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Origins. Lecture 8; April 24 2014. Previously on Origins (Prof Tutino). Giordano Bruno and Renassaince Science The debate over heliocentrism: the Galileo Affair WHAT I GOT OUT OF IT:
OriginsLecture 8; April 24 2014Previously on Origins(Prof Tutino)
  • Giordano Bruno and Renassaince Science
  • The debate over heliocentrism: the Galileo Affair
  • The relation between religion and science is historical and cultural. We need to understand the context of our debate. Scientists need to be aware of their surroundings .
  • In the debate there are issues of “power” in broad terms
  • Previously on Origins(Prof Hecht)
  • Religion is a complex phenomenon which must be understood in its multidimensional components
  • Over the course of time and in different cultures the relationship between religion and other areas of knowledge has changed significantly.
  • The debate is still open about what is the relation between religion and science in particular, with many points of view, often in contrast
  • Science and Myth
  • Prof Hecht raised the issue as to whether the scientific method is a myth in the sense that it is self-validating and inherently true
  • As we will see I do not think this is the case.
  • However, it is sometimes incorrectly portrayed or abused as such. For example it is unfortunately common for people to say “it’s science” as a synonym of it’s true.
  • Likewise, it is a danger to consider scientists as custodians (or “priests”) of the truth
  • My opinion is that the beauty and power of science is exactly that it is not a myth, and we should engage in the public understanding of science and of the scientific method to clarify the distinction
  • Methodological introduction
  • Demarcation: what is science?
  • Remember Prof Hecht’s lecture on junk-science
  • Falsification: how do you test scientific theories?
  • Measurements and errors
  • Repeatibility:
  • Determinism and probability
  • The unexplained and the supernatural
  • Corroboration: what is a “good” scientific theory
  • Science and Epistemology“Epistemologist”“Scientist”Demarcation: what is science?
  • We need to define what is science. Common methodology:
  • In the same way, we need to agree on the meaning of words in order to have a conversation.
  • The solution has to be a CONVENTION
  • dependent on history and culture
  • Demarcation: Popper’s solution
  • The currently agreed solution to the demarcation problem is very well described by Karl Popper: Science is falsifiable via experiments
  • IS THIS THE SAME AS MYTH? We will see what Prof Hecht thinks…
  • Karl Popper 1902-1994Demarcation does not mean isolation: science and cultureScientific model or theory
  • A scientific theory is a logically self-consistent model or framework for describing the behavior of a related set of natural or social phenomena.
  • In general it originates from experimental evidence
  • It is always corroborated by experimental evidence, in the form of successful empirical tests.
  • In this sense a theory is a systematic and formalized expression of all previous observations that is predictive, logical and testable (falsifiable).
  • Scientific theories are always tentative, and subject to corrections or inclusion in a yet wider theory. A model does not aspire to be a “true” picture of reality.
  • Example: gravity, from Newton to EinsteinExample: gravity, from Newton to Einstein
  • 1919 solar eclipse measurement: 1.61+-0.40”
  • Einstein 1.75”; Newton 0.875”
  • Measurements
  • Measurements must be REPEATABLE
  • Measurements have uncertainties
  • A measurement without an uncertainty is meaningless
  • Physics view of the universe can change dramatically1929: The universe is expanding1998: the universe is acceleratingA sociological comment…
  • What is a guaranteed way to have a spectacular career in science?
  • Prove the current paradigm wrong!
  • There is no higher compliment than “transformative” or “revolutionary” science
  • Probability and science
  • The results of experiments are often cast in terms of probabilities.
  • The same is true for scientific theories: Probabilistic predictions are not in conflict with the empirical method because they can be falsified
  • Heisenberg’s uncertainty principle
  • What does it mean?
  • NOT that science is not precise
  • It means that some quantities cannot be determined simultaneously with infinite precision.
  • For example the uncertainty on position and momentum (~speed) is larger than
  • ΔxΔp=h/2π
  • Physical cosmology: some questions
  • Is the Universe evolving?
  • If so, how and when did it form?
  • How big/old is the universe?
  • How/when did galaxies/stars/planets form?
  • Is there extraterrestrial life in the Universe?
  • How much these questions are historical and cultural versus perhaps “biological” is not for me to answer.NOTE THAT THERE IS NO QUESTION ABOUT THE PURPOSE/MEANING OF THE UNIVERSE. WHY?Physical cosmology
  • Experiments and Observations force us to modify/change our view of the Universe. Examples:
  • Galileo’s observations of Sun spots proved that the heavens are not time-invariant
  • Hubble’s measurement of galaxy redshifts showed that the Universe is not static
  • High speed motions of stars in galaxies show that either we do not understand gravity or there is a large amount of “dark matter”, i.e. different stuff that the ones that makes you and me (and Earth)
  • Tools of the trade:Telescopes as time machinesPhysical cosmology: a fundamental dilemma
  • Experiments and observations can only be from one point in space and time: Earth now.
  • Yet we would like to construct a scientific theory that describes the universe everywhere and at all times.
  • …and its solution
  • Hypothesis: our local sample of the universe is no different from more remote and inaccessible places
  • This assumption is deeply rooted in two fundamental principles of physics:
  • The laws of physics (whatever they are!) do not depend on space and time. Popper calls it “the principle of the uniformity of nature”
  • Physical explanations of natural phenomena should be as simple as possible (Ockham’s razor)
  • A testable working solution
  • We can measure whether we are in anyway in a special place in the Universe.
  • We will discuss this at length in this class
  • We can test the laws of physics through observations. Examples:
  • Spectroscopy of distant stars and galaxies to probe atomic physics. Do we see the same transitions?
  • Constants of nature (such as the electron charge). Where they different a few billion years ago?
  • Unexplained…
  • There are plenty of phenomena we do not “understand”. Example:
  • How does your cell-phone work?
  • However, they are measurable phenomena with repeatable experiments
  • Technology may appear “magic” or “myth” but it IS FUNDAMENTALLY NOT
  • …vs magic/miracles
  • Magic and miracles imply a behavior that differs than expected - i.e. NON REPEATABLE
  • If miracle were proven to exist, this would falsify one of the fundamental hypothesis of science, that is that the laws of nature do not “bend” to people’s or (deity’s) will.
  • A “good” scientific theory
  • What constitutes a “good” scientific theory?
  • If a theory can never be proven right, how is one theory better than another?
  • Note the use of the derogatory expression “just a theory” by creationists
  • According to Popper:
  • The better theory is the one that passes more stringent tests, both in number and in quality
  • The better theory is the more falsifiable one, if it doesn’t fail
  • Old theories often become limiting cases of new theories
  • (e.g. Newton vs Einstein)
  • How about validating the method?
  • What constitutes a “good” method?
  • Is the scientific method good?
  • Does the question even make sense?
  • My view is that a method is good as long as it allows you to achieve what you want. What do you want?
  • The scientific method answers some questions/obtain some results. What are they?
  • If we need to answer other questions we need different tools.
  • Summary
  • Demarcation: what is science?
  • Falsification: how do you test scientific theories?
  • Measurements and errors
  • Repeatibility:
  • Determinism and probability
  • The unexplained and the supernatural
  • Corroboration:
  • what is a “good” scientific theory
  • The EndSee you on Tuesday!
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