lecture29

Slide1 : A grand summary of this course


Life in Other Worlds : Life in Other Worlds What is life? A process of systems that are capable of extracting energy and reproducing It could be much more general, and very different, than we know or think What is the physical base for life? A physical mechanism capable of supporting extraction and utilization of energy In our case: carbon-based substrate Where can we look for life as we know it? Easy answer: in places like our own Earth What we need is water, carbon, oxygen, silicon, calcium, phosphorus and temperature condition not too extreme Caution: it took Earth 4.5 billion years to develop intelligent life We have been a “communication civilization for about 100 years Is this typical?


Can life form in other worlds? : Can life form in other worlds?


The Habitable Zone(only for life like ours) : The Habitable Zone (only for life like ours)


Potential candidates in the Solar System : Potential candidates in the Solar System


Atmospheric spectraonly Earth conducive to life : Atmospheric spectra only Earth conducive to life But Mars could have had life in the past


Mars Exploration : Mars Exploration


Looking for Martian fossils(none found) : Looking for Martian fossils (none found)


Martian Meteorites : Martian Meteorites


Is this evidence of life on Mars? : Is this evidence of life on Mars?


Life or mineral forms? : Life or mineral forms?


Mineral formation or fossile life? : Mineral formation or fossile life?


Cosmos (our own Galaxy, in fact) too big for travel : Cosmos (our own Galaxy, in fact) too big for travel Enormous problems of storage/production of energy Travel for small-size sip to nearest star at 1/3 c needs 40,000 times the whole yearly US energy production Full size exploration way longer than human life span. Need colonies: will we remain what we are after 100 years in space? Communication seems more doable SETI Arecibo message Voyager message


Radio telescopesRadio is best for distant communication (best of all: water hole) : Radio telescopes Radio is best for distant communication (best of all: water hole)


The Arecibo Telescope : The Arecibo Telescope


The Arecibo Message : The Arecibo Message Coded in binary numbers Numbers 1 to 10 Atomic numbers of H, C N, O and Ph Chemical formulas for sugars and proteins DNA molecular structure Number of units in DNA Height of human in wavelengths (12.3 cm) Human figure Population of Earth Solar system schematic Arecibo transmitting antenna (telescope) Diameter of telescope in wavelength


The Voyager Message : The Voyager Message


The message on the spacecraft : The message on the spacecraft


Drake Equation:The number of “cummunication capable” civilazations in out Galaxy : Drake Equation: The number of “cummunication capable” civilazations in out Galaxy NC = N* x fp x nLZ x fL x fI x FS N*: number of stars per galaxy, ~ 1011 fp: fraction of stars with planets, 0.01 to 0.5 nLZ: planets per star in life zone over 4 Gyr, 0.01 to 1 fL: fraction of suitable planets where life begins, 0.01 to 1 fI: faction of life forms that develop intelligence, 0.01 to 1 FS: fraction of star’s life with communicative intelligence, 10-8 to 10-4 2x10-5 < NC < 107


Drake Equation visualized : Drake Equation visualized