What is empty space? : the physics of dark energy Chris Blake (Swinburne University) Our place current in model the Universe of cosmology Local cluster Local group Milky Way The Universe Earth Solar system No such thing as nothing : the Casimir effect S. Harris Astronomy Cartoons What does a cosmologist do? Page 1 | Page 2 | Page 3 Move your mouse pointer over the thumbnails on the left to display the cartoons. Copyright © 2006 by Sidney Harris. No reproduction other than for personal enjoyment without written permission. Our current picture of the Universe The Universe is expanding ... ... and the expansion is speeding up ! ... ... driven by an unknown “dark energy” My research : galaxy maps Making the map : redshift Australia is a world-leader in this science ! Our observations You are here Our result : new evidence for dark energy After 5 years of work ... Is dark energy the quantum vacuum energy? Measured dark energy density = 10-26 kg m-3 Predicted vacuum energy density = 10+96 kg m-3 “The worst prediction in the history of physics” In that case , what is dark energy? New laws of gravity? Extra dimensions? New cosmic materials? Good prospects for the future Square Kilometre Array radio telescope ... Thank you ...