Does the proton-to-electron mass ratio vary in time or space? · revision history

Revision 2

Accepted · core change · record

Changes against revision 1:

Title
Does the proton-to-electron mass ratio vary in time or space?
Plain
Molecular vibrations depend on the ratio of proton to electron mass, while atomic transitions mostly do not, so comparing them tests whether this ratio changes. Both laboratory molecular clocks and ancient molecular absorption in distant galaxies are used.
Precise · changed · core
Revision 1: Determine whether $\mu = m_p/m_e$ varies, either as $d\ln(\mu)/dt$ today from comparisons of molecular (for example HD+, H2+, N2+, Sr2) and atomic clocks, or as $\Delta \mu/\mu$ at redshift $z > 1$ from H2 and CH3OH absorption, at the $1e-17$ per year and $1e-7$ levels respectively.
Revision 2: Determine whether $\mu = m_p/m_e$ varies, either as $d\ln(\mu)/dt$ today from comparisons of molecular (for example HD+, H2+, N2+, $\mathrm{Sr_2}$) and atomic clocks, or as $\Delta \mu/\mu$ at redshift $z > 1$ from $\mathrm{H_2}$ and $\mathrm{CH_3OH}$ absorption, at the $10^{-17}$ per year and $10^{-7}$ levels respectively.
Settled by · changed · core
Revision 1: A molecular-clock to atomic-clock ratio tracked for several years with fractional uncertainty below 1e-17, or a radio methanol absorption measurement with sub-1e-7 precision.
Revision 2: A molecular-clock to atomic-clock ratio tracked for several years with fractional uncertainty below $10^{-17}$, or a radio methanol absorption measurement with sub-$10^{-7}$ precision.
Kind
well-posed
Answer type
yes-no
References
(empty)
Literature status
open
Status note
(empty)
Posed since
(empty)

Decisions