Topic 4.3 - Cosmology 0.0 / 5 ? AstronomyCosmologyGCSEEdexcel Created by: goldstar3Created on: 04-06-18 21:12 F) Discovery of quasars Astronomers in diff regions of EM spectrum 1950s: stong radio sources matched with stars Position of 3C 273 precisely determined By Cyril Hazard and John Bolton Parkes Radio Observatory, Australia Due to lunar occultation 1 of 8 J) Discovery of CMB By accident Penzias and Wilson Attempting to detect radio Steady uniform 'noise' from all parts of sky, day and night Had eliminated radio interference Stronger than expected 2 of 8 I) Significance of CMB All directions in space Remnants of the Big Bang First temp was 3000K Wavelength was 1 micrometer Now 1000 times longer at microwaves as universe has expanded 1000x Temp of universe has fallen by factor of 1000 to 3K 3 of 8 K) COBE & WMAP COBE detected ripples in radiation Variation in density of matter where galaxies formed WMAP studied dark matter and dark energy Determined age of universe within 1% Allows us to learn about structure of early universe Confirmed dark energy Planck Observatory recently Origin of cosmic structure and early universe 4 of 8 L) Dark Matter Invisible to astronomers Doesn't emit/reflect radiation Detectable gravitational effects Includes: black holes, neutrinos etc Thought to make up 90% of mass of universe Galaxy had higher velocity than it should have had This is because it had the mass of dark matter, increasing its velocity Gravitationally bends light (gravitational lensing) If Universe exceeds critical density, will lead to 'Big Crunch' 5 of 8 M) Dark Energy Universe expanding at accelerating rate Previously expected gravity would be causing expansion to slow down Could cause Universe to expand forever 6 of 8 N) Expanding Universe Redshift of galaxies CMB Relative abundance of elements in Universe fits with predictions Problems: missinh mass rate of expansion should be decelerating why is there more matter than antimatter? 7 of 8 P) Other Evolutionary Models Steady State agrees Universe is expanding but matter is constantly created Density remains constant No observational evidence Cyclic Universe suffers lack of evidence There are problems with all models 8 of 8
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