Astro 105: The Milky Way

Lecture XVII:
Life & The Universe
Are we Alone?

Cool Planet & SETI links


http://www.alienearths.org/index.php

 1 ,2

index.html

 

Sometimes I think we are alone. Sometimes I think we are not.

In either case the thought is staggering.

buckminster fuller

How common is life?

Are we an accident?, a one in a billion billion chance. Never repeated

Are we as common as dust?

How can we tell?

The Search for Extra-terrestrial Intelligence (SETI) is one of the grandest endeavors we have ever undertaken.

It may also be a complete waste of time?

How can we tell?

History of the Universe (Highlights)


 

Some highlights of cosmic history are noted along this arrow of time, from the beginning of the universe to the present. Noted along the top of the arrow are the major phases of cosmic evolution.

Notice how quickly life begins after Earth's Formation.

What does it take to make Life?

Life on earth is constructed from pretty basic building blocks.

Just a bunch of organic molecules called proteins and nucleic acids .

Proteins are made of amino acids, they are the structure of the organism.

Nucleic Acids are made of bases and are the information storage units.

Deoxyribonucleic Acid (DNA) - billion atom double helix molecule

Its DNA that is the self-replicating blueprint for life.

Thus life is formed from non-life.

How does this happen?

"The spark of life"

Experiments have been performed which try and recreate conditions on the young Earth.

The question is: did conditions exist which would allow for the synthesis of the complex molecules (amino acids etc) needed to make DNA?

Once the earth cooled after formation water (rain) condensed and collected in pools.

The Earth's early atmosphere contained little oxygen but a lot of organic molecules released by "out gassing" from volcanoes.

Organic Molecules may also have rained down on Earth from Comets and Asteroids.

Lightning was an abundant source of "free" energy.

When water, CO2 methane and ammonia are combined and electric spark is added a primordial soup of amino acids soon forms.
 

 

Chemical Apparatus for Synthesizing Biochemical Molecules -

This chemical apparatus is designed to synthesize complex biochemical molecules by energizing a mixture of simple chemicals. In the diagrammed procedure, the gases are placed in the upper bulb to simulate the primordial Earth atmosphere and then energized by spark-discharge electrodes. After about a week of recycling the gases through the lightning like electrical discharge, amino acids and other complex molecules can be found in the trap at the bottom, which simulates the primordial oceans into which heavy molecules would have fallen from the atmosphere.

Do you just have to wait long enough for this stuff to turn into DNA?

Important Point!

"Given so much time, the impossible becomes possible, the possible probable, and the probable virtually certain. One only has to wait. Time itself performs miracles."

buckminster fuller

 

Oxygen atmosphere gets added later.

It’s the byproduct of the first cells (prokaryotic).

Life creates the present atmosphere.

Without life the oxygen rich atmosphere we have would go away via chemical reactions.

Only later did O breathing cells (Eukaryotic) emerge.


 

A fossilized organism found in sediments radioactively dated as 2 billion years old. This primitive system possesses concentric spheres or walls connected by smaller spheroids. The roundish fossils here measure about a thousandth of a centimeter.
 

So perhaps Life is not so Uncommon?

Mars rock.

But here we are talking rudimentary forms of life.

What about Intelligence?

Some argue that intelligence is "selected for" in evolution.

Once life gets going natural selection in Evolutionary Theory makes it almost certain that intelligence will develop and thrive.

Others argue that intelligence has not yet proven to be such a hot evolutionary advantage.

Sharks are dumb and they have been around for hundreds of millions of years.

Evolution works by chance.

Random mutation leads, once in a million times, to superior adaptation.

For intelligence to form you need a million million chance events.

So it formed here. Why should it form elsewhere?

 

"Convergence hypothesis" - life developed eyes many time here, legs formed many times here.

Maybe there is a convergence of patterns that evolution "chooses" and intelligence is one of them.

It is interesting to note that the people who think evolution produces lots of cosmic intelligence are astronomers.

Evolutionary Biologists are the ones who are most skeptical of extra-terrestrial intelligence.

How Many Intelligent Civilizations Might There Be Out There?


The Drake Equation

Frank Drake was one of the pioneers SETI came up with an formulation of of the question "How many" that has proven to be quite useful.

WE want to know the number of intelligent civilizations, Nic, there are out there right now.

We can write the equation as

Nic = R*PpPeNePlP iLic

 

where

 

Note:

R*Pp PeNeare about physics and astronomy

PlPi are about biology and evolution

Lic is about "sociology"

Drake's equation is really just a way of quantifying our ignorance.

Let’s try some numbers (right out of a textbook)

 




Ecosphere = zone around a star in which life could form
(Water remains liquid)

Habitable Zones Around Stars - The extent of the habitable zone is much larger around a hot star than around a cool one. For a star like the Sun (a G-type star), the zone extends from about 0.85 A.U. to 2.0 A.U. For an F-type star, the range is 1.2 to 2.8 A.U. For a faint M-type star only planets orbiting between about 0.02 and 0.06 A.U. would be habitable.


