1. What was the first measurement that led us to believe the universe is expandi
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1. What was the first measurement that led us to believe the universe is expanding? Briefly explain in one to two sentences. 2. Which of the following explains how the first generation of galaxies was formed? A. The universe attains a density more than the critical density and recollapses B. Regions of higher density (evidenced in CMB observations) exert a slightly greater gravitational pull and accumulate matter C. Supernova explosions occur at the end of a star's life when fusion stops and gravity takes over D. Dark energy acts against gravity to accelerate the expansion of the universe 3. i) Which of the following does not describe an era of the Big Bang? A. All matter is compacted into a dense hot plasma and pair production/annihilation proceed B. Fusion produces helium; no new protons/neutrons form and only annihilation proceeds, leaving only matter (as opposed to antimatter) C. Nuclear fusion stops and H/He nuclei fill the universe D. Nuclei of elements heavier than iron are formed in stars E. Electrons bind to nuclei during recombination event, forming neutral atoms ii) Match the eras to the correct descriptions above Particle era Era of nucleosynthesis Era of nuclei_ Era of atomsExplanation / Answer
1) The works of Vesto Slipher and Hubble demonstarted that universe has a finite age.
In the early part of the 20th Century ,Hubble and others found that certain stars inside certain nebulae were galaxies but found them outside the milky way .They also observed that these galaxies were so large and very distant.The observed spectra of these galaxies show that there is a red shift caused by doppler effect.They observed that the distant galaxies have a greater red shift. Greater red shift means that they are moving away faster.
This is the first measurement that led to us to believe that the universe is expanding.
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