London: How the universe got its magnetism?
For long, it has been a mystery. Now, physicists claim to have
attempted to solve it by using laser to create magnetic fields
similar to those involved in formation of the first galaxies.
Magnetic fields exist throughout galactic and
intergalactic space, what is puzzling is how they were created
originally and how they became so strong.
A team, led by Oxford University, used a high-power laser
to explode a rod of carbon, similar to pencil lead, in helium
gas. The explosion was designed to mimic cauldron of plasma --
an ionised gas containing free electrons and positive ions --
out of which the first galaxies formed.
The physicists found that within a microsecond of the
explosion strong electron currents and magnetic fields formed
around a shock wave.
They took these results and scaled them through 22
orders-of-magnitude to find that their measurements matched
the "magnetic seeds" predicted by theoretical studies of
galaxy formation, the 'Nature' journal reported.
"Our experiment recreates what was happening in the early
Universe and shows how galactic magnetic fields might have
first appeared. It opens up the exciting prospect that we will
be able to explore the physics of the cosmos, stretching back
billions of years, in a laser laboratory here on Earth," said
Dr Gianluca Gregori, who led the team.
The results closely match theories which predict
that tiny magnetic fields -- "magnetic seeds" -- precede the
formation of galaxies. These fields can be amplified by
turbulent motions and can strongly affect the evolution of the
galactic medium from its early stages.
Dr Gregori said in a release: "In the future, we plan
to use the largest lasers in the world, such as the National
Ignition Facility in California, to study the evolution of
cosmic plasma."
PTI
First Published: Monday, March 26, 2012, 15:48