The Scientific Method


Mr. Andersen gives a brief description of the scientific method.

Transcript Provided by YouTube:

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Hi. This is Mr. Andersen. Today I’m going to give you a little podcast on
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scientific method. Scientific method is used by scientists but it’s also used by anybody
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who wants to understand how the world works. And so imagine we have a guy here. Let’s make
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him kind of nerdy. So we’ll give him some goggles. There we go. And he’s wondering maybe
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for example what makes a rainbow work? Well scientific method can be used to kind of answer
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that question. Or let’s say he’s daydreaming and wondering, let’s say if I’ve got a plant
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that’s growing in a pot, and I play music for that. What kind of music is going to make
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that plant grow faster? And so to answer that question, you can use scientific method. And
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so maybe we’ll think about this one right here. So, first of all we need a little bit
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of history. The history begins with Aristotle. And so there were a lot of philosophers back
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in the times of the Greeks. But the one that really applies to science is Aristotle. And
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here’s a picture of him. This is actually his teacher. This would be Plato. And then
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this is Aristotle right here. I like this picture here because you can notice that this
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guy is kind of motioning upwards. Plato is talking about metaphysics and understanding
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how the world works just from this thought, philosophical kind of a look. But Aristotle
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here has got his hand facing downwards. And what that implies is that he is looking at
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nature. In other words the natural sciences. Now what did Aristotle use to answer all of
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these questions about how the world works. He used his brain. And he used intuition.
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And the good thing about that is that is was incredibly smart. We’ve found a lot of things
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that Aristotle speculated about have actually been proven to be true. And we maybe didn’t
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know it until maybe 100 years ago. So really, really bright. The problem with that is that
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he was so bright that a lot of people after that never tested what he actually said. So
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an example, he said if you have a large object and a small object and you drop both of those
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objects at the same time the larger object is going to reach the ground first. And that
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was just kind of intuition for him. We now know that that’s not true. So let’s fast forward
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1000 years, or even more than that. And we go to this guys, Abu Ali al-Hasa who was a
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Persian. He lived in modern day Iraq. And he would be the first person to really develop,
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at least in history, to develop this scientific method. This is a quote, “Truth is sought
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for its own sake. And those who are engaged upon the quest for anything for its own sake
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are not interested in other things. Finding the truth is difficult and the road to it
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is rough.” And so we have this guy to thank for the word hypothesis and theory. And the
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idea that you first of all try to answer a question and then you can prove is that answer
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is true. Wasn’t a scientist though, didn’t really do experiments. And so then we have
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to fast forward a little bit to Galileo Galilei. Galileo Galilei lived in Italy. He, unlike
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Aristotle, always wanted to prove if it was right or not. And so he used the scientific
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method to answer questions. Example of questions, Aristotle remember said that large objects
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are going to fall faster than small objects. And it’s really hard to see that. Imagine
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back in the time of Galileo you don’t have a motion sensor. You don’t have a watch. And
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so it’s hard to figure out which one is actually falling faster. So how do you do that? Well
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one way to do it is actually to have an inclined plane. And if you have an inclined plane like
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this, you can time it. And you don’t have to be so good on the timing. It’s still gravity
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that is making this ball roll down the inclined plane. But he made these really detailed measurements
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and he was able to determine that all objects fall at the same rate. Which goes to that
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story of him dropping two weighted balls, which is probably true, from the top of this,
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the Leaning Tower of Pisa and then showing that all objects fall at the same rate. A
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lot of those stories are what, they’re just stories. But that’s Galileo Galilei. The next
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person I want to fast forward to is a group of people. And those are the Myth Busters.
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The reason I add the Myth Busters here, not because they’re scientists, but they’re modern
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day people using the scientific method. And so they’ll answer many questions. But they
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answer those questions by developing first a hypothesis and then testing it. And they
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go out of their way to make sure that they’re truly answering the question. So let’s get
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into the scientific method. Scientific method was used by a famous scientist. This one right
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here would be Isaac Newton. This one would be Charles Darwin. And this one right here
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was Niels Bohr. But they all use essentially the same method. And it always begins with
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a question. And so first of all you start with what question you want to answer. And
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so an example we could say right here is, let’s say we have a plant. And that plant
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is growing. And we’re going to play music for it. And we’re going to play different
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types of music. So maybe our question is, what type of music is actually going to make
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that plant grow best? So now we make a hypothesis. Maybe I’m of the mind that country music is
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going to make that plant grow fastest. And so that would be my hypothesis. Now we sometimes
