electrons, or the photons in a beam of light — are borne along on waves of some type, like driftwood on a tide. Physicists' inability to detect de Broglie's posited waves led them, for the most part, to abandon pilot-wave theory. Recently, however, a real pilot-wave system has been discovered, in which a drop of ...

Seemingly competitive co-catalysts cooperate to accelerate chemical reaction

2013-07-29
CHESTNUT HILL, MA (July 29, 2013) – A new, computationally-inspired approach has led a team of Boston College chemists to re-conceptualize a highly valued catalytic process, dramatically increasing the efficiency of a chemical transformation that selectively produces chiral, or handed, molecules valued for medical and life sciences research, the team reports in the current online edition of the journal Nature Chemistry. The new approach allows for reducing the reaction time to less than an hour, down from a period of two to five days, the team reports. That gain was accompanied ...

Head hits can be reduced in youth football

2013-07-29
WINSTON-SALEM, N.C. -- Less contact during practice could mean a lot less exposure to head injuries for young football players, according to researchers at Wake Forest Baptist Medical Center and Virginia Tech. Their study of 50 youth-league players ages 9 to 12 -- the largest ever conducted to measure the effects of head impacts in youth football -- found that contact in practice, not games, was the most significant variable when the number and force of head hits incurred over the course of a season were measured. Numerous studies in this area have been done on high school ...

LAST 30 PRESS RELEASES:

Exercise as an anti-ageing intervention to avoid detrimental impact of mental fatigue

UMass Amherst Nursing Professor Emerita honored as ‘Living Legend’

New guidelines aim to improve cystic fibrosis screening

Picky eaters by day, buffet by night: Butterfly, moth diets sync to plant aromas

Pennington Biomedical’s Dr. Leanne Redman honored with the E. V. McCollum Award from the American Society for Nutrition

CCNY physicists uncover electronic interactions mediated via spin waves

Researchers’ 3D-printing formula may transform future of foam

Nurture more important than nature for robotic hand

Drug-delivering aptamers target leukemia stem cells for one-two knockout punch

New study finds that over 95% of sponsored influencer posts on Twitter were not disclosed

New sea grant report helps great lakes fish farmers navigate aquaculture regulations

Strain “trick” improves perovskite solar cells’ efficiency

How GPS helps older drivers stay on the roads

Estrogen and progesterone stimulate the body to make opioids

Dancing with the cells – how acoustically levitating a diamond led to a breakthrough in biotech automation

Machine learning helps construct an evolutionary timeline of bacteria

Cellular regulator of mRNA vaccine revealed... offering new therapeutic options

Animal behavioral diversity at risk in the face of declining biodiversity

Finding their way: GPS ignites independence in older adult drivers

Antibiotic resistance among key bacterial species plateaus over time

‘Some insects are declining but what’s happening to the other 99%?’

Powerful new software platform could reshape biomedical research by making data analysis more accessible

Revealing capillaries and cells in living organs with ultrasound

American College of Physicians awards $260,000 in grants to address equity challenges in obesity care

Researchers from MARE ULisboa discover that the European catfish, an invasive species in Portugal, has a prolonged breeding season, enhancing its invasive potential

Rakesh K. Jain, PhD, FAACR, honored with the 2025 AACR Award for Lifetime Achievement in Cancer Research

Solar cells made of moon dust could power future space exploration

Deporting immigrants may further shrink the health care workforce

Border region emergency medical services in migrant emergency care

Resident physician intentions regarding unionization

[Press-News.org] Experimental quest to test Einstein's speed limit
Physicists use dysprosium to put bounds on maximum speed of electrons