0.1 The Language of Science

Science is the study of natural phenomena. The language used in science can be confusing sometimes. Many often use terms like fact, hypothesis, law, and theory to explain natural phenomena incorrectly. The distinction between these terms is subtle. Theories, laws, and facts can start as hypotheses when they are first proposed and before they are rigorously tested. Generally, a fact is a very elementary statement based on some measurement, such as water boiling at 100 °C (212 °F). A Law is based on a collection of individual facts and is an attempt (usually with mathematics) to relate one set of measurable quantities to another (mass, speed, temperature, viscosity). Example, F=ma, V = d/t, PV = nkT. A theory attempts to explain why certain laws exist and why certain facts are true under specific conditions. Example 1: Planetary orbits are elliptical (fact) because gravity is an inverse-square force (law), and matter operates under Newton’s Laws of Motion. Example 2: Matter is comprised of atoms, and this explains how gases behave (laws), why we have specific chemical reactions (laws), and why the Periodic Table exists (facts). Are some facts more certain than others? Water always boils at 100°C at sea level, but at higher altitudes, it boils at lower temperatures. So, every fact depends on the specific circumstances under which it was measured.

• Fact – A basic statement based on some measurement, experiment, or observation. All facts are true under specific conditions.
• Hypothesis – A tentative statement, such as ‘if A happens, then B must happen,’ that can be tested by direct experiment or observation. A proven hypothesis can be expressed as a law or a theory.
• Law – A logical relationship between two or more things based on facts and proven hypotheses. It is often a mathematical statement of how two or more quantities relate.
• Theory – An explanation for why certain laws and facts exist that can be tested to determine their accuracy.
• Belief – A statement that is not scientifically provable in the same way as facts, laws, hypotheses, or theories.

0.2 The Scientific Method

The scientific method is a step-by-step procedure that many scientists use to study the world. Often, scientists begin by observing some event or object and want to know why the event happened or why the object formed. Then, they develop a hypothesis to explain their observation and create an experiment to test the hypothesis. If the test results support the hypothesis, they develop a conclusion about the event or object. If the results don’t support the hypothesis, they go back, alter it accordingly, and retest it.

Exercise 0.2 – Everyday Use for the Scientific Method

You walk into an empty classroom and attempt to turn on the projector, but it doesn’t turn on (Figure 0.2). Use the scientific method to investigate and solve your problem. Write a statement about your issue for each step of the scientific method.

1. What is your observation?
   

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2. What is your question?
   

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3. What is your hypothesis?
   

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4. What is your data?
   

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5. What is your analysis?
   

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6. What is your conclusion?
   

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The Scientific Method and Geology

The scientific method in geology can look quite different. This is because many of the events that geologists investigate have already happened, so they can’t make any direct observations. What geologists find is the evidence left behind by that event. An example is a solidified lava flow. Geologists know the lava likely came from a volcano, but they didn’t observe the eruption and can’t test the hypothesis by creating a new eruption. They have to rely on facts they know about current lava flows and volcanic eruptions to interpret past ones. In a sense, you might consider geology to be a historical science. Geology is the intersection of the other sciences (chemistry, physics, biology, and mathematics) applied to studying the Earth.

Uncertainty

Because geologists often study past events they can’t directly observe, they must deal with uncertainty. Uncertainty in science doesn’t mean that scientists don’t believe their results or that their research is flawed. It represents natural variability in taking measurements. Often, a scientific investigation does not yield an exact measurement. Instead, scientists make repeated experiments that give a range of measurements around a central value. This is where accuracy, precision, and statistics come in (Figure 0.3). For every measurement we make, there is an actual value that we are trying to obtain. In the next exercise, you will determine the weight of a rock. Simply put, accuracy is how close a measurement is to the actual true value, whereas precision is how close those measurements tend to be to each other.

For example, if geologists are trying to figure out when a volcano erupted lava, they would radiometrically date the solidified lava flow to determine when it formed (a topic discussed later). Remember, a single measurement may not be entirely accurate; therefore, repeated measurements are necessary. If the measurements are around the same age, geologists are more certain about their results.

When doing any calculations for this or other exercises, you should consider the number of significant digits that you use. Your calculator will give you many significant digits, but these may not be appropriate for your result. The number of significant digits for your answers depends on the way you calculate. For addition and subtraction, round to the lowest significant number. For multiplication and division, your final answer should have the same number of significant digits as the least precise value given in the original problem. If you have forgotten how to do this, here is a refresher.

Extrapolation

Geologists often have limited data to work with when forming hypotheses and conducting analyses; after collecting data, they extrapolate their results. Extrapolation is a type of estimation based on current data. Imagine you are a geologist working in a tropical rainforest. Do you think you will find many rocks? Probably not, and if you do find any, they are likely to be in rivers. Here’s the cool part: whatever you figure out about these rocks, you can guess that the whole rainforest has the same rocks. That’s extrapolation!

0.3 The Scale of Geology

Geologists work at various scales, ranging from continents and mountain ranges to the atoms that comprise rocks and minerals. Some scales, such as geologic time, are so vast that they’re difficult to truly comprehend. The Earth is 4,540,000,000 years old. To put this into perspective, if you have a penny for every year the Earth has been around, you will have $45.4 million! More on geologic time in another chapter.

Additional Information

Exercise Contributions

Introduction to Science and Geology section was modified by Jessica Kristof and Ricardo L. Silva from the original Chapter 1: Introduction to Science and Geology by Daniel Hauptvogel, Virginia Sisson, Michael Comas, Somaria Sammy in Hauptvogel et al. (2024). 

References

Hauptvogel, D., Sisson, V., and Comas, M. (2024). Investigating the Earth: Exercises for Physical Geology. Houston, TX: UH Libraries