Search for Life: SETI by Robert Nemiroff Michigan Technological University.

Search for Life: SETI 

byRobert Nemiroff

Michigan Technological University

Physics X: About This Course

• Officially "Extraordinary Concepts in Physics"• Being taught for credit at Michigan Tech

o Light on math, heavy on concepts o Anyone anywhere is welcome

• No textbook requiredo Wikipedia, web links, and lectures onlyo Find all the lectures with Google at:

"Starship Asterisk" then "Physics X"  o http://bb.nightskylive.net/o asterisk/viewforum.php?f=39

The Drake Equation:• N = R* x fp x ne x fl x fi x fc x L

• N is the number of civilizations in our Galaxies that are contactable 

• R* is the rate of star formation• fp is the fraction of stars that have planets• ne is the number of habitable planets per above star• fl is the fraction of above planets that develop life• fi is the fraction of above life planets that develop intelligent life• fc is the fraction of intelligent life planets that are contactable• L is the expected lifespan of such a intelligent life civilization

The Drake Equation

• Possible plausible values:o R*=10 stars/year; fp=0.5; ne=2o fl=1; fi=0.01; fc=0.01; o L=10,000 years

• Then N~10• Where are they?  

The Fermi Paradox

If life is abundant in the Universe• where are they?• why don't they communicate?

Question made famous by Enrico Fermi in 1950• over lunch

The Fermi Paradox

Possible solutions: •  Human civilization is unique

o chanceo theology

•  High tech civilizations destroy themselves•  High tech civilizations destroy each other

o when two civilizations meet, one always militarily superior•  The Universe is naturally dangerous

o ask the dinosaurs

The Fermi Paradox

Possible solutions:

•  High tech civilizations choose to remain quieto self-preservationo Star-Trek like prime directive (zoo hypothesis)o energy efficient (like Cable TV)

• We can't understand their communicationso they are too alieno we don't know how to searcho signals look to us like noise

Fermi Paradox:  von Neumann probes

• Self-replicating spacecraft that travel the universe.• Make the Fermi paradox less restricted.• Might absorb large fraction of rocky planets.• Astrochicken: Might be part biological  • RJN ponderable: vN probe = DNA ?

Radio, The Big Ear, And The Wow! SignalCredit and Copyright: Rick Scott

APOD: 1998 September 17

The Very Large Array of Radio TelescopesCredit: Dave Finley, AUI, NRAO, NSF APOD: 2006 May 14

A Big Dish at the VLA Radio ObservatoryCredit & Copyright: Victor Bobbett APOD: 2006 November 29

Arecibo: The Largest TelescopeCredit: NAIC, Cornell U., NSF APOD: 1998 November 29

How to Search for AliensCredit: SETI@home, UC Berkeley SETI Team

APOD: 1999 May 17

An Anomalous SETI SignalCredit & Copyright: SETI League 2004 March 7

The Voyagers' Message in a BottleCredit: Voyager Project, JPL, NASA

APOD: 2002 August 31

A Message From EarthCredit: Frank Drake (UCSC) et al., Arecibo Observatory (Cornell, NAIC)

2005 March 13

A Cosmic Call to Nearby StarsCredit & Copyright: Yuvan Dutil & Stephane Dumas 2006 April 2

M13: The Great Globular Cluster in HerculesCredit & Copyright: Eddie Guscott APOD: 2004 May 11