Scientific method in Geosciences: Multiple hypotheses, Multiple modes of Inquiry

How is science made in the Earth Sciences? And, why should you care? Even if you are not interested in becoming an Earth scientist, or any kind of scientist, understanding how science works is empowering. This is because science and scientific thinking are at the heart of our modern way of life and they influence every aspect of our lives. Understanding how science works can help you discern fact from fiction and inform your life choices and political decisions.

Backyard Geology

 

Modern science is based on the  scientific method, or

The  scientific method follows these steps:

• Formulate a question or observe a problem
• Apply an hypothesis
• Perform an experiment to prove or disprove the hypothesis.
• Analyze collected data and interpret results
• Submit findings for peer review 
• After repeatedly performing experiments and collecting data, devise an evidence-based theory

But these steps can look different in the Earth sciences, let’s take a look.

1. Observation, problem, or research question

The procedure begins when scientists identify a problem or research question, such as a geological phenomenon that is not well explained in the scientific community’s collective knowledge. This step usually involves reviewing the scientific literature to establish what is known and to consult previous studies related to the question.

Earth scientists can study processes they cannot observe directly. This could be because the events happen over long periods of time, happened long ago, or happened in a remote/unaccessible location. An example of the last one would be the Earth’s core. To circumvent these challenges, Earth scientists have developed strategies to test their hypothesis. These strategies make up the scientific method of geosciences.

2. Hypothesis

Once the scientists define the problem or question, they propose an answer, a hypothesis. A hypothesis must be specific, rational, and falsifiable. In addition, it is best that you formulate your prediction on the basis of other scientific work or known observations. Earth scientists often develop multiple hypotheses, not just one, and gather data and evidence from these multiple lines. To test hypotheses, scientists use methods drawn from other sciences such as chemistry, physics, biology, or even engineering.

3. Testing Hypotheses: Experiments and Revisions

The next step is developing an experiment. Earth scientists conduct classic experiments in the lab. However, an experiment can take other forms, such as:

• Observing natural processes and their products in the field and comparing them to those found in the rock record.
  • • • • For Example, a sedimentologist studies how wind moves and forms dunes and different ripples in a desert. This knowledge helps her to interpret ripple structures preserved in rocks, and even to interpret dunes and aeolian processes from images collected on Mars!
• Studying changes across time or space.
  • • For Example, an atmospheric scientist analyzes how the composition of the atmosphere has changed since humans started measuring it and compares it to geologic records and indirect observations of past atmospheres.
• Using physical models. This is more akin to the “classic experiment”.
  • For Example, a team of scientists builds a model for landslides using a long and steep ramp and flushing down different materials, and changing the ramp angle
• Using computer models.
  • For Example, climatologists develop computational models to study the climate system and make predictions. These scientific models undergo rigorous scrutiny and testing by collaborating and competing groups of scientists around the world.
• Considering multiple lines of evidence. To establish a scientific finding, all lines of evidence must converge. That means that all the results you collect using different methods must agree with the finding, the math must be sound, and the methods must be thoroughly described.

Regardless of what form an experiment takes, it always includes the systematic gathering of objectivedata. The scientists interpret this data to determine whether it contradicts or support the hypothesis (step 2). If the results contradict the hypothesis, then scientists can revise it and test it again. When a hypothesis holds up under experimentation, it is ready to be shared with other experts in the field. The findings are scrutinized by the scientific community through the process of peer review.

Examples. Multiple lines of evidence and collaboration.

 

To determine past tsunami events, scientists compare the deposits left by modern tsunamis to those found in the rock/sediment record, such as the one pictured above. But how can you be sure that a tsunami indeed deposited the sediment sequence and not a landslide, a delta, or a sudden flood? To resolve this uncertainty, scientists examine other lines of evidence, for example, are there fossils in the sediments? And if so, what type of organisms?; a landslide and a tsunami would not have fossils;  what is the age of the sediments? a tsunami would show sequences that are of the same age instead of spanning over longer periods of time; what does that tell us about the deposition rate? a tsunami event piles up sediments almost instantly! and was this event recorded somewhere else? Tsunamis have been seen across the Pacific Ocean so their deposits can be found in distant coastal areas!

