1445 Introductory Astronomy I

1
1445 Introductory Astronomy I

• Chapter 0a
• The Scientific Method
• R. S. Rubins
  Fall, 2008

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A Word from Albert Einstein

• The most beautiful thing we can experience is
  the mysterious.
• It is the source of all true art and all
  science.
• He to whom this emotion is a stranger,
• who can no longer pause to wonder and stand
  rapt in awe,
• is as good as dead his eyes are closed.
• 
  Albert Einstein (1879 1955)

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The Scientific Method (simplified)

• The scientific method is a continuous process of
  observation, hypothesis or theory, prediction and
  then further observation and experiment.

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Intelligent Design Statement

• Evolution is just a theory, not the truth.
• What is a scientific theory?
• Does the truth exist in science?
• The word theory, as used above, actually means
  the scientific word hypothesis, which is just
  an educated guess, made to explain an observation
  or group of observations.
• Scientists are engaged in refining the theories
  that best explain the observed phenomena. The
  facts may change in the light of improved
  observation, so that in science one can never
  claim that the truth is known.

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Scientific Theories 1

• The development of scientific theories is based
  on the belief that there is an underlying order
  to the Universe, the essence of which may be
  grasped by the human mind.
• A scientific theory is a model which explains a
  portion of the Universe, using a small set of
  general rules or equations, and a minimum number
  of arbitrary assumptions.
• Between competing theories, the one with the
  fewest arbitrary assumptions is usually
  preferred. This philosophical choice is known
  as Occams razor , named after William of Occam
  (1285-1349).

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Scientific Theories 2

• A scientific theory must make testable
  predictions about the results of future
  observations.
• All scientific theories are provisional, in the
  sense that they can never be proved to be
  absolutely true.
• A theory is disproved if even a single
  observation disagrees with its predictions.
  However, any such observation must be confirmed
  independently.
• Often, a new theory is just a modification of the
  older one, but on rare occasions, it has
  revolutionized our understanding of the
  universe.

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Scientific Theories 3

• Its results must be both repeatable and
  verifiable.
• It is based on models, often mathematical, which
  must be tested by new observations.
• Science is understood to be an unfinished
  business, and scientists are aware that even
  well-established theories may turn out to be
  incomplete or limited in range of application.
• Science is universal, and scientists come from
  all races and religions.
• ____
• Scientific progress is not a democratic
  procedure. It is not advanced by majority vote,
  even among leading scientists.

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Science and Pseudoscience 1

• Unlike the doctrines of pseudoscience, scientific
  theories are not belief systems, so that trust or
  faith in an idea is not part of the scientific
  method.
• While scientific theories must make testable
  predictions about the results of future
  observations, the ideas of pseudoscience, which
  are based on supernatural hypotheses, cannot be
  tested objectively.
• A strength of science is its fluidity, which
  keeps it open to the adoption of new ideas as our
  knowledge grows.
• Pseudoscience, usually based on a rigid doctrine,
  tends to resist change.

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Science and Pseudoscience 2

• From astrophysical observations, the age of our
  universe has been found to be about 14 billion
  years old.
• Geological and physical data show that the age of
  the solar system is about 4½ billion years.
• A vast amount of geological and biological data
  indicate that the evolutionary history of
  primates on the Earth goes back about ten million
  years, while fossil skulls indicate identifiable
  humans have existed for about 100,000 years.
• There are no observational data supporting a
  world that has existed for a much shorter time.

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The Scientific Method

• The attraction of the scientific method goes
  beyond its enormous power and scope, however.
  There is also its uncompromising honesty. Every
  new discovery, every theory is required to pass
  rigorous tests of approval by the scientific
  community before it is accepted.
• Paul Davies, in The Mind of God, 1992

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Nature of Physics 1

• It is the search for order in the Universe at all
  levels, from the smallest sub-atomic particles to
  the largest distributions of galaxies.
• It is a study of matter, energy, motion, space
  and time, based on experimental observations.
• Its aim is to explain the complexity of all
  measurable phenomena in terms of the smallest
  number of fundamental laws.
• Mathematics is the language of physics.

