Perspectives on Life in the Universe

BASED IN THE FACULTY OF SCIENCE, Te Ao Mārama is one of a handful of organisations and institutes worldwide interested in the deep, simple “fundamental” questions that are hard to answer and which transcend traditional disciplinary boundaries. Its name means the “world of life and light”, the idea of breaking into light from darkness, and it is committed to working on these questions by drawing from both mātauranga and science.

This year Te Ao Mārama was honoured to host the Vice-Chancellor’s Lecture Series – three evening lectures and a panel discussion – themed “Perspectives on Life in the Universe”. World leading scientists shared how new developments in astrobiology, astronomy, astrophysics and fundamental science are expanding our understanding of the origin and evolution of the Universe. Their research efforts range from our planet, to our Solar System, to exoplanets so far away they almost defy imagination.

Finding the planets that are not too hot and not too cold

Until 1995 the idea of life on other planets was mostly confined to science fiction. Then along came the Doppler technique – an indirect method for finding extrasolar planets – and the study of planets orbiting other stars became a key area of astronomy. Other techniques for detecting planets use reflex motion and oscillation, radio velocity, transit method and gravitational microlensing.

New Zealand is uniquely positioned for these astronomical observations because, as Professor David Bennett explains, “we need to see into the centre of our galaxy and the centre is 30 degrees south of the equator, so it is much easier to observe from the southern hemisphere”.

Being able to observe planets orbiting around other stars has helped us to develop theories on how planets form, including a standard calculation of the ‘habitable’ zone.

“If planets are too close to a sun, any water will dissipate into vapour and if planets are too far away from a sun, any water will freeze,” David says. “Planets in the habitable zone have liquid water and are often called “Goldilocks” planets…. we know that life is possible within the habitable zone, but not outside it.”

So far, we have discovered 4,000 planets but only about 30 of these planets have the temperature and conditions that could potentially hold liquid water. In the meantime, there are many other questions to explore such as ‘what is life from first principles?’.

“If we can agree on an answer to this, maybe we will find other places we should be looking for life, like the methane lakes of Saturn,” David says.

He says one of the keys to finding signs of life is spectra, “a prism that breaks light down into its different spectrums so we can see what consistency of methane, carbon dioxide and oxygen a planet
has”.

“The presence of oxygen on earth is entirely due to plants. If we destroyed all the plants, the oxygen would rapidly go away. If we observe oxygen on an earth ‘twin’ that’s a good sign that there might be life there.”

Defining life as we understand it

So how exactly are scientists tackling the search for extraterrestrial life in all the nooks and crannies of our Solar System? And is there any point in searching for life on other planets if we don’t even understand what life is, or how and where it forms?

Professor Maria-Paz Zorzano discussed the latter as one of the panellists and during her own lecture.

“What is life? We were discussing this and decided that it was pretty difficult to define,” she says. “Life is something that uses energy in a chemical form. All the life forms that we know of on earth are based on carbon chemistry – so they have carbon, hydrogen, oxygen and nitrogen.

“We also know that life forms try and fight against ageing and damage from the environment, as well as creating extra copies of themselves containing genetic information that comes from the ‘parent’.”

Defining life is an ongoing debate which leads on to questions about what life needs to thrive and flourish. There is agreement that carbon-based life forms need liquid water and nutrients, “but then we also need to investigate ‘what are the limits of life’?” says Maria-Paz.

“We are not particularly tolerant, we need protection from ultraviolet radiation, we need a moderate temperature, we need certain pressures. But there are micro-organisms we’ve investigated that can enlarge our concept of limitations.”

This is where Professor Kathy Campbell’s astrobiology research comes in (see Some liked it hot). Her focus is on life in the Universe at the microbial level, because the single cell life form is the simplest we are aware of and may leave remaining biosignatures inside rocks on other planets, such as Mars.

“Is there other life in the Universe? The answer is we don’t know that yet. We know that planets and their satellites had different conditions in the past. So, we are looking for remnants of carbon chemistry and microbial forms inside a rock – a protective environment for one or two cells to survive,” Maria-Paz says.

Building the Lego of the Universe

From a physicist’s perspective, there are two truly fundamental ingredients for life: material that is able to support complex systems and a Universe that can supply the energy needed to sustain it.

World-leading cosmologist and physicist, Professor Richard Easther, says particle physics and cosmology can shape our thinking about the existence and persistence of life in the Universe, as well as when and where it can form.

“Physicists are ‘reductionists’, we know that almost everything is made out of something else,” he says. “Everything – and I do mean everything – that we touch or see or smell or taste is made out of atoms.”

But like Lego even these can be broken down into smaller ‘parts’ – protons, neutrons, electrons, quarks, gluons, etc. Given these raw materials and the laws of physics, Richard says it is possible to build up the properties of all the atoms that exist and all the compounds they can form.

“However, it is not just enough to have the ‘possibility of atoms’ – the Universe actually has to make them. Everything we can imagine has once been part of a star and it takes billions of years to build up the supply of atoms that went into our Solar System. But if we are going to have chemistry or anything else we need chemical elements and that takes time.”

Where does that leave our quest to find the origins of life and the existence of life elsewhere in the Universe? The research is moving forward, constantly adapting and evolving in small steps and giant bounds, as Te Ao Mārama and other international initiatives confront these big questions at the frontier of science and philosophy.

Our advice while we are waiting for new insights? To quote our world-leading cosmologist, “Given that no one seems to have all the answers yet, we should take this time to appreciate that the level of emergent complexity in the Universe is truly amazing!”

Listen to Fundamental Questions on Life in the Universe - A Panel Discussion with Kim Hill.