The North American west coast has experienced tsunamis and earthquakes every 400 years on average due to the subduction zone (see Chapter 2). Indigenous Nations living on the west coast record being nearly wiped out by tsunamis in their traditional stories. Geoscientists, Brian Atwater and collaborators, have documented +9 magnitude earthquakes off the coast of Washington, but the scientific community met their results with skepticism. They simply could not believe the existence of such strong earthquakes!. Such an earthquake would have triggered a tsunami that could be felt across the Pacific Ocean basin! At a society meeting with geologists from all over the world, the U.S. team found out from Japanese colleagues that Japan, which has a culture of incredibly detailed historical record-keeping, was similarly hit by tsunamis in the same time frame, and they had the dates to the day! The dates of the tsunami events, which were obtained with Carbon 14, showed a perfect match between continents. Centuries of recorded observations on both sides of the Pacific, and scientific collaboration, confirmed this discovery.

4. Peer review, publication, and replication

Science is a social process. Scientists share the results of their research in conferences and by publishing articles in scientific journals, such as Science and Nature. Reputable journals and academic outlets will not publish an experimental study until they have determined its methods are scientifically rigorous, and the evidence supports the conclusions. Before they publish the article, scientific experts in the field (not part of the study) scrutinize the methods, results, and discussion; this is the peer-review process. Once an article is published, other scientists may attempt to replicate the results and use the findings to further their own research agendas. Replication is necessary to confirm the reliability of the study’s reported results. A hypothesis might be proven false in studies conducted by other scientists. New technology can be applied to published studies, which can aid in confirming or rejecting once-accepted ideas and/or hypotheses.

5. Theory development

In casual conversation, the word >theory implies guesswork or speculation. In the language of science, an explanation or conclusion made into a theory carries much more weight because experiments support it and the scientific community widely accepts it.

A hypothesis that has been repeatedly confirmed through documented and independent studies eventually becomes accepted as a scientific

A scientific theory is the best explanation after being confirmed by multiple independent experiments. Confirmation of theory may take years, decades, or even longer. For example, the scientific community initially dismissed ideas contributing to the theory of plate tectonics, such as the hypothesis of Continental Drift, most actively pioneered by Alfred Wegener in 1912.

The theory of evolution by natural selection is another example. Originating from the work of Charles Darwin in the mid-19th century, the theory of evolution has withstood generations of scientific testing for falsifiability. It has been updated and revised to accommodate knowledge gained by using modern technologies, but the latest evidence continues to support the theory of evolution.

Science is a dynamic process. Technological advances, breakthroughs in interpretation, and new observations continuously refine our understanding of Earth. We will never stop learning about our Earth. As new findings are published, we must revise and update our scientific knowledge and discard ideas that are proven false by new observations. Science is a living entity.

In conclusion, Earth scientists do not use a single, all-encompassing “scientific method”. Instead, multiple modes of inquiry respond to the complexity and spatial and temporal scales of Earth systems.

“The unique thing about the geosciences is that the knowledge, skills, and methods are brought together, refined, and evolved over time to make them most suitable for understanding the complex processes of Earth, its working in the past and the present, and its likely behavior in the future.” (Manduca and Kastens, 2012).

GeoEthics

Geoscientists must act in ethical ways to contribute to the welfare of human beings. The saying “with great knowledge comes great responsibility” holds true for Earth and environmental scientists. Earth scientists must uphold high standards in research and conduct. The research and reflection upon the values which underpin behaviors and practices between humans and Earth systems is the arena of the “Geoethics” (Di Capua and Peppoloni, 2019). The International Association for Promoting Geoethics (IAPG) provide tools to “understand the complex relationship between human action on ecosystems and the decisions geoscientists make in the discipline that impact society, including improving the awareness of professionals, students, decision-makers, media operators, and the public on an accountable and ecologically sustainable development.” Source: https://www.geoethics.org/geoethics-school

All of us, human beings, have responsibilities to Earth. We do not exist apart from this planet and our behaviors impact other people, other species, the larger biosphere, hydrosphere, atmosphere, and lithosphere. Our actions impact the Earth system. As you progress in your learning, strive to think critically and to identify ethical issues. Do not be afraid to question and discuss your observations with your instructor and with peers. Just remember to do so respectfully, considering other points of view and practicing active listening.