The Universe today is old, cold, low-density, and expanding.  If we run
the expansion backwards, we will eventually find a Universe where all
the matter was in one place where the density and temperature are nearly
infinite.  We call this hot, dense initial state of the Universe the Big
Bang.  This lecture introduces the Big Bang model of the expanding
universe, and how the history of the Universe depends on two numbers:
the curretn expansion rate (H0), and the relative density of matter and
energy (Omega0).  Combined with observations, these give us an estimate
of the age of the Universe of 14.0 +/- 1.4 Gyr.  Recorded 2006 February 27 in
1008 Evans Laboratory on the Columbus campus of The Ohio State
University.

Lecture 36: The Big Bang

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A new podcast, Astronomy 141, Life in the Universe, is available
for those interested in continuing an exploration of topics in
modern astronomy.

Astronomy 141 Podcast Teaser

Where are Lectures 1-4?  This is a good question, and one I've gotten
from many listeners.  Here's the answer.  Recorded 2006 Nov 27 on the
Columbus campus of The Ohio State University.

Lectures 1-4: An Explanation

Welcome to the Astronomy 162 Lecture Podcasts!  This is a brief message
from me explaining the podcasts, and welcoming new and old listeners.
Recorded 2006 Mar 10 on the Columbus campus of The Ohio State
University.

Welcome to Astronomy 162

How can we search for extraterrestrial intelligence, and what are we
looking for?  This second part of a 2-part lecture picks up where we
left off yesterday by examining SETI, the Search for ExtraTerrestrial
Intelligence, and reviews what we might look for and how.  We will use
this as a point of departure to then briefly review where we have come
and what we have learned in Astronomy 162, bringing this course to a
close for Winter Quarter 2006.  Recorded 2006 Mar 10 in 1008 Evans
Laboratory on the Columbus campus of The Ohio State University.

Lecture 44: Life, the Universe, and Everything (Life Part II)

Are we alone in the Universe?  This is the first part of a 2-part
lecture that will explore the question of life and the Universe.  We
will look at the conditions needed for life, and address the question of
how often we expect those conditions to be satisfied in our own Galaxy.
In this part, we introduce the Drake Equation and make some basic
estimates.  To be honest, it was supposed to be one lecture, but I ran
over time and ran into the bell.  Oops!  Very embarrasing.  Tomorrow's
lecture will finish up our discussion of life in the Universe, and then
wrap up Astronomy 162 for the quarter.  Recorded 2006 March 9 in 1008
Evans Laboratory on the Columbus campus of The Ohio State University.

Lecture 36: The Big Bang

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