Don
Marolf
Click the link to see the full resolution
PowerPoint slides for Marolf's talk.** **To
see his extensive course notes that
usefully supplement his talk download the PDF
from
http://gabriel.physics.ucsb.edu/~marolf/MasterNotes.pdf
**Pg. 1 **Marolf's talk
"Teaching Black Holes" described the
one-semester course on SR, GR, and cosmology that he teaches to a
class of 20-30 students with only calculus as a prerequisite.
He uses the 'physics first' approach, building his course around an
exploration of the idea of the event
horizon and its relation to the black hole. He uses
spacetime diagrams as a principal tool
of analysis.
**Pg. 2** To be useful they must be
rescaled, i.e.
set *c = 1. *They can then be used to develop
a
representation of constant acceleration consistent with the ideas of
relativity (PDF). Due to the
observer's motion, information in certain parts of the spacetime is
inaccessible to the accelerating observer; the
boundaries of these regions
constitute horizons.
Examining the front and back ends of a very long rocket
in an accelerated frame, he shows how to extract
quantitative information
from spacetime diagrams of accelerating frames. You can also do this kind of
analysis with, for example, the
Schwarzschild metric,
**Pg. 3 **but, Marolf strongly argues,
spacetime diagrams are
pedagogically more effective than mathematical formalism for introducing
students to acceleration in SR and GR. He illustrated his point using
3-dimensional spacetime diagrams (*t,x,y*) to look at
flat spacetime from different
perspectives and to examine a
simple star.
(He also reminded us that "drawing a picture always explains a lot to
the person who draws the picture.")
**Pg. 4** The star
provides a way to show how as it compacts under gravity a
horizon develops along with
trapped rays of light.
The possibility of a black
hole emerges.
**Pg. 5** Make the star smaller while keeping the mass constant.
Diagrams show approach to
Schwarzschild radius. They show a boundary between inside and
outside regions with light rays unable to
escape: a black hole. All information which enters is trapped.
Summary:
GR predicts black holes
Spacetime can become highly curved and a horizon forms
Light rays become trapped -- a black hole
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