Axions are a primary component of Dark Matter thereby making dark matter superconducting and not subject to gravity like ordinary matter.
The following article from the New Scientist indicates that axions are
a primary component of Dark Matter thereby making dark matter
superconducting and not subject to gravity like ordinary matter.
http://space.newscientist.com/article/d ... nergy.html
Two-speed gravity
"If Galileo could have dropped a lump of dark matter and a lump of
normal matter from the top of the Leaning Tower of Pisa, he might have
expected them to fall at the same rate," says Orfeu Bertolami at the
Instituto Superior Técnico in Lisbon, Portugal. "But he would have
been wrong."
Bertolami and his colleagues studied a galaxy cluster known as Abell
cluster A586 to see if dark matter and normal matter fall in the same
way under gravity. He says this cluster is ideal because it is
spherical, suggesting that it has settled down: "The only motion we
are seeing now is due to gravity toward the cluster's centre."
The team studied 25 galaxies in the cluster using gravitational
lensing Б " the shift in the apparent position of a light source
caused by gravity bending the light. When they analysed the positions
of galaxies using conventional models, things just didn't add up. "It
only makes sense if the normal matter is falling faster than the dark
matter," Bertolami says.
This is the first astronomical observation to suggest that Einstein's
principle of equivalence is violated, says Bertolami (read a preprint
of the article). "If dark energy interacts with dark matter in some
way, it could be affecting its motion."
Superconductors inspire quantum test for dark energy
Dark energy is so befuddling that it's causing some physicists to do
their science backwards.
"Usually you propose your theory and then work out an experiment to
test it," says Christian Beck of Queen Mary, University of London. A
few years ago, however, he and his colleague Michael Mackey of McGill
University in Montreal, Canada, proposed a table-top experiment to
detect the elusive form of energy, without quite knowing why it might
work. Now the pair have come up with the theory behind the experiment.
"It is certainly an upside-down way of doing things," Beck admits..
Dark energy is the mysterious force that many physicists think is
causing the expansion of the universe to accelerate. In 2004, Beck and
Mackey claimed that the quantum fluctuations of empty space could be
the source of dark energy and suggested a test for this idea. This
involved measuring the varying current induced by quantum fluctuations
in a device called a Josephson junction Б " a very thin insulator
sandwiched between two superconducting layers.
Beck reasoned that if quantum fluctuations and dark energy are
related, the current in the Josephson junction would die off beyond a
certain frequency (see A table-top test for dark energy?). But they
hadn't worked out what exactly caused the cut-off.
Now the duo say they know, and last week Beck presented the theory at
a conference on unsolved problems for the standard model of cosmology
held at Imperial College London.
Frequency cut-off
Quantum mechanics says that the vacuum of space is seething with
virtual photons that are popping in and out of existence. Beck and
Mackey suggest that when these virtual photons have a frequency below
a certain threshold, they are able to interact gravitationally,
contributing to dark energy.
Their theory is inspired by superconducting materials. "Below a
critical temperature, electrons in the material act in a fundamentally
different way, and it starts superconducting," says Beck. "So why
shouldn't virtual photons also change character below a certain
frequency?"
If so, virtual photons should behave differently below a frequency of
around 2 terahertz, causing any currents in the Josephson junction to
taper off above this frequency. Physicist Paul Warburton at University
College London is building such a dark energy detector and could have
results next year.
Some evidence that dark energy works like this may already have been
found. In 2006, Martin Tajmar at the Austrian Research Centers
facility in Seibersdorf and his colleagues noticed bizarre behaviour
in a spinning niobium ring. At room temperature, niobium does not
superconduct, and accelerometers around the ring measured that it was
spinning at a constant rate. But once the temperature fell, the
niobium started to superconduct, and the accelerometers suddenly
picked up a signal (Gravity's secret).
Odd acceleration
"We measured an acceleration even though the ring's motion hadn't
changed at all," says Clovis de Matos, who works at the European Space
Agency in Paris and established the theory behind the experiment. He
thinks the results could be explained if gravity got a boost inside
the superconductor. "Beck and Mackey's gravitationally activated
photon would have that effect," he says.
The controversial experiment seemed to fall foul of Einstein's
equivalence principle, which states that all objects should accelerate
under gravity at the same rate. It implied that "if you have two
elevators, one made of normal matter and one made of superconducting
matter, and accelerate them by the same amount, objects inside will
feel different accelerations", de Matos says. Astronomers may have
seen a similar violation of the principle (see "Two-speed gravity",
below).
The odd acceleration detected in the niobium ring also suggests that
energy isn't conserved in the superconductor Б " another major
violation of known physics. Dark energy could solve that problem,
however. "We did the sums and found out that energy wasn't conserved,
but perhaps that was just because we were missing dark energy," de
Matos says.
Paul Frampton, a cosmologist at the University of North Carolina at
Chapel Hill, thinks Beck and Mackey's reasoning is flawed. "I don't
think for a second they'll measure dark energy, but they should
certainly try."
