Alcohol constrains Physical Constant in the Early Universe

sciencebriefs:

Radio-astronomical observations of a distant galaxy indicate that the ratio of the proton’s mass to that of the electron has hardly changed over cosmic history. This fundamental constant of nature has changed by at most one hundred thousandth of a percent in the past 7 billion years.

Scientists measured methanol absorption at several characteristic frequencies. Methanol was observed in a distant galaxy at redshift z=0.89. The resulting stringent limit on the proton-to-electron mass ratio shows that molecules and molecular matter are, with high accuracy, the same now as 7 billion years ago.

A fundamental constant such as the proton-to-electron mass ratio cannot be calculated from any currently known theory, it can only be measured. Earth-bound experiments agree upon its value, but the explanation for it is still unknown. Therefore, a possibility remains that the proton-to electron mass ratio was different in different places in the universe or at different epochs in cosmic history. The methanol molecule is a very sensitive probe for detecting a drift of the proton-electron mass ratio. Some lines in the microwave spectrum of this molecule would undergo a rather large shift upon a variation of the proton-to-electron mass ratio µ, while other lines (“anchor lines”) are not affected.

From an analysis of the quantum level structure of the methanol molecule it can be derived that two of the lines in the spectrum, both observed near 25 GHz, behave like anchor lines. Their sensitivity to a drifting µ is small. The other two lines are sensitive to a drifting constant.

More:

• Cosmic alcohol, vintage seven billion years, measures physical constant
• Relative masses of 7-billion-year-old protons and electrons confirmed to match those of today’s particles
• Physical constant passes the alcohol test