New Ideas from Astronomy and Cosmology. Martin Buoncristiani Session 5 4/21/2011

Transcription

1 New Ideas from Astronomy and Cosmology Martin Buoncristiani Session 5 Agenda Introduction Space, Time and Matter Early views of the cosmos Important Ideas from Classical Physics Two 20 th Century revolutions in Physics Relativity Quantum Theory Interwoven with Ideas from Astronomy and Cosmology The Big Bang Theory The Theory of General Relativity Modern theory of gravity introduced by Albert Einstein to replace Newton s Gravitation. Three possible geometries for space time. Main Idea: Replace the idea of force with curvature of spacetime. Matter distorts the space around it. This distorted space affects the motion of particles nearby. The Big Bang: a theory of how the universe developed over time. About 13.7 Billion years ago the universe we observe today was a hot, dense blob of matter and energy a few millimeters in diameter. Over time it evolved into the cooler, sparser universe we see today. 1

2 Big Bang Theory Depends on General Relativity Geometry of ST = Matter - Energy Distribution 3 Parameters Involved: G is the Gravitation Constant (Newton) C is the speed of light Λ is the Cosmological Constant Cosmological Principle Matter is distributed throughout the universe more or less uniformly. Ingredients of The Big Bang Radiation Matter Energy Radiation: electromagnetic radiation (light) across the spectrum. Ordinary Matter: the matter that makes up atoms neutrons, protons and electrons. Also called baryonic matter Dark Matter: invisible matter whose existence inferred from the general motion of celestial objects Dark Energy: energy that is required for consistency with general relativity and observations. Matter Example 1 Urbain Jean Joseph Le Verrier ( ) was a French mathematician who specialized in celestial mechanics and is best known for his part in the discovery of Neptune. Example 2 Missing mass in galaxies v = G M R v = G M R 2

3 Example 3 General Relativity prediction of mass in the universe Types of Matter Energy Atomic matter Dark Matter Dark Energy Evidence for the Big Bang 1) Expansion of the universe, 2) Abundance of light elements, 3) Cosmic Microwave Background. Hubble s Law In 1929 Edwin Hubble ( ) discovered that the further a galaxy is from us the faster it is moving away. Velocity = H 0 x Distance H 0 = 70.8 ± 4.0 (km/s)/mpc Expanding Universe Doppler Effect Frequency increases approaching Frequency decreases receding 3

4 Velocity dependent red shift Age of the universe = 13.7 Gy Size of the universe = 50 GLy Nucleosynthesis Microwave radiation in space was discovered in 1965 by Arno Penzias and Robert Wilson at the Bell Telephone Laboratories in Murray Hill, New Jersey. In 1992, NASA's Cosmic Background Explorer (COBE) satellite detected tiny fluctuations, or anisotropy, in the cosmic microwave background. It found, for example, one part of the sky has a temperature of Kelvin (degrees above absolute zero), while another part of the sky has a temperature of Kelvin. The Wilkinson Microwave Anisotropy Probe (WMAP) was launched in June of 2001 and has made a map of the temperature fluctuations of the CMB radiation with much higher resolution, sensitivity, and accuracy than COBE. The new information contained in these finer fluctuations sheds light on several key questions in cosmology. By answering many of the current open questions, it will likely point astrophysicists towards newer and deeper questions about the nature of our universe. 4

5 Cosmic Microwave Background Wilkerson Microwave Anisotropy Probe 5

6 4/21/2011 Hubble Space Telescope observations of a gravitational lens discovered in the Sloan Digital Sky Survey database by the Sloan Lens ACS Survey. Light from a distant blue galaxy (upper right, top) is deflected by the gravitational field of an intervening elliptical galaxy (upper right, center) to give an image in the form of a nearly complete Einstein ring (upper right, lower). By analyzing the combined image (upper left) it is possible to learn about the distribution of dark and luminous matter in the elliptical galaxy as well as create a magnified image of the background source galaxy. SOURCE: A. Bolton for SLA CS and NASA/ESA. The source 3C 75, shown here in X-rays (blue) and radio waves (pink), is a rare example of two galaxies caught in the act of merging. Not only do their stars merge, but their central black holes each producing a pair of jets containing gas moving outward at a speed close to that of light also will do likewise in perhaps a few hundred million years. Many similar mergers involving smaller black holes in the nuclei of younger galaxies are thought to have taken place. When black holes coalesce, they create intense bursts of gravitational radiation. SOURCE: Xray NASA/CXC/AIfA/D. Hudson and T. Reiprich et al. Radio NRAO/VLA /NRL. signals will require deploying a space-based observatory Adaptive optics image obtained at the Gemini and Keck Observatories of three planetary-mass objects orbiting the nearby A star HR The bright light from the star has been subtracted to enable the faint objects to be seen. A dust disk lies just outside the orbits of the three planets, just as in our solar system the Kuiper belt lies outside the orbit of Neptune at 30 AU. SOURCE: National Research Council of Canada -Herzberg Institute of Astrophysics, C. Marois and Keck Observatory. Hubble Space Telescope observations of a gravitational lens discovered in the Sloan Digital Sky Survey database by the Sloan Lens ACS Survey. Light from a distant blue galaxy (upper right, top) is deflected by the gravitational field of an intervening elliptical galaxy (upper right, center) to give an image in the form of a nearly complete Einstein ring (upper right, lower). By analyzing the combined image (upper left) it is possible to learn about the distribution of dark and luminous matter in the elliptical galaxy as well as create a magnified image of the background source galaxy. SOURCE: A. Bolton for SLA CS and NASA/ESA. 6

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