Molecular material has not changed at all in 7 billion years
A proton weighs 1836.152672 times as much as an electron. Experiments with extraterrestrial alcohol have demonstrated that this ratio was exactly the same 7 billion years ago, at least within an error margin of one-hundredth thousandth of a percent. The value of this fundamental physical constant – and with that the structure of all molecular material - has therefore remained unchanged throughout the second half of the lifespan of our universe. A Dutch-German research team led by FOM workgroup leader Prof.dr. Wim Ubachs (VU University Amsterdam) published this result 13 December in the scientific journal Science.
The idea for the study arose when the researchers discovered that the structure of the methanol molecule (CH3OH, the simplest form of alcohol) is extremely sensitive for small changes in the mass ratio between a proton and an electron. The structure of extragalactic alcohol could therefore yield information about the history of this ratio. Dutch researchers suggested to their German colleagues that they search the cosmos for extragalactic alcohol. And that is how the study started using a radio telescope with a 100-metre diameter dish located near the village of Effelsberg in the German Eiffel.
In a distant galaxy they found molecules that absorbed certain frequencies of radio waves characteristic for the methanol molecule. From the 'cosmological redshift' of the absorptions -which are associated with the expansion of the universe - they determined the age of the molecules: 7 billion years. From precise frequency measurements of the radio waves absorbed, the researchers could calculate that the physical constant has not changed. Ubachs: "These observations teach us that over the past 7 billion years molecular material has not changed; at least not by more than one-hundred thousandth of a percent."
The research was carried out by FOM workgroup leader Wim Ubachs (VU University Amsterdam), FOM PhD student Julija Bagdonaite (VU University Amsterdam), Paul Jaifnsen (VU University Amsterdam), Rick Bethlem (VU University Amsterdam) and two radio astronomers from the Max Planck Institute in Bonn.
Reference
'A Stringent Limit on a Drifting Proton-to-Electron Mass Ratio from Alcohol in the Early Universe' Science Express (advanced prepublication) 13 December 2012.
More information
http://www.nat.vu.nl/~wimu/Methanol-Science-Ned.html
Contact
Wim Ubachs +31 (0)20 598 79 48.