Adam Riess

"is about the gravity of empty space, the gravity of the vacuum. And the vacuum is a concept that we address in and quantum mechanics. Quantum mechanics is physics on microscopic scales, while Einsteins theory of general relativity ... is physics on macroscopic scales. These two theories are both great, but they dont work together. We dont have whats called a quantum theory of gravity, the way the two are united. However, dark energy actually requires you to use both of these branches of physics. So our hope is that by observing how the universe actually does physics at that interface, we will learn how to unify those."

"I think . I never would have guessed it. Even as an undergraduate, once I’d learned a little physics, I would have thought that the universe was eternal, static, and always in equilibrium. So in graduate school when I found out that the universe was expanding, I was awestruck. Then I learned if we could measure the expanding universe, the way we record the growth of a child with marks on a doorframe ... , we could determine the age of the universe and predict its ultimate fate. This was staggering! I knew this is what I wanted to do. Since that time, charting the expanding universe to determine its nature has been my passion. Though I have to add: knowing what I know now, that the , I feel like King Alfonso X of Castile who saw Ptolemy’s and reportedly said “If the Lord Almighty had consulted me before embarking on creation thus, I should have recommended something simpler.”"

"Today we are able to make very precise measurements of the by measuring the distances and s of . The shift in a supernova’s due to the expansion of space gives its redshift (z) and the relation between redshift and distance is used to determine the expansion rate of the universe. Supernovae with greater redshifts, lying at greater distances, reveal the past expansion rate as their light was emitted at an epoch when the universe was younger. Supernovae Type Ia were the suitable candidate for these measurements as you need objects that are very luminous (thus can be observed even when they are very far) and highly uniform (so that intrinsic scatter doesnt blur the signal). Supernovae Type Ia are the most luminous of the common supernova types, peaking at 4 billion , and thus allowing us to look at extreme large distances."