1. ON THEORIES V . H . B E L V A D I @ vhbelvadi v h b e l v a d i . c o m p h y s i c s c a p s u l e . c o m what are they and how do they work? ickr.com/josefstuefer

2. Scope ! You will be able to answer ! What is a theory? What are accuracy and precision? What are the characteristics of a good theory? What are theories in philosophy and in physics What is the scientic method? ickr.com/ryanwick 3. Contents 1 Denition of a theory 2 Systems and phenomena 3 Levels of theorising 4 Accuracy and precision 5 Good theory as a machine 6 Karl Poppers characteristics 7 Provable v. unfalsiable 8 Theories of philosophy v. theories of physics 9 Five more characteristics of a theory 10 Assumptions 11 The scientic method 12 Lex Parsimoniae 4. A man may die, nations may rise and fall, but an idea lives on. ! JOHN F. KENNEDY ickr.com/andrewtarvin 5. Theories are ideas 6. A supposition or a system of ideas intended to explain something. Oxford Dictionary 7. &the something is generally a phenomenon the explanation must be independent of the something Something 8. Let us examine this 1. How does a door rotate? 2. It works like one-quarter of a revolving door. 3. It works based on a hinge. Depends on another door 1. Why does a coin have two sides? Not a phenomenon 9. What is a phenomenon? - to manifest (itself) ! An event that is observable, occurs over a period of time and is measurable in some units and may or may not require the use of instruments. In physics: [phai-no-me-non] 10. System or phenomenon? A system is a portion of the universe chosen for study, which responds to any number of varying conditions. An event inside a system is a phenomenon. 11. Example 1 A aquarium is a system. When an aquarium is kept on re, its water boils. When water is drained out, plants and sh die. When sh swim, their ns move to and fro. Phenomena Example 2 A panchayat is a system. When somebody throws a stone, others react. If it does not function well, people protest. If it rains, the panchayat meet is cancelled. Phenomena All these are simply parts of a system reacting to some occurrence inside or from outside that system 12. THEORY Hypothesis Law UNPROVEN SPECULATIVE PROVEN RESULTS, NOT MECHANISMS PROOFS MECHANISMS Facts 13. Terms in brief Axiom the starting point of a reasoning, cannot be proven e.g. a line can be drawn between any two points Postulate similar to an axiom, often only slightly more accurate Theorem a logical consequence of a set of axioms with proof Corollary a trivial theorem with little consequence to the problem it is often very close in similarity to a previous axiom or theorem Hypothesis a statement capable of being proven, not yet proved Law a proven statement, often tested over time with certainty 14. Accuracy+precision or,degreeofbeingunquestionable Axiom Postulate H ypothesis Theory Law Scientic process of thought 15. What are accuracy and precision? Accuracy Precision = Experimental or observational result Expected or known correct result Accurate,preciseAccurate,imprecise Inaccurate,impreciseInaccurate,precise 16. A theory must be precise and make accurate predictions. 17. So, when people say,! I have a theory they actually mean! they have a hypothesis 18. A theory is like a machine Image: Frdric Bisson 19. Takes in known facts Provides explanations Makes predictions THEORY 20. The unknown In other words: A good theory The known Discovery A useless theory Also useless 21. Karl PopperKarl Poppers CHARACTERISTICS OF A GOOD SCIENTIFIC THEORY 22. 1 Easy to verify 23. 2 Make predictions 24. 3Make prohibitions 25. 4Must be testable 26. 5Failed tests of falsication are supportive evidences 27. But let us not forget that Popper supported Empirical falsication 28. whereas most science is still based on Francis Bacons Inductivism 29. Stephen Hawking sums it up 30. A theory is a good theory if it satises two requirements 31. It must accurately describe a large class of observations by relying on few arbitrary elements 32. It must make denite predictions about the results of future observations 33. Provable?! or Unfalsiable? 34. Provable Unfalsiable 35. Provable Unfalsiable = can be proved 36. Provable Unfalsiable = can be proved = cannot be disproved 37. Example What is a ame? 38. Example What is a ame? Lighting into a ame can be a phenomenon 39. A ame is a! body that! gives out! light and is! too hot to! hold in! ones hand Proposed! theory 40. Provable? 41. Provable? Yes. All ames are hot and glowing. 42. Unfalsiable? 43. Unfalsiable? No. The cold ame experiment. 44. Find experiment instructions at j.mp/1tK5L0S 45. A glowing! body of! ignited gas! that is! generated by! something! on re. Alternate! theory 46. Provable? 47. Provable? Clearly. 48. Unfalsiable? 49. Unfalsiable? Yes. All known ames are generated by things on re and all known ames are composed of gasses. 50. TYPES OF THEORIES Theories of philosophy Theories in physics 51. TYPES OF THEORIES Theories of philosophy Theories in physics used in all sciences/social sciences; stated in english etc. used in physics, in addition to theories of philosophy; stated in mathematics 52. Theories in physics e.g. (James Clerk) Maxwells theory of electromagnetism 53. How does it work? The mathematics Dx Dy Dz charge volume = 54. How does it work? Electric ux ! (amount of electric eld vectors emanating from a point) Amount of Amount of charge per unit volume The English 55. } These equations give us a physical picture of LIGHT Physical meaning Light is a wave that looks like this: 56. If it is a good theory, What does it explain? What does it predict? 57. What does it explain? What does it predict? 58. What does it explain? What does it predict? The use of magnetism to store computer memory * Remember! The theory is from the 1860s, so it was a prediction then: this form of computer memory was used until the 1980s. 59. Some more characteristics 60. Replication 61. Unity One technique applicable to a wide range of problems 62. Fecundity The ability to give rise to new ideas 63. Independence of auxiliary hypotheses arising for or as a result of a given theory 64. Iteration Improve accuracy to improve/retain validity 65. Iteration Improve accuracy to improve/retain validity e.g. The orbit of planet Mercury 66. 7% 67. Assumptions An assumption can be a theory only if it is meant to be applied only in cases when the assumption is true 68. The scientic method Ask a question Formulate a hypothesis Determine the predictions of the hypothesis Theory, law etc.if correct make corrections if wrong Test the hypothesis Compare results & hypothesis 69. Occams razorwhen multiple explanations seem to exist among competing hypotheses, the one with the fewest assumptions should be selected William of Ockham late 1200s - early 1300s Lex Parsimoniae leks - par - see - moan - e - yea 70. Thank you VHBELVADI.COM / ON-THEORIES @vhbelvadi