Monthly Archives: August 2006

MOND Theories Come Up Short

My brother Ryan pointed out yesterday’s NASA press release about recent observations made by the Chandra X-ray observatory which rule out MONDian theories as possible explanations for the galactic rotation curve problem. Beginning in 1933, astronomers have observed that galaxy clusters rotate around each other too quickly to be explained by Newtonian physics or even Einstein’s general relativity. Some scientists posited a halo of dark matter surrounding galaxies which could explain the rotation speeds. Other scientists attempted to modify newtonian dynamics hence the acronym MOND.

This discovery rules out MONDian theories as a possible explanation. Of course we still don’t have direct evidence for dark matter, but at least we can eliminate one path of exploration.

Nature has a more illuminating article on the subject, and they also link to the Astrophysical Journal preprint at