Following the Big Bang, the universe consisted only of nonmagnetic
elements and particles. Now, a new mechanism has been discovered for
the magnetisation of the universe even before the emergence of the first
stars. Before the formation of the first stars, the luminous matter
consisted only of a fully ionised gas of protons, electrons, helium nuclei and lithium nuclei which were produced during the Big Bang.
"All higher metals, for example, magnetic iron could, according to
today's conception, only be formed in the inside of stars", says
Reinhard Schlickeiser at the Institute of Theoretical Physics of the Ruhr-Universität Bochum. "In early times therefore, there were no permanent magnets in the Universe."
The parameters that describe the state of a gas are, however, not constant. Density and pressure, as well as electric and magnetic fields
fluctuate around certain mean values. As a result of this fluctuation,
at certain points in the plasma weak magnetic fields formed - so-called
random fields. How strong these fields are in a fully ionised plasma of
protons and electrons, has been calculated by Schlickeiser, specifically
for the gas densities and temperatures that occurred in the plasmas of
the early universe.
The result: the magnetic fields fluctuate depending on their position
in the plasma, however, regardless of time - unlike, for example,
electromagnetic waves such as light waves, which fluctuate over time.
Everywhere in the luminous gas of the early universe there was a
magnetic field with a strength of 10-20 Tesla, i.e. 10 sextillionth of a Tesla. By comparison, the earth's magnetic field has a strength of 30 millionths of a Tesla. In MRI scanners,
field strengths of three Tesla are now usual. The magnetic field in the
plasma of the early universe was thus very weak, but it covered almost
100 percent of the plasma volume.
Stellar winds or supernova explosions of the first massive stars
generated shock waves that compressed the magnetic random fields in
certain areas. In this way, the fields were strengthened and aligned on a
wide-scale. Ultimately, the magnetic force was so strong that it in
turn influenced the shock waves.
"This explains the balance often observed between magnetic forces and
thermal gas pressure in cosmic objects", says Prof. Schlickeiser. The
calculations show that all fully ionised gases in the early universe
were weakly magnetised. Magnetic fields therefore existed even before
the first stars. Next, the Bochum physicist is set to examine how the
weak magnetic fields affect temperature fluctuations in the cosmic
background radiation.
For more information: R. Schlickeiser (2012): Cosmic magnetization:
from spontaneously emitted aperiodic turbulent to ordered equipartition
fields, Physical Review Letters, DOI: 10.1103/PhysRevLett.109.261101 Journal reference: Physical Review Letters.
Image credit: http://www.astro.ex.ac.uk/news.html
Source: The Daily Galaxy via Ruhr-Universitaet-Bochum
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