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refer to as a hypothesis as an educated guess. But with scientists that’s kind of a misnomer.
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It’s not so much a guess as we know what’s going to happen. We just have to prove it.
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Doesn’t mean that our hypothesis is always correct. But we start with a hypothesis which
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is this idea of what we think might happen. Next up is independent variable. And so in
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an experiment the question will always tell you what the two variables are. And so listen
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carefully as I say that. I want to determine how the type of music effects plant growth.
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Now I don’t know if you heard that but there are two variables inside there. One was the
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type of music and the other one is plant growth. And so if we go to independent variable, the
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way that I talk about this in class is the independent variable is the variable that
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I change. And so I change the independent variable. It’s the one thing that I manipulate
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and so that’s that first variable in an experiment. The dependent variable then is a resulting
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variable. In other words it results as an action of the independent variable. So if
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we go back to that question again. How does music effect plant growth? What’s the independent
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variable? It’s going to be the type of music that I play. What’s the dependent variable?
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That’s going to be plant growth. So what do we have down here. What are control variables?
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Those are everything that we keep the same. And so in this experiment what are some things
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that we want to keep the same? Well the species of plant would be one thing. Maybe the amount
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of light it gets. The amount of water it gets. The nutrients it gets. The volume of the music.
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The amount of time that we play the music. And so those are all going to be the control
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variables. Everything that we keep the same. And the trick is, if we don’t control all
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the variables. In other words if we have a few variables that change, not only the independent
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variable, then we can never know if we actually show that that independent variable has any
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effect on it. Okay. Let’s got to the next ones then. So what do we do next then? So
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this is a great picture right here. This is actually Einstein. And this in the background
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is another really famous astronomer. His name is Edwin Hubble. And so the Hubble Space Telescope
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is named after him. And what he was famous for was measuring the red shift in the universe.
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This idea that the universe is always expanding. Einstein doubted that and eventually said
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it was the biggest mistake that he ever made. So let’s go to the next group then. What’s
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a control group. So thinking back to that experiment with the plant, well not only would
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we have one group that we are actually taking those plants and playing music for, but in
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a totally different room we’re going to have another group of plants. And those plants
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in the other room are going to receive no music at all. And so that kind of, the control
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group kind of seems counter intuitive. But what is the control group? It’s another group
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of plants that we’re not exposing music to. Why would be do that? Well we want to make
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sure that it’s really the music that is effecting the plants. And it could be something else.
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And so if we see differences between these groups and the control group and the other
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one, then we can say that’s accounted to by the music. Next we collect data. Data usually
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is collected in a data table. But it’s always organized in a graph. When you do a graph,
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a thing to remember is that the independent variable will always go on the bottom. And
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the dependent variable is going to go on the side. If we’re doing plant growth, maybe that’s
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going to be a bar graph. Where we’ve got independent variable are the types of music. And we put
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those on the bottom. And the dependent variable is going to be amount of plant growth. Or
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maybe it’s going to be a graph like this where we’re changing something, maybe the volume
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of the music over time and we’re looking at plant growth. It should say plant growth and
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we’re getting a graph that maybe that looks like. . . That’s getting a little bit messy.
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Okay. So what is a conclusion? A conclusion is going to address that question. And so
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conclusion is looking back at the question, saying “Hey. Is our hypothesis correct?” Or
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is it incorrect? The next thing you have to do as far as science goes is you have an obligation
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to publish the results of your experiment. And we do those in primary research. We do
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those, excuse me, in some kind of a scientific journal. And so when Watson and Crick discovered
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the structure of DNA, the first thing they did was they wrote it up in an article in
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“Nature”. And what that allows other scientists to do is to repeat their experiment and that’s
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how science builds itself. And so if you’ve ever wondered how a science book is made,
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a science book is made by scientists. And those scientists collect data. And that science
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is tested by other scientists over and over and over again. And eventually we have a truth.
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And that’s what science is. And it’s a lot different from other disciplines that you
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have. A nice thing about science is that other scientists are always trying to prove other
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scientists wrong. And so by doing that it’s this wonderful check and balance. And we eventually
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arrive at this wonderful truth. Thanks to the scientific method. So that’s scientific
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method and I hope that’s helpful.


This post was previously published on YouTube.

Photo credit: Screenshot from video.