New strange finding about dark matter

Below a popular summary about the article Dark Energy-Dark Matter Interaction and the Violation of the Equivalence Principle from the Abell Cluster A586 by O. Bertolami, F. Gil Pedro and M. Le Delliou. The article reports an experimental finding interpreted as a possible violation of Equivalence Principle. This finding certainly provides important information about the real nature of dark matter but I would not interpret it in terms of the failure of Equivalence Principle.

"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 - 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 (www.arxiv.org/astro-ph/0703462 ). "If dark energy interacts with dark matter in some way, it could be affecting its motion."

In the article an estimate for the ratio ρ_K/ρ_W of the kinetic energy and potential energy densities of visible matter around Abell cluster is deduced. It is found to be about -.76 +/-.05 instead of -.5 predicted by virial theorem. If dark matter accelerates slower radially, its contribution to the potential energy per volume is smaller at a given distance and potential energy density remains smaller than otherwise so that ρ_K/ρ_W is larger than predicted by the virial theorem.

Let us assume that this finding is not a fake. How could one one understand it in TGD framework? The characteristic difference between ordinary and dark matter in TGD framework is that dark matter in astronomical length scales corresponds to very large values of Planck constant forming macroscopic quantum phases in astrophysical length scales. The rate of dissipation is expected to be proportional to 1/hbar and should therefore be much slower for the dark matter than its visible counterpart. This conforms with the much longer time scale of quantum coherence.

Consider in this framework the free fall experiment for objects consisting of visible and dark matter.

• One cannot just pick up two objects which are both at rest. One must assume that in the initial situation both matter and dark matter have non-radial velocity component with respect to the galaxy cluster which is gradually reduced by dissipation so that finally a radial fall towards center results. For dark matter this reduction occurs at much slower rate so that the assumption that dark matter would have ended in a free radial fall need not hold true or it has ended in free radial fall much later. Therefore the radial component of the velocity for dark matter should be smaller as the naive interpretation of observations suggests.

• If dark matter is in quantum state at Bohr orbit situation is like in hydrogen atom: dark matter makes transitions to lower orbitals through discrete quantum jumps with the duration of quantum jump scaling like hbar. It would never end up to the situation in which radial free radial fall takes place! One would have a situation similar to that what one encountered more than century ago with hydrogen atom: no infrared catastrophe was observd although classical theory predicted it. If so, the solution of the recent depressing situation in quantum gravitation (to put it mildly) would be the same as in the similar situation for a century ago (also at that time physics was thought to be done apart from some minor details!)

The idea about Bohr orbits of astrophysical size sounds of course weird but the basic finding which led to the evolution of ideas about dark matter and spectrum of Planck constants was the Bohr quantization of orbital radii for inner planets and outer planets with a huge value of Planck constant hbar= GMm/v₀, v₀≈ 10^-4. Evidence for a similar quantization has been observed for exoplanets. The explanation would be that dark matter moves along Bohr orbits and planetary visible matter attached to it gravitationally follows.

For references about planetary Bohr orbitology and details about TGD based model for it, see the chapter TGD and Astrophysics of "Classical Physics in Many-Sheeted Space-Time".