PHYS 005 Lecture Notes - Lecture 15: Cosmological Principle, Accretion Disk, Cosmological Constant
5 Jul 2018
School
Department
Course
Professor
5/09 Session 15 - The Darkness of the Universe and the Expanding Universe
Ch. 26 Sections 1,2
G2
BH was active as long as it was eating a cloud of gas- G2
NOTHING HAPPENED- question mark?
Cosmology
study of origin, evolution
, structure & change of Universe
Why is most of the universe dark?
Isaac Newton considered stars to be scattered RANDOMLY in an infinite space
●Universe is holding stars randomly- eventually all come together
○Actually, universe is moving AWAY from us
■INFINITE- distance btw stars are always becoming LARGER
Newton believed infinite universe was static
●Problem: it would not change w. times- Olbers
○You would always see stars & it’ll be bright, but not true
Cosmological Constant
●Matter curves space & time
○If space is curved- light will travel in curved ways
●What happens to time when the Universe curves? Einstein’s theory of relativity
○Universe is collapsing or expanding
■No evidence for either- early astronomers believed to be static
●LAMBDA Λ- included to make everything static
○Like a balloon- perfect equilibrium
■Expanding air keeps balloon in its form- static
■Air SURROUNDING pushes balloon in
●Is static-> air pushing outward = air pushing inward
○**NO PHYSICAL BASIS FOR LAMBDA
1915-1920- Hubble finds cepheid stars, hubble law
●Universe is EXPANDING @ a LINEAR rate
○10x further away, expanding 10x faster
●LAMBDA IS FALSE
Observation of supernovae type 1a
●Moving a faster pace the further away they are
○Universe is ACCELERATING, bring BACK LAMBDA
○Greater redshift
Document Summary
5/09 session 15 - the darkness of the universe and the expanding universe. Bh was active as long as it was eating a cloud of gas- g2. Cosmology study of origin, evolution , structure & change of universe. Isaac newton considered stars to be scattered randomly in an infinite space. Universe is holding stars randomly- eventually all come together. Actually, universe is moving away from us. Infinite- distance btw stars are always becoming larger. Problem: it would not change w. times- olbers. You would always see stars & it"ll be bright, but not true. If space is curved- light will travel in curved ways. No evidence for either- early astronomers believed to be static. Lambda - included to make everything static. Expanding air keeps balloon in its form- static. Is static-> air pushing outward = air pushing inward. Universe is expanding @ a linear rate. Moving a faster pace the further away they are.
