Hey it's Professor Dave, I want to tell
you about the scientific method.
What is within the domain of science?
Rocks, the ocean, the human
body, stars and planets, the list goes on.
If we want to learn about these things
we must learn about the way we learn, so
we must certainly understand the
scientific method, which is rooted in the
time of Aristotle, but truly came to
maturity around the time of Galileo and
Newton. This is the framework from which
we attain all of our knowledge about the
universe.
Some people believe that there are
things we can know that science could
never explain. But science is the study
of everything. It comes from the Latin
word that means to know.
Science doesn't currently know
everything, there are things we are
trying to figure out in every scientific
field right at this very moment. But we
know so much that we didn't know before
and every day we know a little more.
It's important to understand how the
scientific method works, and why it's the
only way to actually truly know anything
about the world that is outside your own
subjective personal experience. A certain
fraction of our culture tends to reject
science, making statements like "well, we
don't know if that's true, it's just a
theory". But these kinds of statements
reflect a deep misunderstanding of
certain concepts. Let's first define the
terms observation, hypothesis, theory, and
law, as they pertain to science. When most
people use the word "theory" in common
language, they mean a guess. But that is
actually what hypothesis is. A hypothesis
is a tentative explanation of
observations. Let's say we make an
observation about a natural phenomenon
like an object falling to the ground.
We could observe the object and how fast it
falls, and we might try to guess
something fundamental about the
phenomenon of falling. Maybe we would
hypothesize that objects fall at a speed
that is proportional to their mass, so
heavier things fall more
quickly and lighter things fall more
slowly, as that seems pretty intuitive.
We may then get an idea for some way to
test our hypothesis. An experiment is a
way that we can gather empirical
evidence that will either support or
refute the hypothesis by comparing data
to predictions we have made. In this case
the experiment is pretty obvious.
We could drop objects of varying masses
from the same point and see how fast
they fall, like Galileo is rumored to
have done from the top of the Leaning
Tower of Pisa in 1589. We might choose to
drop an apple and a feather, and the
result would seem to support our
hypothesis, but if we are clever we will
realize that we need to eliminate all
the extraneous variables. When we do
science, the ideal situation is to limit
an experiment to one independent
variable and one dependent variable.
The independent variable is the one that we
can alter at will, in this case the mass
of the object, since we could drop an
object of any mass. The dependent
variable, in this case the speed at which
the object falls, is the one that should
change its value based on the value of
the independent variable, if there is any
correlation between them. So if we are
testing how the rate of descent
correlates with the mass of the object
we must drop two objects that are
identical in every way
apart from their mass. No other variables
like shape or wind resistance should be
involved. That way all the data we
collect will be specific to our inquiry.
If we were to drop two spheres with
differing masses we would see, just as
Galileo did, that they fall at precisely
the same rate. This would refute our
prior hypothesis and force us to refine
the existing one or develop a completely
new one. If we can add to a hypothesis so
that it becomes comprehensive enough to
correlate a larger body of data with
just a couple of equations or postulates
it can become a theory.
This is how Newton arrived at his
gravitational theory. He took the data
from Galileo about objects falling on
earth as well as data from Kepler about
the orbits of the planets around the Sun
and he realized that it could all be
explained by a single concept, and
furthermore a single equation.
This equation explains the motion of any
object in a gravitational field, wether
on Earth or in space, so it correlates a
tremendous amount of data and explains
observable phenomena simply and
elegantly. We can even use this equation
to do predictive calculations, which is
how we send objects through space.
We could send a probe towards the outer
solar system using math to predict that
at a certain time the probe and a
particular planet will be near each
other so that it can take pictures of
the planet. And when that time comes
there it is, just as the math said it
would be. So a theory is not a guess.
In fact, many theories have been shown to
be consistent beyond reasonable doubt.
There is no doubt that gravity is real.
We use atomic theory every day, and if
atoms weren't real, chemistry could not
exist. So that we can do chemistry at all
makes atomic theory consistent beyond
reasonable doubt. The same can be said
for the big bang theory, evolutionary
theory, and so forth. A big misconception
is that a theory has less certainty than
a law, and that a theory would become a
law if proven to be true. This is not at
all the case. A law is a summary of
observations, which is very different
from a theory. Take gravity for example.
The law of gravity says that if you drop
something it will fall to the earth.
Every time we drop something, it falls to
the earth, so it's a law. It's just what
happens. But this law does not explain
why this happens. For that we need a
theory, like general relativity, which is
Einstein's theory of gravity that
improved on Newton's. This says that
space-time is warped around massive
objects. So the theory explains why an
object would fall to the earth as well
as why the planets revolve around the
Sun. So in reality, a theory is worth more
than a law.
Furthermore, theories must make
predictions. If it doesn't make concrete
quantitative, falsifiable predictions
about reality, it's not science. And if
the theory makes predictions that turn
out to be false, then we have to discard
the theory. That's what makes science so
powerful. If we find a theory that
correlates data and every prediction it
makes about future events is true, and to
high degrees of precision, then that
theory must have some explanatory power
about the nature of the universe. So that
is how we do science. We start with
observation, from which we formulate a
hypothesis, and then gather empirical
data through experiments. If the data
yields consistent results we might
formulate a law, or if we can organize
all the data into an equation or set of
postulates, we have a theory. And in this
way, common sense and intuition, which are
biased due to our innate desires and
limited mental capacity, don't hold a
candle to the rigorous and impartial
approach that is the scientific method.