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- [Voiceover] Let's explore the scientific
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scientific method
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which, at first might seem a little
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bit intimidating, but when we walk
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through it, you'll see that it's actually
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almost a common-sense way of looking
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at the world and making progress in our
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understanding of the
world and feeling good
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about that progress of our understanding
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of the world.
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So, let's just use a tangible example
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here, and we'll walk through what we could
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consider the steps of the scientific
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method, and you'll see different steps
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articulated in different
ways, but they all
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boil down to the same thing.
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You observe something
about reality, and you say,
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well, let me try to come up with
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a reason for why that observation
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happens, and then you try
to test that explanation.
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It's very important that you come up with
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explanations that you
can test, and then you
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can see if they're true, and then based on
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whether they're true, you keep iterating.
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If it's not true, you come
up with another explanation.
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If it is true, but it
doesn't explain everything,
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well once again, you try
to explain more of it.
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So, as a tangible example,
let's say that you live in,
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in I don't know, northern
Canada or something, and let's
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say that you live near
the beach, but there's
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also a pond near your
house, and you notice that
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the pond, it tends to
freeze over sooner in
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the Winter than the ocean does.
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It does that faster and
even does it at higher
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temperatures than when the ocean seems
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to freeze over.
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So, you could view that
as your observation.
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So, the first step is you're
making an observation.
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Observation.
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In our particular case
is that the pond freezes
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over at higher temperatures than the ocean
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does, and it freezes over
sooner in the Winter.
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Well, the next question that you might
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wanna, or the next step you could view as
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a scientific method.
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It doesn't have to be
this regimented, but this
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is a structured way of thinking about it.
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Well, ask yourself a question.
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Ask a question.
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Why does, so in this
particular question, or in
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this particular scenario,
why does the pond tend
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to freeze over faster and
at higher temperatures
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than the ocean does?
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Well, you then try to answer
that question, and this
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is a key part of the scientific method
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is what you do in this third step
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is that you try to create
an explanation, but what's
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key is that it is a testable explanation.
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So, you try to, you create a testable
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explanation.
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Testable explanation,
and this is kind of the
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core, one of the core
pillars of the scientific
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method, and this testable
explanation is called
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your hypothesis.
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Your hypothesis.
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And so, in this particular
case, a testable
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explanation could be
that, well the ocean is
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made up of salt water, and this pond is
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fresh water, so your testable explanation
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could be salt water,
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salt water has lower freezing point.
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Has lower freezing,
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freezing point.
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Lower freezing point, so it takes colder
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temperatures to freeze
it than fresh water.
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Than fresh water.
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So, this, right over here, this would
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be a good hypothesis.
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It doesn't matter
whether the hypothesis is
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actually true or not.
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We haven't actually run
the experiment, but it's
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a good one, because we can construct an
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experiment that tests this very well.
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Now, what would be an example of a bad
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hypothesis or of something
that you couldn't
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even necessarily consider as part of the
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scientific method?
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Well, you could say that there is a
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fairy that blesses that, let's
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say that performs magic
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performs magic
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on the pond
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to freeze it faster.
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Freeze it faster.
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And, the reason why this
isn't so good is that
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this is not so testable,
because it's depending
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on this fairy, and you
don't know how to convince
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the fairy to try to do it again.
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You haven't seen the fairy.
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You haven't observed the fairy.
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It's not based on any observation, and so
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this one right over here, this would not
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be a good hypothesis for the scientific
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method, so we would
wanna rule that one out.
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So, let's go back to our
testable explanation,
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our hypothesis.
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Salt water has a lower freezing
point than fresh water.
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Well, the next step would be to
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make a prediction based
on that, and this is the
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part where we're really
designing an experiment.
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So, you could just view
all of this as designing.
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Let me do this in a different color.
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Where we wanna design an experiment.
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Design an experiment.
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And in that experiments
lets say, and let's see,
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the next two steps I will put as
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part of this experimental.
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Whoops.
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I messed up.
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Let me, I did my undo step.
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So, the next part that I
will do is the experiment.
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Experiment.
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And there you go.
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So, the first thing is,
we'll say I take, you know,
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there's all sorts of things
that are going on outside.
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The ocean has waves.
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You know, maybe there are boats going by
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that might potentially break up the ice.
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So, I just wanna isolate
that one variable that
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I care about, whether something is salt
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water or not, and I want a control for
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everything else.
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So, I want a control for whether there's
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waves or not or whether
there's wind or any
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other possible explanation for why the
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pond freezes over faster.
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So, what I do, in a very
controlled environment
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I take two cups.
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I take two cups.
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That's one cup and two cups, and I put
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water in those cups.
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I put water in those cups.
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Now, let's say I start with
distilled water, but then
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this one stays, the
first one right over here
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stays distilled, and
distilled means that through
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evaporation I've taken
out all of the impurities
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of that water, and in the second one
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I take that distilled
water, and I throw a bunch
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of salt in it.
