Astronomical observations now constrain the parameters of cosmology to unprecedented precision.  Many lines of evidence indicate the presence of a novel form of non-baryonic dark matter that permeates the cosmos and outweighs normal baryonic matter by roughly 5:1.  As yet, there is no persuasive laboratory detections of these hypothesized dark matter particles.  An alternative hypothesis is that instead of dark matter, fundamental duynamical laws need revision at very low accelerations. I will discuss the evidence for and against these ideas.

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Colloquia are held Tuesdays in Room 1410 at 4:00 pm (preceded by light refreshments at 3:30). If you have additional questions, please call 301-405-5946.