String theory, one well-backed bet for a next-generation theory of physics, proposes the existence of tiny, curled-up dimensions we can’t see. That could include the presence of extra dimensions, for example. “If variations are present, they would reveal new physics,” he says. “If we found a measurement that differs from this, it would be a big deal: finally something really new.” Paolo Molaro, who researches variations in constants at the Astronomical Observatory of Trieste, Italy, agrees. “We have a basic set of equations that is half a century old and has never been contradicted by any measurement,” says Carlo Rovelli at the University of Aix-Marseille in France. ![]() That could be important at a time when physicists seem to have reached an impasse in their efforts to unveil deeper truths about reality. That makes it 100,000 times more accurately pinned down than “big G”, the constant that determines gravity’s strength, for example.īut as Dirac had hinted, perhaps electromagnetic interactions were weaker or stronger in the past, or are different in distant parts of the universe. Lab experiments show that the most it could vary by in our neck of the woods is a few parts per 10 billion. On Earth, at least, alpha keeps itself within strict bounds. The standard cosmological model requires another 12 parameters, including the Hubble constant, which describes the universe’s expansion rate, and factors to do with dark matter and dark energy densities.To reproduce physics in general, you must add in the gravitational constant (aka “big G”), the speed of light and the Planck constant, which gives the basic size of quantum things.The standard model of particle physics requires at least 19 such numbers, including the fine structure constant, also known as alpha, the mass of the Higgs boson, and a bevy of others characterising particle masses and interaction strengths.There seems to be no rhyme or reason for these numbers: they are just there, and we must measure them in experiments. Make alpha much smaller, and molecular bonds fall apart at lower temperatures, altering many processes essential to life.Ī large bugbear of physicists is the way our theories of nature require us to inject a set of arbitrary numbers to make them reflect reality. Go a bit further and nuclear fusion factories within stars grind to a halt and can no longer produce carbon, the element on which life is based. Increase it too much, and protons repel each other so strongly that small atomic nuclei can’t hold together. ![]() ![]() It is itself constructed from the speed of light, the electron’s charge, pi – few physical theories are complete without pi – and a couple of other fundamental constants, carefully arranged so that it is just a pure number, independent of human influence: 0.00729735, just a whisker away from 1/137.Ĭhange this number by a smidgen, and you change the universe. This is the quantum theory of the electromagnetic force, and describes the interactions between light and matter. Alpha lies at the centre of a theory Dirac initiated and Feynman worked on: quantum electrodynamics, or QED. The fine structure constant, also known as alpha, is a case in point. How could we be sure they haven’t changed over cosmological time? In 1937, physicist Paul Dirac wrote to the journal Nature, questioning astronomer Arthur Eddington’s attempts to calculate the constants from scratch. If you found a bug, have a question or an idea, please check AOS contribution guide and don't hesitate to create new issues.The idea that constants of nature – things like the speed of light, strength of forces and the masses of various particles – might not be so constant has an illustrious history. init ( ) // You can also pass an optional settings object // below listed default settings AOS.
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