Mr. Andersen gives a brief description of the scientific method.
Transcript Provided by YouTube:
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.
This post was previously published on YouTube.
Photo credit: Screenshot from video.