PHYS 182 Lecture Notes - Lecture 10: Fizeau Experiment, Velocity-Addition Formula, Special Relativity
PHYS182: Our Evolving Universe
2017-10-05 LEC 10
Next Week
- Tuesday: Tutorial
- Thursday: Midterm
o Closed book
o Bring a formula sheet & calculator
o Format: HW Type questions, essay component
- Focus (in order of priority): class material, homework problems, readings
o Guest lectures not included
o Material up to today’s lecture
Review: Space-time must be curved and space-time is a dynamic entity, so you can have gravitational
waves
Localized mass curves space
If you have mass everywhere, this mass must do something
The curvature must be uniform in space
- Localized mass curves space in a way that is independent of time
- Uniformly distributed mass produces curvature of space-time which is not visible as curvature of
space,
If there is no matter at all, space time can be visualized as a flat surface
If you have homogeneously distributed matter, it produces a distorted sheet that expands as time passes
A field: something that produces values everywhere in space and changes in time ‘
Gravitational lensing
- A galaxy curves the space in the region
around it
- Light is bent by the mass of the galaxy
because it produces curvature
- Light can reach us by bending around the
galaxy
- You will see a ring à Einstein ring
o These images of Einstein rings
verify the curvature of space-time
Gravitational redshift
• Shaft on the surface of the earth, and a laser light travelling from the bottom to the top. There is
an emission frequency and a detection frequency
• In Newtonian theory à FD = FE
• General relativity (observed) à FD < FE
• If the shaft were in free-fall, then Newtonian physics would be
applicable
• Relative to the freely falling frame, the shaft is accelerating upward
o This is the gravitational redshift, and it applies to light from
a black hole
Document Summary
Thursday: midterm: closed book, bring a formula sheet & calculator, format: hw type questions, essay component. Focus (in order of priority): class material, homework problems, readings: guest lectures not included, material up to today"s lecture. Review: space-time must be curved and space-time is a dynamic entity, so you can have gravitational waves. If you have mass everywhere, this mass must do something. Localized mass curves space in a way that is independent of time. Uniformly distributed mass produces curvature of space-time which is not visible as curvature of space, If there is no matter at all, space time can be visualized as a flat surface. If you have homogeneously distributed matter, it produces a distorted sheet that expands as time passes. A field: something that produces values everywhere in space and changes in time . A galaxy curves the space in the region around it. Light is bent by the mass of the galaxy because it produces curvature.
