Extra-terrestrial life is the existence of life outside of the Earth. Are we alone in the universe? So far the only life we know about inhabits our planet – Earth – but there are planets that orbit other stars in a similar way to how the Earth orbits the Sun.

You could count people's opinions at different points during the activity and see if people change their minds. First take a poll at the beginning of the activity, before any information has been seen and before any discussions. Take another poll after the group has watched the video and seen the information against extra-terrestrial life. Finally take another poll after the debate. Emphasise that it is ok to change your mind in light of new information and that this is what scientists do all the time.

If the groups are very uneven you might want to randomly put some people into the other group to make the debate more interesting.

The negative argument is known as the Fermi paradox. There is little evidence about the original incident that generated the argument, but have a look at Wikipedia for more information.

Counterarguments to Fermi's Paradox include:

  • The vastness of the Universe means other life forms are too far away to communicate or we cannot communicate for technical reasons.
  • It would be physically unlikely to make contact with other life forms.
  • They choose not to be observed
  • They are already here!


Curriculum links

Data, evidence, theories and explanations
1b. how interpretation of data, using creative thought, provides evidence to test ideas and develop theories
1c. how explanations of many phenomena can be developed using scientific theories, models and ideas
1d. that there are some questions that science cannot currently answer, and some that science cannot address.
2.1 Critical thinking and enquiry
a.  question and reflect on different ideas, opinions, assumptions, beliefs and values when exploring topical and controversial issues and problems
d. evaluate different viewpoints, exploring connections and relationships between viewpoints


Scottish Curriculum

Science - Curriculum for Excellence level 4 SCN 3-06a. Planet Earth - Space: By using my knowledge of our solar system and the basic needs of living things, I can produce a reasoned argument on the likelihood of life existing elsewhere in the universe .
SCN 4-06a. By researching developments used to observe or explore space, I can illustrate how our knowledge of the universe has evolved over time.
SCN 4-20a. Topical Science: I have researched new developments in science and can explain how their current or future applications might impact on modern life
SCN 4-20b. Having selected scientific themes of topical interest, I can critically analyse the issues, and use relevant information to develop an informed argument

Environmental Science National 4 & 5

Potentially relevant to modules: Earth's Resources (living and non-living environment components of the Earth)
Physics National 4 & 5 Potentially relevant to modules: Space (solar system and its exploration)

Is there anybody out there?

exoplanetDo you think there might be other life in the universe? Discuss!

After thinking about the information below in the 'For' and 'Against' sections, try and decide what your personal opinions are. Don't worry if you don't agree with your friends. Famous scientists don't agree on this either. Split up into two groups: those who think there is life elsewhere in the universe and those that don't.

Image: An artist's impression of a planet outside our Solar System.

Each group should have 10-20 minutes planning time to come up with a 2 minute presentation and some challenging questions to ask the other group.

Background information

For: watch the video here to learn about the techniques used to look for extra-terrestrial life and how it is improving, then read more about the search for extra-terrestrial life here.


Against: Scientists have calculated that the universe is nearly 14 billion years old. There are a vast number of stars and planets so the chances of there being life somewhere else seems quite high. However...if there was other life in the universe then some of it may be less advanced than life on Earth and some may be more advanced than life on Earth. If there were life forms more advanced than us then why haven't we heard of them or been able to detect anything from them? This argument is known as Fermi's Paradox and thought to have been described by the physicist Enrico Fermi in 1950 over lunch.