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Chapter 8Self-reproducing computer programs

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Enrico Fermi, 1901-1954

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“The Pope”

fermium

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The Fermi Paradox

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Where are they?

lead to a lunch-time questionfrom Fermi:

A morning discussion aboutextra-terrestrial life…

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The Fermi Paradox…

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300,000 l-y300300,000 l-y

Milky Way

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The Fermi Paradox…•Our sun is a typical star• Billions of stars are billions of years older than the sun• Plenty of time for advanced cultures to explore the Milky Way

5Where are they?

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The Fermi Paradox…

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Where are they?

We don’t know

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John von Neumann, 1903-1957

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“the faste

st mind

I ever met”

“the cle

verest man I

ever knew, w

ithout

exception”

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John von Neumann, 1903-1957…• member of the Hungarian Phenomenon• the Martians of the Manhattan Project• von Neumann• Szilard• von Karman• Wigner• Teller

• strongly anti-communist 8

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John von Neumann, 1903-1957…• interested in self-replicating machines•von Neumann Universal Constructor

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von Neumann probesself-replicating probes

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von Neumann probes…current state of the art: 3D printing

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Artificial life

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Jewish folklore

Most famously,16th century Prague

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Artificial life…

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1770

Wolfgang von Kempelen

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Artificial life…

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Artificial life (A-Life)

Very contentious topic

Two general forms•Strong A-Life•Weak A-Life

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A-Life…Strong:

"life is a process which can be abstracted away from any particular medium“ (JvN)

Computer programs are not simulating life but are synthesizing itIn some sense it defines away the distinction 16

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A-Life…Weak:

Impossible to create life outside of a chemical medium.

Simulations useful to investigate underlying processes of biological life

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A-Life…

Some objections (Mitchell)•Autonomy•Metabolism•Self-replication•Survival drive•Evolution 18

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A-Life…Scale differences•biological processes have evolved into systems of daunting complexity• interactions at the scale of

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A-Life…Scale differences…•computational processes are currently scale limited to about• interactions

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A-Life…

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an adult hermaphrodite C. elegans worm

www.openworm.org

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Self-replication, DNA, interpreters, etc

Book draws attention to the fact that program self-replication does not include the interpreter, whereas DNA does.

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Computer replication,evolution and

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TheSingularity

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Aside: the Institute for Advanced Study

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Aside: the IAS computer…

25“revenge of the sn

obs”

“no experimental science”