1997-98 -- 05-06 Academic Years
Relativity and Cosmology
28 January 2003: Bill Colson [Morgan Park HS, mathematics}
Is there intelligent life except on earth?
The key to the answer lies in Frank Drake's equation, which gives the number of intelligent civilizations as a product of various factors. This equation is so famous and popular that it has been set to music, as indicated by this excerpt from the website http://www.setileague.org/songbook/equation.htm:
L is the lifespan of advanced societies.Those who are musically challenged may consult the website http://www.setileague.org/general/drake.htm for additional details. Alas, none of these probabilities is known with any precision, so that extra-terrestrial intelligence may or may not exist.
fc is intelligence choosing to communicate.
fi, intelligence evolves.
fl is the fraction on which life emerges.
ne are the planets which could be life-sustaining.
fp is the fraction which develop planets,
R star is the rate of stellar formation.
09 December 2003: Don Kanner (Lane Tech HS Physics
Teacher) General Relativity
Having just used Karlene Joseph's and Dan Caldwell's paper plate and marble centripetal force demonstration in his classroom, Don showed us how to illustrate a celestial object being pulled into a black hole (sparing no expense -- ha!) using a marble whirling around inside a the top of a 1 liter plastic pop bottle held vertically with its mouth pointed toward the floor. When one stops rotating the bottle, the marble continues to whirl around the inside until it falls out the mouth. In Einstein's General Theory of Relativity, gravity corresponds to a distortion (intrinsic curvature) of the space around a mass. We are thus led to following the question: Assuming that the mouth of the bottle is analogous to a black hole, what portion of the area near the mouth of the bottle best fits Einstein's description of space-time distortion?
Now who says that you can't teach about black holes in high school? Don referred to the classic film Frames of Reference by Hume and Ivey. The following description is adapted from information on the website of the Department of Physics and Astronomy of the University of Victoria (BC, Canada) [http://www.phys.uvic.ca]:
FRAMES OF REFERENCE (Educational Services, Inc., 1960) 25 min, snd, b.w.
Professors Patterson Hume and Donald Ivey of the University of Toronto demonstrate the behavior of a body under the force of gravity as viewed from different frames of reference and the behavior of a frictionless puck on a rotating table in the laboratory. Two excerpts from this film are also available which present the above material in a condensed form:
1. "Excerpt 1", 7 min. QA839 F7. Shows gravitational effects.
2. "Excerpt 2", 5 1/2 min. QA839 F72. Shows rotational effects.
PJ Comment: The idea of "tunneling into the center of force" is very old. Isaac Newton criticized the Descartes model of the solar system, pointing out that this would be precisely the outcome of that mode. The Bohr Atomic Model was roundly criticized during the period 1915-1925, because electrons in atomic orbits would be expected to "wind down" into the center of the nucleus, in a time of about 10-9 seconds, because of the total power radiated by a free point charge q experiencing an acceleration of magnitude a. According to the Larmor formula
26 October 2004: Fred Schaal [Lane Tech HS
Fred has been reading the book The Theory of Everything by Stephen Hawking http://www.audiobooksonline.com/shopsite/1590072286.html. Fred indicated that when two black holes collapse together, one would expect the total entropy to be conserved, and that the entropy of a given black hole is proportional to its area. However, this requirement of thermodynamic reversibility does not seem to be true. How come? For more details see these websites on Black Hole Thermodynamics: http://nrumiano.free.fr/Estars/bh_thermo.html and http://www.upscale.utoronto.ca/GeneralInterest/Harrison/BlackHoleThermo/BlackHoleThermo.pdf.
09 November 2004: Fred Schaal [Lane Tech HS
1 +1 = 1
Fred remains puzzled as to how the Volume and surface Area depend upon the radius of a black hole. Apparently, the standard formulas
26 April 2005: Fred Schaal [Lane Tech HS,
Follow-up Question on Book by Michio Kaku
As a follow-up of his comments about this book at the last SMILE meeting mp041205.html, Fred asked an important question concerning developments in twentieth century physics. Here is the question, as well as an answers, given on-the-spot by Porter Johnson.
10 May 2005: Fred Schaal [Lane Tech HS,
There May Be Dark Matter in Your Living Room
Fred called attention to the fact that, according to current theories of cosmology, dark matter should exist. This dark matter interacts very weakly with ordinary matter -- only through gravity, and not the electromagnetic field. In other words, we can't see it, but it may permeate our galaxy. In particular, the flux of dark matter through the earth is estimated to be 106 particles per square-meter per second. But ... We don't feel a thing!
Wow! Thanks for the info, Fred.
24 January 2006: Debbie Lojkutz (Joliet West HS,
Einstein's Big Idea
Debbie brought an activity from the teachers manual of the Einsteins Big Idea program; it demonstrates potential and kinetic energy, specifically the conversion of potential to kinetic energy. Debbie had some ordinary flour placed into plastic cups into which she dropped marbles from various heights above the flour (that is, various potential energies). Each marble, when dropped, would go different depths into the flour; the depths could be measured by using drinking straws, which could be inserted into the flour until they touched the (submerged) marble. (But, shouldn't we measure the distance to the bottom of the marble?) This measurement can then be used to estimate the force stopping the marble in the flour. The depth into the flour should increase with height of the drop. Is it linear, or what? Thanks for the ideas, Debbie!