- All right, I think it's really important
that we stop for a minute
and say, "What is science?"
That's one of the big things I want you
to get out of this class.
A clear understanding of what
science is, how science works.
We're learning astronomy
as a case study, an example
of what science is.
So, what is science?
What makes some things be science
and other things not be science?
What defines science?
Well, first of all, I'll say
science is a social movement.
A social movement.
It's something done by groups of people.
Individual people alone,
well, you got to talk
to other people.
That's an essential
part of what science is.
It's done by groups of people
working together, collaborating,
arguing, disagreeing,
trying to disapprove each other's ideas.
Science is a social movement.
It's groups of people working together
on the largest possible scale.
Many different people, all going
their different directions,
but they're kind of agreeing
to some ground rules.
These ground rules laid
by the Ancient Greeks.
This idea that we're
gonna try to understand
the world around us in
terms of rational, logical,
principles and ideas.
What we're gonna do, is
we're gonna try to figure out
the rules of the
universe, how things work,
and we're gonna do that
through observation,
and through testing our
good ideas and all this.
And so often times, these are taught
as what we call the scientific method.
The scientific...
Often study the scientific
method in grade school,
in all these sorts of thing.
I think there's a great
deal of truth to this.
I wanna go through this idea
of the scientific method
and then talk about how does really apply
to real science as it
is actually practiced
in reality today?
So first of all, in the scientific method,
what do we gotta do?
We gotta, first of all, we
have to have observation
of the natural world.
Every science has people,
has scientists out there,
observing the world.
Whether it's in the
laboratory, out of the lab,
wherever you are, observing.
Making very careful
detailed observations of it.
So observe the natural world
carefully, in detail.
And what could be more
detailed than specific numbers?
So measuring specific numbers.
Measuring specific numbers.
Measuring specific numbers.
That's absolutely vital here.
You know, I don't just
observe this star as hot.
I observe its exact, precise, temperature.
Observing the natural world in this
is an essential part of
the scientific process.
Okay, what do we do?
We make our observation.
Well, that's not enough.
We observe and look for patterns.
We find interesting
patterns in our observations
in the natural world.
And then, we try to understand these.
So we propose hypotheses.
We propose ideas in order to
explain, why these patterns.
So we look for patterns,
we propose hypotheses,
to explain these patterns.
Ideas for why it is.
Okay, why is it that these group of stars
are all kind of reddish,
whereas stars over here aren't?
Well, okay so my hypothesis
is, well, this is all a group
of old stars and then so
they've turned red over time.
And we can about the details
of this, testing this out
and trying to figure out
the specifics of that.
That's an essential idea behind this.
So we're gonna propose
a hypothesis in order
to explain that.
And then we test our hypotheses.
We test our hypotheses anyway we can.
If we can do it experimentally, great.
If we can do a controlled
experiment in the laboratory,
that's a wonderful, fantastic thing to do.
Little bit hard to do
in a lot of astronomy.
You know, it's like,
"Okay take one rotating
super massive black hole,
add two giant planets."
And well, okay, that's kinda tough to do.
So what do we do?
So we test this through more observations.
We test our hypothesis.
How do you test a hypothesis?
You use your hypothesis in order to make
specific predictions and then
you see if they're right.
Okay, if this is right, then
if you observe these stars,
you'll find that the chemical composition
that these stars varies
by, blah, blah, blah,
and then we do the details
of all that sort of thing.
So that's how we put things to the test.
In the laboratory if we can.
If we can't do it in the laboratory,
then by making specific
predictions which can be tested.
Okay let's do a little more.
So we have observe,
we look for patterns,
we propose hypotheses
to explain these and then we test
these hypotheses by making predictions
and we verify them.
Or we deny them.
I mean, maybe they're not
right and we figure out
one way or another, whether
they're right or not.
If the predictions are wrong,
the hypothesis is wrong.
It goes out the window and
we try propose another one.
If on the other hand, we have a hypothesis
which stands up over
a long period of time,
making lots of predictions,
figuring lots of things out,
and it really works over a broad area,
then we can call it theory.
And so we might get to that.
So here's kind of the
classic scientific method.
It's maybe taught in middle
schools throughout the country.
Is this right?
Is this truly how science works?
Well, I wouldn't say it's
true, in terms of a step one,
step two, step three part of the process.
It's not like, "I'm a scientist.
