AAPT Plenary Talk: Rotating Galaxies and Dark Matter
Saturday, Feb.14, 9:00AM - 10:00AM
Speaker:Vera Rubin, Carnegie Institute of Washington
From the time of the earliest humans to the present, each civilization has told stories about the universe. How we understand the universe is dictated in large measure by the available technology. In the last century, we learned that we inhabit a galaxy of 200 billion stars, that the universe is populated by billions of galaxies, and that galaxies are moving away from each other. Equally important, we now understand that everything evolves: stars are born, evolve, and die; galaxies grow at the expense of their neighbors. I will describe the evidence that the stars, galaxies and clusters of galaxies that populate the universe make up less than 5% of its matter. The remaining matter is dark, and is only detected by its gravitational effect on the bright matter we study. While virtually everything we know about the universe we have learned in the 20th century, still more remains unknown.