Wednesday, March 19, 2008
Announcements:
- Our second exam will be held in class on Monday and will include
topics from Chapters 6 - 12. The format will be similar to the
first exam: approximately 25 multiple-choice questions and one or
two essay questions.
- If you wish, you can take the exam on Thursday (tomorrow). Let me know so that I can make arrangements with you.
- When you email me about your group project, be sure to copy your group members to facilitate good communication with everyone.
- News: The FCC's 700 MHz wireless spectrum auction ended yesterday and brought in $19.5 billion.
Assignments:
- Study for the exam on Friday; get a good night sleep; remember
to bring a Scantron sheet, pencil, and a calculator.
- If your group has not already told me your Web Project topic, let me know as soon as possible so that I can add it to the list.
Chapter 12 - Extraterrestrial Life and
Pseudoscience
This chapter addresses the really big questions of "Where did we come
from?", and "Are we alone in the universe?"
SETI is the Search for
Extraterrestrial Intelligence, and has been active mostly through
private funding via the SETI Institute
which was founded in 1984.
Planets beyond our solar system are being discovered on nearly a weekly
basis now. Currently 228 exoplanets have been identified.
These planets cannot be seen directly, but their existence can
be inferred by observing a periodic wobble (astrometry) or dimming
(photometry) of a parent star, or by observing a periodic shift in the
emission spectrum of a star from red to blue and back again (doppler
spectroscopy).
The number of planets in our galaxy that likely have intelligent life
that could communicate with us is found from: N =
n1*f1*f2*f3*n2*f4*f5*f6
where:
n1 = number of stars in our Milky Way galaxy:
~400 billion
f1 = fraction of these stars that are single stars
(as opposed to binary or tertiary stars): ~0.5
f2 = fraction of single stars that are like our sun
(not too big or too small): ~0.1
f3 = fraction of sunlike stars that have planetary
systems: 0.1 to 1.0
n2 = number of Earthlike planets in each planetary
system: 0.1 to 1 or more
f4 = fraction of planets where life has arisen or
will arise: 0.01 to 1.0
f5 = fraction of planets where intelligence
develops: 0.000001 to 0.01
f6 = fraction of those planets with intelligent life
that could communicate with us: probably less than 1 ppm
Conclusion: While there are perhaps millions or even billions of
planets in our galaxy where life has developed, it is unlikely that we
will have the opportunity to communicate with intelligent life on
another planet due to the great distances and relatively short lifetime
of technological societies compared to planet lifetimes.
Pseudoscience often masquerades
as science, but is not grounded in empirical evidence.
Examples include: astrology, UFOs, creationism, ESP,
fortune-telling, witches and ghosts, etc.
Review of Exam 2 from last year.