Re: Our Interstellar Neigborhood

From: Robert J. Bradbury (bradbury@aeiveos.com)
Date: Fri May 30 2003 - 11:04:34 MDT

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    On Fri, 30 May 2003 Spudboy100@aol.com wrote:

    > 2) Does having a "swiss-cheese" galaxy promote or hinder the
    > development of other intelligent species. or neither?

    Well we have seen papers that nearby gamma ray bursts are
    probably fairly harmful to life as we know it. There was
    also a report (this week I think) about the discovery of
    some galaxy with a huge density of stars that are or will
    become super-novas. This is also probably not good place
    for life. So it seems likely that the Earth has not
    been exposed to nearby GRB or significant quantities
    of supernovas.

    But if the so-called "chimney/hole) around us is only a
    few million years old then it probably hasn't impacted
    the general development of life here too much.

    > 3) Would large regions of ionized interstellar gas, affect the propagation or
    > detection of radio signals? If so, this would explain Fermi's paradox?

    Radio signal propagation interference would more properly be called
    upon to resolve the "SETI" paradox -- i.e. "Why haven't we heard
    from them yet?" But that can easily be resolved by "Because we
    are too dumb to be bothered to communicate with." The Fermi paradox
    is more properly "Why aren't they 'here' yet?". The studies in the
    article cited (below) might explain that. Even though we might live in
    a nice neighborhood ourselves we might live in a "bad neighborhood"
    to get to. Traveling at any significant fraction of the speed of light
    means you have to deal with running into particles (be they ionized H,
    neutral H, or any other atoms/molecules). Its expensive to start a trip
    at 0.1c then have to slow down to 0.01c then speed back up to 0.1c.
    The "walls" of the local bubble may make it very expensive to get to
    us in terms of the cost of matter (ablation of the particle shields)
    and energy (having to slow down and speed back up). So we might
    effectively be "shielded" from colonization.

    A lot more work needs to be done on the various costs (matter and
    energy) of interstellar travel and why and how people would do it.

    Robert

    Background story:
    > 2003-05-30
    >  http://www.sciencedaily.com/releases/2003/05/030530081808.htm
    > 3-D Map Of Local Space Shows Sun Lies In Middle Of Hole Piercing Galactic
    > Plane



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