Science and How It Works

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Science and How It Works

• Physics 270 Experimental Physics

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The Scientific Method
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Science as a Collection of Facts
Fact 1
Fact 2
Fact 3

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Real Science

• One possible definition activities aimed at
  understanding the natural world
• Scientists have shared values and perspectives
  that characterize a scientific approach to
  understanding nature a demand for naturalistic
  explanations supported by empirical evidence that
  are testable against the natural world.
• Other shared elements include observations,
  rational argument, inference, skepticism, peer
  review and reproducibility of work.

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Physics is many things

• Observations of phenomena
• Experiments
• Empirical formulas
• Models
• Laws / Theory

Lets do some experiments!
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Approaching Problems

• Develop multiple approaches since you arent sure
  which one will work.

Start
Goal
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This is not a pipe

• Painting by Rene Magritte

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In science results are presented using
precise (though technical) arguments,

• with
• testable consequences
• falsifiability
• reproducibility

Experimental Verification And Reproducibility
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Truth in science
Descriptions of some aspect of nature in terms
of a model. Any view of the natural world that a
scientist devises is just a model loaded with
assumptions and approximations of that world.
Models, in general, have limited applicability.
As data and technology improve, models are
replaced by others which explain a larger range
of phenomena.
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Theories Knowledge

• Theory the best available description of nature
  as close to truth as we get.
• Theories are validated by experiments.
• There is no truth-meter in science.
• Experiments expose the limitations or
  incorrectness of theories.
• Something may only be known if it is proven to be
  true.
• Beliefs may be true or false.
• Rationality is the best test of truth.
• Our senses can easily be fooled!

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Reductionism versus Wholism
Reduction Reduce a complicated problem into its
constituents and aims to understand that complex
problem through the study of its
components Wholism a phenomena must be viewed
as a whole in order to understand its structure
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Reductionist Example The Structure of
Proteins Proteins consist of amino acids. These
are assembled into ribosomes. The order of
assembly is determined by RNA after it is copied
from DNA. DNA consists of 4 units called
nucleotides. The structure of proteins is very
complicated, but here the problem has been
reduced to the assemblage of simpler building
blocks.
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Holistic Example An ant hill Complex physical,
chemical, and biological structure built and
sustained by millions of ants. Cannot be
understood by braking the ants into tiny
parts. Its essence is in the complexity of the
whole.
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Deduction versus Induction

• Deduction logical development of the
  consequences of an explanation
• starts with theoretical model
• ? testable prediction
• ? observations under specific conditions
• ? confirmation or rejection of the prediction
  and/or the model

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Example The Discovery of the Neutrino

• Enrico Fermi proposed the existence of the
  neutrino in 1930 because the observed decay
  products from beta decay seemed to violate mass
  and energy conservation.
• In 1956, Cowen and co-workers detected its
  existence.

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Deduction versus Induction
Induction generalization of observed
patterns starts with observations ?observed
patterns ?development of model ?testable
predictions ?competition of models ?theory
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Example Cause of Cholera

• John Snow in 1854 observed that patients who had
  contracted cholera had been drinking water from a
  particular pump in London.
• He suspected that the cholera was spread by
  contaminated water.
• Led to Louis Pasteurs formulation of germ theory
  in 1857.
• Bacteria and viruses were later confirmed by
  direct observation, establishing their connection
  to disease.

http//espanol.video.yahoo.com/watch/327162/214077
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Fallacies

• Circular Reasoning Begging the question
• Appeal to emotion
• Argument from authority
• Sweeping Generalization
• Irrelevant Conclusion
• Denying the antecedent

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Truth in Experimental Science

• For a given measureable parameter, there exists a
  true value of that parameter for a set of
  circumstances at a given time.
• We do not know what it is, nor do we have any
  independent means of knowing it.

Precision versus Accuracy
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Probabilistic versus Deterministic Models