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Announcements

Announcements. Exam 2 is next Thursday March 7. Will cover Chapters 3 – 6. Sample Questions are posted Project topics are due before spring break (March 7). Decide on a topic and come talk to me about it. The topic can be anything of current cosmological interest. Black Holes and relativity.

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Announcements

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  1. Announcements • Exam 2 is next Thursday March 7. Will cover Chapters 3 – 6. Sample Questions are posted • Project topics are due before spring break (March 7). Decide on a topic and come talk to me about it. The topic can be anything of current cosmological interest.

  2. Black Holes and relativity Newtonian physics won’t work here. We need new physics

  3. What is meant by “the Universe”? • Must distinguish between “the universe” and “the visible universe” • The Universe…all things physical and all things which can influence the physical: matter, energy, space-time • The Visible Universe…that part of the universe which we can see from Earth: a sphere with a radius of about 13.8 Gly

  4. Are space & time part of the universe? According to Newton space and time are absolute and separate and are what the universe exists in. According to Einstein space-time interacts with and influences the physical so it is part of the universe

  5. If space and time are part of the universe then there was no “before” the universe nor did the universe expand into empty space

  6. The Anthropic Principle What is our relationship with the universe?

  7. The Weak Anthropic Principle

  8. The Strong Anthropic Principle Gives humanity an important “position” in the universe. Without us the universe would not exist.

  9. The Cosmological Principle

  10. Isotropic at the center but not homogeneous

  11. Homogeneous but not isotropic

  12. Isotropic and homogeneous

  13. Our universe is obviously not homogeneous or isotropic close by

  14. On a scale of a billion lightyears it starts to look isotropic and homogeneous

  15. On the largest scales it is homogeneous and isotropic, mostly

  16. Colored Card Question ClassAction website Cosmology module Cosmological Principle

  17. Another colored-card Question • If you could be instantaneously transported to the edge of the visible universe 14 billion lightyears away from Earth, you would see • the region around you filled with glowing hot gas from the Big Bang • nothing, if you looked in the direction opposite the Earth • pretty much the same thing you see here, just different star patterns. • planets, stars and galaxies unlike anything we see near Earth

  18. One final requirement to understanding the universe The laws of physics are the same everywhere and everywhen

  19. Coordinates

  20. The coordinate system determines how you find the shortest distance between two points s s =

  21. Inertial Reference Frames

  22. Accelerated Reference Frame

  23. A consequence of our reference frame being non-inertial is the Coriolis effect

  24. An inertial reference frame near a gravitational object is free fall Since the inertial mass of an object is equal to the gravitational mass, an object in freefall is in an inertial reference frame

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