Astronomy 141 - Life in the Universe - Autumn Quarter 2009

Astronomy 141 - Life in the Universe - Autumn Quarter 2009

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Astronomy 141 - Life in the Universe - Autumn Quarter 2009 episodes

  • Lecture 46: This View of Life (Course Finale)
    Course finale and summary. We look back over where we've been the last
    eleven weeks, and bring together all of the main themes of this course
    on Life in the Universe. Recorded live on 2009 Dec 4 in Room 1005 Smith
    Laboratory on the Columbus campus of The Ohio State University.
    41 min
  • Lecture 45: The Future of Life in the Universe
    How will life, the Universe, and everything end? This lecture looks at
    the evolution of our expanding Universe to project the prospects for
    life into the distant cosmological future. Recent observations show
    that we live in an infinite, accelerating universe. I will trace the
    evolution of the universe from the current age of stars into the future.
    The final state of the Universe will be cold, dark, and disordered, and
    ultimately inhospitable to life as we understand it or perhaps can
    imagine it. Recorded live on 2009 Dec 3 in Room 1005 Smith Laboratory
    on the Columbus campus of The Ohio State University.
    45 min
  • Lecture 44: The Future of Life in the Solar System
    What is the future of life on Earth and in our Solar System? The Sun is
    the source of energy for life on the Earth, but it will not shine
    forever. This lecture looks at the impact of the various stages of the
    evolution of the Sun on the habitability of the Solar System, with
    particular emphasis on the continued habitability of the Earth. I will
    refer to state-of-the-art computer models of the Sun to get is
    properties at various stages in its past and future life. NOTE: Due to
    a recorder malfunction this lecture was re-recorded later in the day on
    2009 Dec 2, rather than being live from the class room in Smith
    Laboratory. As such, it is about 10 minutes longer than usual (my
    pacing is off when not in front of class).
    56 min
  • Lecture 43: Extraterrestrial Life
    What does extraterrestrial life look like? This lecture explores
    current thinking about what extraterrestrial life might be like not by
    guessing their appearances, but instead applying lessons learned from
    our growing understanding of how evolution and biochemistry work on
    Earth. I will discuss Universal versus Parochial characteristics,
    Convergent Evolution, Radical Diversity, and other ideas from
    evolutionary biology that might inform how life might emerge on other
    worlds. We will then look at alternatives to carbon biochemistry,
    specifically the possibility of silicon-based life, and alternatives to
    liquid water as a solvent medium for biochemistry, specifically the
    possible role of Ammonia. Finally I will give one example of a highly
    speculative idea about life without chemistry. In the end, the outcome
    of such studies may not be to tell us much about extraterrestrials as to
    help focus questions on how we ourselves arose. Recorded live on 2009
    Dec 1 in Room 1005 Smith Laboratory on the Columbus campus of The Ohio
    State University.
    46 min
  • Lecture 42: The Fermi Paradox
    So, Where is Everybody? Interstellar colonization, in principle, is an
    exponential growth process that would fill the galaxy in a few million
    years even with a very modest star flight capability. This is a small
    fraction of the lifetime of the Milky Way Galaxy, so the Galaxy should
    be teaming with life. But, we so far have no compelling evidence of
    extraterrestrial visitations, alien artifacts, or any other evidences
    that the Galaxy is populated. Physicist and Nobel Laureate Enrico
    Fermi's apparent paradox and some of the proposed resolutions are the
    topic of this lecture. I will review the Fermi Paradox and describe the
    most common possible resolutions. The Fermi Paradox is useful in
    helping to frame the question of extraterrestrial life, even if we so
    far have no answers. At the end I only touch on the Rare Earth
    Hypothesis, but this is a very nuanced question which requires a whole
    other lecture to explore that I have not had time to fully prepare for
    during this busy quarter. Recorded live on 2009 Nov 30 in Room 1005
    Smith Laboratory on the Columbus campus of The Ohio State University.
    45 min
  • Lecture 41: Interstellar Travel and Colonization
    If we ever detect life elsewhere, how will we go visit? This lecture
    considers the challenges of interstellar travel and colonization. The
