Wednesday, March 28, 2012

Will we find other intelligent life?


         The beginnings of 
     belief in 
     extraterrestrial intelligence

     Can you think of 
     any early example?

Many religions!

     For example:

     God is intelligent

         ...and everywhere

    must include 
    interstellar space

A tale of two Well(e)s

    Novel written in 1898 by H.G. Wells
          Here are some 
          more interesting covers

    It inspired an 
    Orson Welles radio show

                    The show was broadcast
          Halloween, 1938

          What happened?

Intelligent Martians was a widespread concept


           Percival Lowell and the canals

           Numerous novels

          "Imagining Mars: a Literary History"
          (by R. Crossley)


        1912: Edgar Rice Burroughs 
        "A Princess of Mars"

             The princess had 
             beautiful green (of course!) hair
             ..and so on


        2012: Story back in the news again


Let's move to more technical approaches

Fermi Paradox

     (Enrico Fermi
     was a 
     renowned physicist)

             Italian-born American physicist (1901-1953)

      Awarded Nobel prize 1938

      Considered a father of the atomic bomb

      Died of cancer
      (possibly due to radiation exposure)

     His "paradox":

        Over 100 billion stars 
        in our galaxy,
        the Milky Way

        Roughly (very) 
        there are 
        100 billion
        to 1 trillion

    So how many stars in the universe?

      What fraction have planets?

           What fraction have 
           Earth-like planets?

                 These are called
                 "Earth analogs"

                      1.4 - 2.7%

                      Do pictures exist 
                      of a few of them?                       

     So why no sign of intelligent life?
         (Er, except here)

    That's the "Fermi Paradox"!

1) Why no sign of intelligent life?
         . . . and . . .
2) Will that change?

Fish supposedly live in the ocean

If you fill a cup at the beach...
...where are the fish?

Drake Equation

N=R  x  fp  x  n x  f x  f x  fc  x  L

N:  # advanced civilizations 
     in Milky Way with which
     we could communicate
R new stars formed per year
fp:  fraction of stars with planets
ne:  Suitable planets per star with planets
fl:   Fraction of suitable planets that do develop life
fi:   Fraction of those planets that develop intelligence
fc:  Fraction of intelligent civilizations that are detectable
L:  Length of time civilizations are detectable

N=R  x  fp  x  n x  f x  f x  fc  x  L
Suppose R is 10/year
Let's estimate the others ourselves!
Note: estimate of 100 billion Earth-like planets in Milky Way as of 2013
   Then what is N?

   Why no little green men (or whatever)?

   Crop circles, UFOs, what other evidence?

   How could we 
   communicate with
   extraterrestrial beings?

Possible problem: 
     we can't communicate with dolphins
     (for example)
     and they're
     right here on Earth!

How to find extraterrestrial life

    (Intelligent or otherwise)

    Find planets

    How to do that?

    Find oxygen

    Why so important?

    Detect radio waves, etc.

Discovering Earth-like planets

    Zero extra-solar planets 
    were known when 
   you were born

   They are being discovered 
   (at an increasing rate)

   First ones were huge and hot

   We are getting better 
   at finding more 
   Earth-like ones

   Here are three:

   Gliese 667 Cc

       from "Gliese Catalog of Nearby Stars"

   Gliese 667:
       A triple star
       all of them small
   Gliese 667 C:
       Star C of Gliese 667

       37% of Sun's mass
       42% of Sun's radius
       1.4% of Sun's brightness
    Should last a lot longer than the Sun!

   Gliese 667 Cc
       2nd planet of Gliese 667
       3.9x mass of Earth
       Orbits Gliese 667 every 4 Earth weeks
           Imagine what the year is like
       Its star would be 
       2.3x as wide in the sky 
       as the Sun
         ...but dimmer per unit area
         ...reddish, since cooler than Sun
         ...temperature should allow liquid water photos exist?

         ...well artists' impressions do
         ...let's check!
         ...only 22.1 light-years away

Gliese 581:
    Red dwarf star
    Might not exist
       But it might!
    Gliese 581 g is a planet
    Roughly 4x Earth mass
    Tidally locked to star
         That is a problem (why?)

         A thick atmosphere could solve the problem
             What would it be like there?

   Gliese 370 b
       Another interesting planet
       wikipedia, etc., has artist's impression
       Also called HD 85512 b
              (we use nicknames, so why not?)
       At least 3x Earth mass
       Gravity 1.4x Earth (at least)
       What would that feel like?
       May have liquid water
           Temperature depends on
           various unknowns

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