Extraterrestrial Intelligence: Are We Alone?

1
Extraterrestrial Intelligence Are We Alone?

• Well have to make many (educated) guesses to
  evaluate odds of ETs in our huge Galaxy
• But for many guesses we have only a SINGLE data
  point our Earth
• This makes it almost impossible to be scientific

2
You are all ET experts now!

• Finally I do not need a tie to symbolize all my
  years of specialized scientific training.
• Honestly I dont know more about this than you
  have learned in Astro 3.
• Isnt college great?
• That is why I cannot put any questions from this
  lecture on the Exam!!

3
A Fearless Estimate

• Drake Equation for the number of technical
  civilizations currently in Milky Way
• N (SFR) x nhabit planets x f life x f intel x
  f tech x L
• Simple accounting of our ignorance, which
  increases from left term to right

4
A Fearless Estimate

• Drake Equation for the number of technical
  civilizations currently in Milky Way
• N (SFR) x nhabit planets x f life x f intel x
  f tech x L
• Star Formation Rate in our galaxy is 5 to 10 per
  year on average (higher in past)the only number
  in Drake Equation which is well determined

5
A Fearless Estimate

• Drake Equation for the number of technical
  civilizations currently in Milky Way
• N (SFR) x nhabit planets x f life x f intel x
  f tech x L
• Multiple planets, including terrestrials or Moons
  are natural byproduct of star formation, BUT
  Earth is currently only one known to be
  Habitable?
• Liquid Water requires special conditions

6
Stellar Evolution

• Stars get brighter as they age along the main
  sequence. This results in an outward migration
  of the habitable zone. The continuously
  habitable zone--the region where liquid water is
  always stableprobably only includes 1 planet.

Initial position of HZ
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Jupiters moons Io, and Europaway beyond the
Habitable Zone
8
Europa Water ocean, under the ice crust, melted
by internal heat sources this could be fairly
common
?Inferred Ocean
9
Is Europa telling us to expand our definition of
Habitable Planet?

• Recently, we have discovered that life without
  the sun is possible.
• Instead of photosynthesis, organisms have been
  discovered living in a variety of places via
  chemosynthesis - the use of chemical energy.
• Could this happen on other worlds?

A deep-sea hydrothermal vent.
10
A Fearless Estimate

• Drake Equation for the number of technical
  civilizations currently in Milky Way
• N (SFR) x nhabit planets x f life x f intel x
  f tech x L
• LAWKI needs complex system of C chains (protein)
  catalysts
• The building blocks (amino acids) are cosmically
  common.
• The miracle of Nuclei acids (DNA and RNA)
• with the right message
• evidently occurred on Earth almost immediately

11
Mars had water seas, but evidence for fossil
life in Mars rock is unconvincing. Well have to
explore Mars further

• Nice shape, but no evolution of shapes evident.
  Way too small!

12
A Fearless Estimate

• Drake Equation for the number of technical
  civilizations currently in Milky Way
• N (SFR) x nhabit planets x f life x f intel x
  f tech x L
• Although intelligence offers some evolutionary
  advantage, there has NOT been any steady march
  towards bigger brains (we took gt3 Gigayears)
• Humans may be a lucky evolutionary accident

13
A Fearless Estimate

• Drake Equation for the number of technical
  civilizations currently in Milky Way
• N (SFR) x nhabit planets x f life x f intel x
  f tech x L
• With the lucky breakthrough of language,
  culture starts Lamarckian evolution
• Weve only had radio communication, space travel
  for less than a century dolphins and chimps
  might never get technical

14
A Fearless Estimate

• Drake Equation for the number of technical
  civilizations currently in Milky Way
• N (SFR) x nhabit planets x f life x f intel x
  f tech x L
• 10 x 1 x 0.001 x 0.1 x 1 x L 0.001 L
• Some pure guesses, but it all comes down to L we
  can only project our own natures onto the aliens

15
A Fearless Estimate

• Drake Equation for the number of technical
• civilizations currently in Milky Way
• N (SFR) x nhabit planets x f life x f intel x
  f tech x L
• Lifetime could be huge (Gigayears) for successes,
  
• or is the power of technology so de-stabilizing
  that civilizations cannot survive it for more
  than
• 1000 years L??