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Nature of Physics 2

• Physics is an experimental science, based on
  theories that are ultimately tested by
  quantitative observations.
• All quantitative measurements are subject to
  experimental error, so that facts may change as
  the precision of a measurement is increased.
• Physicists speak of the beauty and elegance of
  great theories, but only experiment and
  observation allows us to decide whether a theory
  should be retained, modified or discarded.

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Major Physical Theories

• Eighteenth century
• Newtons Laws of Motion and Gravitation.
• Nineteenth century
• Maxwells Equations of Electricity and
  Magnetism.
• Thermodynamics and Statistical Physics.
• Twentieth century
• Special and General Relativity.
• Quantum Mechanics and Quantum Field Theory.
• Twenty first century
• Quantum gravity ?

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The Twin Revolutions of The 20th Century

• By the late nineteenth century, the Laws of
  Nature were thought to be understood.
• What is now known as classical physics was
  destroyed by the twin revolutions of relativity
  and quantum mechanics (QM).
• Special Relativity showed that universe is
  4-dimensional, with space and time inextricably
  linked. General relativity, Einsteins greatest
  achievement, describes gravity in terms of the
  curvature of space-time near matter.
• The fundamental concept of causality is lost in
  QM, where many results can be given only as
  probabilities, defying our common sense. Most
  of the amazing technological developments of the
  present age are consequences of QM.

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Some Cosmological Thoughts

• The laws of physics are assumed to be the same
  everywhere in the universe, including the values
  of the universal constants, such as the speed of
  light c, the charge on the electron e, Plancks
  constant h, and the gravitational constant G.
• Our place in the universe is not special our
  star (the Sun) is unexceptional, and nothing sets
  our galaxy (the Milky Way) apart from other
  galaxies.
• We and our planet are made of star-dust, and
  together form a microscopic part of the visible
  universe.
• The evolution of life on the Earth is just a tiny
  part of the evolution of the universe.

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Science and Religion 2

• His (the scientists) religious feeling takes
  the form of a rapturous amazement at the harmony
  of natural law, which reveals an intelligence of
  such superiority that, compared with it, all the
  systematic thinking and acting of human beings is
  an utterly insignificant reflection.
• This feeling is the guiding principle of his
  life and work It is beyond question closely
  akin to that which has possessed the religious
  geniuses of all ages.
• Albert Einstein, 1934

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Science and Religion 3

• I cannot believe that our existence in this
  universe is a mere quirk of fate, an accident of
  history, an incidental blip in the great cosmic
  drama. Our involvement is too intimate.
• We, who are children of the universe animated
  stardust can nevertheless reflect on the nature
  of that same universe, even to the extent of
  glimpsing the rules on which it runs.
• Through conscious beings the universe has
  developed self-awareness. This can be no
  trivial detail.We are truly meant to be here.
• Paul Davies, in The Mind of God, 1992

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On Science 1

• The characteristics of natureare determined
  always by the material with which we work, by
  nature herself.
• We look and we see what we find, and we cannot
  say ahead of time successfully what it is going
  to look like. The most reasonable possibilities
  often turn out not to be the situation.
• . it is necessary for the very existence of
  science that minds exist which do not allow that
  nature must satisfy some preconceived
  conditions
• Richard Feynman, in the The Character of
  Physical Law, 1965.

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On Science 2

• If science is to progress, what we need is the
  ability to experiment, honesty in reporting
  results and finally an important thing the
  intelligence to interpret the results.
• An important point about this intelligence is
  that it should not be sure ahead of time (of)
  what must be. It can be prejudiced...
  Prejudice is different from absolute certainty.
  I do not mean absolute prejudice just bias.
• Richard Feynman, in the The Character of
  Physical Law, 1965.