Search for Extraterrestrial Life PHY 100

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Search for Extraterrestrial LifePHY 100
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How life emerged on earth

• Amino acids, building blocks of life form via
  chemical reactions
• With help of nucleic acids, they combine to form
  proteins in living things
• Sequence of chemical events that leads to
  creation of nucleic acids is unknown but two
  notable theories have emerged from research
  Iron-Sulfur World Theory and RNA World Theory

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Theories of Early Life

• Iron-Sulfur World Theory
• Early life may have formed on the surface of iron
  sulfide minerals in volcanic hydrothermal flow at
  high pressure and high temperature
• Developed by retrodiction from extant
  biochemistry combined with various chemical
  experiments

• RNA World Hypothesis
• Theory that proposed that a world filled with
  life based on ribonucleic acid predates the
  current world we live in based on
  deoxyribonucleic acid (DNA) and protein.
• The RNA world is proposed to have evolved into
  the DNA and protein world of today.

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Miller Urey Experiment

• Amino acids can form via natural chemical
  reactions

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Alternative Biochemistries For Extraterrestrial
Life

• Perhaps we are Carbon Chauvinists
• Nitrogen and Phosphorous
• Make stable covalent bonds and could be a
  basis for biochemistry. Has a strong argument,
  however, is not plausible.
• Silicon Based Organisms
• Has very similar chemical properties to Carbon
  but has a lot of drawbacks. Silicon is far more
  abundant than Carbon (9251). May be plausible in
  different temperatures and pressures than earth.

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SETI

• Search for Extra-Terrestrial Intelligence (SETI)
  is the collective name for a number of activities
  involving the search for extra terrestrial life
• Projects use various methods to search for
  electromagnetic transmissions from civilizations
  on distant planets
• Formerly funded by U.S. Government, mostly
  privately funded currently

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Radio Experiments

• Since radio frequencies are able to penetrate our
  atmosphere, radio telescopes are often used to
  investigate the cosmos.
• Earth emits considerable radio radiation as a
  result of TV and radio. These radiations are easy
  to recognize due to their short wavelengths and
  repetitive nature.
• Therefore, one way of discovering
  extraterrestrial civilizations is to detect
  non-natural radio emissions from outside our
  solar system

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SETI Radio Experiments

• 1960 Frank Drake performs first modern SETI
  experiment, Project Ozma
• Ohio State University SETI Program and the Wow!
  Signal- 1977
• SERENDIP and SERENDIP II at U.C. Berkeley

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Further SETI Projects

• Suitcase SETI and Sentinel
• Project META (Megachannel Extra-terrestrial
  Assay)
• Project BETA
• Project Phoenix
• Allen Telescope Array (ATA)

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The 21 cm Line

• The 21 cm Hydrogen line is considered a favorable
  frequency to search for signals from another
  civilization, as part of the SETI program.
• Pyotr Makovetsky proposed to use for SETI a
  frequency which is equal to pi times 1420.4 MHz.
• Since pi is a Transcendental number, such
  frequency couldn't possibly be produced in a
  natural way as a harmonic, and would clearly
  signify its artificial origin. Such signal would
  not be jammed by HI line itself, or any of its
  harmonics.

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• Volunteer distributed computing project launched
  by U.C. Berkeley in 1999
• Allows any individual to become involved in SETI
  research
• Has over 180,000 active participants which gives
  this program a computational power greater than
  that of the fifth most powerful computer in the
  world

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Criticism of SETI

• The search for extra terrestrial intelligence is
  not an assertion that extra terrestrial
  intelligence exists in the first place
• Other objections to SETIs projects include
  questioning the amount of energy necessary to
  execute the projects and why advanced
  civilizations would use radio in the first place
• Regardless of criticism, SETI does collect useful
  scientific information

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The Drake Equation

• An equation used to guess the potential number of
  extraterrestrial civilizations in our galaxy

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Fermi Paradox

• Contradiction between the high probability that
  extraterrestrial civilizations exist and the lack
  of contact with these civilizations
• Extraterrestrial civilizations reasons for
  spreading beyond planet of origin
• Exploration
• Colonization
• Survival

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Solutions to Fermis Paradox

• It is difficult for life to start and evolve to a
  point that is intellectually and technologically
  advanced and we are the only one in the galaxy
• Advanced civilizations destroy themselves on
  short timescales so they may not have had time to
  reach us

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Conclusion

• Research on the existence of extraterrestrial
  life still remains inconclusive
• SETI efforts continue to search spectrum for
  signals from outside sources but the increasing
  belief is that civilizations, if they did exist,
  did not have enough time to reach us

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For your entertainment

• http//www.youtube.com/watch?vh9eX7URM_hU