AS Science in Society 1.11 Teacher Notes

AS Science In Society 1.11 Teacher Notes

Introduction The activity provides an introduction to ‘extraterrestrials’ by considering their many and varied forms in fiction and their possible forms, if they Science explanations exist, in reality. To do so it uses the idea of adaptation, comparing human adaptations to those of extremophiles, and then speculating on Gb One of the mechanisms alien adaptations to unknown conditions on exoplanets. central to the explanation of evolution is natural selection. There is usually variation Resources between individuals of the Part 1 same species. Some have The War of the Worlds, recording of 1938 radio broadcast, available at: characteristics which give them http://sounds.mercurytheatre.info/mercury/381030.mp3 a better chance of surviving Part 2 and reproducing in a particular Resources for researching fictional alien types. Internet access environment. suggested but use of comics and movie clips (such as the scene in the Mos Eisley Cantina, Star Wars) add interest. There is an interesting article on movie monsters at: http://fathom.lib.uchicago.edu/2/21701757/ Part 3 How Science Works Paper for student table and extremophiles artwork. Resources for researching extremophiles. Internet access is suggested. Cc An event is often Part 4 explained by relating it to a particular scientific List of exoplanet data, as at: theory (or theories). A http://www.planetarybiology.com/hz_candidates/ or the table in scientific theory Appendix 1 exoplanets. proposes an underlying process that results in BBC news item with pictures of exo-planets the observations we http://news.bbc.co.uk/1/hi/sci/tech/7725584.stm have made. Many scientific theories involve objects or The activity properties that cannot This activity will be particularly interesting to students who enjoy be directly observed. science fiction. Part 2 and, the research on extremophiles in part 3, Scientific theories do could be assigned as homework if class time is short. Teachers could not ‘emerge’ from data by a process of logical extract information on a very few exoplanets and provide this to the deduction; proposing an class to remove the need for internet research in part 4. This would explanation always allow more time for discussion of part 3 and part 5. involves imagination and conjecture. An Part 1 explanation is not just a The radio broadcast of The War of the Worlds, made in 1938, was so summary of the data, powerful that many listeners took it for a real news story and significant but is distinct from it. panic followed. It remains powerful, raising issues of the origins and significance of aliens in general culture. It is very much worth listening F this activity shows the impact to as an introduction to the topic. of science on popular culture which comes under the general heading of science and society

©The Nuffield Foundation, 2008 Copies may be made for UK in schools and colleges AS Science In Society 1.11 Teacher Notes

Suggested discussion points:  Aliens are part of a very old tradition of weird beings in stories.  Ideas of aliens from the 1930s of the kind featured in comic books, now seem fantastical to most of us, but there are many people who believe that Earth is visited by aliens. Evidence for this consists of individuals’ stories which are not replicable and have no scientific credibility.  With the coming of flight, people accepted that there might not be an upper limit to human travel, and if that is the case beings from other planets might also be able to move through space. Growing public education about the nature of planets, and that the Earth is just one amongst many, also helped to make space stories a possibility. H G Wells led the way.

Part 2 (This activity would make an entertaining short homework for some classes. ) Following the establishment of fiction that later came to be called ‘science fiction’ by Jules Verne, H G Wells used considerable imagination in creating conquering aliens with their superior technology. The human imagination in general is very reliant on existing models, both in science and in fiction. (Part of the power of mathematics in science is that it takes the human mind to new models, and these are often models for which no physical or visual equivalent previously exists.) The activity demonstrates that the creation of aliens, in written stories and in the minds of the excitable, is very dependent on starting points such as humans, animals or machines.

Part 3 Students are first asked to consider the match between their own bodies and their environment – its adaptation to the conditions in which it must exist. Conditions and adaptations include those relating to biological attack and defence and radiation sensitivity. Body adaptations - the body responds to different external temperatures in order to keep its own temperature constant – it sweats, for example, to increase the rate of energy loss, and can transfer energy by respiration in order to counteract an excessive rate of heat loss - the skin provides a line of defence against small nutrient-raiders. Human social behaviour and use of tools provide defence against larger would-be raiders (or potential predators) - leg strength, for example, is matched to the local gravitational field - human lungs can exchange gases with the air, taking in sufficient oxygen despite the fact that the air contains only about 20% oxygen (meaning that 80% of effort required for breathing is ‘wasted’ in moving nitrogen in and out) - ears - eyes - skin, including skin pigmentation Extremophiles provide a further route into considering adaptation, and also natural selection. Their existence, of course, is particularly significant to speculations about the occurrence of natural selection on diverse and distant planets.

