My lecture on the history of cosmology, how our understanding of the universe we live in improved in the 20th century and the great debate.
What if one walk to the end of the world?The Great Debate
905: Sufi (small cloud)
18th Charles Messier: Catalogs of nebulous objects
1758: Hershel: Andromeda is the nearest great nebulae.
1845 Lord Ross: Elliptical, spiral nebulae
1864: William HugginsSpectrum of Andromeda is similar to stars (continuous and superimposed by dark lines)
Type I Supernovae Binary system One is greater in mass AGB: Rapid mass loss -> angular
momentum …White dwarf attracts the mass of
the companion Mass loss -> Orbit period: hours!
Nova Roche Lobe Astronaut orbiting space shuttle Hill Sphere
The largest sphere, centered at the second body, within which the sum of the three fields is always directed towards the second body. A small third body can orbit the second within the Hill sphere.
Nova Accretion Fusion of H and He Nova is a variable star RS-Oph
WD reaches Chandrasekhar limit
The limit is never attained Increase of pressure -> T near core Convection for 1000 years Carbon fusion (unknown) Oxygen fusion
Type I Supernovae…
Fusion -> Raises T A MS star expands but WD has
degeneracy pressure The story of cold plasma, Pauli,
Heisenberg P = Kn5 / 3 instead of PV = NkT T has minor effect on pressure ->
Nothing to stop T raising Instability
Thermonuclear explosion 1046 j -> Unbind the star
Abs. Mag. = -19.3! Type I supernovae are found all
around the world, elliptical glx, GCs, etc. And S-And.
SN Type Ia. It takes months for SN to dim
The Great Debate April 26 1920On The Scale of The Universe
Harlow Shapley Heber Curtis
The Great Debate Harlow Shapley Milky Way is the
entire universe Andromeda’s
observed rotating (speed of light)
Heber Curtis Andromeda has
more novae than observed in the entire sky
SN S-And Island Universes
Andromeda (M31) Galaxy
Celestial Coordinate Systems
Shapley’s GCs Method