Tag Archives: astrobiology

The Cosmic Zoo, by Dirk Schulze-Makuch and William Bains: a book review

The universe appears to be silent. Even though astronomers have been making incredible advances — building vast new observatories, developing better techniques and analytical approaches, opening up entirely new windows on the universe — none of this has turned up any evidence of extraterrestrial intelligence. This silence is becoming deafening. Indeed, the most important question in science — to my mind, at least — is: are there any intelligent, technologically advanced civilisations out there in the universe? Or is it just us?

One can take many approaches to this question, of course, but it can be useful to think in terms of “barriers”. What barriers must be overcome in order to get from a soup of abiotic, organic chemicals to a technologically advanced species capable of disturbing the universe in a way that distant astronomers can detect? This is an interesting approach because, depending on where you place the barriers, you end up with quite different universes.

For example, you might argue that abiogenesis represents a major barrier. In other words, that the transition from non-life to life takes an unlikely sequence of events — so unlikely that life itself is vanishingly rare. This is certainly plausible. If this argument is correct then we are living in an empty universe (“empty” in the biological sense).

Or you might argue that abiogenesis isn’t an insuperable hurdle, but that the transition from a simple prokaryotic type of cell to the more complex eukaryotic type of cell represents a significant barrier. If that argument is correct then, when we go out and explore new solar systems (or when we use the new generation of incredibly powerful telescopes to study exoplanets), we’ll encounter worlds rich in microbial life but lacking in complex life.

Or you could argue that a barrier lies ahead of us, that technological civilisation itself is a self-limiting phenomenon (and it’s depressingly easy to imagine why that might be the case: nuclear holocaust, biowarfare, climate change as a byproduct of technological life…) This dispiriting thought gives rise to a quite different universe, one in which there might have been many civilisations at a similar stage of technological development to our own — but which died out before they reached the stars.

So, as you can see, it’s interesting to think about the location of barriers on the path from non-life to technological civilisation. The Cosmic Zoo: Complex Life on Many Worlds (Springer, 2017), an ambitious book by Dirk Schulze-Makuch and William Bains, is one of the best studies in recent years on this topic.

Cover of "The Cosmic Zoo"

Cover of “The Cosmic Zoo”

Schulze-Makuch and Bains look at what life does — how it functions — and make a strong case for saying that if life starts on a world then complex lifeforms will at some stage inevitably arise on that world. Many possible barriers that scientists have suggested — the development of photosynthesis, for example, or the rise of multicellularity — are minor speed bumps in the road rather than tall brick walls: the particular biochemical pathway that life took on Earth might be rare, but many different biochemical pathways are available that lead to the same functional outcome. In other words, if abiogenesis is not particularly rare event then when we start to explore the universe we’ll find worlds teeming with complex life forms. The universe will be a cosmic zoo! It’s an enthralling possibility (albeit one that highlights the possibility of a barrier lying somewhere in front of us: a universe that’s silent because it’s rare that technological civilisation survives long).

The Cosmic Zoo is clearly written, mercifully devoid of jargon, and concisely covers a vast amount of material. Every reader, having read this book, will come away with a better understanding of the current state of astrobiological thinking – and also with a much deeper appreciation of the wonders of life here on Earth.

Asimov’s humans-only galaxy

I attended the European Planetary Sciences Congress 2013 in London a couple of weeks ago, and gave a talk to a session on the societal implications of astrobiology.

It was an extremely interesting session. Although everyone there was interested in the possibility of extraterrestrial life, and indeed many participants are actively searching for signs of life beyond Earth, I felt there was a recognition that it’s entirely possible that complex, multicellular life might be rare in the universe. (One of the talkers, David Waltham, has a book out next year entitled Lucky Planet. He argues that the four billion years of good weather enjoyed by planet Earth was an unlikely, although necessary, precondition for the emergence of intelligent life. He’s as gloomy about the prospect of SETI success as I am – although both of us would dearly like to be proven wrong! Be sure to read the book when it appears.)

I was reminded of the session yesterday when I read a yet another criticism of the “humans only” universe portrayed by Isaac Asimov in his Foundation series. Such criticism was often levelled at the Good Doctor: his fictional universe contains only humans and robots, the argument goes, because he lacked the imagination to create convincing aliens. The criticism is unfair. Asimov limited his fictional universe because his editor at the time, John W. Campbell, insisted on a human chauvinism that Asimov simply did not share; better not to write about alien intelligence at all than be forced to write about human superiority in order to guarantee a sale. Besides, Asimov’s novel The Gods Themselves disproves the allegation: Odeen, Dua and Tritt are among the most convincing aliens in all of science fiction.

Even though Asimov the science writer wrote about the likely prevalence of alien intelligences, the humans-only Galaxy of his science fiction writing might turn out to be a better description of reality. That was certainly the tenor of my discussions during EPSC13.


Curiosity sets off for Mars

I worked at the Open University at the time Colin Pillinger and his colleagues were developing the Beagle mission to Mars. As we all know, Beagle disappeared without trace and became another in a long list of failed Mars missions. Today, NASA launched an Atlas 5 rocket. It was carrying the Curiosity rover. I hope Curiosity fares better than Beagle when it reaches Mars in about 9 months time.

Artist's impression of NASA's Curiosity rover

An artist's impression of NASA's Curiosity rover exploring the Martian surface
Credit: NASA

Curiosity is a huge vehicle: Beagle was about as big as one of Curiosity’s wheels! This new, super-sized rover has the capacity to do some truly interesting science. And one of the aims, of course, is to learn more about whether life ever existed on the red planet. This is a crucial question for exobiology. As I will discuss in later posts, if life on Mars got started independently of life on Earth, then we have much better grounds for supposing that life is common in the Universe.