Example

Dress Rehearsal

Your physics textbook asserts the following hypothesis: “Polarizing filters transmit components of incident non-polarized light that are parallel to the polarization axis, and block components vibrating at right angles to the polarization axis. The result is the emergence of polarized light.” Yeah, right.

Your text is explaining in the chapter on light how seeing is affected by polarized light and how 3D effects are created. How do you prove that the hypothesis is true? A little imagination is in order. What do Avatar, Thor, and Transformers have in common? Answer: They’re all in 3D.

Your textbook confirms the hypothesis by first explaining how human eyes create depth. Each eye views objects from a slightly different angle. Your eyes then work together to give impressions of the object at the same time, resulting in depth. You can prove this by holding up a finger at arm’s length. See how your finger moves from side to side as you alternately open and close one eye and then the other? Let’s take that a step further.

To determine which of your eyes is more dominant, hold your finger up again. This time concentrate on an object beyond your finger. Close your right eye. If the finger jumps to the right, your right eye is dominant. When you try this with your left eye closed, your finger will seem to remain where it is. Conversely, if your finger moves to the left while the left eye is closed but remains stationary while the right eye is closed, your left eye rules.

Now, back to the movies…in 3D films, each eye sees just its own view due to the use of polarizing filters. The right sees the right view and the left, the left. The axes of these views are at right angles to each other. When you look at them on the screen with naked eyes, they appear blurry. This is why previews for an upcoming film made in 3D appear blurry.

However, when we watch a film in 3D… and don’t we pay extra for THAT…the polarizing glasses have lenses whose axes are also at right angles. So, your left eye sees polarizing light from the left projector. The right eye sees polarizing light from the right projector, but your brain interprets the two pictures as one, creating that feeling of depth.

You can also test this hypothesis with a stereogram or hologram. When you view a stereogram, certain patterns are hidden from view. By placing the stereogram on your nose and slowly moving it away from you, your eyes can more easily see the missing patterns. This might take several tries, but eventually you get into the groove, and it becomes effortless.

Through the use of these mini-experiments and further research, you can better understand the concepts of polarized light and 3D viewing in order to test what scientists are telling you rather than accepting whatever they say. Remember, you always want to corroborate source information for yourself, and if you discover something fishy, be sure to challenge it!

Source:

Hewitt, Paul G. Conceptual Physics, 3^rd edition. California: Addison-Wesley Publishing Company, 1997.

Drill

Using the word bank, fill in the blanks with the appropriate words.

verify corroborating evaluate evidence challenge

1. To ______________ means to examine and judge carefully.
2. When you confirm or support a hypothesis, data, or findings you are ____________ information.
3. _______________ means to make sure something is true and accurate.
4. You must not take for granted that conclusions are correct. You must be sure to _______________________ them.
5. Personal observation is an example of _______________.

ANSWERS:

1. The correct answer is evaluate. Evaluation is a higher-order thinking skill that involves gathering and synthesizing information in order to come to your own conclusions.

2. The correct answer is corroborating. You know how those television detective shows are always talking about finding corroborating evidence? They are looking for more evidence that supports the evidence or theory they already have about a crime. Scientists are investigators too, and they need to corroborate or support their data and hypotheses with additional evidence in order to be convinced that their findings are accurate.

3. The correct answer is verify. You can verify information a number of ways. You might make a firsthand observation, repeat the experiment yourself, or find additional sources that come to the same conclusions.

4. The correct answer is challenge. When you question or challenge what you read, we call that dialectic thinking, which means thinking that is a dialogue between two points of view. Even if you believe a conclusion is correct, you should always test it with an opposing point of view. This will help you to see any potential problems or biases with the data.

5. The correct answer is evidence. Personal observation is just one kind of evidence you can use to corroborate or challenge the information or conclusions presented in a text. Be careful though; one observation alone is not enough evidence to draw new conclusions or refute the old ones. You’ll need to investigate further and corroborate your own observation with additional data.