But where is everyone?
The Fermi Paradox (reported from a casual conversation between Enrico Fermi and colleagues about extra-terrestrial life, in 1950
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Alien Worlds: Planet Hunting in the Cosmos
by Lisa Kaltenegger
Published by Allen Lane / Penguin Random House books (2024), 275 pages
Introduction
Please don’t be put off by the mention of aliens! Lisa Kaltenegger is a serious scientist who is contributing significantly to the search for and analysis of planets in other star systems. In particular, she is heading up a team who are looking for the characteristics of places both inside and outside the Solar System which may be suitable for life. How do you spot a habitable new world, at such vast distances?
The author was born in Austria, and trained in both astrophysics and engineering. Early on in her career she was captivated by the search for extra-solar planets, and she writes about the events that led to become the Founding Director of the Carl Sagan Institute for Search for Life in the Cosmos, at Cornell University (where she is also Associate Professor of Astronomy). She was aware that characterising life signs requires an interdisciplinary team – including geologists, biologists, astronomers, engineers etc. – and involvement in international collaborations. Such efforts have led her to currently be part of the teams overseeing NASA missions, including an instrument aboard the James Webb Space Telescope.
Inspiration
The first part of the book covers the inspiration of Carl Sagan, the Voyager missions and the photograph of the Pale Blue Dot (the distant view of Earth looking back from the outer Solar System). If everything we have ever known and done, all human endeavour and every detail and beauty of the natural world appears as just one blue-green pixel in a photo, how would we ever spot signs of extra-terrestrial life on far distant planets? She discusses what it takes to make a habitable world, and then challenges our definitions of what life is or could be. There is an emphasis on finding rocky planets in the “Goldilocks” zone (not too hot and not too cold – about the right distance from a star to sustain liquid water on its surface. But the search is not primarily for life like “us”, but any self-sustaining, evolving life-form that would have the capability of changing its environment. Even the chemistry could be different from life as we know it. Kaltenegger was involved from the beginning of identifying extra-solar planets, and her input was crucial to the identification of the first two potential Earth-like planets, Kepler-62 e and Kepler-62 f. Her speciality was the modelling of planets – their geology and atmospheres – depending on the size and orbital distance from different types of stars. This then becomes a guide to what organisms could live and evolve in these habitats, and what the effects of such organic life could have on the atmosphere that could be detectable in the light we can observe.
Does this sound far-fetched? It is certainly visionary, and it occupies and inter-disciplinary space which was lacking. It was done in anticipation of the discovery of the now thousands of extra-solar planets that have been found, including hundreds of candidate planets in the “Goldilocks” zone. Now with JWST the atmospheres of these new worlds can be measured and, through spectral analysis, the presence of tell-tale elements and compounds can be seen. Mind-boggling technology and mind-expanding possibilities.
Discrimination
She writes in a conversational style that sometimes disguises the amount and quality of information she is getting across. And her anecdotes about conferences and international collaborations always have a point – they always illustrate an important point – and they also reveal some day-to-day realities of the life of a working scientist. There are tales of trying to find a good coffee in Vienna and terrifying bus rides in Corsica. But she doesn’t shy away from the discrimination, disrespect and distractions placed in the path of a woman scientist. It is inexplicable that men should still place obstacles in the way of eminent and super-qualified women, but that is the reality of the world in the 21st Century. Yet she has found supportive colleagues and ways to frame the rubbish thrown at her, which allow her to thrive and put aside the detractors.
I thoroughly recommend this book. Lisa Kaltenegger is an engaging figure, a brilliant and innovative scientist who has carved out a niche specialism searching for potentially habitable planets, that met a need just at just the right time. She is building a database of what these alien Earths should look like at the very time that the new telescopes and techniques were discovering them by the hundreds. Surely somewhere out there is a form of life – perhaps quite different from what sci-fi and wishful thinking has come up with – which will change our perspective on the cosmos yet again.
This book review was originally written for New Zenith, the newsletter of Vectis Astronomical Society.
Elsewhere on the Bookshelf
- Reaching for the sky – OffTheShelf (grandpops-bookshelf.co.uk)
- Bright Galaxies, Dark Matters. by Vera Rubin, Masters of Modern Physics series Springer Verlag/AIP Press (1997) – selected papers and writings of the scientist who pioneered the measurement of galactic rotation rates, which provided the evidence for the theory of dark matter; she was a lifelong advocate for women in science.
- Bright Galaxies, Dark Matter, and Beyond: The Life of Astronomer Vera Rubin by Ashley Jean Yeager (MIT Press, 2021)
- Fermi paradox – Wikipedia
- The anthropic cosmological principle by John D. Barrow and Frank J. Tipler (Oxford University Press, 1998) – two of the world’s leading cosmologists-cover the definition and nature of life, the search for extra-terrestrial intelligence
- Drake equation – Wikipedia