scholarly journals LET'S TALK ABOUT VARYING G

2010 ◽  
Vol 19 (14) ◽  
pp. 2289-2294 ◽  
Author(s):  
ADAM MOSS ◽  
ALI NARIMANI ◽  
DOUGLAS SCOTT

It is possible that fundamental constants may not be constants at all. There is a generally accepted view that one can only talk about variations of dimensionless quantities, such as the fine structure constant α e ≡ e2/4πϵ0ℏc. However, constraints on the strength of gravity tend to focus on G itself, which is problematic. We stress that G needs to be multiplied by the square of a mass, and hence, for example, one should be constraining [Formula: see text], where m p is the proton mass. Failure to focus on such dimensionless quantities makes it difficult to interpret the physical dependence of constraints on the variation of G in many published studies. A thought-experiment involving talking to observers in another universe about the values of physical constants may be useful for distinguishing what is genuinely measurable from what is merely part of our particular system of units.

1994 ◽  
Vol 159 ◽  
pp. 361-362
Author(s):  
D.A. Varshalovich ◽  
A.Y. Potekhin

Constraints on possible variation rate of the fine-structure constant, , and the electron-proton mass ratio , over cosmological time scales are obtained from analyses of quasar spectroscopic data.


2009 ◽  
Vol 87 (1) ◽  
pp. 25-33 ◽  
Author(s):  
V V Flambaum ◽  
V A Dzuba

The search for variation of the fundamental constants such as the fine-structure constant α (α = e2/hc) and the ratios of fundamental masses (for example, electron-to-proton mass ratio μ = me/mp) is reviewed. Strong emphasis is given to establishing the relationships between the change in the measured frequencies of atomic, molecular, or nuclear transitions and the corresponding change of the fundamental constants. Transitions in which the sensitivity of the frequency change to the variation of the fine-structure constant is strongly enhanced are discussed and most recent experimental results are presented. Most attention is given to the use of atomic, molecular, and nuclear transitions in the study of quasar absorption spectra and in atomic clock experiments.PACS Nos.: 31.25.Eb, 31.25.Jf


2017 ◽  
Vol 5 (2) ◽  
pp. 46 ◽  
Author(s):  
Michael Sherbon

From the exponential function of Euler’s equation to the geometry of a fundamental form, a calculation of the fine-structure constant and its relationship to the proton-electron mass ratio is given. Equations are found for the fundamental constants of the four forces of nature: electromagnetism, the weak force, the strong force and the force of gravitation. Symmetry principles are then associated with traditional physical measures.


2009 ◽  
Vol 5 (H15) ◽  
pp. 326-326
Author(s):  
Paolo Molaro

The fundamental dimensionless physical constants cannot be predicted by theory but can only be measured experimentally. And so it is of their possible variation where there are several theoretical predictions but unfortunately with little theoretical guidance on the expected rate of change. The role of fundamental constants in the representation of nature as well as the implications of their variability for the Equivalence Principle and cosmology have been highlighted in many contributions at this conference (cfr K. Olive and J.P Uzan, these proceedings). Measuring the variability of the fine structure constant α or the electron-to-proton ratio μ by means of absorption lines implies the measurement of a tiny variation of the position of one or a few lines with regard to other lines which are taken as reference. For the fine structure constant the relation between its change and the doppler velocity shift is:


Universe ◽  
2019 ◽  
Vol 5 (6) ◽  
pp. 157 ◽  
Author(s):  
McCullen Sandora

How good is our universe at making habitable planets? The answer to this depends on which factors are important for life: Does a planet need to be Earth mass? Does it need to be inside the temperate zone? are systems with hot Jupiters habitable? Here, we adopt different stances on the importance of each of these criteria to determine their effects on the probabilities of measuring the observed values of several physical constants. We find that the presence of planets is a generic feature throughout the multiverse, and for the most part conditioning on their particular properties does not alter our conclusions much. We find conflict with multiverse expectations if planetary size is important and it is found to be uncorrelated with stellar mass, or the mass distribution is too steep. The existence of a temperate circumstellar zone places tight lower bounds on the fine structure constant and electron to proton mass ratio.


