The Scientific Method
An updated version of this lesson is available at
Visionlearning: The
Scientific Method
A common misperception of science
is that it defines "truth". Science is not truth, but rather it is
a way of thought. It is a process by which experimentation is used
to answer questions. This process of experimentation is called the
scientific method and involves several steps:
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Observation: Scientists are generally curious about their surroundings.
This curiosity leads them to ask questions about the world around them.
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Hypothesis: As scientists formulate questions, they naturally try
to answer those questions. Those attempts to answer questions lead
to hypotheses, or some would say guesses, regarding the question's answer.
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Testing: Of all the steps in the scientific method, the one that truly separates science from other disciplines is the process of experimentation.
In order to prove, or disprove, a hypothesis, a scientist will design an
experiment to test the theory. An important aspect of scientific
experimentation is repeatability. In other words, if two different
people in two different parts of the world perform the same experiment,
they should both get the same results.
The scientific method can be
most easily understood through an example. In the late16th century,
it was generally believed that an object would fall at a speed proportional
to its weight. In other words, the bigger they come, the faster they
fall. The Italian scientist Galileo thought differently about this
idea. Galileo believed that the forces acting on a falling object
were independent of the object's weight. In 1590, Galileo planned
out an experiment. He climbed to the top of the Leaning Tower of
Pisa and dropped several different sized weights off the top of the Tower.
A colleague watched the weights as they fell and recorded his observations.
What did they find?
Let's repeat Galileo's experiment. Magically transported to Italy,
we find ourselves at the top of the Leaning Tower of Pisa with a 1 kg and
10 kg weight. To drop the weights, click on the tower. What
happens when we drop the objects off the Tower ('we squash cars' is not
a correct answer)? Repeat the experiment. What happens?
Is the speed at which an object falls dependent or independent of its weight?
Some questions for you to think about:
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What is the experimental hypothesis?
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Is the experiment repeatable?
Galileo found that two objects
with different weights fall at exactly the same speed. This experiment
disproved the previously held belief that objects with different weights
fall at different rates. Why do two objects with different weights
fall at the same speed? Galileo had discovered that the force of
gravity (which would not be defined until several decades later by a scientist
named Sir Isaac Newton) was constant. Thus, despite their different
weights, two objects will fall (actually the objects are pulled) to the
earth at exactly the same rate.
We have to remember
that what we observe
is not nature herself,
but nature exposed to our
method of questioning.
-Werner Heisenberg |
In one of the most famous
renditions of this experiment, the astronaut David Scott repeated Galileo's
experiment on the moon using a falcon feather and a hammer (On earth, light
objects like feathers are slowed down by wind resistance. The moon
has no air and thus no wind resistance.) You can download a movie
of David Scott repeating Galileo's experiment on the moon at the NASA
Lunar Feather Drop Home Page [Note: You will need to download Apple's
Quicktime before you can view this movie. The movie is a large
(2.2 meg) file and may take some time to download on a 28.8 modem.]
Do you find yourself scratching
your head saying "what the heck is a kg?" It's a metric unit of weight
equal to 2.205 pounds. In the lessons that follow we'll assume you're
familiar with things like the metric system, scientific notation, significant
figures, etc. However, if you need some help with these concepts
the sites listed below offer good explanations and some practice tests
so you can check your skills. To return to this site, just use the
'back' button on your web browser.
| Some review topics:
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Other topics that may be of interest:
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Copyright © 1998-1999, All
Rights Reserved, Anthony
Carpi
The Leaning Tower of Pisa courtesy
of the Leaning
Tower Home Page
Space footage courtesy of NASA
