The discussion centers on the concept of "dark flow," a phenomenon suggested to be caused by influences beyond the observable universe. Astrophysicist Ned Wright critiques the methodology of the original study by Kashlinsky et al., which claims to measure this flow using WMAP data. Ryan Keisler's recent analysis argues that the dark flow is not a physical phenomenon due to the oversight of primary CMB anisotropies. NASA's Goddard Space Center posits that this dark flow could indicate a sibling universe or a different space-time fabric, but definitive conclusions await further data from the European Space Agency's Planck satellite.
PREREQUISITESAstrophysicists, cosmologists, and researchers interested in the implications of dark flow and cosmic structure beyond the observable universe.
Beyond the more detailed critique of Ned Wright here, I'll take a somewhat higher-level view.mathman said:Text is excerpt from:
http://en.wikipedia.org/wiki/Dark_flow
-------------------
Astrophysicist Ned Wright posted an online response to the study arguing that its methods are flawed.[6] The authors of the "dark flow" study released a statement in return, refuting three of Wright's five arguments and identifying the remaining two as a typo and a technicality that do not affect the measurements and their interpretation.[7]
A more recent statistical work done by Ryan Keisler[8] claims to rule out the possibility that the dark flow is a physical phenomenon because Kashlinsky et al. do not consider primary CMB anisotropies as important as they are.
NASA's Goddard Space Center considered that this could be the effect of a sibling universe or a region of space-time fundamentally different from the observable universe. Data on more than 1,000 galaxy clusters have been measured, including some as distant as 3 billion light-years. Alexander Kashlinsky claims these measurements show the universe's steady flow is clearly not a statistical fluke. Kashlinsky said: "At this point we don't have enough information to see what it is, or to constrain it. We can only say with certainty that somewhere very far away the world is very different than what we see locally. Whether it's 'another universe' or a different fabric of space-time we don't know."[9]
The existence and the velocity of dark flow will probably stay disputed until the new accurate cosmic microwave background radiation data by the European Space Agency's Planck satellite are available in 2012.[10]