Scientific Principles and Nature of Science Lecture Notes Outline by jamesdauray

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									      Science: Matter, Energy, and Life




Intuition leads to the flat Earth society and bloodletting; experiments lead men to the moon and microsurgery.
        - Seth Mnookin
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       SCIENCE AS A WAY OF KNOWING
•   Science assumes that the world is knowable.
•   Science seeks to…
       - Search for testable evidence.

       - Form hypotheses and theories.

           Hypothesis: Prediction based on prior
            knowledge and observation.
           Theory: Broad explanation based on
            many experiments and high amounts
            of data.
       - Find additional evidence to strengthen or
         disprove current theories.                  2
    SCIENCE AS A WAY OF KNOWING CONT’D

•    Scientists never work alone; they always
     collaborate as part of the process.
       They check each other for errors.

       Divide up a problem and work on it in

        groups.




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                 Pseudoscience

•   Appears or claims to be science, but does
    not follow scientific principles.
•   Examples…..




                                                4
The Earth is Flat




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Geocentric Solar System




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Spontaneous Generation




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Alchemy




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                              y2k!
•   Many computers only used two digits to store the date, so
    when the new year hit, they would revert to 1900 instead of
    2000.

•   Fears: Computers controlling power grids, nuclear reactors,
    weapons, would fail.

•   Reality:
      Japan had a nuclear power plant false alarm go off.

      Australia had two bus station ticket machines shut down.

      150 slot machines in Delaware shut down.

      The clock on the U.S. Navy’s website had the incorrect

       date.
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                  Doomsday: 2012

•   The Mayan Calendar ends on December 21,
    2012.
•   A huge sunspot or sunflare will cause a polar
    reversal, causing the Earth to spin in the
    opposite direction.
      Earthquakes, tidal waves, volcanic

       eruptions will follow.



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                Scientific Design

•   Reproducibility
     Experiments must be designed and

      recorded such that they can be exactly
      reproduced by other researchers.
•   Controlled Studies
     Comparisons are made between

      experimental and control populations.



                                               11
                      Scientific Fraud
•   There are many examples of published studies or report that
    have been later found incorrect, misleading, or fraudulent.
•   These are always detected, eventually due to the scientific
    method and peer review.
      The net effect is loss of time, resources, and public

       mistrust.
•   Significant recent examples:
      MMR Vaccine / Autism study

      Speed of Himalayan glacier melting

      Human stem cell cloning study




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Scientific Method




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                    Scientific Method

•   Observation
     Information gathered by sight, sound,

      smell, or touch.
       -   Example: Mussels are disappearing from a
           nearby river, which is being polluted.




                                                      17
                      Scientific Method

•   Hypothesis
     A testable explanation for an observation.

       - A hypothesis can be proven wrong, but

         never proven true.
       -   Ex: Fertilizer from a nearby golf course is
           washing into the river and killing the mussels.
•   Prediction
     What will happen if the hypothesis is correct?

       -   Ex: Mussels will die when exposed to the
           fertilizer.
                                                             18
                      Scientific Method
•   Experiment
       Test hypothesis under controlled
        conditions.
       Variable: Factor of interest that is
        being tested.
         - Ex: Fertilizer pollution

       Experimental Group: Receives the
        variable
         - Ex: Exposed mussels

       Control Group: Does not receive
        the variable
         - Ex: Mussels in clean water          19
                Scientific Method
•   Data Analysis
     Organize data from

      experiment into graphs
      or tables.
•   Conclusion
     Compare the results

      with the hypothesis.
•   Communication
     Results are published

      and reviewed by others
      to check for errors.          20
        Modeling and Natural Experiments

•   Modeling - Simulating the phenomenon
    under study in a laboratory.
      Pro: More control over experiment

      Con: All variables must be understood.

•   Natural – Conduct study in the field under
    normal circumstances.
      Pro: Provides a more accurate

       environment
      Con: More difficult to study


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      Case Study: John Snow and Cholera

•   London in 1854 was suffering
    from a severe cholera
    outbreak.
      Symptoms: Diarrhea,

       vomiting, paralysis, death.
•   John Snow did interviews
    and mapped the locations of
    the disease.


                                          22
Cholera in London




                    23
        Other Factors Affecting Experiments
•   Probability
      An attempt to measure and predict the likelihood of an

       event.
        - Flip a coin, probability of tails?

        - Probability of tails twice in a row?

•   Sample Size
      The number of observations used in an experiment or

       study.
        - Higher sample size = lower margin of error

•   Bias
      Do the researchers have something to gain if the

       experiment yields certain results?
                                                                24
        Combating Bias: Scientific Design

•   Blind Experiment
     Conducted so the experimental subjects

      do not know which is the control and which
      is the experimental group.
        - Eliminate the “placebo effect”

•   Double-Blind
     Neither the subject nor the investigators

      know which participants are receiving an
      experimental treatment.
     Minimizes risk of bias.
                                                   25
    PRINCIPLES OF MATTER AND ENERGY

•   Matter - Has mass and takes up space.
      Three phases

        - Solid

        - Liquid

        - Gas

•   Law of Conservation of Matter
      Under normal conditions, matter cannot be

       created or destroyed.
        - There is no away.

                                                   26
                       Energy

•   Energy - The capacity to do work.
      Kinetic Energy

        - Energy contained in moving objects.

      Potential Energy

        - Stored, latent energy available for use.

•   Heat - Energy that can be transferred
    between objects of different temperature.



                                                     27
                Thermodynamics

•   First Law
     Energy is neither created nor destroyed,

      but can be transferred or transformed.
       - All energy sources are finite.

•   Second Law
     With each energy transfer or

      transformation, some energy is lost as
      waste.
       - No process is 100% efficient.


                                                 28
         Second Law of Thermodynamics


                                                                  Mechanical
                                              Chemical              energy
 Solar             Chemical energy             energy              (moving,
energy             (photosynthesis)
                                               (food)              thinking,
                                                                    living)

           Waste                      Waste              Waste                 Waste
           heat                       heat               heat                  heat




                                                                 Fig. 2-11, p. 32
           BUILDING BLOCKS OF LIFE

•   Atom - Smallest particle that exhibits the
    characteristics of an element.
      Protons - Positively charged.

      Electrons - Negatively charged.

      Neutrons - Neutral.




                                                 30
Carbon-12 Atom




                 31
      BUILDING BLOCKS OF LIFE CONT’D

•   Molecule
     Two or more atoms chemically bonded

      together.
       - Can be an element (like O2)

       - Can be a compound (like CO2)

•   Compound
     A molecule that contains more than one

      type of atom.

                                               32
Common Molecules




                   33
                Acids and Bases

•   Acids are compounds that release hydrogen
    ions (H+) in water.
•   Bases are substances that release hydroxide
    ions (OH-) in solution.
•   Strength of acids/bases is measured by
    concentration of H+.
      pH scale

        - 0-14




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