ASTRON 2B03 Lecture Notes - Lecture 11: Skateboarding, Star Cluster
6 Nov 2015
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Both observers are correct, means time is complicated -so we look at observer and how they are moving relative to time. Relativity of simultaneity: -it is relative -events that are simultaneous in one frame but may not be in another -each observer is correct in their own frame of reference. So -we say clocks appear to be moving slowly-moving clocks run slowly, relative to an observer watching this happen. No one else measures someone else"s moving clock to be faster, they always think it is running slow. If an observer far outside our galaxy saw our sun and its position in our solar system it would be a disk near the edge of the system (iclicker question) Galaxy clusters (biggest thing in local universe): -collection of many galaxies (hundreds to a thousand) -millions of light years across in size -weights the same as-a trillion suns. Star clusters: -collection of many stars (up to a million) -50 light years across.
