Are we alone

1
Are we alone?

• The big questions
• Are there minds elsewhere in the universe?
• If so, would we recognize them?

2
The Drake Equation

• Is there life in our galaxy?
• Stars 100 billion (1011)
• Most stars have many planets.
• So lets estimate that there are (1011) planets.
• Planets suitable for sustaining life need a
  solvent.
• Lets estimate that there (1010) such planets.

3
Drake Equation Continued

• To sustain life, stars need to be within the life
  zone of a planet.
• Conservative estimate 1 in a 100. So there are
  108 such planets.
• Planets with a suitably sized star 108
• Conclusion There are 108 or 10 million candidate
  planets.

4
Intelligent Life?

• Natural intelligence requires life and
  evolutionary development over time.
• Stars have been pumping out energy for 10 billion
  years.
• The earth/sun system has been around for only 4.5
  billion years.
• Estimate 106 planets have produced intelligent
  life.

5
Intelligence is scattered

• Our galaxy has a volume of 1014 cubic light
  years.
• So the average distance between planets is 500
  light years.
• Development of life may not be simultaneous.
• Intelligence may manifest itself differently on
  each planet where it exists. (contrast Minsky)

6
A opposing view

• Ward and Brownlee (in Rare Earth) agree that life
  may indeed be widespread in the universe.
• The conditions for the evolution of complex
  life-forms however, may not be widespread.
• We may be a fortunate accident The conditions
  which enabled complex life to form on Earth may
  be rare indeed.

7
Minskys Thesis

• When first we meet those aliens in outer space,
  will we and they be able to converse? I'll try
  to show that, yes, we will -- provided they are
  motivated to cooperate -- because we'll both
  think similar ways.

8
Minskys Proof

• I'll propose two reasons why aliens will think
  like us, in spite of different origins. All
  problem-solvers, intelligent or not, are subject
  to the same ultimate constraints -- limitations
  on space, time, and materials. In order for
  animals to evolve powerful ways to deal with such
  constraints, they must have ways to represent the
  situations they face, and they must have
  processes for manipulating those
  representations.

9
Radical Translation

• If there are intelligent aliens, theyll speak a
  language.
• Our task will be to translate the language.
• That task is aided by the constraints any
  language is subject to.

10
Economics

• Any alien that has cognition will use symbols
• Symbols are needed for the economical development
  of representations.
• Symbols can be economically created, modified and
  reused.

11
Sparseness

• Any intelligent alien will have something like
  arithmetic
• Arithmetic cant be different than our arithmetic
  though the symbols could be different.

12
Other Conceptual Necessities

• Concept of an object
• Cause/effect reasoning
• Reliable communication
• Concept of Self