Life in the UniversePhilosophy and Science

BRENT SILBYUnlimited (UPT)

Evolution of Life elsewhere

How likely is it the emergence of life?So far we know of only one planet with life - Earth

Is the emergence of life a one off cosmic accident? Or is it acertainty given the right conditions?

Scientists are looking for life elsewhere in the universe in twoways:1 Sending robotic probes to Mars

2 SETI

Evolution of Life elsewhere

Viking missions to Mars in 1970s

These probes had a limited laboratory, which tested the soil onMars.

Evolution of Life elsewhere

Robot arm scooped soil into the portable laboratory

Evolution of Life elsewhere

The probes were equipped with a gas chromatograph-mass spectrometer, and 3 other experiments

The gas chromatograph-mass spectrometer tested for organiccompounds in the soil--a sign of life, while the other experimentstested for metabolic activity--another sign of life

All experiments came back negative

Evolution of Life elsewhere

The rovers “Spirit” and “Opportunity” that have been on Mars since the early 2000s were not designed to test for life.

They have determined that the planet once had flowing water,which would make it suitable for the type of life we know.

Robot “Phoenix” landed in the Martian north pole in 2008. It isdesigned to test for life frozen in the perma-frost.

Photo from Spirit’s camera

Robotic explorers on Mars

Martian landscape takenby Curiosity shortly afterit arrived in 2012

Evolution of Life elsewhere

Philosophically, what would it mean if the probe discovers evidenceof life (either present or past)?

1 It would shift our egocentric view of our own importance

Earth ain’t so special

2 It would show us that emergence of life is more commonthan we once thought

3 The fact that Mars is now life-less has implications for theway we think about the future of life on Earth

Ecosystems are fragile… The continuation of life is not guaranteed

Evolution of Life elsewhere

Another way to look for life elsewhere in the universe is theSETI project

Search for Extraterrestrial Intelligence

Can’t go to other star systems, but we can listen for signals

Evolution of Life elsewhere

Probably won’t detect a signal purposely sent to us, but we might detect their internal communications

We have been leaking signals out to space for the last 100 years,so any species that lives within a radius of 100 light years fromus will be just starting to hear us

If they are listening…

Evolution of Life elsewhere

Galaxy is 100,000 light years across, so our signals have traveled0.1% distance across the galaxy

Intelligence of similar age to us on other side of galaxy wouldhave reached similar distance.

Evolution of Life elsewhere

Maybe an ancient civilization discovered radio communication100,000 years ago.

If they lived on other side of the galaxy, we will just be starting to hear their first broadcasts.

If we decided to direct a response to them, they wouldn’t receive itfor 100,000 years. There will be no 2-way conversation witha species that distant.

They may be extinct before our signal reaches them

Evolution of Life elsewhere

SETI researches hope to find a species that is much closer

What is the probability of an intelligent species close enough for a 2-way conversation?

The Drake Equation

Frank Drake proposed a formula to calculate the probability ofextraterrestrial life.

N=R*fpneflfifcL

The Drake Equation

N=R*fpneflfifcLN - The number of civilizations in the galaxy able and willing to

engage in interstellar communication

R* - The rate of star formation in the galaxy (# new stars per year)

fp - The fraction of stars with planets

ne - The fraction of habitable planets in an average system

fl - The fraction of habitable planets on which any form of lifearises (microbes, mollusks, etc.)

fi - The fraction of inhabited planets on which life evolves into“intelligent” beings

fc - The fraction of alien societies that develop the technologicalability to communicate with outside planetary systems, andthe desire to do so

L - The average lifespan of a technologically advanced civilization(that is, how long a typical civilization survives before it becomesextinct or self-destructs)

10

0.52

1

0.01

0.01

10000

The Drake Equation

N = 10 × 0.5 × 2 × 1 × 0.01 × 0.01 × 10000 = 10

Only 10 technological civilizations in the Milky Way Galaxy

What if the average lifespan of a technological civilization turnsout to be lower?

Perhaps only 200 years…

N is then only 0.2, which would mean intelligent life is very rare !

Even if we found nearby life, could we communicate with them?

Through history we have had incredible problems communicatingacross cultures within our own species.

Could we ever have meaningful communication with a speciesthat does not have anything in common with us?

Plaque on one of the Voyager space probes

Plaque on the Pioneer deep space probewould an extraterrestrial species understand this? Do you?

This is what it means

Representation of the hyperfine transition of hydrogen.Why hydrogen? It is the most common element in the universe.

The small vertical line represents binary digit 1.

The spin/flip transition of the atom from electron statespin up to spin down can specify a unit of length (wavelength 21cm).

This also specifies a unit of time. Both units are used as measurementsin other symbols.

Hand raised, shows opposable thumb.Also a goodwill gesture, sure to bemisunderstood.

Height of woman shown between thetwo lines. There is a binary figure there(difficult to make out)It is binary number 8 (1000). In unitsof wavelengths (8*21cm) =168 cm

Relative position to sun. 14 of these lines correspond to the periods of pulsars usingthe hydrogen flip transition frequency of the unit. These periods change over time sothe epoch of the launch can be calculated. The lengths of lines show the relativedistances from the pulsars to the sun.The 15th line extends behind the woman and gives relative distance of sun to center ofgalaxy.

Map of solar system

Bit numbers above the planets indicate their relative distance tothe sun.

Interestingly, one of the hardest things for an extraterrestrial tounderstand here would be the arrow showing the direction ofPioneer. Why? Any thoughts?

Arrows are an artifact of human hunter-gatherer societies. Finderswith different cultural history will find the arrow meaningless.

Importance of the search

Answering the question about intelligent life elsewhere isimportant to us

If we discover intelligent life, then it gives us hope for long termsurvival

It would show that it is possible for intelligent life to survive

If we do not discover intelligent life in the universe, it could mean that intelligence is not an adaptation with long term survival viability

Importance of the search

Intelligence is nothing more than an evolutionary experiment, justlike teeth or fur.

There is no guarantee that it will survive long-term.

Evolution selects traits that provide an adaptive advantage.

Intelligence was adaptive when it first emerged, butperhaps it is now mal-adaptive.

Intelligence gives us the ability to alter the Earth for our shortterm survival needs. Long-term is not an issue for us.

Closing thought

Consider cancer cells

They are excellent reproducers, reproducing fast and effectively

However, they eventually bring about the death of the organismwithin which they live.

Is it possible that intelligence suffers from a similar problem?

We reproduce without end and extend our lives, consumingeverything in our path until eventually there will be nothing left toconsume.

Earth will no longer be suitable to sustain us and we will die out.

What does this mean? Should we continue on this path orchange our ways?

Watch Carl Sagan clip Anthropocentrism

Powerpoint by BRENT SILBY

Produced at UPTChristchurch, New Zealand

www.unlimited.school.nz