Some recent precision experiments that are likely to influence the accepted values of the fundamental constants are reviewed briefly: the measurement of the velocity of light, the possibility of redefining the metre in terms of the caesium time standard, developments that may allow the introduction of an atomic mass standard, the use of the Josephson effect to maintain electrical standards, and some experiments that have led to an improved precision for the fine structure constant.


Universe ◽  
2019 ◽  
Vol 5 (6) ◽  
pp. 149 ◽  
Author(s):  
McCullen Sandora

In a multiverse setting, we expect to be situated in a universe that is exceptionally good at producing life. Though the conditions for what life needs to arise and thrive are currently unknown, many will be tested in the coming decades. Here we investigate several different habitability criteria, and their influence on multiverse expectations: Does complex life need photosynthesis? Is there a minimum timescale necessary for development? Can life arise on tidally locked planets? Are convective stars habitable? Variously adopting different stances on each of these criteria can alter whether our observed values of the fine structure constant, the electron to proton mass ratio, and the strength of gravity are typical to high significance. This serves as a way of generating predictions for the requirements of life that can be tested with future observations, any of which could falsify the multiverse scenario.


Current attempts to construct unified theories of fundamental particles and their interactions are described, with emphasis on their ability to understand the values of the fundamental constants. Examples include grand unified theories, which enable one to estimate the fine structure constant, the neutral weak interaction mixing parameter and certain quark masses. Finally, a review will be presented of the prospects offered by supersymmetry for understanding the scale of the weak interactions and for an eventual unification with gravity.


2007 ◽  
Vol 22 (27) ◽  
pp. 4937-4950 ◽  
Author(s):  
V. V. FLAMBAUM

Review of recent works devoted to the variation of the fine structure constant α, strong interaction and fundamental masses (Higgs vacuum) is presented. The results from Big Bang nucleosynthesis, quasar absorption spectra, and Oklo natural nuclear reactor data give us the space-time variation on the Universe lifetime scale. Comparison of different atomic clocks gives us the present time variation. Assuming linear variation with time we can compare different results. The best limit on the variation of the electron-to-proton mass ratio μ = me/Mp and Xe = me/ΛQCD follows from the quasar absorption spectra:1[Formula: see text]. A combination of this result and the atomic clock results2,3 gives the best limt on variation of [Formula: see text]. The Oklo natural reactor gives the best limit on the variation of Xs = ms/ΛQCD where ms is the strange quark mass:4,5[Formula: see text]. Note that the Oklo data can not give us any limit on the variation of α since the effect of α there is much smaller than the effect of Xs and should be neglected. Huge enhancement of the relative variation effects happens in transitions between close atomic, molecular and nuclear energy levels. We suggest several new cases where the levels are very narrow. Large enhancement of the variation effects is also possible in cold atomic and molecular collisions near Feshbach resonance. How changing physical constants and violation of local position invariance may occur? Light scalar fields very naturally appear in modern cosmological models, affecting parameters of the Standard Model (e.g. α). Cosmological variations of these scalar fields should occur because of drastic changes of matter composition in Universe: the latest such event is rather recent (about 5 billion years ago), from matter to dark energy domination. Massive bodies (stars or galaxies) can also affect physical constants. They have large scalar charge S proportional to number of particles which produces a Coulomb-like scalar field U = S/r. This leads to a variation of the fundamental constants proportional to the gravitational potential, e.g. δα/α = kαδ(GM/rc2). We compare different manifestations of this effect. The strongest limits6kα + 0.17ke = (-3.5 ±6) × 10-7 and kα + 0.13kq = (-1 ± 17) × 10-7 are obtained from the measurements of dependence of atomic frequencies on the distance from Sun2,7 (the distance varies due to the ellipticity of the Earth's orbit).


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