THE SCIENTIFIC METHOD

1. Observe (use your senses or augmentations of them:
microscope, telescope) -- The sky is blue.

2. Hypothesize (come up with a possible explanation of the observation)

  • Someone has painted it blue.
  • Blue light is more easily scattered than red so the blue
    sky is scattered sunlight.

    3. Test HYPOTHESIS through a PREDICTION

  • If the latter is true, then if sunlight passes through more of the atmosphere,
    the sun should lose green and yellow light too.

    4a. perform EXPERIMENT

    4b. OR make new OBSERVATION

  • The sun is indeed red/orange near dawn and dusk.

  • If in agreement, perform new test (and keep doing so)
  • If in disagreement, discard or modify hypothesis

    Only if MANY tests are passed can a HYPOTHESIS
    be called a THEORY.

    If the THEORY applies in a wide range of situations, it may be raised to the status of a LAW
    (e.g. Newton's LAW of Gravity)

    STILL, even a LAW can be wrong (or only partly right)
    Einstein showed that Newton's Laws don't hold exactly if velocities are close to
    the speed of light or if lots of mass is concentrated in a small volume.

    SO NOTHING IN A TRUE SCIENCE IS EVER ABSOLUTELY PROVEN TRUE,
    though most of what is discovered and tested in a
    "hard" science is VERY LIKELY to be correct.

    Categorize: astronomy, biology, chemistry, geology,
    medicine, meteorology, oceanography, physics as
    OBSERVATIONAL or EXPERIMENTAL sciences.

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    But the preceding is idealized.

    In reality, even good scientists often don't discard hypotheses when they fail
    an experimental or observational test.

    Why not?

  • A. Experiment is wrong.
  • B. Experiment is misinterpreted.
  • C. Psychological/sociological/political difficulty in giving up long-held beliefs.
    Eventually the weight of evidence becomes overwhelming and there is a
    PARADIGM SHIFT or SCIENTIFIC REVOLUTION.

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    The above are characteristics of ANY SCIENCE.

    The key point: scientific results are falsifiable.
    If they cannot eventually be tested, they fall outside the realm of science
    and enter philosophy, religion, etc.

    Pseudo-sciences (astrology, alchemy, numerology, palmistry, crystal/pyramid power etc.)
    do not allow themselves to be tested and ``believers'' hold to
    them even in the face of strong counterexamples.

    What about: anthropology, history, political science, psychology, sociology?

  • These social or "soft" sciences rely to one extent or another on
    scientific methods, but also invaraibly carry a great deal of preconceptions that allow for
    many disparate interpretations to be drawn from the same data.
  • While in the natural or "hard" sciences, the range of interpretations is
    usually much less.

    Aside from this OBSERVATIONAL ---EXPERIMENTAL dichotomy, since the
    advent of calculus many sciences have distinguished these
    approaches from THEORETICAL science, driven by applied mathematics.

    ASTRONOMY IS AN OBSERVATIONAL SCIENCE.

    ASTROPHYSICS IS AN EXPERIMENTAL/THEORETICAL/OBSERVATIONAL SCIENCE.

    Today we typically use these terms interchangeably since so much of
    what we learn combines observations with theory and some experimental work.

    Modern science has a third, (nearly) equal aspect: COMPUTATIONAL.

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  • SEE APPENDIX 1 of Chaisson and McMillan for a review of SCIENTIFIC NOTATION

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    Read Chapter 1 before the next lecture.