1. The Fermi Paradox “So where is everyone?”

2. Enrico Fermi 1901-1954

3. The Fermi Paradox The belief that the universe contains many technologically advanced civilizations, combined with our lack of observational evidence to support that view, is inconsistent. Either this assumption is incorrect (and technologically advanced intelligent life is much rarer than we believe), our current observations are incomplete (and we simply have not detected them yet), or our search methodologies are flawed (we are not searching for the correct indicators).

4. Logic … We are not special in our development (life on Earth) Thus via the Drake Equation, life should be relatively common in the Milky Way. Even traveling at slow speeds, colonization should have lead to outposts everywhere by now. (Milky Way is 10 billion years old.)

5. Even worse … Von Neuman machines Build self replicating machines and let them explore the galaxy. In this way, while colonization is not performed, the presence of civilizations would be felt everywhere in the galaxy. Probes are not encumbered by the physical limitations of life (air, water, aging etc.). Relatively easy to produce.

6. An aside … Von Neuman machines might consume all the resources in a galaxy! (They could develop exponentially.) If so, any civilization capable of producing these machines would not!

7. The contradiction Colonization should have occurred No evidence of such rampant colonization

8. Solution #1 We are the first technologically advanced civilization capable of interstellar travel and communication. If so, SETI is a waste of time … no one out there to talk to. This solution sounds much like the Geocentric Model of the Solar System … Earth special (unique, rare) and does not seem likely. Nothing in astronomy or biology suggests we are special.

9. Cosmic Calendar (inspired by Carl Sagan) Imagine the age of the universe (and thus life on Earth) compressed to 1 calendar year. January to November inclusive. Each month is 1 billion years, each second is 390 years. AugustMarchNovember

10. To note … Many generations of stars have formed since the Milky Way developed in February. The Sun and Earth formed in August and by September, life had appeared on Earth.

11. December ….

12. To note … The dinosaurs existed from December 25 through 30! The entire human history is less than 30 seconds long (~10,000 years)! Planets capable of harboring life in our galaxy could have formed in July! Almost any assumptions you make result in a conclusion that civilizations have had ample time to form and develop and colonize

13. Comparable age and development? Perhaps a more useful question to ask is ‘Are other civilizations technologically comparable to us?’ We have had space travel and interstellar communication capability a short time. How long will we keep it? More likely other civilizations very advanced or very inferior technologically speaking.

14. Colonization Like the Von Neuman machines, interstellar colonization would result in the relatively rapid spread of settlements throughout the Milky Way galaxy. The coral model. Note that colonization does not represent a solution to the population explosion on a planet (like Earth).

15. Human Population Humanity is experiencing an exponentially growing population which is, arguably, unsustainable. Approximately 100 million people born annually.

16. Why colonize? Assuming the attitudes associated with life on Earth are not unique, then our history is resplendent in voyagers of exploration and colonization Other civilizations may colonize to avoid their culture becoming extinct (existing on more than one planet). Perhaps colonization is spurred on by the need to flee persecution, etc.

17. Other solutions to the Fermi Paradox: Solution #2 Civilizations common but have not colonized the galaxy. –TECHNICALLY TOO DIFICULT (OR TOO EXPENSIVE IN TIME AND ENERGY) – THE DESIRE TO COLONIZE IS NOT COMMON (WE ARE ATYPICAL) –DESTRUCTION OF THE CIVILIZATION OCCURS BY THEMSELVES OR THROUGH NATURAL CAUSES (ASTEROIDS, ETC.)

18. Other solutions to the Fermi Paradox: Solution #3 There is a galactic civilization out there and they have chosen to keep us isolated (Star Trek’s Prime Directive). Thus there is no paradox! Sometimes called the Zoo hypothesis … but we may still yet detect their signals even if they choose not to communicate with us. Time likely needed for SETI to succeed.

19. Other solutions to the Fermi Paradox: Solution #3 cont. The Sentinel hypothesis suggests that galactic civilizations are indeed monitoring us, waiting for us to reach the right level of technology … allowing us to join the Galactic Club.

20. Too expensive? It often comes down to money … ‘It is fine o argue about the number of civilizations that may exist. After the argument, there is no easy substitute for a real search out there … we owe the issue more than mere theorizing.’ … Philip Morrison Answering the Fermi Paradox will arguable be a turning point in our history.