Transcript Explorations of the Universe

Explorations of the Universe
One Voice in the Cosmic Fugue
What’s a Fugue?
• From a Latin word for “flight”
• From the same root as the word “fugitive”
• Variations on a theme are played on top of
one another, creates an aural impression of
rapid flight
• No true fugues anywhere in the episode!
Artistic Conventions and Science
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Anthropomorphism
Accelerating Events
Picturing the invisible
Bringing the past to life
Restoring Lost Details
What if?
DNA
• Deoxyribonucleic acid
• Total length of human DNA in a single cell
is about a meter
• A human body contains about 20 trillion
cells
• The total length of DNA in a human body is
thus 20 trillion meters, or twenty billion
kilometers, the circumference of the orbit of
Pluto.
"Evolution is a Fact, Not a
Theory - It Really Happened"
• Here's Sagan at his in-your-face best.
• Why is Evolution a Hot-Button Issue?
– Science versus other modes of Knowledge
– Ideological Abuses of Science
– Dualistic nature of Western Culture (Fact vs.
Fiction)
“Of course, long before you mature,
most of you will be eaten.”
“The picture’s
pretty bleak,
gentlemen. The
earth’s climate is
changing, the
mammals are
taking over, and
we all have
brains the size of
a walnut.”
“Now this
end is called
the
thagomizer,
after the late
Thag
Simmons.”
“Evolution’s been good to you, Sid.”
The Cosmic Calendar
• Human History = 5000 years
• Dinosaurs = 150,000,000 years
• Dinosaurs had:
– 30,000 years for every year of human history
– 80 years for every day
– 8 hours for every second
Prebiotic Evolution
• The basic molecules of organic chemistry
are easily made
• The first self-replicating molecule was
almost certainly not DNA
• DNA assembles from simpler materials all
the time
Plants and Animals
• CO2 + H2O + Energy = Sugars, Starches,
etc. + O2 (toxic waste) - “The sky is made
by life”
• O2 is actually toxic (even to us!)
• Idea: Take the sugars and starches (from
somebody else) combine it with the waste
O2, and get energy
Amazing Events in Life History
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“Invention of Sex” - Who Needs It?
We are a team - Mitochondria
The Great Freeze 900-600 m.y. ago
Mass Extinctions
– Dinosaurs = 4th worst
– Permian extinction (220 m.y. ago) took out
90% of all species
Randomness, Order and
Evolution
• Are the following letter sequences random:
crvn, smrt, vrlo, gdje, trg?
• In Serbo-Croatian, the words mean,
respectively, red, death, very, where and
town square.
• Moral: the fact that something looks
random doesn't mean it is. It may convey
meaning in a way you don't understand.
Randomness, Order and Evolution
• Is the following number sequence random:
592653589793238462643383279?
• It not only looks random: it is random.
• But lacking in meaning? No. These are the
digits of pi beginning with the fourth
decimal place.
• Random does not mean “meaningless”
The Scientific Meaning of Random
• Something cannot be predicted with better
accuracy than that predicted by statistics.
• It takes as much information or effort to
describe an event fully as it does simply to
produce the event itself. The event is its
own simplest description
Randomness and Evolution
• Biological systems are far too complex to
describe or predict mathematically
• We have incomplete information,
• Significant events like climate change or
asteroid impact are unpredictable.
Randomness and History
• Mongols in Europe, 1242
– In three months, the Mongols wiped out military
opposition in the Balkans
– Ordered to turn back to select a new Khan
– Mongols never returned
• Gallipoli, February 1915
– Object: force passage to the Black Sea and Russia
– Intense artillery forced British fleet to retreat
– Turks had 5 minutes’ ammunition left
Can Order Arise Naturally?
• The Second Law of Thermodynamics is often
paraphrased as:
– ”Things always go from bad to worse”
– ”Disorder in the Universe is always increasing"
• The core of the Second Law is entropy
• Entropy can decrease locally if it increases
elsewhere
• Intuitive notions of disorder are of no relevance
whatsoever
Chemical Reactions are not
Random
Na Cl Na Cl Na Cl Na Cl Na Cl Na
Cl Na Cl Na Cl Na Cl Na Cl Na Cl
Na Cl Na Cl Na Cl Na Cl Na Cl Na
Cl Na Cl Na Cl Na Cl Na Cl Na Cl
Na Cl Na Cl Na Cl Na Cl Na Cl Na
Cl Na Cl Na Cl Na Cl Na Cl Na Cl
Na Cl Na Cl Na Cl Na Cl Na Cl Na
Cl Na Cl Na Cl Cl Na Cl Na Cl Cl
The Geologic Record
• Physical evidence records mostly smallscale, gradual processes
• Fossils show a gradual increase in
complexity with time
• Fossil forms intermediate between major
groups are well documented
• Over most of its history, life on Earth was
simple
Selection
• Deliberate selection for desirable traits by
humans (only since ca. 1700)
• Unsystematic selection for desirable traits
by humans (domesticated animals and
plants)
• Unconscious and unintentional selection by
humans (self-domestication of animals)
• Natural selection with no human
intervention at all
Lessons from Selection
• Artificial selection has produced organisms
radically different from their natural state
• Natural selection has resulted in dramatic
changes in natural populations with and
without human intervention
• Microorganisms and viruses change with
dazzling speed (mutation of flu viruses,
resistance to antibiotics)
This Descended from Wolves?