"Today I'm on step one, I'm gonna observe.
"Tomorrow I will find a pattern.
"Step three, I'll propose a hypothesis
"to the day after that."
No, no, forget about it.
These are things which must be happening
for the activities of a group of people
to keep together be called a science.
That's a key idea here.
There are scientists
who totally specialize
in all their whole career, they're just
coming up with hypotheses.
They're doing theoretical work.
Or they'll specialize in observations,
they do observations, that's what they do.
Others do experimental, where you know,
we specialize a ton in the sciences.
So this is all going on.
However, in order for a group of people,
the activities of a group of many dozens,
hundreds, thousands, hundreds of thousands
of people all around the world,
in order for this group as a whole
to say, "Okay, together this
is a scientific community.
"These people are doing science."
In order for that to be true,
then you must have people
who are observing and people
who are proposing hypotheses
and people who are testing these things.
And so I would say, the
scientific method is true
if you apply it on a global scale.
There are plenty of
scientists who never get
to every single step in
the scientific process,
and it's certainly not
done in a linear fashion.
You don't do step one, step
two, step three, step four.
Constantly, all the time,
you have different people
observing and testing
and proposing hypotheses,
denying them.
And by testing and observing
these, well you're making
more observations, so this
is a little bit of a cycle.
You're testing this
through more observations,
so these two steps, in a way,
are really the same thing.
There's the general
observations, observations
to test hypotheses, and well,
these are all interconnected.
So you constantly got these things
going together in a cycle.
So these are kind of the essential ideas,
the essential steps of
the scientific process.
And of course, I gotta
mention the importance
of math in all of this,
that science requires us.
So again, gotta talk about math.
Math is huge.
Especially in astronomy,
in the physical sciences.
Astronomy, physics, these
sorts of things, chemistry.
Shoot, even biology these
days includes a ton of math.
So mathematics is a
necessary and essential part
of the scientific process.
So when we say observe, what we mean
is we measure specific numbers.
Specific numbers.
When I propose a hypothesis,
that's not just some idea,
some set of words to do that.
Usually, a hypothesis in
astronomy, I'm talkin'
about a set of equations.
Hypothesis.
Or, you know, a grown up
hypothesis that's really worked
a ton all over the place.
Well that becomes a theory.
Theory, this is a mathematical thing.
These are equations
or other mathematical structures.
And from these, what do I do?
I can then predict
specific, precise numbers
and if this theory is right, I can go out
and measure this star.
And well, because this star is a mass
of two times the mass
of the sun, its surface
temperature should be exactly this.
And its total luminosity
and the total energy
it's putting out should be exactly this.
And then I go out and
measure those things.
And if I have a theory which can predict
those specific numbers
before I measure them,
and it's right, then
that's taken seriously.
That's the real evidence behind this.
So I'm observing specific
numbers, my hypotheses
are equations, systems of equations,
other mathematical structures.
And then the testing.
The testing of a theory,
the testing of a hypothesis
means, take the theories predicted, purely
from equations, and could
these numbers predicted
from equations, measure them in reality
and compare them to each other.
And if the hypothesis predicts numbers
that are the same as the ones we observe,
then we take it seriously
and test it some more.
And if it works, if it
works all over the place
then we call it a theory.
And a theory is therefore
a set of equations
that allow us to predict a
wide variety of phenomena.
If it predicts a lot of specific numbers,
I can go out and verify.
And when I talk about the big bang theory.
The big bang theory isn't just some idea.
You've heard it summarized
in the newspaper,
on television, or something like that.
The big bang theory isn't just some words,
it's a set of equations that
makes specific predictions
about how our universe
began and how it works
and how all these things go.
So this testing sorta thing
means comparing numbers.
Comparing numbers.
You compare the numbers that come out
of your theoretical
equations and you compare
the numbers that I
observe with my telescope
and my light meter.
And if the numbers match,
then that's considered
strong evidence.
That's why we use so much
math in the sciences,
because math is about details.
What could be more specific and precise
than a specific number?
And so if we can get the numbers to work,
then we say, "Hey, my
theory, my hypothesis
"just may have something to it."
And that's my quick summary
of the scientific process.
What it is that makes science work
and how it's become such
a fantastically successful
social movement.
How it's become such a
fantastically successful
enterprise is because all sciences
have these ideas, these
steps, these processes
going on, being done by different people.
Wonderful.
