Astronomers at the University of St Andrews believe they can
“simplify the dark side of the universe” by shedding new light on
two of its mysterious constituents.
Both
dark matter and dark energy could be two faces of the same coin
Dr HongSheng Zhao
University of St Andrews
Dr HongSheng Zhao, of the University’s School of Physics and
Astronomy, has shown that the puzzling dark matter and its
counterpart dark energy may be more closely linked than was
previously thought.
Only 4% of the universe is made of known material - the other 96%
is traditionally labelled into two sectors, dark matter and dark
energy.
A British astrophysicist and Advanced Fellow of the UK's Science
and Technology Facilities Council, Dr Zhao points out, “Both dark
matter and dark energy could be two faces of the same coin.
“As astronomers gain understanding of the subtle effects of dark
energy in galaxies in the future, we will solve the mystery of
astronomical dark matter at the same time.“
Astronomers believe that both the universe and galaxies are held
together by the gravitational attraction of a huge amount of unseen
material, first noted by the Swiss astronomer Fritz Zwicky in 1933,
and now commonly referred to as dark matter.
Dr Zhao reports that, "Dark energy has already revealed its
presence by masking as dark matter 60 years ago if we accept that
dark matter and dark energy are linked phenomena that share a common
origin.”
In Dr Zhao’s model, dark energy and dark matter are simply
different manifestations of the same thing, which he has considered
as a ‘dark fluid’. On the scale of galaxies, this dark fluid behaves
like matter and on the scale of the Universe overall as dark energy,
driving the expansion of the Universe. Importantly, his model,
unlike some similar work, is detailed enough to produce the same 3:1
ratio of dark energy to dark matter as is predicted by cosmologists.
The
search for dark-matter particles so far has concentrated on
highly-energetic particles. If dark matter however is a twin
phenomenon of dark energy, it will not show up at instruments
like the LHC, but has been seen over and over again in galaxies
by astronomers
Dr HongSheng Zhao
University of St Andrews
Efforts are currently underway to hunt for very massive
dark-matter particles with a variety of experiments. The Large
Hadron Collider (LHC) at the European Organization for Nuclear
Research (CERN) in Geneva is a particle accelerator that amongst
other objectives, could potentially detect dark matter particles.
According to Dr Zhao, these efforts could turn out to be
fruitless. He said, "In this simpler picture of universe, the dark
matter would be at a surprisingly low energy scale, too low to be
probed by upcoming Large Hadron Collider."
“The search for dark-matter particles so far has concentrated on
highly-energetic particles. If dark matter however is a twin
phenomenon of dark energy, it will not show up at instruments like
the LHC, but has been seen over and over again in galaxies by
astronomers."
However, the Universe might be absent of dark-matter particles at
all. The findings of Dr Zhao are also compatible with an
interpretation of the dark component as a modification of the law of
gravity rather than particles or energy.
Dr Zhao concluded. “No matter what dark matter and dark energy
are, these two phenomena are likely not independent of each other."
Dr Zhao and his collaborators' findings have recently been
published by Astrophysical Journal Letters in December 2007, and
Physics Review D. 2007.