Astrophysical constraints on the proton-to-electron mass ratio with FAST

Understand

That the laws of physics are the same at all times and places throughout the Universe is one of the basic assumptions of physics.

• Astronomical observations provide the only means to test this basic assumption on cosmological time and distance scales.
• The possibility of variations in the dimensionless physical constant {\mu} - the proton-to-electron mass ratio, can be tested by comparing astronomical measurements of the rest frequency of certain spectral lines at radio wavelengths with laboratory determinations.
• Different types of molecular transitions have different dependencies on {\mu} and so observations of two or more spectral lines towards the same astronomical source can be used to test whether there is any evidence for either temporal or spatial changes in the physical fundamental constants.