Featured Research

from universities, journals, and other organizations

Fundamental constants 'change': Gravity weaker, electromagnetic force stronger, according to latest recommended values

Date:
July 20, 2011
Source:
National Institute of Standards and Technology (NIST)
Summary:
The electromagnetic force has gotten a little stronger, gravity a little weaker, and the size of the smallest "quantum" of energy is now known a little better. NIST has posted the latest internationally recommended values of the fundamental constants of nature.

The internationally recommended values of the fundamental constants of nature have been updated.
Credit: Mohr,Talbott/NIST

The electromagnetic force has gotten a little stronger, gravity a little weaker, and the size of the smallest "quantum" of energy is now known a little better. The National Institute of Standards and Technology (NIST) has posted the latest internationally recommended values of the fundamental constants of nature.

Related Articles


The constants, which range from relatively famous (the speed of light) to the fairly obscure (Wien frequency displacement law constant) are adjusted every four years in response to the latest scientific measurements and advances. These latest values arrive on the verge of a worldwide vote this fall on a plan to redefine the most basic units in the International System of Units (SI), such as the kilogram and ampere, exclusively in terms of the fundamental constants.

The values are determined by the Committee on Data for Science and Technology (CODATA) Task Group on Fundamental Constants, an international group that includes NIST members. The adjusted values reflect some significant scientific developments over the last four years.

Often the biggest news in a fundamental constant value is a reduced uncertainty -- scientists know the value better. The uncertainty in the value of the fine-structure constant alpha (? = 7.297 352 5698 x 10-3), which dictates the strength of the electromagnetic force, has been slashed in half to 0.3 parts per billion (ppb). Since alpha can be measured in a uniquely broad range of phenomena from the recoil of atoms to the magnetic properties of electrons, the consistency of the measurements acts as a barometer of scientists' general understanding of physics. Alpha will also be a critical constant after a redefinition of the SI: it will remain an experimentally determined constant, while quite a few others' values will be fixed to define the basic measurement units.

Also improved is the Planck constant h, which defines the size of the smallest possible "quantum" (packet) of energy, and is central to efforts to redefine the SI unit of mass. The latest value of h (6.626 069 57 x 10-34 joule seconds) takes into account a measurement of the number of atoms in a highly enriched silicon sphere. That value currently disagrees with the other fundamental method for determining h, known as the watt-balance. Even so, when all the values are combined, the overall uncertainty of h (44 ppb) is smaller than in 2006, and the values from the two techniques are getting closer to each other.

The 2010 CODATA values incorporate two new experimental measurements of G, the Newtonian constant of gravitation, which dictates the strength of gravity. The latest value of G (6.673 84 x 10-11 m3 kg-1 s-2) is about 66 parts per million smaller than the 2006 value. Other adjustments have been seen in the constants such as the radius of the proton and other constants related to atoms and gases such as the Rydberg and molar gas constants.

The CODATA task group is preparing a full report on the 2010 adjustments (for now, there is a brief overview), and the report will include recommendations for future measurements. A plan to adopt a fully constant-based SI, being voted upon this October by the General Conference on Weights and Measures, is contingent upon the values of the fundamental constants such as h reaching certain levels of precision and accuracy that will require further measurement advances in the coming years.


Story Source:

The above story is based on materials provided by National Institute of Standards and Technology (NIST). Note: Materials may be edited for content and length.


Cite This Page:

National Institute of Standards and Technology (NIST). "Fundamental constants 'change': Gravity weaker, electromagnetic force stronger, according to latest recommended values." ScienceDaily. ScienceDaily, 20 July 2011. <www.sciencedaily.com/releases/2011/07/110720085828.htm>.
National Institute of Standards and Technology (NIST). (2011, July 20). Fundamental constants 'change': Gravity weaker, electromagnetic force stronger, according to latest recommended values. ScienceDaily. Retrieved January 27, 2015 from www.sciencedaily.com/releases/2011/07/110720085828.htm
National Institute of Standards and Technology (NIST). "Fundamental constants 'change': Gravity weaker, electromagnetic force stronger, according to latest recommended values." ScienceDaily. www.sciencedaily.com/releases/2011/07/110720085828.htm (accessed January 27, 2015).

Share This


More From ScienceDaily



More Matter & Energy News

Tuesday, January 27, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

More Guns Found in Carry-on Bags at US Airports

More Guns Found in Carry-on Bags at US Airports

AP (Jan. 27, 2015) — The Transportation Security Administration says officers discovered 2,212 firearms during safety screenings last year, a 22 percent jump over 2013. (Jan. 27) Video provided by AP
Powered by NewsLook.com
Cablevision Enters Wi-Fi Phone Fray

Cablevision Enters Wi-Fi Phone Fray

Reuters - Business Video Online (Jan. 26, 2015) — The entry by Cablevision and Google could intensify the already heated price wars for mobile phone service. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
Hector the Robot Mimics a Giant Stick Insect

Hector the Robot Mimics a Giant Stick Insect

Reuters - Innovations Video Online (Jan. 26, 2015) — A robot based on a stick insect can navigate difficult terrain autonomously and adapt to its surroundings. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
Raw: Pilot Uses Full-Plane Parachute in Crash

Raw: Pilot Uses Full-Plane Parachute in Crash

AP (Jan. 26, 2015) — A pilot en route to Hawaii crashed his single-engine plane into the Pacific Ocean Monday and escaped safely thanks to the use of a full-plane parachute. US Coast Guard video captures the dramatic landing. (Jan. 26) Video provided by AP
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:

Strange & Offbeat Stories

 

Space & Time

Matter & Energy

Computers & Math

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