MOND & TeVeS: Unifying Dark Matter & Dark Energy

[ohwilleke]

MOND is a theory the modifies the theory of gravity in weak fields which predicts, from luminous matter observations only, most of the galactic dynamics which motivated dark matter theory. It was developed by an Israeli scientist by the name of Milgrom in 1983.

TeVeS is a relativistic generalization of MOND developed by Milgrom's colleague Bekenstein in 2004. It reduces to general relativity in strong gravitational fields and to MOND in weak gravitational fields, while resolving problems earlier versions of MOND had with phenomena such as gravitational lensing, conservation laws, superluminal modes, and so on.

A paper posted in arxiv this month (http://www.arxiv.org/abs/astro-ph/0504130), by two University of Michigan physicists (Go Blue!), has determined that it is possible to tweak TeVeS to eliminate the need not only for dark matter, but also for dark energy. From the abstract:

Can Relativistic MOND Theory Resolve Both the Dark Matter and Dark Energy Paradigms?
Authors: J. G. Hao, R. Akhoury
Comments: 6 pages, 5 eps Figures

In this paper, we study cosmology within the frame work of a recently proposed relativistic MOND theory and consider the dynamical scalar field of the theory as a possible candidate for dark energy. We also demonstrate, in specific cosmological models, that there is a de Sitter attractor which makes the scalar field play the role of a cosmological constant at late time.

 

[misskitty]

So wait, what is it that you're getting at? The concept of Dark Matter and Energy has been explained before but I don't understand what it is. Even though I've read multiple explanations several times. So is your post getting at evidence that supports Dark Matter?

 

[Chronos]

MOND offers a way out of the most vexing problem associated with dark matter - we can't seem to detect the stuff by any means other than gravitational effects. And making dark matter go away may help make dark energy go away [there are reasons to suspect they may be different manifestations of the same underlying effect]. But like any competing theory of gravity, it still has a lot of hoops to jump through before gaining broad acceptance. As a minority opinion, at present, it does not draw as much attention as deserved. Presumably that will change unless someone finds a fatal flaw. Theories never die of old age, they're assassinated.

 

[ohwilleke]

For want of a better place to put this information, I'll note that Bekestein's primary field of research is black holes and that he is a scientific colleague of Hawking. See: http://en.wikipedia.org/wiki/M-theory

Strominger and Vafa have shown that D-brane techniques can be used to count the quantum microstates associated to classical black hole configurations. The simplest case first explored was static extremal charged black holes in five dimensions. Strominger and Vafa proved for large values of the charges the entropy S = logN, where N is equal to the number of quantum states that system can be in, agrees with the Bekenstein-Hawking prediction (1/4 the area of the event horizon).