What do students think will happen to the universe?

Title: Investigating Undergraduate Students’ Ideas About the Fate of the Universe
Authors: Mallory Conlon, Kim Coble, Janelle M. Bailey, Lynn R. Cominsky
First Author’s Institution: University of Illinois at Urbana-Champaign
Journal: Physical Review Physics Education Research 13 020128 (2017)

Most students in introductory astronomy courses have never taken an astronomy course of any kind. Instead, their astronomy knowledge is likely informed by television shows or movies, which can both vary in their accuracy of portraying space. These students will likely never take another astronomy course as introductory astronomy courses are often used to fulfill a general science requirement for their degree program. Thus, introductory astronomy courses cannot just focus on historical  developments, but should also discuss more recent topics. Today’s paper focuses on one such recent topic, the fate of the universe, and what students think about it.

We know that the universe is expanding due to dark energy. What we don’t know though is how this expansion rate may change with time and what will happen to the universe in the very distant future. We can predict what will happen to the expansion rate by looking at the Friedmann equation, which among other things, depends on the curvature of space and the amount of dark energy in the universe.  If there is no dark energy in the universe and space has a positive curvature (like the surface of a sphere), the universe could only expand so far before collapsing back on itself; this is called the big crunch. Alternatively, if the universe had no curvature (like a piece of paper) or negative curvature (like a horse saddle), the universe could expand and cool forever; this is called the big chill. If there is dark energy however, the universe will expand indefinitely, either resulting in a big chill or the universe could expand so fast, that even molecules could be ripped apart, an outcome called the big rip. Our current scientific knowledge suggests that the amount of dark energy is and will remain constant and that space is not curved, meaning the big chill is the most likely fate of the universe. However, this is not a settled scientific question.

Since it is not a settled question, students could have a variety of views on what the fate of the universe is. To answer this question, today’s authors gave students in introductory astronomy courses at three universities questionnaires about their ideas on what will happen to the universe before covering the material in class. Specifically, the questionnaire asked What is the long-term fate of the universe? and as a follow-up question, How do we know? 191 of the 254 students answered the first question and around 135 of the students answered the second question, the rest did not answer the question. The researchers then grouped similar responses and created labels to summarize the groups of responses.  As an extension of the study, questions about the fate of the universe were also included on an exam at one of the universities. These questions asked students to describe two possible scenarios for the fate of universe and discuss the conditions of the universe needed for that fate to occur. Additionally, the students were asked which scenario best describes our universe based on current observational evidence.

So what did the researchers find? On the questions given before relevant instruction, 28% of the students didn’t know or didn’t answer the question. The rest of the responses are shown in figure 1. Around 40% of  the students gave a response that is one of the three possible fates of the universe (big chill, big crunch, or big rip). Interestingly, there was a large variety in the student’s answers as 17 different categories of responses were present, suggesting students have a wide range of ideas on what will happen to the universe.

Figure 1: Student responses to  the question What is the long-term fate of the universe? Responses could fall in multiple categories so total percentage can be more than 100%. Figure 1 in paper.

Similarly, when asked to explain how we know what the long-term fate of the universe will be, 49% of the students didn’t answer or said they didn’t know. The next most popular response was we don’t know, which 23% of the students said. This response implies that scientists don’t have the evidence to explain how they know what the long-term fate of the universe is. Only 15% of the students said that we know the fate of the universe from research, science, or theory. The full spectrum of responses is shown in figure 2.

Figure 2: Student responses to the question How do we know [the long-term fate of the universe]? Responses could fall in multiple categories so total percentage can be more than 100%. Figure 2 in paper.
Across both of these questions, only 1% of the students gave a correct response, while 11% of the responses were marked as partially correct. While this degree of correctness may be expected for students who have not been formally taught the material, it does suggest that students come into the course with a wide range of knowledge on the long-term fate of the universe. For reference, the researchers were expecting a correct answer to mention that the universe is expanding due to dark energy and that the universe will end in a big chill or big rip. The support for this conclusion is from observations of the cosmic background radiation or redshift measurements of Type Ia supernova.

The researchers then looked at the similar questions that appeared on the exams for one of the courses. Unfortunately, this paper only briefly talks about these results. The authors do not describe how students answer questions about the fate of the universe or how we know after learning about it in their astronomy course. The authors do say that less than 10% of students answer correctly post-instruction, but more students attempt to answer the questions and fewer students give wrong answers.

So what can we take from this study? First, students come into science courses with a wide variety of background knowledge they have absorbed from media. The authors suggest that instructors should be aware of what students know coming into a course and try to build upon their current ideas as much as possible. Second, including current research topics exposes students to the tentative nature of science, in contrast to the usually settled nature of most material covered in an introductory course. By including current research topics, instructors could expose students to how different explanations of a phenomenon are evaluated in the scientific community.

Figures used under Creative Commons Attribution 4.0 License.

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