News in Science

Law of nature 'not so constant' after all

One of the fundamental laws of physics does not appear to be constant throughout the universe and may change depending on where you are, suggest researchers.

Professor John Webb, from the University of New South Wales, and colleagues, say their findings could help explain why it was possible for life to develop on Earth but perhaps not in other parts of the universe.

According to standard model, the strength of electromagnetism - one of the four fundamental forces of nature - should be constant throughout the cosmos, but Webb and colleagues have found otherwise.

"The strength of electromagnetism ... seems to vary across the universe," says Webb.

The work, reported in the journal Physical Review Letters, looked at gas in 300 distant galaxies up to 12 billion light years away when the universe was just a fraction of its current age.

Webb and colleagues studied the light from even more distant quasars, which had passed through those galaxies.

Quasars are powerful energy beams generated by supermassive black holes and are among the brightest objects in the universe.

As this light passes though galaxies, specific wavelengths are absorbed by the gas, resulting in an absorption spectrum telling scientists about the chemicals the gas consists of.

Webb and colleagues first used the 10-metre Keck Observatory telescope in Hawaii to examine this ancient light and detected changes in electromagnetism.

Fine structure constant not so constant

This initial research found the fine-structure constant, which measures electromagnetism, varied across the universe.

"It appears to get stronger in one direction and weaker in the other, meaning the universe appears to be dipolar," says Webb.

In order to rule out equipment aberrations with the telescope, Webb and colleagues collected data from a second observatory the Very Large Telescope (VLT) in Chile's Atacama Desert.

The VLT looked at a different part of the sky, but came up with findings consistent with Keck, showing the same rate of change, and in the same direction.

"The discovery if proven, would have profound implications for our understanding of space and time because the fine structure constant determines the strength of the electromagnetic interaction which keeps electrons attached to their atoms," says Webb.

"If this is different in different parts of the universe then different laws of physics could mean different properties for chemicals and even biology. A four per cent change in the fine structure constant would mean differences in the production of elements, which would affect how stars burn, changing the production of heavy elements such as those needed for the formation of life".

Webb says: "If correct the findings would answer a question that's puzzled scientists for decades: why do the laws of physics seem to be so finely-tuned for the existence of life?"

"The answer may be that other regions of the universe are not quite so favourable for life and the laws of physics we measure in our part of the universe are merely 'local by-laws', in which case it is no particular surprise to find life here."

Call for further investigation

Cosmologist Professor Matthew Colless, Director of The Australian Astronomical Observatory says it's an "intriguing" result which needs to be followed up and replicated by other researchers.

"They've been extremely careful in their analysis to try and rule out problems from things like subtle systematic effects," says Colless.

"If the fine structure constant does vary not just with time but also space then that would require a major rethink of quantum mechanics and our standard model of physics."