Possible new definitions of the kilogram

2005 ◽  
Vol 363 (1834) ◽  
pp. 2249-2264 ◽  
Author(s):  
R.S Davis
Keyword(s):  
International System ◽  
Fundamental Constants ◽  
Planck Constant ◽  
Fundamental Physical Constants ◽  
Target Uncertainty ◽  
Long Term Stability ◽  
Modern Physics ◽  
Newtonian Constant ◽  
Fundamental Physical

Summary The kilogram is the unit of mass in the International System. Its definition dates from 1889 and, therefore, predates most of modern physics. The definition simply states that the ‘kilogram’ is the mass of an object known as the international prototype. Thus, we have the extraordinary situation that certain fundamental physical constants (the Planck constant, the Newtonian constant of gravitation, the mass of an electron, the mass of an atom of carbon-12, etc.) are measured in terms of an artefact that was manufactured in the nineteenth century. We begin by describing what is presently known about the long-term stability of artefact standards and how this stability can be experimentally monitored with respect to fundamental constants of physics. Finally, we suggest that present experiments are close to achieving the target uncertainty of the order 10 −8 , although the current incoherence between two classes of experiments is cause for concern.

The determination of best values of the fundamental physical constants

2005 ◽  
Vol 363 (1834) ◽  
pp. 2105-2122 ◽  
Author(s):  
Barry N Taylor
Keyword(s):  
Least Squares ◽  
Science And Technology ◽  
Fundamental Constants ◽  
Fundamental Physical Constants ◽  
Physical Constants ◽  
Self Consistent ◽  
Modern Physics ◽  
Least Squares Adjustment ◽  
Fundamental Physical

The purpose of this paper is to provide an overview of how a self-consistent set of ‘best values’ of the fundamental physical constants for use worldwide by all of science and technology is obtained from all of the relevant data available at a given point in time. The basis of the discussion is the 2002 Committee on Data for Science and Technology (CODATA) least-squares adjustment of the values of the constants, the most recent such study available, which was carried out under the auspices of the CODATA Task group on fundamental constants. A detailed description of the 2002 CODATA adjustment, which took into account all relevant data available by 31 December 2002, plus selected data that became available by Fall of 2003, may be found in the January 2005 issue of the Reviews of Modern Physics . Although the latter publication includes the full set of CODATA recommended values of the fundamental constants resulting from the 2002 adjustment, the set is also available electronically at http://physics.nist.gov/constants .

scholarly journals Definition of the mole (IUPAC Recommendation 2017)

2018 ◽  
Vol 90 (1) ◽  
pp. 175-180 ◽  
Author(s):  
Roberto Marquardt ◽  
Juris Meija ◽  
Zoltán Mester ◽  
Marcy Towns ◽  
Ron Weir ◽  
...  
Keyword(s):  
International System ◽  
International Committee ◽  
Fundamental Physical Constants ◽  
Weights And Measures ◽  
Technical Report ◽  
System Of Units ◽  
Iupac Recommendation ◽  
Definition Of ◽  
Base Units ◽  
Fundamental Physical

AbstractIn 2011 the General Conference on Weights and Measures (CGPM) noted the intention of the International Committee for Weights and Measures (CIPM) to revise the entire International System of Units (SI) by linking all seven base units to seven fundamental physical constants. Of particular interest to chemists, new definitions for the kilogram and the mole have been proposed. A recent IUPAC Technical Report discussed these new definitions in relation to immediate consequences for the chemical community. This IUPAC Recommendation on the preferred definition of the mole follows from this Technical Report. It supports a definition of the mole based on a specified number of elementary entities, in contrast to the present 1971 definition.

MULTIDIMENSIONAL COSMOLOGY AND FUNDAMENTAL CONSTANTS

2009 ◽  
Vol 24 (08n09) ◽  
pp. 1473-1480 ◽  
Author(s):  
V. N. MELNIKOV
Keyword(s):  
Black Holes ◽  
Fundamental Constants ◽  
Fundamental Physical Constants ◽  
Cosmological Singularity ◽  
Brane Worlds ◽  
Multidimensional Cosmology ◽  
Multidimensional Models ◽  
Different Sources ◽  
Fundamental Physical ◽  
Kaluza Klein

Studies of multidimensional models with different sources (models with S -branes, thin and thick brane worlds, Kaluza-Klein type models in curvature-nonlinear multidimensional gravity etc.) and their application to the cosmological constant, cosmological singularity, hierarchy and coincidence problems are presented. Their observational predictions: variations of fundamental physical constants, new types of black holes and wormholes are discussed.

scholarly journals The importance of cylinder passivation chemistry for preparation and long-term stability of multicomponent monoterpene primary reference materials

