• QUESTIONS BEFORE LECTURE 27

now try to answer these

• What solution did Einstein find to his tensor equation for a homogeneous, isotropic universe? Why didn't he like it?
• What is the purpose of the "cosmological constant" Lambda which Einstein introduced?
• Explain how neighbors in an expanding circle universe move a way from each other faster if they are farther apart.
• What's meant by the "1-sphere" or "2-sphere" or "(3+1)-sphere"?
• What did Hubble observe in 1927?
• What is meant by "the reddest news is the oldest news?'
• Where was the Big Bang?
• What sequence of events in the early universe gave off light?
• Why was the light trapped? How did it finally get released? What is it called now?
• How was the Cosmic Microwave Background Radiation (CMBR) discovered?
• What is there about the structure of the CMBR that supports the Big Bang theory?
• Why is lithium an important element to observe?