History of Cosmology

We live in an infinite, static Universe. Since we are not pulled into a tiny ball, the Universe must be static. The smallest heterogeneity would unbalance everything and cause collapse so God steps in from time to time to re-balance everything.

Could use small telescopes with precise measurements to catalog stars and predict locations.

Newton showed that the effects of gravity are everywhere, not just on Earth. The force of gravitation is measurable. If the mass and location is known, the history and future of a system can be predicted. This set up the idea of the "Clockwork Universe" which gave a sense of universal order.

Triumph of Newtonian physics. Neptune explained Uranus' problematic orbit.

Herschel decided to make a model of the Universe (with a lot of assumptions).

Herschel saw stars that looked different, and concluded that the Universe must be evolving therefore it cannot be static or stable. If the Universe is not stable, there is chaos.

His mirrors tarnished often which required frequent polishing and reshaping the mirror. Professionals did not want to do this.

Mapped the spectrograph of the Sun.

"We can never know the composition of the stars..."

Most powerful telescope (6ft), but it couldn't see anything due to weather. Discovered a spiral, cannibal galaxy who's form implied that it must be in motion. Professionals couldn't see these because they had tiny telescopes. Discovered that the Andromeda galaxy is a spiral.

Robert Bunsen and Gustav Kirchfhoff discovered laws of spectrum analysis. Absorption lines are from a hot star surrounded by cooler gas. Spectroscopy led to discovery of the Red Shift. Amateurs measured stellar compositions.

Amateur, Classified stars based on spectra (first serious spectroscopy)

Potential of reflecting telescopes was known, but professionals didn't want to switch.

They only found a few elements

Amateurs, discovered Helium

Given to Edward Holden (Director of Lick Observatory) which was then used to get Holden fired. Mounting did not follow the stars.

Images of Orion Nebula finally did not depend on the eyesight of the observer. Amateurs did the photography because guiding the telescopes for a long night was a lot of work. It also required knowledge of chemistry and some leisure time to tinker with new ideas.

Showed that cameras could be used to make maps.

Built on top of Mount Hamilton with the biggest refracting telescope.

Search for the speed of light - is it constant?
The Aether was the medium through which light traveled and through which the Universe moves.

Amateur astronomer photographed tilted spiral nebula - is it a solar system? He made the first atlas of nebulae.

Found by Edward Barnard

Edward Pickering hired a lot of women to catalog stars.

Interpreted the Mars "canals" as evidence of superior intellect. He saw the veins in his own eyes. He mapped his own eyeball...

X-rays not predicted

Radioactvity

Discovered electron which was not predicted by Newtonian physics

Is this due to Andromeda being similar to the Sun or to the Solar System?

1899- He took spectrum of spiral nebula M31. Which he noticed looked like that of the sun. Wondered if it was beginning of new solar system, or is it a universe of sun type stars. Worked with spectroscopy. Studied in Berlin at Potsdam observatory because it was still custom to build them in urban areas even though it wasn't the best option.

Keeler used the Crossley telescope @Lick instead of the refracting. Took hella pictures and found spiral galaxies everywhere. Proved that reflecting telescopes were important to professionals. Estimated that the Crossley could see 0.5 Million spirals.

Spiral galaxies are commonplace. Are each of these separate island universes? If our Milky Way has been replicated, are we not special?

Quantum theory (photons) helps avoid (UV catastrophe).

Calculate the size of molecules in a liquid.

Proved quantum theory of light

Astrophysical observatory, good seeing, solar telescopes, reflecting (1917). Cosmology needed big money at this point, good seeing, big telescopes, and showed American industrial power.

Deals with scenarios of an accelerating frame. We need this for GPS.

Lick Observatory

Responsible for the Crossley. Estimated that more than 1 million spirals could be photographed with the Crossley.

These stars have a direct relationship between brightness and period which allows astronomers to calculate the distance to the Cepheids. These are known as standard candles.

Since the stars in the Small and Large Magellanic Clouds are roughly the same distance from us, their brightness could be compared and a bunch of Cepheid Variables were found.

Vesto Slipher took 70+ hour exposures and measured galaxy velocities. He was hired by Lowell and worked at Mt Wilson Observatory?

Essay on the theory of Gen. Rel. - gravity is a field.
Space tells matter how to act and matter tells space what shape to be. Light is bent by gravity of the Sun - Eddington's experiment.

Mercury is a Problem. Its orbit does not match the Newtonian predictions, but does match Einstein's equations.

General Relativity exists in an accelerated reference frame - non-Euclidean

Harlow Shapley used Solon Bailey's photographs of globular clusters to determine distances to clusters, and suggested that Cepheids could be pulsating stars. Made a graph of Abs, magnitude vs. period (huge problems).

Clusters are located in a spherical halo around the sun therefore they are the edges of the Milky Way. This distribution is much bigger than the Herschel Universe. The Universe/galaxy is 10x bigger than thought. Spiral galaxies must be in our Universe because our galaxy is too big for anything else. Used Levitt's catalog of cepheids to estimate the distance.

1917: Einstein added a cosmological constant to account for his equations saying the Universe would have to be expanding or contracting. He still believed in a static universe.

Could now build a mathematical model of the Universe.

Repercussions: Einstein upset the entire view of the Universe, it was an era of wanting to believe in someone who could fix everything

George Hale hosted a series of lectures about the scale of the Universe.
The Kapteyn universe is all there is, and it is relatively small, with the sun close to the center. Shapley's universe is also all there is, but it is immense: remember, I used his term "the big galaxy."​

Heber Curtis (Lick Observatory):
-spiral nebulae were separate galaxies
-believed in the Kapteyn Universe (small galaxies in a big universe)
-Evidence:
-edge-on spirals look like the Milky Way
-other galaxies have solar spectra
-supernovae in other galaxies are similar to ours, but further from us
-slipher's spiral velocities
-Shapley's calibration curve was wrong

Harlow Shapley (Mt Wilson):
-spirals are part of the Milky Way, which is huge
-Calibration curve
-astrophysics theory
-the objects in the spirals are in motion (Adriaan von Maanan)
-- the spirals could not be separate, distant, island universes and had to be part of our own galaxy. Nobody has ever discovered just how van Maanan managed to mis-measure the photographs.

Great Debate was a draw, and not resolved until 1923.

Redid Herschel's Universe with new observations and statistics. It was 17 kpc wide which was a small universe, but it seemed reasonable.

The Kapteyn universe is all there is, and it is relatively small, with the sun close to the center. Shapley's universe is also all there is, but it is immense: remember, I used his term "the big galaxy."​

Palomar, CA

Became a US citizen and worked at Princeton (1940)

Szilard realizes Einstein's E=mc2 and understanding of nuclei can be used to make a huge bomb.

Gold foil experiment

Hans Bethe explained the life of stars. (Eddington suggested this in 1914.)

Lise Meitner, Otto Hahn

-Meeting at U Cal Berkeley for 184" cyclotron
-largest physics grant ever

-was not built in Germany (Great Migration)
-women monitored atomic material

-Gen. Graves got secret funding from the government
-Oppenheimer ran the project

Results of pure and applied physics.