Cosmos visualized: Development of a qualitative framework for analyzing representations in cosmology education

Our aesthetic response to the Universe, and the complexity of concepts through which we understand it, are inherently bound together in how we meaningfully interpret its nature. Over millennia the abstracted and intangible concepts of science have been developed and communicated through a rich array of representations across a variety of modes. The interpretation of such representations is a complex multidimensional and multimodal endeavor. This is particularly an issue in education where novices can struggle to engage with unfamiliar canonical representations. Learning in a discipline can be characterized as a process of developing disciplinary discernment in apprehending and using these representational systems. Using representations concerning the geometry of the Universe, evolution of the Universe, and cosmological expansion as examples, this paper provides an in-depth overview of the various multimodal representations through which concepts in cosmology are understood and communicated. In so doing this work unpacks the salient features of these representations in order to develop an underlying framework which we call the anatomy of representations (AOR). This study, in reviewing and analyzing representations in cosmology, explores this landscape of cosmology representations. This will allow for the characterization of how semiotic resources are mobilized, changed, and connections are made between various representational modes and levels, and an exploration of the landscape of cosmology and cosmology education. The AOR framework is intended as a guide for educators, including textbook authors, to support the development and interpretation of representations.

Figure 1

Image of the cosmic microwave background. This is the faint glow left over from when the Universe was around 380 000 years old. This representation was created based on data from the Planck satellite. Image credit: ESA/Planck Collaboration.

Figure 2

The underlying conceptual framework of this study brings together four theoretical frameworks of disciplinary discernment, representational competence, aesthetics and structure mapping, within the overarching theoretical lens of social semiotics.

Figure 3

Image of the night sky showing the Milky Way galaxy. Image credit: Saeed Salimpour.

Figure 4

Image of Sombrero Galaxy (M104), a lenticular galaxy located around 29 million light years away. Our understanding of cosmology and the scale of the Universe drastically altered when it was determined that objects (galaxies) like M104 were objects (galaxies) like the Milky Way, and not structures within the Milky Way itself. Image credit: HST/ESA/STScI.

Figure 5

Image of the galaxy NGC 4526, showing SN1994D (SN short for Supernova). Type 1a supernovae, which are a particular class of exploding stars, are key to measuring extreme distances in cosmology. They were also key in working out that the Universe on the large scale is undergoing accelerated expansion. Image credit: NASA/ESA, The Hubble Key Project Team and The High-Z Supernova Search Team.

Figure 6

Image of the Hubble Ultra Deep Field (HUDF). This image is a sight to behold, covering a patch of sky about $1/10$ the angular diameter of the full Moon. The angular diameter of the full Moon is ½ degree. The image contains an estimated 10 000 galaxies, in a patch of the sky that appeared “empty.” Images like the HUDF are vital in providing a comparison of the evolution of galaxies in the early Universe (high-redshift) to galaxies as they are “now” (low redshift) like M104 in Fig. 4. Image credit: NASA, ESA, and S. Beckwith (STScI) and the HUDF Team.

Figure 7

Antares and the Rho Ophiuchi dark cloud. One of the early works of David Malin, combining black and white astronomical images (glass negatives), taken in different filters. Image credit: David Malin/AAO/UKS (1979).

Figure 8

The landscape of representations in cosmology, showing the number of representations and the various concepts they encompass categorized according to the four dimensions: Size and scale, spacetime location, composition of the Universe, and evolution of the Universe.

Figure 9

A visualization showing distribution of the representations for each target audience level (Public outreach, high school, undergraduate, postgraduate, and professional) across the four dimensions, as a percentage of the total number of representations $n=247$. The darker shades represent higher percentages.

Figure 10

A visualization showing the distribution of representations communicating specific concepts in cosmology at each of the target audience levels (public outreach, high school, undergraduate, postgraduate, and professional), as a percentage of the total number of representations $n=247$. The darker shades represent higher percentages.

Figure 11

Characteristics of representations (“Reps”).

Figure 12

The anatomy of representations theoretical framework. The reader begins at the outermost layer and gradually works their way to the core. The coloring indicates that the first two layers are related to categorization of representations (oranges), while the inner two layers are a deeper exploration of representations (blues). An interactive version of this is available at https://www.untangleduniverse.com/aor/.

