3 <strong>Topic III. Our Senses and Instrumentation</strong> …
Topic III. Our Senses and Instrumentation
- Science uses both our direct senses and a variety of instruments to extend our ability to observe phenomena. We trust our instruments for the same reasons we trust our senses; interactive exploration and comparison.
- It has been suggested that our trust in "a reality out there" is often strengthened by our actively interacting with the passively-percieved world (banging the table in front of us with our hand). Our “direct” experience with a scientist’s reality is expanding further: from the human senses to the human armed with instruments. The novel instruments that are now with us constantly (e.g. GPS, camera) allow us to interactively explore parts of the world that until recently were inaccessible or accessible only passively, through expensive technology or images made by scientists. This interactive experience of previously inaccessible aspects of the world now revealed by technology is broadening our sense of what counts as "real." We carry with us a growing range of interactive tools, these days primarily in the compact form of our smartphones.
- Addressing the Question: Why is Science Effective?
- Validation of Instruments
- Conception
- Techniques
- Challenges
TOPIC RESOURCES
EXAMPLES
- Exemplary Quotes
- "It sure helped public health and medicine once we realized there were things affecting our health that were just a little too small to see. I wonder if we could have figured that out without the invention of the microscope. I guess we might have just thought there were more invisible entities out there."
- “It didn’t occur to anybody that there was a such a clear periodic pattern in the populations of those wolves and rabbits until somebody just started writing down every sighting—we’re pretty bad at estimating and remembering times between occasional events.”
- “It’s amazing to first see a slow motion picture of a violin string making a note—wouldn’t it be great if our eyes and brains were fast enough to do this?”
- “Do you think that modern technology offering us more different vantage points fundamentally changes our position on any practical questions? For example, does it make a difference that in relatively recent decades we have gotten used to seeing the earth as a whole from space?”
- Cautionary Quotes: Mistakes, Misconceptions, & Misunderstandings
- Students tend to overextend the category of "scientific instruments to enable wider observation" to appeals to authority like books and Google and to tools that add to rather than clarify observations, like PokemonGo and psychedelics.
- Interactive exploration posed a particular challenge for students. Perhaps because of this, many students had difficulty proposing a way to test an instrument.
- “We can't really know anything about other galaxies, because we can only see them through fancy instruments and we can never know if the instruments are telling us the truth.”
- Students continued to be confused about interactive exploration and often did not incorporate the validation of instruments into their understanding.
LEARNING GOALS
- A. ATTITUDES
- Place appropriate trust in instruments where direct observation is not possible (or is less precise/accurate).
- Our raw senses yield a rough representation of reality, sufficient for most people to have a firm belief in a shared objective reality at that level of description. This can be further expanded and refined by systematic observation and instrumentation.
- B. CONCEPT ACQUISITION
- An instrument can have greater precision and accuracy than direct observation or the instruments used to test and calibrate it.
- Validity of a Measure: Is the measure yielding information about the target entity in out in the world, given that the target is something real (i.e., concept is valid).
- Challenges in validating the use of an instrument:
- a. When there is no objective gold standard (e.g. passage of time, what fluid to use in a thermometer)
- b. When direct observation is messy or impossible (e.g. radio waves, size)
- Techniques for validating instruments:
- a. Interactive exploration: Testing an instrument by changing the thing it is measuring in ways you know through other means, and seeing if the instrument recognizes the changes appropriately (e.g. does driving increase a car's odometer; see how singing higher and lower notes affects a sound spectrograph; sprayable electrons in Hacking reading).
- b. Comparison of multiple instruments (e.g. thermometers)
- c. Comparison to direct observation (e.g. naked sight compared to sight with a magnifying glass)
- C. CONCEPT APPLICATION
- Recognize continuum from direct observation to indirect observation via instruments
- Identify when and how interactive exploration, comparison of multiple instruments, and comparison to direct observation can be used to validate instruments.
- Identify cases in which instrumentation is needed to solve problems (e.g. entities/events are too slow, too fast, too small — that is, those for which we cannot rely on our everyday senses and cognitive capacities), especially in policy contexts.
- Explain how our ability to use the techniques for validating an instrument above can lead to more/less confidence in a given measurement.
- Identify where challenges in validating an instrument (and associated lack of confidence about what it is measuring) can make policy decisions more difficult.
CLASS ELEMENTS
- Suggested Readings & Reading Questions
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- Reading Questions: Do you think you "see" through an ordinary microscope? What about an electron microscope? Does using the word "see" imply that what you see is what is really there?
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- Clicker Questions
- Which statement best captures your stance:
- A. I strongly feel the pull of the arguments about limits of our understanding of reality.
- B. I strongly feel their pull, but I think there is a little room for our understanding of reality to be essentially correct some of the time.
- C. I strongly feel their pull, but I am still somehow pretty sure our basic sense of reality is generally right in many of the most important ways.
- D. I’m strongly confident of our ever-growing capacity to capture reality, almost all of it.
- Discussion Questions
- How do we know we can rely on our senses? How do we know when we can't?
- How can we observe a thing that we can never perceive directly with our senses?
- Describe an entity which you believe exists for which you have only very indirect evidence. Why do you believe it exists? Is there anything that might convince you it did not exist? Is there anything that might convince you that although something like it does exist, it has quite different properties than you had thought? Possible answers: electrons, quarks, black holes, dark matter, souls, God, right and wrong, soulmates, etc .
- Suppose you were working for an extremely eccentric art collector. He asks you to measure the beauty of each item in his collection in a systematic way which is not reducible simply to your opinion. How would you go about operationalizing beauty?
- Class Exercises
- CO2 Meter
- Requires a Windows Computer
- Blow into CO2 meter to demonstrate that CO2 in the room can be "interactively explored."
- Diffraction-grating glasses
- IPhone app provides interactive sound spectrogram (Spectogram Pro). Use slide whistle, stringed instrument, whistle (interactive exploration high vs. low), difference in timbre between male & female voices. What differences does the spectrograph instrument show between these sounds? How do these differences map onto differences you can hear? What does the spectrograph show that you can't know just by listening? Do you believe that what the spectrograph shows that you can't hear is real? Why or why not?
- iPhone app (Vernier Video Physics) shows quantitative analysis of slices of time after videotaping the movement of a tossed ball (falling and bouncing).
- A contrasting example (i.e., without much of the interactivity needed to make the "reality" evident): CO2 concentration in room is measured over the course of the class, and the resulting graph of CO2 over time is shown on the projector. You should see a significant increase. Graph should indicate increasing levels of CO2 throughout the class, as the students filling the room fill it with CO2.#h
- Give instructions to find level function on iPhone (this is unlabeled). Ask students to figure out what it does. Discuss how they know that's what it does.
- Practice Problems
- You have three meat thermometers, and they all give different temperatures for your holiday turkey. How would you go about deciding which thermometer to trust?
- You get a fancy new telescope for looking at stars too distant to see with the naked eye. How would you go about testing if it is showing you real celestial bodies, and not just artifacts of the telescope?
- Play some more with the spectroscope on your phones. How do you know it is really showing you sounds, and not responding to something else internal or in the environment? Hint: Interactive exploration!!!
- Homework
- What is the “fundamental philosophical puzzle” that faced scientists trying to calibrate thermometers in the eighteenth century? Explain the key point in your own words. (Based on the reading by Chang: “Spirit, Air and Quicksilver” chapter from Inventing Temperature)
- Data Science Applications:
- What situations do you not have contact with reality?
- How valid are your measures for your target entities?