spaceSpace and Physics

The Constancy Of A “Fundamental Constant” Is Under Challenge


Stephen Luntz

Stephen has a science degree with a major in physics, an arts degree with majors in English Literature and History and Philosophy of Science and a Graduate Diploma in Science Communication.

Freelance Writer

quasars colliding

Artist's impression of colliding quasars. As the most distant objects we can see, quasars allow us to test whether the laws of the universe are the same as far as we can see, and they're producing surprising results. Orin/Shutterstock

One of the most basic assumptions in science is that the laws of nature are universal. However, new research is challenging this idea with evidence indicating a so-called “fundamental constant” varies across the universe, although the differences are at the edge of our capacity to detect. Understandably, the authors face an uphill battle to convince their colleagues, but if the findings are confirmed, the ripple effect could transform the way we see the universe.

Scientists sometimes get results so unexpected even those who made the observation think something is wrong. Usually, an error is quickly found in their measurements or calculations, but occasionally the anomaly persists. That's been the experience of Professor John Webb of the University of New South Wales, who calls his observations “very weird indeed.”


For almost 20 years, Webb has been noticing that light coming from the most distant objects contain spectra subtly different from light produced closer to home. The size of gaps between hydrogen's spectral lines provide a measure of the fine structure constant, a ratio of the velocity of an electron orbiting an atom to the speed of light. The fine structure constant affects the way electrons are bound to their nucleus, so its strength influences the light emitted or absorbed when an electron changes energy levels. It turns up in many aspects of physics, making it important in itself, but it is also composed of three of physics' most commonly used physical constants – the speed of light, the amount of charge on an electron, and Planck's constant.

Twenty years ago, Webb and others reported evidence that the fine structure constant in light from quasars billions of light-years away had different-sized gaps from light produced on Earth. Inevitably, there was considerable skepticism the results were a measurement error. Some observations by other teams were inconclusive, but others backed Webb up.

Now, Webb has co-authored a paper in Science Advances measuring the light of the most distant quasars yet studied in this way, one just a billion years after the Big Bang. Adding their results to existing data strengthens the case for the constant's inconstancy.

Webb admitted to IFLScience even he finds the results hard to believe, but added: “I've always thought when you find something in the data you should report it and not hide it.”


When Webb first found evidence of a varying constant it was thought change might be occurring with time. We see the most distant quasars as they were billions of years ago, so the constant could have been different then. However, additional observations found a constant higher than on Earth in one direction and lower in another, suggesting a change with direction, not time.

That would, Webb noted, be a much more difficult thing for theoreticians to explain. Yet entirely unrelated research, including X-ray measurements of the universe's expansion published just this month, also supports the idea the universe is not the same in every direction. Moreover, Webb told IFLScience the direction of variation observed with other methods appears to match his team's findings, although he's uncertain if there is a linear gradient across the universe or some more complex pattern. Since the fine structure constant is a product of three other constants, it can only change if one or more of these varies. Webb does not want to get drawn into speculating on which.

“The fine structure constant is dimensionless,” he told IFLScience, so it has no units, like a ratio. “Dimensionless constants are more fundamental than those that have units,” he added, making their inconstancy even more surprising.

If the claims prove true, physicists would barely know where to start explaining them, but our own existence might become a little less mysterious.


“For a long time, it has been thought that the laws of nature appear perfectly tuned to set the conditions for life to flourish,” Webb said in a statement. “The strength of the electromagnetic force is one of those quantities. If it were only a few percent different to the value we measure on Earth, the chemical evolution of the universe would be completely different and life may never have got going.”

If the electromagnetic force and other “constants” vary throughout the universe, their suitability for life would be less a coincidence and more a case of us evolving in the one suitable location. Webb speculates physical forces could have their own “Goldilocks Zone.” 

New instruments allowing fine structure measurements further into the infrared made this paper possible. Newly commissioned telescopes, and those under construction, will expand the sample size and confirm or refute these extraordinary reports.


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