16
A Fearless Estimate

• Drake Equation for the number of technical
  civilizations currently in Milky Way
• N 0.001 x L
• 0.001 x 1000 years
• 1 Technical Civilization in our Galaxy
• Pessimistic this is Us! Probably alone until we
  destroy ourselves within several centuries

17
A Fearless Estimate

• Drake Equation for the number of technical
  civilizations currently in Milky Way
• N 0.001 x L
• 0.001 x 1 Billion years
• 1 Million Technical Civilizations
• Optimistic a Swarming Galactic Club, should
  not be too hard to find this super-civilization

Dont forget Course Evals!
9
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ET Question can only be resolved with more
datawho is going to make the first move, us or
them?

• Nearest outpost of the hypothesized galactic
  club might be about 100 light-years away
• Within this volume, we already know most of the
  suitable stars to search for habitable planets.
• With luck, we might even discover strong
  biosignatures remotely, then send probes

19
Were already on the verge of identifying
habitable planets Next Biosignatures might be
detected in the atmosphere of a planet many light
years away

• Disequilibrium chemistry our oxygenated
  atmosphere is a good example. Without life, the
  oxygen would all react with rocks and be gone
  from the atmosphere in a few million years.
• Metabolic by-products O2 , O3 are examples, but
  in other situations, CH4 can be a good
  biosignature (not on Mars, however).

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Our 25 nearest stellar neighbors.
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260,000 stars within 250 light years
22
Pessimists say we have to search almost our
entire galaxy to find intelligent company 200
billion stars offer a lot of possibilities, but
typical distances are now tens of thousands of
light years!
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In that case, why stop with our own Galaxy, since
we could reach thousands more, going another
factor of 100 further in distance
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What can they do to contact us?

• Communication is cheapest
• EM waves such as radio are easy for the
  persistent (e.g. Species) (Arecibo can now
  communicate with a copy of itself on other side
  of the Milky Way Galaxy!)
• But this is a classic needle-in-a-haystack
  problem, with so many frequencies, directions,
  duty cycles, signal patterns, to search. We have
  to make some assumptions about their
  transmission, or try eavesdropping (really
  tough!)

25
Arecibo 1000 foot dish in Puerto Rico, with very
powerful radio transmitter
26
HOLD ON!! Are we SURE we WANT to be Contacted?

• Are you SURE that all advanced ETs are really
  nice and enlightened?
• What if all of those (bad) Sci-Fi movies were
  right!?! (as Tim Ferris reminds us)
• But on the other hand, isnt it more likely that
  only a PEACEFUL Galactic Club could survive
  billions of years?
• Would you like to bet the fate of the entire
  human race that they were wrong? (oops, its too
  late anyway)
• We must never forget just how ALIEN ETs are going
  to be!

27
Even George Lucas cant imagine how strange ETs
will really be, and that is mathematical certainty
These are all just humans, dressed up in fancy
costumes!
28
What can they do to contact us?That requires
speculating about them!

• Odds are overwhelming that they will be thousands
  to millions of years ahead of us, since our
  technical civilization was just born ---- (how
  many people in LA are 10sec old?)
• In thousands of years, one-way voyages of
  colonization should be undertaken by some
  adventurous explorers (giant space stations are
  independent of the home star)

29
If Optimists Correct, Where Are They?

• Theyre uninterested. (Want to talk to ants?)
• 1a. Maybe theyre too far away to have received
  the RECENT news of our development of
  technology
• Remember how LITTLE WE MAY HAVE IN COMMON
  (besides basic math and physics)
• 2. Theyre already here, but incompetent or
  messing with us? NoUFOs internally
  inconsistent
• 3. They are STRICTLY QUARANTINING us new kids on
  the block (Zoo Hypothesis).
• Please credit them with being SERIOUS (unlike USS
  Enterprise!).

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For either possibility 1) or 3), the only sound
position is to assume were alone for now

• Until proven otherwise, this may be the only
  place in the entire Universe where consciousness
  has developed (were only physically
  insignificant)
• We certainly cant count on a bunch of
  super/enlightened beings to swoop down and save
  us just at the brink of some calamity, cures
  cancer, etceven if they are watching, WERE ON
  OUR OWN
• P.S. MM personally PREFERS it that way!
• (my last night on the telescope)

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(Personal) Overview of some of Homo Sapiens
Highs and Lows What snaps would You send to the
Galactic Club? Whatever you say about all these
spectacular Highs and Lows, We HUMANS did them
100 on our own
No matter how many times we mess up, WE HUMANS
will never stop trying I PREFER this to the
prospect of some superior aliens doing it all for
us