Test 1 results

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Test 1 results
Mean 82 Median 87
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Polar circles
At winter solstice
90o L 23.5o 0, - L 66.5o
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Real life complications
The axial tilt angle is not constant, but has a
complex motion determined by many cycles of short
to very long periods. Due to nutation the tilt
oscillates over 9" (about 280 m on the surface)
over a period of 18.6 years. The main long-term
cycle has a period of 41000 years and an
amplitude of about 0.68, or 76 km on the
surface. Currently the tilt is decreasing by
about 0.47" per year, so the Arctic Circle is
moving north by about 15 m per year.
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Precession
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Astrology
Ecliptic and Zodiac
Sun travels 360o/365.25 days 1o/day
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(No Transcript)
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History of Astrology

• Originated by Babylonians about 1000 BC (mundane
  astrology, i.e. applies to the world)
  
• Greeks developed natal (birth) astrology
  (codified by Ptolemy in Tetrabiblos, 2nd century
  AD)

Argues that a person's character and destiny can
be understood from the positions of the Sun,
Moon, and planets at the moment of his or her
birth.
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Astrology big business

• 10,000 practicing astrologers
• 1000 full-time professionals
• 20 astrological journals
• 10 new books a week
• 1000 newspapers with astrological forecasts
• 5 million people spend 200 M per year
  consulting astrologers

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Horoscope

• Natal chart uses astronomical information and
  date and location of birth
  
• Planets, Moon, Sun in signs of zodiac
• Interpretation step positions of celestial
  bodies are used to predict a persons character
  and destiny

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Does it work?

• No evidence that it does
• Lots of evidence that it doesnt

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Math Corner

• How do we decide if a test is statistically
  significant?
  
• Coin tossing experiment (flip a coin 20 times and
  count how many heads show up)

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Statistically Significant

• If N hits expected, deviations of sqrt(N) from
  the expected value
  
• Example flipping a coin
• 18 flips 9 plus or minus 3 (33 error)
• 20,000 flips 10,000 plus or minus 100 (1
  error)
  
• If someone claims that he can predict the
  outcome and his predictions are within sqrt(N) of
  the mean value, he is a liar.
  

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Example (Gauquelin)

• 15,560 successful individuals in 10 professions
• No statistically significant relation between Sun
  sign and profession
  
• Gave a free horoscope evaluation to anyone who
  wanted it
  
• 95 said they recognized themselves
• but it was the horoscope of Frances worst mass
  murderer

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Example - Silverman

• 2978 marriages and 478 divorces in Michigan
• No correlations between astrological signs and
  statistics of marriages/divorces found

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Example - McGervey

• Birth dates and biographies of 6000 politicians
  and 17000 scientists
  
• Found the astrological signs for both group to be
  distributed completely at random

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Astrology conclusion

• No predictive power
• No scientific basis
• Broad psychological appeal
• Cheap, easy, and entertaining
• May help some people (as do many forms of
  empathetic counseling)
  
• Useless or damaging in other cases

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Pseudoscience Why bother?

• Many people view science as just another belief
  system
  
• Poor understanding about the difference between
  science and pseudoscience
  
• Widespread ignorance of what constitutes
  evidence
  
• Ideological doctrines (religious, political etc.)
  obstructed the progress in science and culture
  many times in history Inquisition, Nazi Germany,
  Communist Russia etc.

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How to recognize pseudoscience?
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Goals

• Science The primary goal of science is to
  achieve a more complete and more unified
  understanding of the physical world.
  
• Pseudosciences are more likely to be driven by
  ideological, cultural, or commercial goals.

Some examples astrology (from ancient Babylonian
culture,) UFO-ology (popular culture and mistrust
of government), Creation Science (attempt to
justify Biblical interpretation)
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Predictive?

• science Must be (falsifiability). Workers in
  the field commonly seek out counterexamples or
  findings that appear to be inconsistent with
  accepted theories.
• pseudoscience No. A challenge to accepted dogma
  is often considered a hostile act if not heresy,
  and leads to bitter disputes or even schisms.

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Role of evidence?

• science independently verifiable, no
  contradictions allowed. Each principle must be
  tested in the crucible of experience and remains
  subject to being questioned or rejected at any
  time.
• pseudoscience anecdotal, not independently
  verifiable. Observations or data that are not
  consistent with established beliefs tend to be
  ignored or actively suppressed.

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Innovation?

• science can incorporate new evidence models
  change old ideas are built upon, modified where
  necessary
  
• pseudoscience relatively rigid and authoritarian
  since it is not based on empirical evidence. The
  field has evolved very little since it was first
  established. The small amount of research and
  experimentation that is carried out is generally
  done more to justify the belief than to extend
  it.

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Authority?

• science no special experts recognized.
  Scientific ideas and concepts must stand or fall
  on their own merits, based on existing knowledge
  and on evidence.
• pseudoscience often based on ancient authority
  high priests and priestesses

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Appeals to our needs and desires?

• science may or may not
• pseudoscience yes