Scientific laws and theories serve distinct purposes. A scientific law, for example, predicts the consequences of certain starting points. A theory, on the other hand, might make similar predictions but also offer an explanation for why those predictions are true.
Laws are predictive and descriptive; theory proposes explanations. A law might state that two variables are always directly proportional to one another, but a theory would offer an explanation for why that is the case. That’s the simple answer. But it’s not always that easy to understand the difference between a law and a theory. Let’s take a closer look.
Law
Law is a generalization of several observations compiled after a certain number of events. When the law is established, there are no explanations or exceptions. It’s an evident fact recorded as a result of observations. Law is a rule that governs the behavior of a phenomenon.
The law is:
- The mathematical explanation of a natural phenomenon.
- Law is accepted by all scientists.
- Law is a certain truth and never replaced.
Example: Law of motion, Law of independent assortment.
Theory
A scientific theory is a system of knowledge that describes and explains a certain set of phenomena, provides justification for all formulated provisions and reduces the laws discovered in a separate field to a single basis.
For example, molecular kinetic theory explains phenomena whose nature is related to the structure of matter.
In physical science, four fundamental theories can be distinguished: classical mechanics, molecular-kinetic theory, electrodynamics, and quantum theory.
The theory is:
- The best possible explanation of a natural phenomenon.
- There can be many theories for the same phenomenon.
- Theory can be replaced with a better one.
Example: Theory of relativity, Germ theory of disease.
We can infer from the preceding discussion that the law is a mathematical description of a natural occurrence, whereas a theory may be the greatest conceivable explanation for a natural event.
Which best explains how Ivanovski’s work led to a change in the germ theory?He tried to promote his hypothesis as a law.
He used a new experimental method to test his hypothesis.
He used a more powerful bacterial strain than other scientists had.
He obtained results that confirmed what other scientists were thinking.
What do hypotheses, theories, and laws have in common?
data
predictions
explanations
observations
Gregor Mendel was the first scientist to use statistics to analyze scientific data. Before Mendel’s experiments, scientists believed that organisms acquired traits from their environment and passed them on to their offspring. After Mendel’s discoveries were accepted, scientists realized that traits passed to offspring were the result of genes being passed from parents to offspring. This is an example of:
a theory changing because a new scientific method was developed.
a law changing because a new scientific method was developed.
a hypothesis changing because a new scientific method was developed.
an observation changing because a new scientific method was developed.
Which is the correct order in the scientific process?
ask a question ® form a hypothesis ® make an observation
ask a question ® make an observation ® form a hypothesis
make an observation ® form a hypothesis ® ask a question
make an observation ® ask a question ® form a hypothesis
The development of a new experimental method is most likely to change a theory if it makes it possible to:
analyze samples when they are frozen.
perform the experiment in a different lab.
obtain and analyze results more quickly.
study a larger sample size than before.
Gregor Mendel demonstrated that traits are passed from parents to offspring independently of one another under all circumstances that he tested. All other genetics researchers have observed this as well. Based on this information, the statement “traits are passed from parents to offspring independently of one another” is
a law.
a hypothesis.
a theory.
an observation.
How does a law differ from a theory?
A law is a theory that has been proven to be true and universal.
A theory is a group of hypotheses that prove a law is true.
A law is a statement of fact, but a theory is an explanation.
A theory is a proposed law that has not yet been peer reviewed.
Which occurs directly before forming a hypothesis?
proposing a law
drawing a conclusion
developing a testable question
analyzing experimental data
A testable hypothesis could be formed from which question?
Are bass more active in the daytime than at night?
When whales jump out of water, are they happy?
Are red tulips prettier than tulips of other colors?
Why are gerbils more popular as pets than hamsters are?
In which situation would new technology be most likely to cause a change in an existing theory about new structures a cell?
The new technology makes it possible to detect and analyze a structure more rapidly.
The new technology allows scientists to confirm the presence of an existing structure in a cell.
The new technology makes it possible to produce additional structures that were not previously there.
The new technology allows detection of a structure that could not be detected previously.
How should you test a hypothesis?
by writing a mathematical equation
by making a single observation
by performing a controlled experiment
by answering a series of questions
