Dark matter is a substance that is as mysterious as it is of importance to the world we live in because (rather than love or money) it makes the world go ‘round – at least that is what we think based on common understandings of gravitational physics: The Milky Way Galaxy (especially in its fringe area) is rotating much faster than the amount of visible mass surrounding the sun can theoretically explain. One widely accepted explanation for this is the gravitational force said to derive from halos of additional matter, which is itself invisible and untraceable and only ‘shows’ itself through its gravitational attraction for the material around it.
The problem: studies conducted to trace these puzzling particles regularly fail to do so. The most recent one, and also the most precise one undertaken to date, yet again found no evidence for dark matter in the vicinity of our sun. By mapping the actual motions of stars, Dr. Christian Moni Bidin and his team at University of Conception (Chile) calculated the amount of mass present and found it to match the mass of visible stars, dust and gas. While this does not prove that dark matter does not exist at all, it questions models of its distribution in the galaxy. To make things even more complicated, one of the prominent alternative explanations to dark matter, Modified Newtonian Dynamics (MOND) (which adjusts physical laws altogether to explain galaxy rotation) could also be affected by these recent findings. So – what makes the world go round (the way it does)?
More info:
http://www.eso.org/public/archives/releases/sciencepapers/eso1217/eso1217.pdf
http://www.eso.org/public/news/eso1217/
http://www.space.com/15333-dark-matter-missing-sun.html
http://www.space.com/7967-elusive-dark-matter-hidden-earth.html
http://en.wikipedia.org/wiki/Modified_Newtonian_dynamics#Further_reading
Tobias Boll