Scientific method vs. hollow earth theory
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Scientific method vs. hollow earth theory


Shoot for the moon and if you miss you'll land among the stars...



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Scientific method vs. hollow earth theory Presentation Transcript

  • 1. PHY 156 – Spring 2009 I.3 – Nature of Science Science is the great antidote to the poison of … superstition. Adam Smith, The Wealth of Nations, 1776
      • Goals:
        • Define “science”: What are its essential properties?
        • Know how to apply science to get answers :
        • How does the process work?
        • Know the language of science
        • Why is it so confusing?
        • Distinguish science from non-science
  • 2. Doing Science
    • Hollow Earth Society: claims the Earth is a hollow ball and we are living inside it
    • Evidence:
      • Survey of Great Lakes around turn of 20 th century showed Earth’s surface as concave
      • The soles of your shoes curve up not down – you’re walking on the INSIDE surface!
    • How would you convince them?
  • 3. Which is more important in science: getting the correct answers, or the process of finding and testing answers?
      • The answers themselves
      • The process of finding and testing answers
  • 4. Science
    • A way of knowing – a process
    • Not just a collection of facts
    • “ Science is facts; just as houses are made of stones, so is science made of facts; but a pile of stones is not a house, and a collection of facts is not necessarily science”
    • Henri Poincar é
  • 5. Questioning your assumptions Is the sky blue on a clear day? How do you know? Did someone tell you? Did you see it for yourself? What if I told you it wasn’t? Do you BELIEVE the sky is blue or do you ACCEPT it as reality? J. Heafner:
  • 6. Observed Fact (A) or Inference (B)?
    • Observed Fact: in principle, anyone can verify it for himself/herself
    • (can be directly & repeatedly observed)
    • Inference: uses observed facts + assumptions / logic / math
    • The Moon’s angular size is 0.5 º
      • (The Moon spans an angle of 0.5 º on the sky)
    • The universe is nearly 14 billion years old
    • The Earth is 93 million miles from the Sun
  • 7.
    • Goes beyond patterns
    • Figuring out the “rulebook” for nature
    • Hallmark of Science: #1
    • Science seeks explanations for observed phenomena that rely solely on natural causes
    Explaining the Observations
  • 8. Science isn’t everything…
    • Even when we have a well-tested “rulebook”….
    • knowing the rules doesn’t tell us where they come from!
  • 9. Figuring out the Rules
    • Where Creativity Comes In: Coming up with the explanation
    • “ We especially need imagination in science. It is not all mathematics, nor all logic, but is somewhat beauty and poetry. “
    Maria Mitchell (1818 – 1889) Astronomer and first woman elected to American Academy of Arts & Sciences
    • How Science Keeps us Honest:
    • “ What distinguishes Science from other forms of learning is its emphasis on predicting and testing (experimentally) as a way of sorting out ideas which sound good, but are false, from ones which present a more accurate model of how the world actually works .”
          • Doug Duncan
  • 10. Science
    • “ Science is a way of trying not to fool yourself”
          • Richard Feynman
    • Science:
      • Latin scientia means knowledge
      • Today, knowledge that makes predictions that can be tested through rigorous observation and experiment
    • Hallmark of Science: #2
    • Scientific model must make testable predictions about natural phenomena.
      • If predictions don’t agree with observations, the model must be revised or abandoned
  • 11. Hallmarks 2) Testing against observations
    • Verifiable observations:
      • What counts as an observation that can be used to test predictions?
      • It’s acceptable if, in principle, (given appropriate training / equipment), you could conduct the test yourself
    • Eyewitness accounts?
  • 12.
    • Scientific Claims / Hypotheses
    • Must be a natural explanation
    • Must be backed up with evidence:
      • Must explain observed phenomena
      • Its predictions must agree with observations
    • Must be capable of being proven wrong
      • Must be testable!
    • Non-science: Any claim that does not meet these criteria (Hallmarks) is not scientific , regardless of whether it is ultimately true or false!
  • 13. Concept Check Is this a scientific claim? Lightning is caused by the god Zeus throwing bolts at the Earth; doing so whenever he is angry A) Yes B) No
  • 14.
    • Sanity Check! (Credit to Paul Hewitt)
    • Which of the following statements is a scientific claim?
    • Human beings will never set foot on the Moon.
    • ( B ) Some of the laws that govern Nature cannot be detected by scientists.
    • (C) It is possible that in some other galaxy the laws of physics are fundamentally different than the laws we are acquainted with in this galaxy.
    J. Heafner:
  • 15. Science or not?
    • Non-science:
      • That which is assumed to be unexplainable
        • All scientists search for explanations that are assumed to exist.
        • Science can’t be used to get an answer that doesn’t exist. Science has limitations!
      • If they hypothesis isn’t at risk, it isn’t science!
      • If the evidence doesn’t support it, it isn’t science!
  • 16.
    • Is Earth round?
    • Does Earth really spin?
    • Does Sun orbit Earth?
    • Is Earth’s rotational axis tilted?
    • Is Earth at the center of the Universe?
    • Do other planets orbit Earth?
    • Is there a supreme deity?
    • Does casual use of <5mW handheld green laser pointers ruin astrophotos?
    The Language of Science: Consider these questions... J. Heafner:
  • 17.
    • If you answered “yes” or “no” without
    • considering the scientific validity of the question,
    • considering HOW you know the answer,
    • or considering WHY you accept the answer,
    • then you’re operating under a “belief system” rather than under valid science.
    Language Continued J. Heafner:
  • 18.
    • Science and belief systems can peacefully coexist…
    • … AS LONG AS we understand that they have different, and not interchangeable, purposes.
    • It’s about:
        • Observed Facts
        • Inferences (observations + logic)
        • What natural explanation best fits the evidence ?
        • Continued testing of models
    J. Heafner:
  • 19.
    • Belief:
    • To you: has nothing to do with evidence
    • To scientists: “We believe” often equivalent to “evidence tells us”
      • Should say: “Evidence tells us that electrons behave this way.” rather than “We believe electrons work this way.”
    • Faith:
    • To you: unquestioning belief without evidence
    • Scientists sometimes say: “We have faith in our results” when they mean “We have confidence in our results”
    • Scientific results
    • NOT based on faith.
    • Based on evidence.
    • Who is to blame for muddled terminology?
    • Scientists! We’re terrible communicators!
    Consistent Terminology J. Heafner:
  • 20. What we should say…
    • Scientists have determined that…
    • Scientists have confidence in …
    • Scientists have concluded that …
    • Analysis of data suggests…
    • This evidence leads to the logical conclusion…
    • Observations of ___ support the idea of __
    • The weight of the physical evidence supports …
    • The best observational / experimental evidence indicates ….
    • So why don’t we?
  • 21. Clicker Question
    • Only one of the statements below uses the term theory in its correct, scientific sense. Which one?   
    • I have a new theory about the cause of earthquakes, and I plan to start testing it soon. 
    • Evolution is only a theory, so there's no reason to think it really happened. 
    • Einstein’s theory of relativity has been proven true
    • I wrote a theory that is 152 pages long.
    • Big Bang Theory has been tested and verified through repeated and varied observations
  • 22.
    • To you: “theory” connotes “uncertainty”
    • To me: “scientific theory of…” is equivalent to “body of knowledge known as…” (e.g. relativity), and means it is well-tested and accepted!
      • Example: Big Bang Theory
      • Theory of Relativity
    Consistent Terminology J. Heafner:
  • 23. Jargon Alert!
    • You’ll know when I use an astronomical term you don’t understand – but as you’ve seen, we may use common words differently!
  • 24.
    • Process: Idealized Scientific Method
    Organized approach to explaining observed facts with a TESTABLE model of nature Hypothesis = tentative explanation Question = curiousity Results: should be same no matter who conducts the test Modification & Self-correction! Creativity! Astronomy relies on Observation more than Experiment Inferences based on results  verification or falsification
  • 25. Hallmarks of Science (from text)
    • 3) Science progresses through the creation and testing of models of nature that explain observations as simply as possible
    Occam’s Razor: All else being equal , scientists prefer the simplest explanation
  • 26. Clicker Question
    • Which of the following is not part of a good scientific theory? 
    • A scientific theory must explain a wide variety of phenomena observed in the natural world.  
    • A scientific theory cannot be accepted until it has been proven true beyond all doubt. 
    • A scientific theory must make testable predictions that, if found to be incorrect, could lead to its own modification or demise.  
    • A scientific theory should be based on natural processes and should not invoke the supernatural or divine.
  • 27. Never “proof”
    • Can never “prove” a model or theory
    • Confidence grows as repeatedly verified, supported by evidence
    • Scientific theory
      • Well-tested
      • Generally accepted
      • Not proven absolutely
    • New observations might not match predictions  theory must be modified
  • 28. Convincing Others
    • For a model to become an accepted theory, everyone must agree !
  • 29. Back to Hollow Earth
    • Hollow Earth Society: claims the Earth is a hollow ball and we are living inside it
    • Is this a scientific claim?
  • 30.