Proton-to-electron mass ratio has been very slightly changed in 7 billion years

Scientists have found that the constant i.e. the ratio of the mass of a proton to the mass of an electron has been very slightly changed i.e. by only one hundred thousandth of a percent or less over the past 7 billion years.

This research has been published online in the journal Science.

Scientists in this research worked on Effelsberg 100-m radio telescope and observed a distant galaxy, toward the quasar system PKS 1830-211, that is about 7-billion light years away. With the help of this telescope, they observed the special light features showing the absorption of methanol i.e. a simple form of alcohol containing carbon, hydrogen and oxygen. Those light features were able to show the ratio of the mass of the protons and electrons.

Effelsberg radio observatory with the 100m radio telescope (Credits: MPIfR/Photo: Peter Sondermann/VisCom)

“This idea makes the methanol molecule an ideal probe to detect a possible temporal variation in the proton-electron mass ratio,” astrophysicist Wim Ubachs of VU University Amsterdam said in a statement. “We proposed to search for methanol molecules in the far-distant universe, to compare the structure of those molecules with that observed in the present epoch in laboratory experiments.”

Their observations showed that even after half of the life of Universe has passed but proton-to-electron mass ratio, μ or β, has not been changed more than 10^-7.

Researchers wrote, “Based on radio-astronomical observations of PKS1830-211, we deduced a constraint of ∆μ/μ = (0.0 ± 1.0) × 10−7 at redshift z = 0.89, corresponding to a look-back time of 7 billion years. This is consistent with a null result.”

If this would be changed, it would result in the change in the properties of atoms and many of the objects in this universe.

“If you see any variations in that fundamental constant, then you would know that something is wrong in our understanding of the foundations of physics,” said  Karl Menten, director of the Max-Planck-Institut für Radioastronomie in Germany and head of the Institute’s Millimeter and Submillimeter Astronomy Department. “In particular, it would imply a violation of Einstein’s Principle of Equivalence, which is at the heart of his General Theory of Relativity.”

Reference:

Julija Bagdonaite, Paul Jansen, Christian Henkel, Hendrick L. Bethlem, Karl M. Menten, Wim Ubachs (2012). A Stringent Limit on a Drifting Proton-to-Electron Mass Ratio from Alcohol in the Early Universe Science : DOI: 10.1126/science.1224898