Dark Dark Energy R DARK G Cosmology is the study of the Universe's 1. Shape Cosmology is the study of the Universe's 1. Shape 2. Size Cosmology is the study of the Universe's 1. Shape 2. Size 3. Age Cosmology is the study of the Universe's 1. Shape 2. Size 3. Age 4. Structure Cosmology is the study of the Universe's 1. Shape 2. Size 3. Age 4. Structure 5. Evolution Cosmology is the study of the Universe's 1. Shape 2. Size 3. Age 4. Structure 5. Evolution 6. Fate Cosmology is the study of the Universe's 1. Shape 2. Size 3. Age 4. Structure 5. Evolution 6. Fate 7. Galaxies Edwin Hubble (1889 1953) HUBBLE ULTRA DEEP FIELD DOPPLER EFFECT PING PONG BALLS If this is the size of the pastry at time zero. and this is the size of the pastry one hour later.. Two things are obvious. 1. The raisins have not moved as individuals, but the dough between them has gotten larger. A B 2. Raisin A has moved away at 5 cm per hour. Raisin B has moved away at 10 cm per hour. Newton said that gravity is going to be attracting all things. This means that the Universe would do one of two things. The universe has enough gravity to stop the expansion of the universe, and pull it back together The Universe has reached escape velocity, such that it can continue to expand forever, while continuing to slow down. It would never quite reach the point of stopping. But how would one see what was happening 10 billion years ago? 100 Watt Bulb Both have the same luminosity But how would one see what was happening 10 billion years ago? 1000 Watt Bulb 10 Watt Bulb 10 x the distance Find two supernova, with known characteristics, in a galaxy with a known distance, and a target galaxy. A galaxy happens about every 100 years in an average galaxy. Find two supernova, with known characteristics, in a galaxy with a known distance, and a target galaxy. A galaxy happens about every 100 years in an average galaxy. So every year is you look in 100 galaxies, Or 10 per year if you look in 1,000 galaxies. Katzman Automatic Imaging Telescope It was expected to find galaxies here, because of gravity and them slowing down. They were not. Galaxies would be here, if they were not slowing down at all. They were not here either. Galaxies were here. Much, much farther away than they had any right to be. Einstein believed in a static universe. He kind of had to, to make his numbers work. Lambda = 8 pi x G x density of the vacuum Albert Einstein's own numbers said that the Universe would implode upon itself. F grv Albert Einstein introduced his cosmological constant, or the density of the vacuum as a needed evil, to keep a static universe in the face of his own numbers and theories of gravity and time. 17 years later, Edwin Hubble showed that the Universe was in fact expanding, and Einstein called the cosmological constant his biggest blunder. Now, it seems pretty sure that the Universe is expanding at an increasing rate, and if he made a mistake, it is only that the repulsive force of the cosmological constant was of the wrong magnitude. It was not equal to gravity. In this room the down arrow of gravity dominates, but the up arrow of dark energy is not non-existent. Gravity still dominates in our local group of 14 galaxies, but dark energy is emergent. But in the Universe as a whole, at that great distance, the force of the density of the vacuum, the cosmological constant, dark energy, overwhelms. Dark energy is stronger at large distances, and now, because of two reasons. At distance, gravity is weaker because of the laws of inverse squares. Dark energy is stronger at large distances, and now, because of two reasons. At distance, gravity is weaker because of the laws of inverse squares. Dark energy appears to be a property of space itself, and as the universe expands, there will be more and more space. Dark matter is thought to be non-luminous, weakly interactive matter that does have gravitational attraction. Fritz Zwicky first postulated Dark Matter. He lived from 1898 to He was arrogant, abrasive, abusive and absolutely brilliant. Dark matter, he said, supplies the gravity needed to stop galaxies from flying apart. What is dark energy? It may be the quantum fluctuations of virtual particles that cause the evaporation of black holes. Absolutely no one knows for sure. Any explanation of Dark Energy must include a solution for quantum mechanics (for which time is an integral part) Any explanation of Dark Energy must include a solution for quantum mechanics (for which time is not wanted nor needed) And also for general relativity, in which time is an integral part. This is the reason that Einstein hated quantum mechanics. He called it spooky changes at a distance. How will the galaxy end? It will end in fire or ice. The direction of the dark energy could change (again) and we could actually end in a crunch. The direction of the dark energy could change and we could actually end in a crunch. About a billion, billionth of a second after the big bang, gravity changed from a repulsive fore, into the attractive force we now see. Some say the world will end in fire, Some say in ice. From what I've tasted of desire I hold with those who favor fire. But if it had to perish twice, I think I know enough of hate To know that for destruction ice Is also great And would suffice. By Robert Frost ( ) (Poem first published in Harper's Magazine, December issue 1920)