Experiment
An experiment is a test that a scientist carries out to find out whether an idea about the world is right. The idea being tested is called a hypothesis. According to the biology textbook Biology 2e, a researcher tests a hypothesis by carrying out one or more experiments designed to rule out one or more of the possible explanations.[1] Experiments are a central part of science: the Stanford Encyclopedia of Philosophy says that, in physics, it is experiment that provides the evidence on which our knowledge of the physical world rests.[2]
Variables and controls
Every experiment has one or more variables and one or more controls.[3] A variable is any part of the experiment that can change while it is being carried out.[4] Many experiments compare two groups. The experimental group receives the change the researcher wants to test, while the control group is the same in every way except that it does not receive that change.[5] If the results for the two groups are different, the difference must come from the change being tested rather than from some outside cause.[6]
What experiments do
Experiments can do several jobs in science, and the Stanford Encyclopedia of Philosophy notes, in its entry on experiments in physics, that a single experiment may do several of them at once.[7] Experiments do not always give the right answer: the same entry points out that theoretical calculations, experimental results, and the comparison between experiment and theory may all be wrong.[8] The branch of philosophy of science that studies the roles experiment plays is called the epistemology of experiment.[9]
The English philosopher Francis Bacon claimed that it was possible to carry out what he called a "crucial experiment" (experimentum crucis), an ideal experiment that could decide on its own which of two rival hypotheses is correct.[10]
Limits
Experiments are easiest to use in sciences such as physics and chemistry. In subjects such as archaeology, psychology and geology, repeating experiments is harder, so the experimental method is less easy to apply. These subjects are still sciences.[11]
References
- ↑ "1.1 The Science of Biology". Biology 2e. OpenStax, Rice University. Retrieved 20 October 2026.
To test a hypothesis, a researcher will conduct one or more experiments designed to eliminate one or more of the hypotheses.
- ↑ "Experiment in Physics". Stanford Encyclopedia of Philosophy. Retrieved 20 October 2026.
It provides us with knowledge of the physical world, and it is experiment that provides the evidence that grounds this knowledge.
- ↑ "1.1 The Science of Biology". Biology 2e. OpenStax, Rice University. Retrieved 20 October 2026.
Each experiment will have one or more variables and one or more controls.
- ↑ "1.1 The Science of Biology". Biology 2e. OpenStax, Rice University. Retrieved 20 October 2026.
A variable is any part of the experiment that can vary or change during the experiment.
- ↑ "1.1 The Science of Biology". Biology 2e. OpenStax, Rice University. Retrieved 20 October 2026.
The control group contains every feature of the experimental group except it is not given the manipulation that the researcher hypothesizes.
- ↑ "1.1 The Science of Biology". Biology 2e. OpenStax, Rice University. Retrieved 20 October 2026.
Therefore, if the experimental group's results differ from the control group, the difference must be due to the hypothesized manipulation, rather than some outside factor.
- ↑ "Experiment in Physics". Stanford Encyclopedia of Philosophy. Retrieved 20 October 2026.
a single experiment may play several of these roles at once.
- ↑ "Experiment in Physics". Stanford Encyclopedia of Philosophy. Retrieved 20 October 2026.
Theoretical calculations, experimental results, or the comparison between experiment and theory may all be wrong.
- ↑ "Experiment in Physics". Stanford Encyclopedia of Philosophy. Retrieved 20 October 2026.
Epistemology of experiment is a branch of philosophy of science focusing on the diverse roles that experiment plays in science
- ↑ "Experiment in Physics". Stanford Encyclopedia of Philosophy. Retrieved 20 October 2026.
Francis Bacon went so far as to claim that it was possible to perform what he called a crucial experiment (experimentum crucis), an ideal experiment of sorts that can determine alone which of two rival hypotheses is correct.
- ↑ "1.1 The Science of Biology". Biology 2e. OpenStax, Rice University. Retrieved 20 October 2026.
when it comes to disciplines like archaeology, psychology, and geology, the scientific method becomes less applicable as repeating experiments becomes more difficult.