Part 4 Students look at some data for some confirmed exoplanets. You may wish to reduce the amount of information provided by using the table exoplanets in Appendix 1 which has a few selected planets from the table on the web site. For some, an introduction along the lines of, “What is an exoplanet?” will be required. Plenty of artists’ impressions are available on the internet to support this.

Confirmed exoplanets are, at the time of writing, all significantly larger than the Earth. This is almost certainly due to limitations in identification techniques rather than due to the non-existence of smaller exoplanets. The large size of these bodies has implications for the development of life, in that only complex life forms that can withstand gravitational fields stronger than that on Earth will be able to survive. The nearest to Earth in size, of those listed is GI581.

©The Nuffield Foundation, 2008 Copies may be made for UK in schools and colleges AS Science In Society 1.11 Teacher Notes

Students can be encouraged to simply speculate on whether the listed information is relevant and then to consider its implications.  Distance from the Solar System, for example, is highly unlikely to be relevant.  Being closer than the Earth-Sun distance to a star that is hotter than the Sun (which is indicated in general terms here by the star having more mass) is likely to be a bit too hot for comfort.  Orbit eccentricity is interesting because it can give rise to seasons (whereas seasons on Earth are due to tilt and not eccentricity). High eccentricity does not necessarily make life impossible, although it’s unlikely to encourage it, especially when planets spend a long time at different distances and so have long (as well as possibly extreme) summers and winters.

The interesting point about the work is that there are a lot of 'possiblies' and 'hmmmms' - all we can do is speculate (until more detailed data becomes available).

Part 5 The scientific plausibility of imagined aliens can now be approached in the light of consideration of issues of diversity, natural selection and adaptation. Students produce a total ‘score’ for their named aliens based on the level of imagination involved in their creation, the power of their dramatic roles, and their scientific plausibility.

November 2008

©The Nuffield Foundation, 2008 Copies may be made for UK in schools and colleges AS Science In Society 1.11 Student sheets

Introduction

Humans are good at making up stories. Stories are often about winning or losing, love and hate, dreams and demons. Aliens (or extraterrestrials) make good demons.

Many aliens in stories are quite similar to humans, with two forward-facing eyes, and standing on two legs. Some are based partly on humans and partly on other animals (including lizards and insects). Other imagined aliens are created from other starting points, such as plants, bacteria or machines.

Your body is suited to conditions on Earth. For example, your body can withstand a pressure of about 100 000 Pa. It’s doing that all of the time, thanks to the air pressing on you. On very high mountains you nose might bleed because your internal pressure is too big compared with the air pressure acting on you. In space (without a space suit) this internal pressure will rip open your skin and burst your eyeballs. You are not adapted for conditions in space. Aliens who have a home planet that is different from ours are not likely to be comfortable with conditions here.

Scientists have now discovered several hundred exoplanets. These are planets in orbit around stars other than the Sun. But they do not all lie in the ‘goldilocks zones’ of their star neighbourhoods, where light from the star is ‘just right’ for keeping average planet temperature at a suitable level for life to exist. The conditions on these planets are likely to be very different from the conditions here on Earth.

The activity

Part 1 The War of the Worlds

One of the first ‘aliens’ stories is The War of the Worlds, written by H G Wells in 1898. Forty years later a radio station in New York broadcast the story, with actors playing radio reporters and scientists as if they were ‘live’ at the scene of events. A lot of people thought that they were listening to a real news broadcast, and many tried to get away from the areas concerned. Listen to a recording of the 1938 radio show.

Discuss:  Why do aliens make a strong story?  The idea of an alien invasion was plausible enough in 1938 to cause real panic. How plausible is it to us, more than 100 years after the story was first written, that such an invasion could happen?  Why were there no stories about aliens until about 1900? Did alien stories become common because of the success of the early stories like War of the Worlds, or because people were becoming more educated about space in general?

