Featured Research

from universities, journals, and other organizations

Experimental quest to test Einstein's speed limit

Date:
July 29, 2013
Source:
University of California - Berkeley
Summary:
Special relativity states that the speed of light is the same in all frames of reference and that nothing can exceed that limit. UC Berkeley physicists used a novel experimental system -- the unusual electron orbitals of dysprosium -- to test whether the maximum speed of electrons follows this rule. The answer is yes, to tighter limits than ever before. They plan another experiment a thousand times more sensitive, approaching the realm where theory may break down.

Left to right, Dmitry Budker, Nathan Leefer and Michael Hohensee with their experiment to test Einstein’s speed limit.
Credit: Photo by Andreas Gerhardus

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 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.

Tabletop experiment

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.


Story Source:

The above story is based on materials provided by University of California - Berkeley. The original article was written by Robert Sanders. Note: Materials may be edited for content and length.


Journal References:

  1. M. A. Hohensee, N. Leefer, and D. Budker. Limits on Violations of Lorentz Symmetry and the Einstein Equivalence Principle using Radio-Frequency Spectroscopy of Atomic Dysprosium. Physical Review Letters, 2013; DOI: 10.1103/PhysRevLett.111.050401
  2. N. Leefer, C. T. M. Weber, A. Cingöz, J. R. Torgerson, and D. Budker. New limits on variation of the fine-structure constant using atomic dysprosium. Physical Review Letters, 2013; (accepted) [link]

Cite This Page:

University of California - Berkeley. "Experimental quest to test Einstein's speed limit." ScienceDaily. ScienceDaily, 29 July 2013. <www.sciencedaily.com/releases/2013/07/130729111914.htm>.
University of California - Berkeley. (2013, July 29). Experimental quest to test Einstein's speed limit. ScienceDaily. Retrieved September 17, 2014 from www.sciencedaily.com/releases/2013/07/130729111914.htm
University of California - Berkeley. "Experimental quest to test Einstein's speed limit." ScienceDaily. www.sciencedaily.com/releases/2013/07/130729111914.htm (accessed September 17, 2014).

Share This



More Matter & Energy News

Wednesday, September 17, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Stocks Hit All-Time High as Fed Holds Steady

Stocks Hit All-Time High as Fed Holds Steady

AP (Sep. 17, 2014) — The Federal Reserve signaled Wednesday that it plans to keep a key interest rate at a record low because a broad range of U.S. economic measures remain subpar. Stocks hit an all-time high on the news. (Sept. 17) Video provided by AP
Powered by NewsLook.com
Space Race Pits Bezos Vs Musk

Space Race Pits Bezos Vs Musk

Reuters - Business Video Online (Sep. 16, 2014) — Amazon CEO Jeff Bezos' startup will team up with Boeing and Lockheed to develop rocket engines as Elon Musk races to have his rockets certified. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
MIT's Robot Cheetah Unleashed — Can Now Run, Jump Freely

MIT's Robot Cheetah Unleashed — Can Now Run, Jump Freely

Newsy (Sep. 16, 2014) — MIT developed a robot modeled after a cheetah. It can run up to speeds of 10 mph, though researchers estimate it will eventually reach 30 mph. Video provided by Newsy
Powered by NewsLook.com
Manufacturer Prints 3-D Car In Record Time

Manufacturer Prints 3-D Car In Record Time

Newsy (Sep. 15, 2014) — Automobile manufacturer Local Motors created a drivable electric car using a 3-D printer. Printing the body only took 44 hours. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins