Glaciation

1
Glaciation

• global warming will taper off when fossil fuel
  sources are exhausted (a few hundred years)
• ice age glaciations will resume, with likelihood
  of mass extinctions

2
(No Transcript)
3
Solar Aging

• progressive warming of the sun will cause all
  life to end within a half billion years from now
• within 5 billion years the sun will expand into a
  red giant and consume the earth altogether
• following this the sun will blow off its outer
  layers and become a dwarf, with minimal energy
  output
• relocating to another life conducive planet would
  be risky, and probably involve generations of
  space travel

4
Extraterrestrial Life

• could be based on a non carbon element (eg,
  silicon), but it would require an atmosphere and
  some kind of surface liquid (eg, ammonia)
• without constraints of carbon molecules and water
  medium, life could be supported at a greater
  range of temperatures
• lack of an atmosphere or liquids suggest life is
  unlikely on the moon, Mars, or surface of Venus

5
Planets Conducive to Life

• life could exist in the Venusian clouds where
  water, sunlight, CO2, pressures and temperatures
  comparable to earth's surface are found (though
  very little oxygen)
• life could similarly exist on the lower clouds of
  the outer planets
• life might also exist on outer planet moons,
  comets, and asteroids (some of which are composed
  of up to 1 of organic materials)

6
(No Transcript)
7
(No Transcript)
8
Extraterrestrial Intelligence

• life, as well as intelligent life, is likely to
  be replicated elsewhere in the universe
• if technical civilizations avoid
  self-annihilation, lifetimes could be very long,
  comparable with stellar evolutionary time scales
• estimates of up to a million technical
  civilizations currently extant in the Milky Way
  galaxy

9
Extraterrestrial Communications

• if randomly distributed, the distance of the
  nearest such civilization to earth is estimated
  at several hundred light years
• radio transmission seems the most likely means of
  making contact with such civilizations
• government funded efforts (based on radio
  telescopes aimed at nearby stars) are already
  underway