Download Lecture 39. Does Life Elsewhere Seem Likely? The

Lecture 39. Does Life Elsewhere Seem
Likely? The Psychological Impact of Finding Life
Elsewhere.
reading: Chapter 14
Does Life Elsewhere Seem Likely?
Heavy elements/protoplanetary disks/extrasolar planets
are abundant, and likely increasing with time
The chemical elements that comprise life and water are
pervasive in the universe
Organic compounds are also pervasive in the universe
- interstellar medium
- PAHs, amino acids, simple organics in meteorites and comets
- organic synthesis on the early Earth
Life seems to have appeared early in Earth’s history
Does Life Elsewhere Seem Likely?
Life on Earth is robust
- life in extreme environments/life is pervasive
- has survived very nasty extinction events
Life is adaptable
- Darwinian evolution has resulted in pervasive life
- filling niches
- natural selection has made that life very successful
- adept at competition for resources
The vastness of space/number of galaxies/number of stars in
the galaxies
The Rare Earth Thesis
Peter Ward and Don Brownlee at the
University of Washington, 2000
-microbial life should be widespread in
the universe
-complex life such as plants and animals
will be extremely rare
-Earth is “lucky”
-complex Earth life is the result of an
extraordinary set of conditions and
random chance events
-microbial life appeared quickly; complex
life recently
-Earth is also special:
-in the habitable zone
-life-friendly atmosphere
-Jupiter and the Moon beneficial
-placid part of the galaxy
Again, the question:
Is life a natural product of habitable planetary systems?
OR
Is life rare - a rare coming together of unlikely events?
How To Answer These Questions?
Put this in the scientific context of hypothesis testing.
-study of early life on Earth
-exploration of our solar system (Mars, Europa)
-search for terrestrial extrasolar planets
-search for signatures of life on extrasolar planets
-search for ETL by SETI-type searches
What Would Be The Psychological Impact of Finding
Life Elsewhere?
Intense public interest in the exploration of life on Mars and
elsewhere in the galaxy.
We are part of a vast cosmos.
We are part of the Earth and the solar system.
Finding evidence for life elsewhere would change our perspective
on the world and the cosmos.
Copernicus, Galileo, Kepler, and Newton changed our world view.
Darwin and Wallace also changed how we view organisms changing
through time.
The War of the Worlds
Radio adaptation by Orson Welles of the H.G. Wells’ classic novel.
Performed by Mercury Theatre on the Air on Halloween, 1938.
Presented as a series of radio news bulletins
Mysterious Martian Canals
1877 Map of martian canali by astronomer Giovanni Schiaparelli
Mysterious Martian Canals, cont.
Percival Lowell
wealthy amateur astronomer
founder of Lowell Observatory, Flagstaff, AZ
strong proponent of canals used for irrigation
dark spots at their intersections were oases
changed with the seasons
canals constructed to channel Mars’ scanty
water supply
Fundamental Questions About Life in the Solar System
Are other planets sterile?
Is it related to Earth life?
Is it an independent origin of life?
Does it use similar molecules as Earth life?
How do we look for an independent origin of life if it is
completely different?
Microbial Life vs. Intelligent Life
Which would have a more profound impact on our lives?
Many Americans think only discovery of intelligent life
will have a profound effect.
But most scientists think that discovery of microbial life
will be just as profound.
The origin of life is not a unique event.
Hard to predict just how people and society will react.
Alien Contact in Science Fiction
1. ETs could be a source of help in solving society’s problems
(assumes we need outside help to solve our problems and
ET would be willing to help) or learning about the secrets of
the universe.
2. Fears about destruction or bodily harm
(either deliberately or accidentally)
3. Analogies with human history (contact between modern and non-technical societies results
in subsuming of the non-technical into the modern, with loss
of the non-technical culture)
SETI is Prepared!
Declaration of Principle Concerning Activities Following
the Detection of Extraterrestrial Intelligence:
1. verify the most plausible explanation of the evidence is ETL
rather than natural phenomena. If it can’t be verified, may
disseminate the info as an unknown phenomenon.
2. before announcing it, must inform all other observers or research
organizations party to the declaration to confirm by
independent observation. Inform national authorities.
3. Inform observers throughout the world via Central Bureau for
Astronomical Telegrams of the International Astronomical Union.
Inform secretary general of the UN. Inform:
Intl Telecommunication Union
Intl Academy of Astronautics
Committee on Space Research
Intl Institute of Space Law
Intl Astronomical Federation
Commission 51 of the Intl
Commission J of Intl Radio Science Union
Astronomical Union
4. Confirmed detection disseminated promptly, openly, and widely by
discoverer through scientific channels and the public media
SETI is Prepared!
5. All data made public to international scientific community
6. Evidence should be recorded and stored permanently in
a form to make it available for analysis and interpretation
7. Seek international agreement to protect the appropriate
electromagnetic frequencies.
8. No response to a signal will be sent until appropriate
international consultations have taken place.
9. SETI and Intl Astronomical Union will conduct a continuing
review on the procedures for detection and the handling
of data. An international committee of scientists will serve
to analyze data and provide advice on release to the public.
Maintain lists of people to contact if contact is made.
Astrobiology as a Science
Exploring how planets and moons work.
Exploring stars and galaxies to understand how the universe works.
Learn more about the fundamental nature of life in the context
of the solar system and the universe.
How did life come to exist - how did it change with the planet?
What does it mean to be alive and what does it mean to be human?
Have A Wonderful Summer!