Gravity may be the master of the universe, but it has had a key assistant in shaping the cosmos — magnetism. Exactly how that force, which comes from the motion of electric charges, got its start however, has been a mystery — until now.
A new experiment shows that a relatively simple system that's not initially magnetized can generate magnetic fields out of nothing, said University of Michigan astrophysicist Paul Drake.
"From the standard theories of the Big Bang, you don't start with a strong magnetic field. It has to arise out of what the universe does," Drake told Discovery News.
Working in a laboratory in France, scientists fired high-energy lasers that pulse in a billionth of a second with a trillion times the intensity of sunlight into a helium-filled chamber. The lasers are made of carbon rods, similar to what is found in ordinary pencil lead.
When they pulse, some of the carbon atoms are ripped apart and explode, creating a blast wave that moves out into the gas and generates a magnetic field.
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The process is similar to what happens when a star explodes. It shows one mechanism by which the universe formed and evolved.
Gravity gets the process started, eventually giving rise to collapsing objects that send out shock waves.
"Shocks are the driving force for the formation of magnetic field, and all this precedes galaxy formation," lead researcher Gianluca Gregori, with Oxford University in the United Kingdom, told Discovery News.
Once magnetic fields are established, turbulence takes over, making them larger and sustaining them over the eons.
"It's been rather mysterious that the universe is as magnetized as it," Drake said. "When you do simple calculations, any magnetic field formed in the early phases of the universe one would think should have vanished by now."
Magnetic fields are found everywhere in the universe, even in places where they seemingly shouldn't exist, such as the voids between clusters of galaxies.
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Gravitation is the driving force for the formation of shocks and shocks are the driving force for the formation of magnetic field, and all this precedes galaxy formation," Gregori explained.
Gregori plans to repeat his experiment using the world's largest laser at the Lawrence Livermore National Laboratory in California. It has 10,000 times as much energy as the lasers used in his study.
"If we can use a bigger laser we can drive this shock wave even more powerfully," Gregori said.
"The process that we're investigating now is one possibility (for the origin of magnetic fields), but people have come up with different ideas. The experiments are a tool to guide you to what could be the answer," he said.
The research appears in this week's journal, Nature.
