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