Prelude to Evolution
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Biology
Linnaeus
Selective Breeding
Lamarck
• 1825
• Voyage of Beagle
• 1850 • Mendel - genes
• Origin of Species
Geology
Hutton
LyellUniformitarianism
Geologic Column
Linnaeus
• Classification of Organisms
• Kingdom-Phylum-Class-Order-FamilyGenus-Species
• Included Man and Apes in the Primates
• Encountered little opposition
• System was viewed as descriptive only
• Static, hierarchical, meshed with social
prejudices of the day
Classification of Dogs and Humans
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Kingdom
Animalia
Phylum
Chordata
Class
Mammalia
Order Carnivora (Dogs) Primates (Humans)
Family Canidae
Hominidae
Genus Canis
Homo
Species familiaris
sapiens
The Five Kingdom System
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Animals
Plants
Protista (one-celled organisms)
Fungi
Bacteria*
Ediacaran Fossils? (ca. 700 m.y. ago)
What’s Bigger Than a Kingdom?
• Bacteria differ from all other kingdoms in
lacking a cell nucleus
• We need a bigger box
• Superkingdoms or Domains
– Monera (Bacteria)
– Archaea
– Eukarya (have cell nucleus)
• Need electron microscopes and molecular
biology to see differences
Prelude to Evolution
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• 1750 •
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Biology
Linnaeus
Selective Breeding
Lamarck
• 1825
• Voyage of Beagle
• 1850 • Mendel - genes
• Origin of Species
Geology
Hutton
LyellUniformitarianism
Geologic Column
Jean Lamarck, 1795
• Animals change in response to their
environment
• Changes passed to offspring
• Example: the Giraffe
• First modern theory of evolution
• Wrong, but contributed the idea that the
environment shapes organisms
Prelude to Evolution
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• 1750 •
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• 1800 •
Biology
Linnaeus
Selective Breeding
Lamarck
• 1825
• Voyage of Beagle
• 1850 • Mendel - genes
• Origin of Species
Geology
Hutton
LyellUniformitarianism
Geologic Column
Why was Darwin on the Beagle?
• British Navy SOP: ship’s surgeon (Dr.
McKenzie) is the expedition naturalist
• Rigid rules against fraternization
• Depression ran in Captain Fitzroy’s family
• Solution: hire an extra civilian naturalist
• Real job: social peer and gentleman
companion to the captain
• Problem: Darwin and Fitzroy were ideological
opposites
Evolution By Natural Selection
• Charles Darwin and Alfred Russell Wallace,
1859
• Organisms are adapted to their environments
• Individuals vary
• More organisms are born than can possibly
survive
• Variations best suited to the environment
tend to survive and be passed on.
Why the Furor over Evolution?
• Pieces had been falling into place for over
100 years
• All the main tenets of Natural Selection
were well known
• Seemed Cruel
• Seemed purposeless (“random”)
• Conflicts with Religion
• Sexual Connotations
• Ideological Abuses
Sexual Connotations
• This was the Victorian era, and you can’t
discuss evolution without reproduction
• For an allegedly prudish era, they produced
a lot of undraped art and figureexaggerating fashions
• They weren’t so much prudish as mindnumbingly sentimental
How
Sentimental
Were the
Victorians?
Conflicts with Religion
• Death and the Fall
– Traditional: Death due to Adam’s fall
– Darwin: Death is intrinsic part of life
– So where does Christianity fit?
• Could a merciful God design Natural
Selection?
– The Paradox of Predestination
– Does predation have any moral dimension?
• How to Interpret the Bible?
– Literal versus metaphorical and allegorical
Ideological Abuses
• Evolution Disproves Christianity
– Atheism vs. Fundamentalism
• Evolution Negates Purpose in Life
– Nihilism vs. Religious and Marxist Schools
• Evolution = “Survival of the Fittest”
– Social Darwinism vs. Religious and Marxist
Schools
• Racist Applications
“Evolution Disproves Christianity”
• Where did all these atheists come from?
• They were there all along, but keeping a
low profile (compare resurgence of racism
in recent years)
• Moral: suppression is always more
dangerous to the suppressor
• Two final words: Soviet Union
The Five Fundamentals (1910)
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Literal Inerrancy of the Bible
Virgin Birth and Divinity of Christ
Atonement for sin at the Crucifixion
Resurrection of Christ
Second Coming
How Fundamentalists See It
The Scopes Trial, 1926
• Intended as a deliberate test of Tennessee’s
anti-evolution law
• Clarence Darrow (defense) vs. William
Jennings Bryan (prosecution)
• Climax came when Darrow grilled Bryan
on the stand
• Inherit the Wind, based on the trial, is good
drama but very inaccurate history
The Biggest Single
Misconception About Religion
• Many scientists consciously avoid saying
“science believes”
• Draw distinction between subjective beliefs
and documented evidence
• PROBLEM: EVERY RELIGION
REGARDS ITS DOCTRINES AS
PROVEN FACTS
Lysenko (USSR 1930’s)
• Rejected Darwin because of social darwinist
abuses of evolution, “purposelessness”
• Reverted to Lamarckian theories
• Likened struggle for existence to Marxist
class struggle
• Was close friend of Josef Stalin
• Effectively shut down Soviet biology 19301945
Racism and
Evolution
(Ernst
Haeckel,
1874)