New Limits on the Possible Variation of Physical Constants

الأصل · EN

Recent detections of high-redshift absorption by both atomic hydrogen and molecular gas in the radio spectra of quasars have provided a powerful tool to measure possible temporal and spatial variations of physical `constants' in the Universe. We have compared the frequency of high-redshift Hydrogen 21 cm absorption with that of associated molecular absorption in two quasars to place new (1 sigma) upper limits on any variation in y = gₚ.alpha² (where alpha is the fine structure constant and gₚ is the proton g-factor) of |Delta(y)/y| < 5.10⁻⁶ at redshifts z=0.25 and z=0.68. These quasars are separated by a comoving distance of 3000 Mpc (H₀=75 km/s/Mpc and q₀=0). We also derive limits on the time rates of change of |(d.gₚ/d.t)/gₚ| < 10⁻¹⁵/y and |(d.alpha/d.t)/α| < 5.10⁻¹⁶/y between the present epoch and z=0.68. These limits are more than an order of magnitude smaller than previous results derived from high-redshift measurements.