July 5, 2013
White Dwarf Study Shows Nature’s Constants May Not Be So Constant
Lee Rannals for redOrbit.com - Your Universe Online
An international team of astronomers wrote in the journal Physical Review Letters they were able to test a controversial theory about the constants of nature.
The team studied a distant white dwarf star using the Hubble Space Telescope to measure the strength of the electromagnetic force, or alpha, one of the four fundamental forces that shape the universe as we know it. The researchers hoped to determine whether the laws of physics were constant throughout the universe.
"This idea that the laws of physics are different in different places in the cosmos is a huge claim, and needs to be backed up with solid evidence," said Dr Julian Berengut of the University of New South Wales' School of Physics. "A white dwarf star was chosen for our study because it has been predicted that exotic, scalar energy fields could significantly alter alpha in places where gravity is very strong."
Scaler fields are forms of energy that appear in theories of physics that seek to combine the Standard Model of particle physics with Einstein's general theory of relativity.
"By measuring the value of alpha near the white dwarf and comparing it with its value here and now in the laboratory we can indirectly probe whether these alpha-changing scalar fields actually exist," said Berengut.
The team studied the light absorbed by nickel and iron ions in the atmosphere of a white dwarf known as G191-B2B. The ions are kept above the surface by the star's strong radiation, despite the pull of its extremely strong gravitational field.
"This absorption spectrum allows us to determine the value of alpha with high accuracy. We found that any difference between the value of alpha in the strong gravitational field of the white dwarf and its value on Earth must be smaller than one part in ten thousand," Dr Berengut says. "This means any scalar fields present in the star's atmosphere must only weakly affect the electromagnetic force."
He said more precise measurements of iron and nickel on Earth would be needed in order to complement the high-precision astronomical data. "Then we should be able to measure any change in alpha down to one part per million. That would help determine whether alpha is a true constant of Nature, or not," Berengut added.
Team member Professor Martin Barstow of the University of Leicester, who presented the work at the Royal Astronomical Society National Astronomy Meeting in St Andrews, Scotland said the team's work was limited by the need to use very old laboratory measurements from the 1970s.
"In the future, with better laboratory data to complement the high-precision astronomical data, we should be able to measure the change in alpha down to one part per million. At that level we would be able to place strong restrictions on whether alpha is a true constant of nature," Barstow said.