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Nature’s cosmic laws not constant?

Hubble image of a galaxy

Measurements of the light from distant galaxies seen in different directions into the cosmos, suggest that the laws of physics might vary from one part of the Universe to another.

ONE OF THE MOST CHERISHED principles in science—the constancy of physics—may not be true, according to research carried out at the University of New South Wales (UNSW), Swinburne University of Technology and the University of Cambridge.

The study found that one of the four known fundamental forces, electromagnetism—measured by the so-called fine-structure constant and denoted by the symbol ‘alpha’—seems to vary across the Universe.

The first hints that alpha might not be constant came a decade ago when Professor John Webb, Professor Victor Flambaum, and other colleagues at UNSW and elsewhere, analysed observations from the Keck Observatory, in Hawaii. Those observations were restricted to one broad area in the sky.

However, now Webb and colleagues have doubled the number of observations and measured the value of alpha in about 300 distant galaxies, all at huge distances from Earth, and over a much wider area of the sky.

In addition to Webb, the team includes PhD graduate Dr Julian King, PhD student Matthew Bainbridge and Professor Victor Flambaum at UNSW; Dr Michael Murphy at Swinburne University of Technology, and Professor Bob Carswell from Cambridge University.

Astonishing results

The new observations were obtained using the European Southern Observatory’s ‘Very Large Telescope’ in Chile.

“The results astonished us,” said Professor Webb. “In one direction—from our location in the Universe—alpha gets gradually weaker, yet in the opposite direction it gets gradually stronger.”

Illustration of variations in the fine-structure constant

Observations of the fine-structure constant, alpha, in the spectra of light from quasars seen in different directions in space, show that it varies. This could indicate that the laws of physics vary in different parts of the Universe. Image courtesy Dr Julian Berengut, UNSW, 2010.

“The discovery, if confirmed, has profound implications for our understanding of space and time and violates one of the fundamental principles underlying Einstein’s General Relativity theory,” Dr King added.

“Such violations are actually expected in some more modern ‘Theories of Everything’ that try to unify all the known fundamental forces,” said Professor Flambaum. “The smooth continuous change in alpha may also imply the Universe is much larger than our observable part of it, possibly infinite.“

Custom-made cosmos?

“Another currently popular idea is that many universes exist, each having its own set of physical laws,” Dr Murphy said. “Even a slight change in the laws of Nature means they weren’t ‘set in stone’ when our Universe was born. The laws of Nature you see may depend on your ‘space-time address’—when and where you happen to live in the Universe.”

Professor Webb said these new findings also offer a very natural explanation for a question that 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 as we know it, and that 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,” he said.

Adapted from information issued by Swinburne University of Technology. Images courtesy NASA, ESA and the Hubble Heritage Team (STScI/AURA).

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The Universe: not so universal after all?

Nebulae

Careful measurements of the light coming different parts of the universe suggest that the laws of physics might not be the same everywhere.

  • Laws of physics might not be the same everywhere
  • Strength of electromagnetism found to vary throughout cosmos

The laws of physics are different in different parts of the universe, according to new evidence uncovered by a team of Australian and British astrophysicists.

One of the supposed fundamental constants of Nature appears not to be constant after all, the team says in a report of the discovery submitted for publication in the journal Physical Review Letters.

The report describes how the “magic number” known as the fine-structure constant—dubbed alpha for short—appears to vary throughout the universe, says the team from the University of New South Wales, Swinburne University of Technology and the University of Cambridge. The work is currently under peer review.

Professor John Webb

Professor John Webb of the University of NSW, one of the members of the international team of researchers.

“After measuring alpha in around 300 distant galaxies, a consistency emerged: this magic number, which tells us the strength of electromagnetism, is not the same everywhere as it is here on Earth, and seems to vary continuously along a preferred axis through the universe,” says Professor John Webb of the UNSW School of Physics.

“The implications for our current understanding of science are profound. If the laws of physics turn out to be merely “local by-laws”, it might be that whilst our observable part of the universe favours the existence of life and human beings, other far more distant regions may exist where different laws preclude the formation of life, at least as we know it.”

“If our results are correct, clearly we shall need new physical theories to satisfactorily describe them.”

A better theory needed?

The researchers’ conclusions are based on new measurements taken with the Very Large Telescope (VLT) in Chile, along with their previous measurements from the world’s largest optical telescopes at the Keck Observatory, in Hawaii.

Co-author Julian King, a UNSW doctoral student, says that after combining the two sets of measurements, the new result “struck” them: “The Keck telescopes and the VLT are in different hemispheres; they look in different directions through the universe. Looking to the north with Keck we see, on average, a smaller alpha in distant galaxies, but when looking south with the VLT we see a larger alpha.

Keck Telescope

The astronomers used the Keck Observatory in Hawaii, as well as the Very Large Telescope in Chile (not shown here) to make their measurements.

“It varies by only a tiny amount—about one part in 100,000—over most of the observable universe, but it’s possible that much larger variations could occur beyond our observable horizon.”

Co-author Dr Michael Murphy, of Swinburne University of Technology, says the discovery will force scientists to rethink their understanding of Nature’s laws.

“The fine structure constant, and other fundamental constants, are absolutely central to our current theory of physics. If they really do vary, we’ll need a better, deeper theory,” Dr Murphy says.

While a “varying constant” would shake our understanding of the world around us, Dr Murphy notes: “Extraordinary claims require extraordinary evidence. What we’re finding is extraordinary, no doubt about that.”

“It’s one of the biggest questions of modern science—are the laws of physics the same everywhere in the universe and throughout its entire history? We’re determined to answer this burning question one way or the other.”

Other researchers involved in the research are Professor Victor Flambaum and doctoral student Matthew Bainbridge, from UNSW, and Professor Bob Carswell at the University of Cambridge.

Adapted from information issued by UNSW / NASA / ESO / W.M. Keck Observatory.

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