    problem is one of basic physics (the enormous energy requirements of
    star flight) coupled with the vast, irreducible distances between the
    stars. I will describe various starship concepts that use reasonable
    extrapolations of current technologies (nuclear propulsion and solar
    sails), ignoring for our discussions science-fiction exotica like
    faster-than-light drives and wormholes. My interest is in the
    scientific aspects of the problem, not an exploration of speculative
    fiction. I then turn to interstellar colonization, and how even
    a relatively modest star-flight capability might allow a determined
    civilization to colonize the entire galaxy very rapidly. This has
    implications for how we might interpret the results of Drake Equation
    type arguments about the frequency of intelligent life in the Galaxy,
    and leads to the Fermi Paradox that will be the topic of the next
    lecture. Recorded live on 2009 Nov 25 in Room 1005 Smith Laboratory on
    the Columbus campus of The Ohio State University.
    46 min
  • Lecture 40: SETI - The Search for Extra-Terrestrial Intelligence
    Is anybody out there? This lecture reviews the ideas behind SETI, the
    Search for Extra-Terrestrial Intelligence, an effort to find other
    intelligent communicating civilizations by tuning in on their radio or
    other electromagnetic communications. I will discuss the basic
    approaches being taken by various SETI efforts, and what we expect to
    find. In addition to listening, we have also been broadcasting,
    intentionally or otherwise, messages into space, and we have sent
    physical artifacts with descriptions of our home on robotic spacecraft
    headed out of our solar system into interstellar space. Recorded live
    on 2009 Nov 24 in Room 1005 Smith Laboratory on the Columbus campus of
    The Ohio State University.
    47 min
  • Lecture 39: The Drake Equation
    How many intelligent, communicating civilizations live in our Galaxy?
    We have no idea. One way to approach the question and come up with
    quasi-quantitative estimates is the Drake Equation, first introduced by
    radio astronomy Frank Drake in the 1960s. I will use the Drake equation
    as an illustration of the issues related to the question of
    extraterrestrial intelligence, and to set the stage for future lectures
    on the likelihood of finding other intelligences in our Universe.
    Recorded live on 2009 Nov 23 in Room 1005 Smith Laboratory on the
    Columbus campus of The Ohio State University.
    46 min
  • Lecture 38: The Pale Blue Dot - Seeking Other Earths
    Are there other Earths out there? Do they have life on them? This
    lecture looks at the search for ExoEarths - Earth-sized planets in the
    habitable zones of their parent stars, and what we might learn from
    measuring them. The ultimate goal of all planet searches is to find
    other Earth's, what the late Carl Sagan so poetically called
    the "pale blue dot" as seen from the depths of space. This lecture
    discusses what we might learn about such planets from studies of our own
    Earth, spectroscopic biomarkers that might reveal life, and variability
    studies that might give us insight into surface features (continents
    and oceans) and weather (clouds and even climate). Recorded live on
    2009 Nov 19 in Room 1005 Smith Laboratory on the Columbus campus of
    The Ohio State University.
    45 min
  • Lecture 37: Strange New Worlds
    What are the properties of the 400+ exoplanets we have discovered so
    far? This lecture reviews the properties of exoplanets, and finds a
    couple of surprises: Jupiter-mass planets orbiting close to their parent
    stars, and Jupiter-mass planets in very elliptical orbits. Both seem to
    require some mechanism for migration: strong gravitational interactions
    with either the protoplanetary disk or other giant planets to cause the
    planets to move inward from their birth places beyond the "Ice Line".
    We will then briefly discuss why we are seeing systems very different
    from our own, mostly we think a selection effect due to our search
    methods to date. Microlensing, however, is more sensitive to systems
    like ours, and is starting to find them. Earths, however, remain
    elusive so far, but the hunt is on. Recorded live on 2009 Nov 18 in
    Room 1005 Smith Laboratory on the Columbus campus of The Ohio State
    University.
    47 min

About Astronomy 141 - Life in the Universe - Autumn Quarter 2009

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Astronomy 141, Life in the Universe, is a one-quarter introduction to