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23 Mar 09

Climate Variations Don't Invalidate the Reality of Global Warming - washingtonpost.com

Great quote about how we know about Global Warming

www.washingtonpost.com/...AR2009032003191.html - Preview

globalwarming science research

  • Data collected over the past 150 years by the 188 members of the World Meteorological Organization (WMO) through observing networks of tens of thousands of stations on land, at sea, in the air and from constellations of weather and climate satellites lead to an unequivocal conclusion: The observed increase in global surface temperatures is a manifestation of global warming. Warming has accelerated particularly in the past 20 years.

Drake equation - Wikipedia, the free encyclopedia

  • The Drake equation states that:



    N = R^{\ast} \times f_p \times n_e \times f_{\ell} \times f_i \times f_c \times L \!


    where:



    N is the number of civilizations in our galaxy with which communication might be possible;


    and



    R* is the average rate of star formation in our galaxy

    fp is the fraction of those stars that have planets

    ne is the average number of planets that can potentially support life per star that has planets

    fℓ is the fraction of the above that actually go on to develop life at some point

    fi is the fraction of the above that actually go on to develop intelligent life

    fc is the fraction of civilizations that develop a technology that releases detectable signs of their existence into space

    L is the length of time such civilizations release detectable signals into space.
  • By plugging in apparently "plausible" values for each of the parameters above, the resultant expectant value of N is often (much) greater than 1. This has provided considerable motivation for the SETI movement. However, we have no evidence for extraterrestrial civilizations. This conflict is often called the Fermi paradox, after Enrico Fermi who first asked about our lack of observation of extraterrestrials, and motivates advocates of SETI to continually expand the volume of space in which another civilization could be observed.
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Observable universe - Wikipedia, the free encyclopedia

  • In Big Bang cosmology, the observable universe consists of the galaxies and other matter that we can in principle observe from Earth in the present day, because light (or other signals) from those objects has had time to reach us since the beginning of the cosmological expansion
  • The age of the universe is about 13.7 billion years
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