Do the laws of physics change from one region of space to another? (Image: NASA/ESA/R. Thompson/U of Arizona)

New evidence supports the idea that we live in an area of the universe that is “just right” for our existence. The controversial finding comes from an observation that one of the constants of nature appears to be different in different parts of the cosmos.

If correct, this result stands against Einstein’s equivalence principle, which states that the laws of physics are the same everywhere. “This finding was a real surprise to everyone,” says John Webb of the University of New South Wales in Sydney, Australia. Webb is lead author on the new paper, which has been submitted to Physical Review Letters.

Even more surprising is the fact that the change in the constant appears to have an orientation, creating a “preferred direction”, or axis, across the cosmos. That idea was dismissed more than 100 years ago with the creation of Einstein’s special theory of relativity.


Sections of sky

At the centre of the new study is the fine structure constant, also known as alpha. This number determines the strength of interactions between light and matter.

A decade ago, Webb used observations from the Keck telescope in Hawaii to analyse the light from distant galaxies called quasars. The data suggested that the value of alpha was very slightly smaller when the quasar light was emitted 12 billion years ago than it appears in laboratories on Earth today.

Now Webb’s colleague Julian King, also of the University of New South Wales, has analysed data from the Very Large Telescope (VLT) in Chile, which looks at a different region of the sky. The VLT data suggests that the value of alpha elsewhere in the universe is very slightly bigger than on Earth.

The difference in both cases is around a millionth of the value alpha has in our region of space, and suggests that alpha varies in space rather than time. “I’d quietly hoped we’d simply find the same thing that Keck found,” King says. “This was a real shock.”

Bar magnet

Moreover, the team’s analysis of around 300 measurements of alpha in light coming from various points in the sky suggests the variation is not random but structured, like a bar magnet. The universe seems to have a large alpha on one side and a smaller alpha on the other.

This “dipole” alignment nearly matches that of a stream of galaxies mysteriously moving towards the edge of the universe. It does not, however, line up with another unexplained dipole, dubbed the axis of evil, in the afterglow of the big bang.

Earth sits somewhere in the middle of the extremes for alpha. If correct, the result would explain why alpha seems to have the finely tuned value that allows chemistry – and thus life – to occur. Grow alpha by 4 per cent, for instance, and the stars would be unable to produce carbon, making our biochemistry impossible.

Extraordinary claim

Even if the result is accepted for publication, it is going to be hard to convince other scientists that the laws of physics might need a rewrite. A spatial variation in the fine-structure constant would be “truly transformative”, according to Lennox Cowie, who works at the Institute for Astronomy in Hawaii. But, he adds, extraordinary claims require extraordinary evidence: “That’s way beyond what we have here.” He says the statistical significance of the new observations is too small to prove that alpha is changing.

If the interpretation of the light is correct, it is “a huge deal”, agrees Craig Hogan, head of the Fermilab Center for Particle Astrophysics in Batavia, Illinois. But like Cowie, he suspects there is a flaw somewhere in the analysis. “I think the result is not real,” he says.

Another author on the paper, Michael Murphy of Swinburne University in Australia, understands the caution. But he says the evidence for changing constants is piling up. “We just report what we find, and no one has been able to explain away these results in a decade of trying,” Murphy told New Scientist. “The fundamental constants being constant is an assumption. We’re here to test physics, not to assume it.”

Updated on 9 September: The analysis of VLT data was amended to credit Julian King