Physics 303—The
Universe in Ten Weeks—Spring 2006
Final Review Sheet
The final will be comprehensive, but will focus more heavily on material since the midterm in Chs. S3 and 16-24. See the previously published ÒMidterm Review SheetÓ for a summary of important topics from Chs. 1,2, S2, S4, 14, and 15.
Bring a calculator.
You may bring two sheets (8 ½ x 11, both sides) of any notes you like.
No need to bring scantron form or paper; all answers will be written on exam sheets.
Exam will consist of ~50% multiple choice and ~50% free response (simple calculations, short answers, brief essays, etc.)
During the exam you may not 1) use any type of communication device or 2) wear a brimmed hat.
Brief summary of important
topics:
Chapter S3
The idea that the sensation of a uniform gravitational force is the result of something pushing on you. That absent such a push, there is no detectable force. (This must be distinguished however from tidal forces which occur when the strength of gravity changes appreciably over the size of the object as would happen between the feet and head when falling into a black hole.
The equivalence principle: The local indistinguishability of gravitation and acceleration.
General relativity explains gravitational effects in terms of the curvature of spacetime.
The effect of gravity on clocks: Higher clocks run faster than lower clocks.
The idea that freely moving objects move along straight paths through curved spacetime.
The prediction of and search for gravitational waves.
Chapter 16
The birth of stars from the gravitational collapse of a molecular cloud.
How gravitational energy is released during the collapse and trapped raising the temperature of the core.
How gravitational equilibrium after the initiation of fusion determines the final balance between gravity and thermal pressure.
The role of degeneracy pressure in determining the minimum mass for a star undergoing fusion in its core.
The role of radiation pressure in determining the maximum possible mass of a star.
Chapter 17
The primary difference between Òlow massÓ and Òhigh massÓ stars in terms of what goes on in the core in the later stages of life.
The connection of red giant phases with inert cores.
The reignition of the core (the Òhelium flashÓ) and the resulting decrease in luminosity and increase in temperature (implying a decrease in size). The Òhorizontal branchÓ on the H-R diagram.
The endpoint of low mass stars: planetary nebulae and white dwarves.
The multiple shell burning stages and multiple red giant phases of high mass stars.
Why iron canÕt be fused to release energy.
The endpoint of high mass stars: supernovae and neutron stars.
Mass exchange in binary systems
Chapter 18
Electron degeneracy in white dwarves and the inverse relationship between mass and size.
The white dwarf limit.
Accreting systems and the difference between novae and Òwhite dwarf supernovaeÓ
Neutron degeneracy in neutron stars.
Pulsars as rotating neutron stars.
Neutron stars in binary systems: X-Ray binaries
Black holes: The difference between the event horizon and the ÒsingularityÓ within.
The need for a quantum theory of gravity to understand the nature of the singularity.
Tidal forces near a black hole.
The evidence for the existence of black holes: Massive companions in X-ray binaries and massive compact cores in galaxies.
The nature of gamma-ray bursts, the evidence for a distant origin, and the unresolved questions about their source.
Chapter 19
The nature of the components of a spiral galaxy like the Milky Way: The bulge, the disk, and the halo.
Determining enclosed mass from orbital speeds.
The role of supernovae in enriching the interstellar medium and provoking new star formation.
Spiral arms as stellar nurseries.
Galactic evolution: The reason that halo stars are old and randomly orbiting
and the later formation of the disk.
The evidence for the supermassive black hole at the center of the galaxy.
Chapter 20
The difference between spiral and elliptical galaxies: dust or no dust.
Why stars in elliptical galaxies are, therefore, necessarily old.
How collisions between spiral galaxies may result in eliminating the dust and the formation of elliptical galaxies.
The central regions of galactic clusters and their preference for elliptical galaxies.
How we measure the distance to galaxies via main sequence fitting, Cepheid variables, and white dwarf supernovae.
HubbleÕs law!!
The implications of HubbleÕs law for
the age of the universe.
The Òcosmological redshift:Ó Larger
wavelengths as the result of the expansion of space itself.
Chapter 21
The formation of galaxies from initial density enhancements in the universe.
The reason that galactic collisions are common while stellar collisions—even during a galactic collision—are rare.
Quasars and active galactic nuclei and the likely role of supermassive black holes.
How Quasars help us study the intergalactic distribution of matter.
Chapter 22
The way observed motions (rotations curves and galactic orbits in clusters), temperatures (hot gas in clusters), and gravitational lensing reveal the presence of mass.
The evidence for dark matter: The large amount by which the mass determined from its effects exceeds the mass determined from direct observation (luminosity).
The possibility (considered remote) that we donÕt sufficiently understand gravity.
The candidates for dark matter: Ordinary and extraordinary.
What MACHOs are and why they appear to be ruled out.
What WIMPs are and why the evidence increasingly points to the fact that the universe is made primarily out of a type of matter that we have not yet directly observed in our laboratories.
Toe role of dark matter in determining the large scale structure of the universe.
Cosmic evolution and the fate of the universe: Expansion and recollapse scenarios.
Recent evidence for accelerated expansion of the universe and the role of dark energy.
Chapter 23
The cosmic microwave background as
a predicted (and now observed in detail) remnant of the Big Bang.
The relationship between temperature, size, and time in an expanding universe.
The need for a quantum theory of gravity to deal with the Big Bang singularity before 10-43 s.
Early phases in the evolution of the universe: ÒFreezing outÓ of the fundamental forces.
Middle phases: matter-antimatter
annihilation, combination of nucleons in to nuclei, combination of nuclei and
electrons into atoms.
The surface of last scattering at
380,000 years.
Later phases: gradual formation of
galaxies from atoms.
The role of inflation in answering
outstanding questions: Where does the structure come from? Why is the universe so uniform and so
close to the critical density?
Testing inflation theory by looking at
the detailed fluctuations in the cosmic microwave background.
Chapter 24
The way geological evidence for a 4.5 billion year old Earth supports the time scales we determine both from cosmological observations and our understanding of stellar evolution.
The central role of DNA in providing both the mechanism for evolution and the study of connections between lifeforms.
Time scales for life on Earth: Early microorganisms, Cambrian explosion, age of reptiles (dinosaurs), age of mammals.
The apparent requirements for life:
Nutrients, energy, liquid water.
The search for extraterrestrial life in and outside of the solar system.
Habitable zones.
The search for extraterrestial
intelligence.
Factors in the Drake equation.
Limitations on interstellar travel.
The Fermi paradox.