Life in the Universe

("Damn it Jim, I'm a Doctor not a bricklayer." Bones McCoy

Would we recognize it ?

The Search for Extraterrestrial Intelligence (SETI)

The mission of the SETI Institute is to explore, understand and explain the origin, nature and prevalence of life in the universe.

This is not the BEM syndrome, but some guys actually make up SETI songs.

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Life as we know it

Organic - Carbon based / Silicon (?) DNA / RNA

How do we make these molecules?

1950s - Urey and Miller mixed H2O, CH4, NH4 & H2 stimulated this w/ electric sparks

BINGO! complex molecules that included amino acids
The problem is that the Earth's early atmosphere probably wasn't like this SO....
get all 5 essential compounds of the human gene

These match up w/ the Murchison meteorite & meteorites found in Antarctica

"Primordial Soup" research continues

Other Solar Systems?

We look for

  • wobbles (Doppler) in a star's orbit
  • transit
  • microlensing

    Only found one by 1995 SS w/ 3 planets - 9 Earth masses it located around a Pulsar, found 2 more planets 1996, over 120 now


The Drake Equation

N = R* Fp Ne Fl Fi Fc L


  • R* - rate of star formation
  • Fp - stars w/ planets (or maybe ) and satellites
  • Ne - # of planets on which life could survive per solar system
    • archaebacteria - no O - use CO2 + H2 --> CH4 & they have different RNA
    • "Goldilocks Effect" - .95AU to 1.5AU
  • Fl - life arises
  • Fi - intelligent life
  • Fc - communication w/ other civilization - technology's =
  • L - lifetime of a civilization

So if we are going to be optimistic

R* ~ 4 x 1011

Fp~ 1/3

Ne ~ 2

Fl ~ 1/3

Fi x Fc ~ 1/100

L ~ 1/107

(note we have only had radio telescopes for 50/ 4 x 109 yrs of Earth history)

Then N ~ 10 some estimates as high as 107

Even if they are out there - they are very far away!

N = 10 --> 10,000 LY apart (100,000 LY Milky Way)

N = 107--> 10 LY apart (assumes equal distance)

How do we talk to them?
Anybody want an old 300 channel receiver?-76k

SETI at Home