2018 ◽  
Author(s):  
Nicholas D. C. Allen ◽  
David R. Worton ◽  
Paul J. Brewer ◽  
Céline Pascale ◽  
Bernhard Niederhauser
Keyword(s):  
Reference Materials ◽  
Chemical Reactivity ◽  
International System ◽  
High Chemical ◽  
Term Stability ◽  
Long Term Stability ◽  
System Of Units ◽  
Primary Reference ◽  
High Chemical Reactivity

Abstract. Monoterpenes play an important role in atmospheric chemistry due to their large anthropogenic and biogenic emission sources and high chemical reactivity. As a consequence, measurements are required to assess how changes in emissions of monoterpenes impact air quality. Accurate and comparable measurements of monoterpenes in indoor and outdoor environments require gaseous primary reference materials (PRMs) that are traceable to the international system of units (SI). PRMs of monoterpenes are challenging to produce due to the high chemical reactivity and low vapour pressures of monoterpenes and also their propensity to convert into other compounds, including other terpenes. In this paper, the long-term stability of gravimetrically prepared static monoterpene PRMs produced in differently passivated cylinders, including sampling canisters, was assessed. We demonstrate that static PRMs of multiple monoterpenes can be prepared and used as a suitable long-term standard. For the first time the effect of cylinder pressure and decanting from one cylinder to another on the chemical composition and amount fraction of monoterpenes was also studied. Gravimetrically prepared PRMs of limonene in high pressure cylinders were compared to a novel portable dynamic reference gas generator based on dilution of pure limonene vapour emitted from a permeation tube.

scholarly journals Why is G the Least Precisely Known Physical Constant?

1987 ◽  
Vol 42 (7) ◽  
pp. 663-669 ◽  
Author(s):  
C. C. Speake ◽  
G.T. Gillies
Keyword(s):  
Physical Constant ◽  
The Other ◽  
Fundamental Physical Constants ◽  
Relative Precision ◽  
Ground Movements ◽  
Physical Constants ◽  
Newtonian Constant ◽  
Fundamental Physical

CODATA has recently published its readjustment of the fundamental physical constants and assigns a relative precision of 128 x 10-6 to G, the Newtonian constant of gravitation. Given that most of the other constants in physics have relative precisions of ~10-6 or better, we examine the reasons why the value for G remains so imprecise: The role of G in physics in general is considered and the most recent experimental determinations are examined. Constraints are given for perturbing effects in G measurements and a key result is that horizontal ground movements must be taken more carefully into account in future more precise terrestrial experiments.

scholarly journals Fundamental physical constants: looking from different angles

2005 ◽  
Vol 83 (8) ◽  
pp. 767-811 ◽  
Author(s):  
S G Karshenboim
Keyword(s):  
Fundamental Physical Constants ◽  
Physical Constants ◽  
Modern Physics ◽  
Fundamental Physical

We consider fundamental physical constants that are among a few of the most important pieces of information we have learned about Nature after intensive centuries-long study. We discuss their multifunctional role in modern physics including problems related to the art of measurement, natural and practical units, the origin of the constants, their possible calculability and variability, etc.PACS Nos.: 06.02.Jr, 06.02.Fn

scholarly journals DISCRETE QUANTUM GRAVITY: A MECHANISM FOR SELECTING THE VALUE OF FUNDAMENTAL CONSTANTS

2003 ◽  
Vol 12 (09) ◽  
pp. 1775-1781 ◽  
Author(s):  
RODOLFO GAMBINI ◽  
JORGE PULLIN
Keyword(s):  
Quantum Gravity ◽  
Selection Process ◽  
Einstein Equations ◽  
Fundamental Constants ◽  
Fundamental Physical Constants ◽  
Physical Constants ◽  
Random Fashion ◽  
The One ◽  
The Universe ◽  
Fundamental Physical

Smolin has put forward the proposal that the universe fine tunes the values of its physical constants through a Darwinian selection process. Every time a black hole forms, a new universe is developed inside it that has different values for its physical constants from the ones in its progenitor. The most likely universe is the one which maximizes the number of black holes. Here we present a concrete quantum gravity calculation based on a recently proposed consistent discretization of the Einstein equations that shows that fundamental physical constants change in a random fashion when tunneling through a singularity.

scholarly journals ON THE ISSUE OF STUDYING FUNDAMENTAL PHYSICAL CONSTANTS

2020 ◽  
Author(s):  
M. Volkova ◽  
Keyword(s):  
Fundamental Constants ◽  
Fundamental Physical Constants ◽  
Physical Constants ◽  
Fundamental Properties ◽  
The World ◽  
Fundamental Physical

The article analyzes the most profound and fundamental properties of the world around us, manifested in the sense of fundamental physical constants. The stages of studying and forming ideas about fundamental constants are considered.

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