The Science of Life in the Universe

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Chapter 2 The Science of Life in the Universe
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Walter Alvarez (1997) T. rex and the Crater of
Doom. Princeton University Press, 185 pp.
the Cretaceous held no place for us. We
are the beneficiaries of Armageddon.
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Estimated number of Earth-crossing asteroids
larger than a given diameter Data from NASA
International Near-Earth-Object Detection
Workshop (1992) The Spaceguard Survey
(JPL/CIT)
log10(number of asteroids)
log10(diameter, km)
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Impact frequency with Earth by Solar System
debris as a function of diameter (meters) Data
from Dr. Eugene Shoemaker (USGS), and published
in Alvarez (1987) Physics Today, 40 (7),
p. 24-33.
Time to impact with Earth (years)
Diameter (meters)
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Mars
S
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S. Weinberg (1999) A Designer Universe?
The New York Review (Oct. 21 issue), p.
46-48.
You dont have to invoke a benevolent designer
to explain why we are in one of the parts of the
universe where life is possible in other parts
of the universe there is
no one to raise the question.
S. Weinberg (2001) Can science explain
everything? Anything? The New York Times Review
of Books.
earth is one of a vast number of planets,
whose distances from their stars is largely a
matter of chance, a planet that by chance
condensed too close or too far from its star
would not be the home of philosophers.
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iClicker question
The planets in our Solar System are known to
orbit the Sun. (A) TRUE (B) FALSE
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iClicker question
Based on current information, what object in our
Solar System, besides the Earth, may have a deep
ocean? (A) MARS (B) TITAN (C) EUROPA
(D) NONE of these choices
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iClicker question
What is your guess-timate of the number of
civilizations currently in our galaxy? (A) 1
(B) 10s (C) 100s (D) 1000s (E)
gt10,000
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iClicker question
What is your guess-timate of the number of
civilizations currently in our galaxy that are
both technologically capable and intellectually
interested in communicating? (A) 1 (B) 10s
(C) 100s (D) 1000s (E) gt10,000
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Stonehenge
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Interpretation of retrograde loop by the Ptolemy
model
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Ellipse
a
b
Keplers First Law
Eccentricity (a2 b2) / a2
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Keplers Second Law
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iClicker question
Earth is closer to the Sun in January than in
July. Therefore, in accord with Keplers 2nd Law
(A) Earth moves at a higher orbital speed in
July than in January (B) Earth moves at a
higher orbital speed in January than in July
(C) Since Earths orbit is circular with an
eccentricity of zero, the original statement is
false.
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P2 a a3
Keplers Third Law
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Keplers Third Law
P2 (4p2/GM)a3 where P orbital period
(seconds) G gravitational constant
G 6.673 x 10-11 m3 kg-1
sec-2 M mass (kg) of central object a
semi-major axis of orbiting object
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P2 (4p2/GM)a3
The red line for our Solar System is a general
result. Consequently all planets orbiting all
stars should plot along the same line.
(A) TRUE (B) FALSE
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P2 (4p2/GM)a3
Planets orbiting stars having greater masses than
the Sun will plot below the red line shown in the
graph above for our Solar System.
(A) TRUE (B) FALSE
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P2 (4p2/GM)a3
Planets orbiting stars having lower masses than
the Sun will plot below the red line shown in the
graph above for our Solar System.
(A) TRUE (B) FALSE
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Example of Keplers Third Law
P2 (4p2/GM)a3
Estimate the mass of
the Sun using the Earths orbit. The semi-major
axis of the Earths orbit 1.495 x 108 km. The
orbital period of the Earth 365.25 days.
M (4p2/GP2)a3
Convert kilometers to meters and days to seconds
a 1.495 x 1011 meters P 3.156 x 107
seconds
Mass of Sun 1.985 x 1030 kg
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P2 (4p2/GM)a3
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P2 (4p2/GM)a3
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slope (4p2/GM) M (4p2/G)/slope M (5.9161 x
1011 m-3 kg sec2) / slope
Slope of 55 Cancri system 3.2452 x 10-19 m-3
sec2 Slope of Solar System 2.9736 x 10-19 m-3
sec2
Mass (Sun) 1.989 x 1030 kg Mass (55 Cancri)
1.823 x 1030 kg
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Satellites in geosynchronous orbit
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Apollo 17 landing site on eastern edge of Mare
Serenitatis
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P. R. Gross and N. Levitt (1994) Higher
superstition The Academic Left and its Quarrels
with Science. The Johns Hopkins Univ. Press,
314 pp.
Science is, above all else, a reality-driven
enterprise. Every active investigator is
inescapably aware of this. It creates the pain
as well as the delight of research. Science
succeeds precisely because it has accepted a
bargain in which even the boldest imagination
stands hostage to reality.
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Science is
specialized, pragmatic, expansive, expensive,
descriptive, approximate, imaginative, skeptical,
reductionist, and
meaningless.
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(1564 1642)
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Sister Maria Celeste (Virginia Galilei),
Convent of San Matteo
(1600 - 1634)
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Phases of the planet Venus
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Sunspots
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Galileo stands accused by the Inquisition in 1633
for heresy. Dialogue on the two chief world
systems Ptolemaic and Copernican
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Portion of Galileos recantation from June 22,
1633
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The Age of Enlightenment (Modernism)

• Major philosophers Bacon, Descartes, Locke,
  Newton, Rousseau, Spinoza, Voltaire
• Skeptical of tradition
• Confidence in human reason and science
• Convinced of the order and harmony of Nature
• Repudiated superstition
• Diminished fear of the Devil, and of God
• God viewed as the Great Watchmaker of the
  Universe, rather than as a vengeful deity

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The Age of Enlightenment (Modernism)

• The State should become the principal instrument
  for progress through education, political
  reforms, and creation of an enlightened
  environment
• Increase in religious toleration and secularism
• Wide-spread belief in the general similarity
  of all human-beings
• Philosophy of Natural Law and Natural Right

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The Declaration of Independence The unanimous
Declaration
of the 13 United States of America
on July 4, 1776 When in the course of human
events, it becomes necessary for one people to
dissolve the political bonds which have connected
them with another, and to assume among the powers
of the earth, the separate and equal station to
which the Laws of Nature and of Natures God
entitle them, a decent respect to the opinions of
mankind requires that they should declare the
causes which impel them to the separation.
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The Declaration of Independence The unanimous
Declaration
of the 13 United States of America on July 4,
1776
We hold these truths to be self-evident, that
all men are created equal, that they are endowed
by their Creator with certain unalienable Rights,
that among them are Life, Liberty, and the
pursuit of Happiness.
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S. Weinberg (1999) A Designer Universe?
The New York Review (Oct. 21 issue), p. 46-48.
As Richard Feynman has said, when you look at
the universe and understand its laws, the theory
that it is all arranged as a stage for God to
watch mans struggle for good and evil seems
inadequate.
M42 in Orion
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C. Raymo (2001) In search of Universes point.
The Boston Globe.
The biggest problem in the world today is not
that the Universe might not have a point, but
that
too many people think they know what the point
is.
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Perhaps

• We should seek Mystery, Meaning, and Order in
  this unfathomably wondrous setting,

• and do so with a humility and modesty born of
  a wisdom that has been hard
  won.

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Alan Boss (2009) for NASA Decadal Survey