Figure 13

One variation on the range of representations showing the Geometry of the Universe. Image credit: NASA/WMAP Science Team.

Figure 14

One variation on the range of representations showing the evolutionary timeline of the Universe. Image credit: NASA/ESA.

Figure 15

Another variation of the evolutionary timeline of the Universe. Image credit: ESA.

Figure 16

The timeline of the evolution of the Universe, focusing on the cosmic microwave background and the WMAP satellite which made measurements of the cosmic microwave background. Image credit: NASA/WMAP.

Figure 17

Timeline of the Universe, another variation of the representations of this concept. Image credit: Center for Theoretical Cosmology.

Figure 18

Timeline of the Universe representation as shown in a popular science article. Image credit: Hu and White (2004).

Figure 19

The expanding Universe representational analogy using chocolate chip cake. Freedman, Geller and Kaufmann [101]. Used with permission.

Figure 20

The expanding Universe representational analogy combining two representations, in the form of a translational move supporting a shift in meaning from spatial links with redshift to raisin bread analogy. Image credit: Georgia State University.

Figure 21

Another variation of the representational analogy showing an expanding Universe. Image credit: Fraknoi et al. [102].

Figure 22

Cosmological redshift, the expansion of space causing the wavelength of electromagnetic radiation to be stretched. Image credit: Freedman, Geller and Kaufmann [101]. Used with permission.

Figure 23

Expanding balloon with painted dots. Notice how inflating the balloon causes not only “space” to expand, rather also the “galaxies-cluster of galaxies” to expand. An example where teacher scaffolding is necessary to clarify analogies. Image credit: Saeed Salimpour.

Figure 24

Expanding balloon with rigid dots. Notice that in this physical demonstration of the analogy, the concept is slightly better communicated. The galaxies themselves are not expanding. Teacher scaffolding is still required to make sense of a potential question that will often arise “What is the Universe expanding into?”. Image credit: Saeed Salimpour.

Figure 25

Expanding balloon analogy showing the stretching of wavelength due to cosmological redshift. Image credit: http://www.astro.ucla.edu/∼wright/balloon0.html.

Figure 26

Expanding balloon wavelength analogy. Here the aim is to communicate the concept that the wavelength of light stretches as the result of space expanding—cosmological redshift. Keen observers would highlight that the wavelength is not actually getting longer, rather the entire waveform is getting larger. Once again, the limit of analogies requires teacher scaffolding. Image credit: Saeed Salimpour.

Figure 27

Original figure from research group, showing the various scenarios relating to the relationship between the matter density (${\mathrm{\Omega }}_M$), and energy density (${\mathrm{\Omega }}_{\mathrm{\Lambda }}$). Image credit: Knop et al. [104].

Figure 28

Modified figure used in an introductory astronomy textbook. Image credit: Freedman, Geller, and Kaufmann [101]. Used with permission.

Figure 29

Modified figure used in a media release. Image credit: https://cerncourier.com/a/on-the-trail-of-dark-energy/.

Figure 30

The evolutionary timeline of the Universe. Image credit: Pritchard and Loeb [106].

Figure 31

Representations from peer-reviewed journal article. Image credit: Pritchard and Loeb [105].

Figure 32

An example of combination, using data generated representation, together with computer modeling, and the possible geometries, seen in Fig. 13. Image credit: OpenStax Astronomy Textbook modification of work by NASA [102].

Figure 33

Measurements of the cosmic microwave background in various frequencies. The data underlying these images is used to reconstruct the signal from the cosmic microwave background, which is masked by emissions from various phenomena and dust. Image credit: ESA and the Planck Collaboration.

Figure 34

Power spectrum of temperature fluctuations in the cosmic microwave backgrounds. Image credit: ESA and the Planck Collaboration.

Figure 35

Power spectrum of the cosmic microwave background, as seen in an introductory astronomy textbook. Image credit: Freedman, Geller, and Kaufmann [101]. Used with permission.

Figure 36

Power spectrum of the cosmic microwave background, as seen in a popular science article. Image credit: Hu and White [107].

Figure 37

The distribution of levels based on the disciplinary-pedagogical space. Adapted from the work of Airey and Eriksson [108].

Figure 38

The idea of unpacking representations. Adapted from the work of Airey and Eriksson [108].