The beginnings of
belief in
extraterrestrial intelligence
Can you think of
any early example?
Many religions!
For example:
God is intelligent
...and everywhere
"Everywhere"
must include
interstellar space
A tale of two Well(e)s
Novel written in 1898 by H.G. Wells
Here are some
more interesting covers
It inspired an
Orson Welles radio show
The show was broadcast
Halloween, 1938
What happened?
Intelligent Martians was a widespread concept
1800s:
Percival Lowell and the canals
Numerous novels
See
"Imagining Mars: a Literary History"
(by R. Crossley)
1900s:
1912: Edgar Rice Burroughs
"A Princess of Mars"
The princess had
beautiful green (of course!) hair
..and so on
2000s:
2012: Story back in the news again
Why?
Let's move to more technical approaches
Fermi Paradox
(Enrico Fermi
was a
renowned physicist)
Italian-born American physicist (1901-1953)
Awarded Nobel prize 1938
Considered a father of the atomic bomb
Died of cancer
(possibly due to radiation exposure)
His "paradox":
Over 100 billion stars
in our galaxy,
the Milky Way
Roughly (very)
there are
100 billion
to 1 trillion
galaxies
What fraction have planets?
What fraction have
Earth-like planets?
These are called
"Earth analogs"
1.4 - 2.7%
Do pictures exist
of a few of them?
So why no sign of intelligent life?
(Er, except here)
That's the "Fermi Paradox"!
So....
1) Why no sign of intelligent life?
. . . and . . .
2) Will that change?
Fish supposedly live in the ocean
If you fill a cup at the beach...
...where are the fish?
Drake Equation
N=R x fp x ne x fl x fi x fc x L
N: # advanced civilizations
in Milky Way with which
we could communicate
R: new stars formed per year
fp: fraction of stars with planets
ne: Suitable planets per star with planets
fl: Fraction of suitable planets that do develop life
fi: Fraction of those planets that develop intelligence
fc: Fraction of intelligent civilizations that are detectable
L: Length of time civilizations are detectable
N=R x fp x ne x fl x fi x fc x L
Suppose R is 10/year
Let's estimate the others ourselves!
Note: estimate of 100 billion Earth-like planets in Milky Way as of 2013
Then what is N?
Why no little green men (or whatever)?
Crop circles, UFOs, what other evidence?
How could we
communicate with
extraterrestrial beings?
Possible problem:
we can't communicate with dolphins
(for example)
and they're
right here on Earth!
How to find extraterrestrial life
(Intelligent or otherwise)
Find planets
How to do that?
Find oxygen
Why so important?
Detect radio waves, etc.
Discovering Earth-like planets
Zero extra-solar planets
were known when
you were born
They are being discovered
(at an increasing rate)
First ones were huge and hot
We are getting better
at finding more
Earth-like ones
Here are three:
Gliese 667 Cc
Gliese:
from "Gliese Catalog of Nearby Stars"
Gliese 667:
A triple star
all of them small
Gliese 667 C:
Star C of Gliese 667
37% of Sun's mass
42% of Sun's radius
1.4% of Sun's brightness
Should last a lot longer than the Sun!
Gliese 667 Cc
2nd planet of Gliese 667
3.9x mass of Earth
Orbits Gliese 667 every 4 Earth weeks
Imagine what the year is like
Its star would be
2.3x as wide in the sky
as the Sun
...but dimmer per unit area
...reddish, since cooler than Sun
...temperature should allow liquid water
...do photos exist?
...well artists' impressions do
...let's check!
...only 22.1 light-years away
(oops)
Gliese 581:
Red dwarf star
Might not exist
But it might!
Gliese 581 g is a planet
Roughly 4x Earth mass
Tidally locked to star
That is a problem (why?)
A thick atmosphere could solve the problem
What would it be like there?
Gliese 370 b
Another interesting planet
wikipedia, etc., has artist's impression
Also called HD 85512 b
(we use nicknames, so why not?)
At least 3x Earth mass
Gravity 1.4x Earth (at least)
What would that feel like?
May have liquid water
Temperature depends on
various unknowns
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