Theory, Law, Hypothesis, Fact, and Beliefs.
In science, the order of importance of these is almost reversed: Theory > Law >
Hypothesis > Facts. In addition, each term has a specific, well-defined use.
“Fact” in Science: It may surprise you to know that a “fact” is generally used the
same way – it is an observation – but it is very specific. For example, if I drop a ball
while holding it in the air above a surface, it is a fact that it will fall to the surface.
This term is usually not used, however — we resort to “observations.” For example,
I observe that when the wind blows, a
flag will flutter.
“Hypothesis” in Science: This is an “idea” that is formulated to
explain observations (or our “facts”). In the above to examples, I
might hypothesize that there is a force that pulls on the ball,
counteracted when I’m holding it. Or that the wind exerts a force on
the flag that causes it to flutter. The purpose of a hypothesis is to
explain one or more observations in a cogent way. A good
hypothesis must be testable – it must be able to make predictions
about what would happen in similar situations – otherwise a
hypothesis can never be verified nor refuted … and it remains “just a
hypothesis.” At present, String “Theory” is really just a hypothesis.
“Law” in Science: Laws are a descriptive generalization about
how some aspect of the natural world behaves under stated
circumstances. For example, Kepler’s Three Laws of Planetary
Motion are (1) Planets travel in ellipses with one focus being the
Sun, (2) planets sweep out equal area in equal time, and (3) a
planet’s period-squared is proportional to its semi-major-axiscubed. Laws are generally made from many facts/observations and
are effectively an “elevated” level from a hypothesis. Another
example are the Laws
of Thermodynamics.
Because a Law is just a description of how something behaves and
it does not explain why it behaves that way, it is usually
considered to be below the level of a theory.
“Theory” in Science: A theory is really one of the pinnacles of
science – what nearly everyone strives to make out of their
hypotheses. A hypothesis is elevated to a theory when it has
withstood all attempts to falsify it. Experiment after experiment
has shown it sufficient to explain all observations that it
encompasses. In other words, a “theory” has never been shown to
be false, despite – usually – hundreds if not thousands of separate
attempts to break it. It explains the observations with one or more
mechanisms and, because it provides that mechanism, it is
considered to be above the level of a Law. Examples these days are the Theory of Relativity, Quantum
Mechanics, the Germ Theory of Disease, and yes, the Theory of Evolution.
I should note that theories are usually conglomerations of several different hypotheses, laws, facts, inferences,
and observations. For example, while the Theory of Evolution is a theory, various mechanisms for it are
generally still hypotheses, such as Natural Selection (though some may quibble with me over that).
Another good example of a Theory is the Standard Model of Particle Physics. This describes how fundamental
particles and forces interact. It is based upon countless experiments and observations and it rests on solid
mathematical framework. It has many different laws in its make-up (such as how particles behave, or how
forces interact) as well as many observations (such as the mass of the proton, or the energy of a tau neutrino).
A third example was partially mentioned above
– Kepler’s Laws of Planetary Motion. Tycho
Brahe and Johannas Kepler made many
detailed observations of planetary positions
over the course of many years. Kepler formed
a hypothesis about how planets moved based
upon the data. From the hypothesis, he
made predictions on where planets would be
later on. When these were confirmed, his
hypotheses were elevated to laws. Later, Isaac
Newton came along and with his Theory of
Gravity was able to provide a physics-based
framework for why and how those laws worked.
Finally, it should also be noted that nothing in science is “forever.” It is always subject to further tests and
observations. In many cases, people really do try to do this since that’s how you make a name for yourself. If
you’re the scientist who has verified for the 123,194th time that a ball and a feather fall at the same rate in a
vacuum, so what? But, if you’re the scientist that has found evidence that gravity itself is not a force emitted by
an object but rather a bending of the fabric of space itself, then, well, you’d be Einstein – a household name.
Below is the assignment on page 8 (left)
In your notebook, write out each statement and say whether it is a belief, fact, hypothesis, theory, or a law.
For every action there is an equal and opposite reaction
F = ma (force is a product of mass times acceleration
Water freezes at 32 F
The Earth is a sphere
Matter is comprised of atoms
Earth’s magnetic field is generated by a conducting fluid in its core.
There are no such things as aliens.
The positions of the planets can cause humans to act a certain way.
Black holes exist.
The Earth’s crust is broken up into plates
Some numbers are luckier than others
If abortion rates increase, then crime decreases.
Silver protects people from evil spirits
Natural selection
Momentum is the product of a body’s mass and its velocity ( p=mv)
The Big Bang
If I use bleach, then the stain will come out
If carbon emissions are reduced, then global warming will stop.