Part 2 Alien imagery in fiction

Find some images of science fiction aliens. You could use a computer to search, with key words such as ‘science’, ‘fiction’ and ‘extraterrestrial’, ‘alien’ or ‘monster’. Or you could look at some old movies or comics.

Collect or look at as many images of different aliens as you can. Classify them in a table like this (leaving the last four columns blank for now):

Humanoid Human/animal Based on forms other starting points (such as plants or robots)

Classify at least 6 types of alien in your table. These are some to get you started (but use completely different ones if you prefer).

daleks, klingons, vogons, babel fish, cybermen, wookies

Discuss: If you were writing for a new series of Doctor Who, what would you use as starting points for creating:

 Evil aliens  Sympathetic aliens

Part 3 Adaptations in reality

Discuss: How is your body adapted to:  the temperature range -5 °C to 35 °C?  sharing your environment with organisms that would, if possible, exploit your body as a source of nutrients  strength of gravity that pulls with a force of about 10 N on every kilogram of your body’s mass?  an atmosphere that is about 20% oxygen (with about 6 x 1024 molecules of oxygen in each cubic metre of space at sea level)?  detection of low power physical vibrations?  detection of some electromagnetic radiation?  avoiding harmful effects of some electromagnetic radiation?

Extremophiles are living things on Earth that are adapted to conditions that would kill most other organisms. Such conditions include high temperature, high pressure or high acidity. Find out the name of one species of extremophile.

Make a large labelled picture of a member of the species. In your labels, explain:  What extreme conditions can it survive?  What special adaptations does it have?  Is it really very different to other forms of life on Earth, or is its basic chemistry the same?

Discuss:  Do extremophiles present a threat to human health?  Does the relatively recent discovery of extremophiles undermine the idea that change amongst living things can happen as a result of natural selection? Or does the concept of natural selection provide a mechanism that can explain how such diversity exists on Earth?

Part 4 Possible adaptation

Use data from either http://www.planetarybiology.com/hz_candidates/ or the table provided by your teacher, to identify the exoplanet in the list that is most similar to Earth. (Note that the planet that forms the top line in the table is the Earth.)

Life on Earth is very varied. Could there be even more variations of life on one or more exoplanets?

In a group, list at least five likely or possible differences between life on Earth (including some or all of humans, birds, fish, insects, plants, fungi, bacteria) and possible forms of life on the exoplanet.

Part 5 Rate your aliens

Think back to the aliens that you listed in Part 2.

Did the creator of each alien use a lot of imagination, or did they just take simple ideas from existing sources?

Do the aliens add to the drama? For example, if they are meant to be scary, are they really scary?

Could they have developed by natural selection on their home planets? Would they be able to travel and survive in the location of the story setting? That is, are they scientifically plausible?

Give each alien a score in the following complete table.

Humanoid Human/animal Based on Imagination Dramatic Plausibility Total forms other score power score score starting points (such as plants or robots)

Appendix 1 Exoplanet data

Name of Star mass Name of Planet Average Orbit Distance of star (as factor planet mass (as distance of eccentricit star from of mass of factor of planet y the Solar the Sun) mass of from star System Jupiter) (as factor (parsecs) of distance of Earth from Sun) Sol / the 1 Earth 0.0032 1 0.017 0 Sun ChaHa8 0.74 ChaHa8 b 18 1.0 0.49 34.6

GL581 0.31 GL581 c 0.0158 0.073 0.16 6.26

UpsAnd 1.27 UpsAnd d 3.95 2.51 0.242 13.47

55 Cnc 1.03 55 Cnc e 0.034 0.038 0.07 13.02

HD142415 1.09 HD142415 1.62 1.05 0.5 34.2 b 14 Her 0.9 14 Her b 4.64 2.77 0.369 18.1

Star mass: Stars with mass larger than the Sun tend to be hotter than the Sun.

Planet mass: Note that all of the exoplanets are larger than the Earth.

Average distance of planet from star: The distance of the ‘goldilocks zone’ from a star depends on how hot the star is.

Orbit eccentricity: The Earth has low orbit eccentricity, which means that its orbit is approximately circular.

Source: The Extrasolar Planets Encyclopedia copyright of Jean Schneider, Paris Observatory