| New Limits on the Possible Variation of Physical Constants (2007) | |||||||||||||
Abstract | |||||||||||||
| 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 21cm absorption with that of associated molecular absorption in two quasars to place new (1 sigma) upper limits on any variation in y j g p ff 2 (where ff is the fine structure constant and g p is the proton g-factor) of j\Deltay=yj ! 5 \Theta 10 \Gamma6 at redshifts z = 0:25 and z = 0:68. These quasars are separated by a comoving distance of 3000Mpc (for H 0 = 75 km s \Gamma1 Mpc \Gamma1 and q 0 = 0). We also derive limits on the time rates of change of j g p =g p j ! 1\Theta10 \Gamma15 y \Gamma1 and j ff=ffj ! 5 \Theta 10 \Gamma16 y \Gamma1 between the present epoch and z = 0:68. These limits are more than an order of magnitude smaller than previous results derived from... | |||||||||||||
Publication details | |||||||||||||
| |||||||||||||