 

Put it all together and you get

Nic = .5 L ic

So what is Lic ? We have been around in high tech mode for only 50 years and we may be on the edge of our own destruction.

Nic = 25

Perhaps we make it and live for another billion years

Nic = 5x10 8

Which is it?


 

 

Rare Earth Hypothesis

Simple Life is Easy to form and likely to exist in many places.
        Deep sea hydrothermal vents
        Deep underground rocks!

Complex Life (Animals) is difficult to form and maybe very very rare.
  Cambrian Explosion      (higher forms of life created in brief spurt 540-500 million years ago)
 Comet Crashes, Climate change can cause mass extinctions

Searching for Extraterrestrial Life

Before we talk about searching (receiving) what about sending

We have already sent intentional messages via radio

1974 Frank Drake beams a raster message towards the globular cluster M13.

In it was encoded a variety of information about us.


 

We have also sent out physical signals on the Pioneer and Voyager space probes each of which was designed to leave the solar system.

The Pioneer 10 Plaque -
A replica of a plaque mounted on board the Pioneer 10 spacecraft. The important features of the plaque include a scale drawing of the spacecraft, a man, and a woman; a diagram of the hydrogen atom undergoing a change in energy (top left); a starburst pattern representing various pulsars and the frequencies of their radio waves that can be used to estimate when the craft was launched (middle left); and a depiction of the solar system, showing that the spacecraft departed the third planet from the Sun and passed the fifth planet on its way into outer space (bottom). All the drawings have computer- (binary) coded markings from which actual sizes, distances, and times can be derived.

Voyager Space Craft and plaque

The sounds of Earth: a gold record attached to the voyager

spacecraft. "Hello" in many languages. Mozart, Chuck Berry etc.

 

Is All of This a Good Idea?

Will we be Sorry for Letting Anyone know We are Here?

We are also letting the Universe know we are here in an unintentional way.

Everyday we beam out radio/TV signals that would allow ETs to learn a great deal about us.

In fact this radio garbage may be the best way to look for other civilizations.
 

Earth Map Showing Manmade Radio "Hot Spots" - Radio radiation now leaks from Earth into space because of the daily activities of our technological civilization. Most of the radiation arises from FM radio stations and television transmitters (shown here as dots), most of them found in western Europe and North America.
 

Radio Station Broadcast Geometry - These stations broadcast their energy parallel to the Earth's surface, so they produce the strongest signal in any given direction when they happen to lie on Earth's horizon, as seen from that direction.
 


 

Daily Variation In Radio Signal "Leak" - The pattern resulting from the sum of all the Earth's television stations, as viewed from a distant star. Earth's radio brightness rises and falls as radio transmitters concentrated on certain parts of the surface rise and set due to our planet's rotation.

OK but what about actually searching for ETs

You want to look for signals which are definitely linked to intelligence.

Where to look?

How do look?

You have to use what you got (EM radiation)

Not UV or optical or X-rays - why?

Use radio (long wavelengths)

What if "they" use Z-rays or something we don't know about?

Then you are Out O Luck

But you have to start somewhere.
 
 

Q) What channels do you search? Every wavelength/frequency may contain a signal.

A) As many as possible. Be smart and guess which one's might be best.

The 21 cm line (Cosmic Watering Hole)

 

Q) Which stars do you search?

A) As many as possible. Also concentrate on the nearest 1000 solar type stars.

Q) How do you know when you have a signal?

A) Hard to know. It has to look different. It has to be something that nature could not create.

easy to be fooled: Spectral Lines, Pulsars

The WOW signal.

Very suspicious, never "heard" again.

Q) Who does SETI

A) Some pretty dedicated people. Its a career killer.

Jill Tartar has been the driving force of SETI
for many years.

 

NASA approved big project.

Build multi-channel receiver, all sky survey.

Congress kills it.

Using private funds the project goes on


Is SETI worth the money?

So what if we find it?

What will it mean  

 

And, finally, your place in it all....

  
    What is our responsibility to life?
  What is our responsibility to the Universe?


   We are endowed with the power to think and question?  


   What do we use it for?

 

 

Reality and Responsibility:

  
Given this gift of intelligence perhaps the real goal is to… 

WAKE UP!

Pursue pleasure and gain your whole life but...how much life do you get?

             

  Great is the matter of Birth and Death
Life slips quickly by
Time waits for no one
wake up, wake up

Zen Saying

Astronomy and Physics teach us to see the world through new eyes everyday.  

Use that to see others' suffering and do something about.
Use that to see the beauty and benevolence all around you.

Wake Up, Wake Up!

FIND OUT WHAT IS REAL.