Featured Research

from universities, journals, and other organizations

Passing the alcohol test: Fundamental properties of molecules have not changed during the past seven billion years

Date:
December 14, 2012
Source:
Max-Planck-Gesellschaft
Summary:
The mass ratio of protons and electrons is deemed to be a universal constant. And rightly so, as the latest radio-astronomy observations of a distant galaxy have shown. Scientists used the 100-metre radio telescope in Effelsberg to measure absorption lines of the methanol molecule at a number of characteristic frequencies. The researchers analysed the spectrum of the simplest of all the alcohols in a very distant galaxy. The result: to a high degree of accuracy molecules and molecular matter have the same properties today as they did seven billion years ago. According to this finding, the mass ratio of protons and electrons in particular has changed by less than one hundred thousandth of a percent in this period.

Schematic image of the methanol molecule. The black sphere represents the central carbon atom, the red one an oxygen atom and the grey spheres represent hydrogen atoms. The yellow arrow represents the internal rotation of the molecule, whose impediment causes a quantum tunnel effect.
Credit: VU University of Amsterdam / Paul Jansen

The mass ratio of protons and electrons is deemed to be a universal constant. And rightly so, as the latest radio-astronomy observations of a distant galaxy have shown. Scientists at the VU University of Amsterdam and the Max Planck Institute for Radio Astronomy in Bonn used the 100-metre radio telescope in Effelsberg to measure absorption lines of the methanol molecule at a number of characteristic frequencies. The researchers analysed the spectrum of the simplest of all the alcohols in a very distant galaxy. The result: to a high degree of accuracy molecules and molecular matter have the same properties today as they did seven billion years ago. According to this finding, the mass ratio of protons and electrons in particular has changed by less than one hundred thousandth of a percent in this period.

Measurements are the only way that physicists can find out about fundamental universal constants such as the proton-to-electron ratio. Although all terrestrial experiments produce the same value for this ratio, it would theoretically be possible for the constant to have a different value in different regions of the universe or at different times in its history. The methanol molecule is a suitable sensor for detecting such deviations.

A number of lines in the radio spectrum of this molecule would exhibit a significant frequency shift if the proton-to-electron mass ratio changed, while other lines would not be affected by this shift. A group at the VU University of Amsterdam only recently found out which property makes methanol such a sensitive sensor: ultimately it is a quantum tunnel effect which occurs if the internal rotation of the molecule is impeded. This effect leads to very high values for the sensitivity coefficients of the corresponding spectral lines, which can all be calculated individually.

"This makes the methanol molecule an ideal test case in order to discover a possible change in the proton-to-electron mass ratio over time," says Wim Ubachs, Professor at the VU University of Amsterdam and head of the physics department. "We therefore proposed a search for line radiation from methanol in the distant universe in order to compare the structure of the molecules thus found with the structure of today's methanol in laboratory experiments."

The team observed a galaxy where a number of different molecules had already been observed. The galaxy, which is in the line of sight of a high-intensity radio source called PKS1830-211, is about seven billion light years away from Earth. The scientists aimed for four different line transitions in the radio spectrum of the methanol molecule with their search program. And they were actually able to see all four lines with the aid of the 100-metre radio telescope in Effelsberg.

"As an optical astronomer it has been an interesting experience to carry out observations at the large wavelengths which occur in the radio range," says Julija Bagdonaite, doctoral student at the VU University of Amsterdam and lead author of the publication. "The methanol molecule had absorbed these radio waves seven billion years ago, and the waves have carried along its fingerprint from the distant past on their passage to Earth."

By analysing the quantum structure of the methanol molecule the researchers were able to deduce that two of its spectral lines which they observed at frequencies around 25 GHz were influenced hardly at all by a change in the proton-to-electron mass ratio. The other two lines reacted much more sensitively to a modification of this parameter.

"The source we investigated is by far the most suitable of all our observational objects for investigating the validity of our local physics even in very distant exotic environments," says Christian Henkel from the Max Planck Institute for Radio Astronomy. "It would be fantastic if we could find more sources of this type which we could use to look even further back into the past."

The scientists also included systematic effects of the observations in the evaluation of the data and thus obtained the following result: in the course of the past seven billion years the mass ratio of protons and electrons has changed by a factor of 10-7 at most and is therefore rightly deemed to be a universal constant. This result can definitely be interpreted to mean that the structure of the molecular matter as derived from spectral observations agrees very accurately with the structure seven billion years ago. Possible deviations amount to a mere one hundred thousandth of a percent or even less.

"If we were really to find deviations in this fundamental constant, we would have a problem with our understanding of the foundations of physics," concludes Karl Menten, Director at the Max Planck Institute for Radio Astronomy. "Most importantly, this would violate Einstein's equivalence principle, the cornerstone of the general theory of relativity."


Story Source:

The above story is based on materials provided by Max-Planck-Gesellschaft. Note: Materials may be edited for content and length.


Journal Reference:

  1. J. Bagdonaite, P. Jansen, C. Henkel, H. L. Bethlem, K. M. Menten, W. Ubachs. A Stringent Limit on a Drifting Proton-to-Electron Mass Ratio from Alcohol in the Early Universe. Science, 2012; DOI: 10.1126/science.1224898

Cite This Page:

Max-Planck-Gesellschaft. "Passing the alcohol test: Fundamental properties of molecules have not changed during the past seven billion years." ScienceDaily. ScienceDaily, 14 December 2012. <www.sciencedaily.com/releases/2012/12/121214102426.htm>.
Max-Planck-Gesellschaft. (2012, December 14). Passing the alcohol test: Fundamental properties of molecules have not changed during the past seven billion years. ScienceDaily. Retrieved July 24, 2014 from www.sciencedaily.com/releases/2012/12/121214102426.htm
Max-Planck-Gesellschaft. "Passing the alcohol test: Fundamental properties of molecules have not changed during the past seven billion years." ScienceDaily. www.sciencedaily.com/releases/2012/12/121214102426.htm (accessed July 24, 2014).

Share This




More Matter & Energy News

Thursday, July 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Creative Makeovers for Ugly Cellphone Towers

Creative Makeovers for Ugly Cellphone Towers

AP (July 24, 2014) Mobile phone companies and communities across the country are going to new lengths to disguise those unsightly cellphone towers. From a church bell tower to a flagpole, even a pencil, some towers are trying to make a point. (July 24) Video provided by AP
Powered by NewsLook.com
Robot Parking Valet Creates Stress-Free Travel

Robot Parking Valet Creates Stress-Free Travel

AP (July 23, 2014) 'Ray' the robotic parking valet at Dusseldorf Airport in Germany lets travelers to avoid the hassle of finding a parking spot before heading to the check-in desk. (July 23) Video provided by AP
Powered by NewsLook.com
Boeing Ups Outlook on 52% Profit Jump

Boeing Ups Outlook on 52% Profit Jump

Reuters - Business Video Online (July 23, 2014) Commercial aircraft deliveries rose seven percent at Boeing, prompting the aerospace company to boost full-year profit guidance- though quarterly revenues missed analyst estimates. Bobbi Rebell reports. Video provided by Reuters
Powered by NewsLook.com
Europe's Car Market on the Rebound?

Europe's Car Market on the Rebound?

Reuters - Business Video Online (July 23, 2014) Daimler kicks off a round of second-quarter earnings results from Europe's top carmakers with a healthy set of numbers - prompting hopes that stronger sales in Europe will counter weakness in emerging markets. Hayley Platt reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins