Scientific method vs. hollow earth theory

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

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  • Scientific method vs. hollow earth theory

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

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