![]() In a block of ice, some regions can freeze with their crystals in different orientations, rather like tiles being laid simultaneously at different ends of a room. This, he suggested, caused a phase change in the quantum fields, like water freezing to ice. He was musing about the first split second after the Big Bang when the universe underwent a rapid expansion, then cooled rapidly. “There is nothing else except fields,” is the way retired Princeton physicist Freeman Dyson once put it.īritish field theorist Tom Kibble, who died in June 2016, came up with the idea of cosmic strings in 1976. A photon is a ripple in the electromagnetic field (which we experience as light), an electron a ripple in the ‘electron field’, a Higgs boson a ripple in the Higgs field, and so on. ![]() Quantum field theorists see the universe as a fabric of all-pervading fields.įields fill space like a fluid, and what we call ‘particles’ are ripples within the fluid. He saw his world as a diaphanous fabric of greenish ones and zeroes. It helps to picture the universe through the eyes of a quantum field theorist. You might wonder how the emptiness of space could be cracked. We can’t see them but gravitational wave detectors might be able to hear the thrums and snaps created as they whip through space. The nascent era of gravitational wave astronomy – just two years old – may finally deliver a tool to test the existence of cosmic strings. For Matthew Bailes, an astrophysicist at Swinburne University of Technology in Melbourne, cosmic strings are a “mathematical curiosity” or worse, “an exotic fantasy”.Īll that may be about to change. String theory invokes vibrating strings tinier than any subatomic particle as the building blocks of the universe. It places cosmic strings in the same category as “string theory”, their controversial namesake at the other extreme of the size scale. For some physicists, a theory that can’t be tested is not worth pursuing. ![]() Neither can any of our astronomical instruments detect these vanishingly thin, intergalactic filaments. “You can’t build an accelerator to test physics at that scale.” However, as time capsules of the early universe, cosmic strings should retain fantastic energies – more than a billion times greater than those released by smashing particles at the Large Hadron Collider, says Ken Olum, a theoretical physicist at Tufts University in Boston, who has contemplated cosmic strings for 20 years. “The fact strings come up all the time makes me confident that they exist,” he says. ![]() Proponents of cosmic strings, like Thibault Damour, a theoretical physicist at the Institute of Advanced Scientific Studies near Paris, are persuaded by the maths that keeps predicting their existence. The huge amount of energy they contain also makes them extremely heavy a few centimetres of cosmic string might weigh as much as Mount Everest. Dubbed cosmic strings, mathematical models see them as invisible threads of pure energy, thinner than an atom but light-years long. These hairline fractures may still be threaded through space-time. Some physicists believe the rapid cooling might have cracked the fabric of the universe. Our universe exploded into being, expanded at a fantastic speed and cooled.
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