Speaking with ETIs: we’re all ears

Michael L AllenHonors College Distinguished Lecture 2013

2013-04-22

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Speaking with ETIs:

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Thesis

Our first experience with alien life will be with a technologicalcivilization located at a great distance.

At a great distance, because the distances between stars are vast.

With a technological civilization, because the light-based (photonic)signature of technological activity will fill our Milky Way galaxy morequickly and more pervasively than any other signature.

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Distance

The distance to even the nearest star isover 300,000 times as great as the distanceto the nearest planets (Venus & Mars)

“Cross talk” can fill a planetary systemwith micro-organisms, but not a galaxy.

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Technology

Industry produces waste heat and light.

This light travels at the fastest speedpossible.

This light travels in all directions.

This light can fill the galaxy.

This light is emitted unintentionally.

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Signals from Earth: unintentional

Radio leakage comes from communications(radio, TV) and power transmission.

Our civilization is now detectable out toabout 100 light years in distance, or to thenearest few 1,000 star systems.

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Signals from Earth: unintentional

Our total power output over the lasthalf-century has increased by a factor ofover 10,000.

Note: our power output may decrease dueto better technology (satellites, digitization)

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Signals from Earth: intentional

The Arecibo message

The Evpatoria message

Both messages used the same basic theory: tosend a bit stream with an implied dimensionality.

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Intentional signals: basic theory

Sent as a series of radio pulses

Two-level (binary) system, like on/off, or left/right, or 1/0

Called a bit stream; analogous to Morse Code

Problem: a bit stream is one-dimensional, difficult to embedinformation

Solution: send a bit stream with an implied dimensionality higherthan 1

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Intentional signals: basic theory

Higher dimensionality is implied by thenumber of prime factors of the totalnumber of bits in the message.

Example: 0000001110010000111000000

This bit stream has 25 bits, and 25 = 5× 5.

Two prime factors implies a 2-dimensionalmessage, i.e., a picture.

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Intentional signals: basic theory

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Higher dimensionality is implied by thenumber of prime factors of the totalnumber of bits in the message.

Example: 0000001110010000111000000

This bit stream has 25 bits, and 25 = 5× 5.

Two prime factors implies a 2-dimensionalmessage, i.e., a picture.

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Intentional signals: basic theory

Higher dimensionality is implied by thenumber of prime factors of the totalnumber of bits in the message.

Example: 0000001110010000111000000

This bit stream has 25 bits, and 25 = 5× 5.

Two prime factors implies a 2-dimensionalmessage, i.e., a picture.

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Intentional signals: basic theory

Higher dimensionality is implied by thenumber of prime factors of the totalnumber of bits in the message.

Example: 0000001110010000111000000

This bit stream has 25 bits, and 25 = 5× 5.

Two prime factors implies a 2-dimensionalmessage, i.e., a picture.

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Intentional signals: basic theory

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Intentional signals: the Arecibo message

Sent as a steam of 1679 bits.

1679 = 73 × 23, implies a73-by-23 matrix image.

The image itself can bedivided into several parts.

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Intentional signals: the Arecibo message

1 Part I: a number system(Implication: mathematics is auniversal language)

2 Part II: some biochemistry

3 Part III: humans

4 Part IV: Earth in the solarsystem

5 Part V: the Arecibo radiotelescope

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Intentional signals: the Evpatoria message

Goal: easy readability.

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Intentional signals: the Evpatoria message

Goal: achieved?

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Receiving a signal:we have not thought through this very well

There exist protocols for announcing the discovery of a signal, and foropening a dialogue with ETIs.1

The sci-fi authors have not explored in detail contact-at-a-distancescenario.

To end: four books from the realm of speculative literature.

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Gregory Benford: Timescape

Will our first ETI encounter be with ourselves?

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Jack McDevitt: The Hercules Text

A flashing star prompts a follow-up investigationwith a radio telescope.

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Carl Sagan: Contact

“This has happened to me!”

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Stanislaw Lem: His Master’s Voice

The Manhattan Project meets Bletchley Park.

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In conclusion...

1 We are not ready to receive anintelligent alien signal.

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In conclusion...

1 We are not ready to receive anintelligent alien signal.

2 The Milky way galaxy is oursto explore.

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In conclusion...

1 We are not ready to receive anintelligent alien signal.

2 The Milky way galaxy is oursto explore.

3 Travel is difficult; the AppleCup will not be played on Marsat any time soon. But when itdoes,

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In conclusion...

1 We are not ready to receive anintelligent alien signal.

2 The Milky way galaxy is oursto explore.

3 Travel is difficult; the AppleCup will not be played on Marsat any time soon. But when itdoes,

4 Go Cougs!

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