Wednesday, September 21, 2011

Dark matter theory: RIP?

BBC reports:
Scientists' predictions about the mysterious dark matter purported to make up most of the mass of the Universe may have to be revised.

Research on dwarf galaxies suggests they cannot form in the way they do if dark matter exists in the form that the most common model requires it to.

That may mean that the Large Hadron Collider will not be able to spot it.

Scientists' best ideas for the formation and structure of the Universe form what is called the "cosmological standard model", or lambda-CDM - which predicts elementary particles in the form of cold dark matter (CDM).
Prof Carlos Frenk at Durham University, working with … the Virgo Consortium has created computer simulations to visualise how the dwarf galaxies formed, using their assumptions about CDM.
The team found that the final results of these simulations did not at all match what we observe....
Prof Frenk said that after working for 35 years with the predictions of the standard model, he is "losing sleep" over the results of the simulations.
But he believes he has found a solution to the CDM problem. He proposes that instead of "cold" dark matter that formed within the first one millionth of a second after the Big Bang, the Universe may instead be filled with warm dark matter (WDM).

Meanwhile at the other “science”:

One of the biggest issues confronting international macroeconomists is whether or not the large and persistent U.S. current account deficits are sustainable.

[One possible reconciliation is the]... the “dark matter” view of Hausmann and Sturzenegger (2007), henceforth HS. HS propose an alternative method to computing net international positions and current accounts.

… from a relative reliability perspective the dark matter view can be quickly dispensed with. HS suggest that the external position for all asset types should be estimated by capitalizing income at a common discount rate. They then compute the net position from  these capitalized values, and form the current account as the year-to-year change in their constructed net position. This explicitly assumes that investment income, a subcomponent of the current account, is the most reliable portion of the entire set of international accounts, and that it is  appropriate to construct positions in this manner. Given that approximately two-thirds of published investment income data are not measured, but are formed by applying estimates (of yields) to estimates (of positions), from a relative reliability perspective dark matter fails. Moreover, while we have sympathy for some parts of the hypothesis, we find the methodology of capitalizing income streams to be questionable. Even if the investment income numbers are entirely reliable, we doubt this method of constructing the current account or position is an improvement over the published estimates.

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