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So, this one is fresh,
very fresh, and in fact,
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far fresher than you would find in a pond.
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It's distilled water.
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And then this is over
here, this is salt water.
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So, you wouldn't see the
salt, but just for our
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visuals, you depict it.
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Then we would make a prediction, and we
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could even view this as Step Four,
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our prediction.
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We predict that the fresh
water will freeze at
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a higher temperature than the salt water.
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So, we'll prediction,
let's say the fresh freezes
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fresh freezes
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at zero degrees Celsius,
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but salt doesn't.
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Salt water doesn't.
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Whoop, not sat.
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Salt water doesn't.
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So, what you then do is that
you test your prediction.
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So, then you test it.
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And how would you test it?
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Well, you could have a
very accurate freezer that
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is exactly at zero degrees
Celsius, and you put
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both of these cups into
it, and you wanna make
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sure that they're identical
and everything where
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you control for everything else.
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You control for the surface area.
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You control for the material of the glass.
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You control for how much water there is.
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But, then you test it.
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Then you see what happened from your test.
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Leave it in overnight,
and if you see that the
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fresh water has frozen
over, so it's frozen
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over, but the salt water
hasn't, well then that
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seems to validate your
testable explanation
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that salt water has a
lower freezing point than
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fresh water, and if it didn't
freeze, well it's like,
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okay, well may that, or if
there isn't a difference,
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maybe either both of them
didn't freeze or both
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of them did freeze, then
you might say, well, okay,
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that wasn't a good explanation.
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I have to find another explanation for why
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the ocean seems to freeze
at a lower temperature.
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Or, you might say, well that's part of the
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explanation, but that by itself doesn't
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explain it, or you
might now wanna ask even
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further questions about, well, when does
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salt water freeze, and what
else is it dependent on?
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Do the waves have an impact?
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Does the wind have an impact?
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So, then you can go into the process
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of iterating and refining.
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So, you then refine
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refine
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refine and iterate on the process.
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When I'm talking about iterate, you're
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doing it over again, but then, based on
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the things that you've learned.
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So, you might come up with a more refined
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testable explanation, or you might come up
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with more experiments that could get you
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a better understanding of the difference
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between fresh and salt water, or you might
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try to come up with experiments for why
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exactly, what is it
about the salt that makes
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this water harder to freeze?
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So, that's essentially the essence of
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the scientific method,
and I wanna emphasize
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this isn't some, you know, bizarre thing.
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This is logical reasoning.
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Make a testable explanation for something
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that you're observing
in the world, and then
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you test it, and you
see if your explanation
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seems to hold up based
on the data from your
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test, and then whether or not it holds up,
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you then keep going, and
you keep refining, and you
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keep learning more
about the world, and the
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reason why this is better
than just saying, oh well,
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look, okay, I see the pond
has frozen over and the
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ocean hasn't, it must be the
salt water, and you know,
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I just feel good about
that, is that you can't
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feel good about that.
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There's a million
different reasons, and you
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shouldn't just go on
your gut, 'cause at some
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point, your gut might be right 90% of
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the time, but that 10%
that it's wrong, you're
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going to be passing on
knowledge or assumptions
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about the world that
aren't true, and then other
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people are going to build
on that, and then all
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of our knowledge is going
to be built on kind of
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a shaky foundation, and
so the scientific method
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ensures that our foundation is strong.
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And I'll leave you with
the gentleman who's often
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considered to be the father, or one of the
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fathers, of the scientific method.
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He lived in Cairo, and in what is now Iraq,
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oh nearly 1,000 or roughly
1,000 years ago, and he
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was a famous astronomer and
physist and mathematician.
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And his quote is a pretty
powerful one, 'cause
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I think it even stands today:
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"The duty of the man who
investigates the writings
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of scientists, if learning
the truth is his goal, ..."
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Let me start over, just
so I can get the dramatic
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effect right.
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"The duty of the man who
investigates the writings
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of scientists, if learning
the truth is his goal,
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is to make himself an enemy of all that
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he reads, and attack it from every side.
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He should also suspect
himself as he performs
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his critical examination
of it, so that he may
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avoid falling into either
prejudice or leniency."
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Hasan Ibn al-Haytham,
and his Latinized name
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is Alhazen.
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So, he's saying be skeptical,
and not just skeptical
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of what other people
write and read, but even
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of yourself, and another
aspect of the scientific
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method which is super
important is, if someone
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says they made a hypothesis
and they tested and they
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got a result, in order for
that to be a good test and in
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order for that to be a good
hypothesis, that experiment
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has to be reproducible.
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Someone can't say, oh it's
only, you know, a certain
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time that only happens once
every 100 years and not,
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that that's why it happened that day.
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It has to be reproducible,
and reproducible
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is key, because then
another skeptical scientist
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like yourself can say, let me see if I can
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reproduce it.
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Let me not just believe
it, because that person
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looks like they're
smart, and they said that
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it is true.
