David S. Stevenson

Life Jim, But Not as We Know It

What forms might life take elsewhere in the universe, and would we recognize it if we saw it? Those are the questions posed by this chapter. Although many of the cases examined may simply be variants of life on Earth, we’ll ask whether the truly fantastic is possible, given the constraints on what it means to be alive.

A Thesis on Life, the Universe and Almost Everything

Throughout this book we’ve presented life as something of an inevitability. Life began on Earth not because of a series of random, rare events but because there was a high probability that its chemistry would naturally produce systems that we would recognize as living organisms. The chemicals used by life on Earth are ubiquitous in the universe, and thermodynamic entropy demands the growth of self-replicating structures through the release of energy (Chaps. 3 and 4). In this context, can we consider life as an inevitable outcome elsewhere (perhaps everywhere) in the cosmos if the chemistry is appropriate?

The Origin of Life on Earth

Chapters 1 and 2 defined what we might consider living and non-living—and refined ideas of how life might acquire some of these characteristics. However, we did not look at how life might have emerged.

Life as the Evolution of Information

There is a myth that is utterly entrenched in society. This myth serves to misinform many of the reality of evolution. This myth is taught widely in schools, on television and sadly pervades much of the Internet. The myth concerns entropy and equates entropy with disorder. Since the word “disorder” became synonymous with entropy, its use to discredit evolutionary processes has become widespread. However, as this chapter aims to show, without entropy, the processes of evolution through natural selection would simply not occur. This chapter demonstrates that rather than thwarting evolution, entropy is the king of evolution through natural selection.

What Is Life

The question of the nature of life, and therefore of the soul and spirit, has troubled people since time immemorial, especially if they are seen as essentially immaterial. It is suggested that the soul may be understood as the process of life, the inter-relationship between the parts of the body, and that the spirit is the driving force that motivates life. This is then related to the role of God in life, and particularly as the originator of new life in salvation.

Ultimately, Can Life Survive?

Over the last few chapters we’ve examined the development, elaboration and potential we or our surroundings have to eliminate life. It’s now time to consider how life must, inevitably, be defeated, not by us or the random collision of Earth with another object, but by the death of the universe. The universe, as a vessel for the creation of life, has an effective finite age—at least in terms of its ability to support life. Although we might hop from planet to planet to avoid an Earthly Armageddon, ultimately, life will not find a way.

Agents of Mass Destruction

Let’s imagine that we actively wanted to wipe out life on Earth—or simply to eliminate the dominant species, us. Given what we already know about how life has weathered the various storms nature has thrown at it, exterminating life might seem rather tricky. However, sterilizing a planet can be done, albeit with far greater difficulty than it would be to terraform a lifeless one.

Life’s Grand Themes

Chapter 1 introduced the broad themes of life. This chapter examines how nature supports its precious cargo.

The Mysterious SN 2005ap and Luminous Blue Flashes

What’s blue, distant and very, very brilliant? With a growing litany of supernovae, one might imagine the discovery of another bright supernova in 2005 would simply add another chapter to this expanding tome, one which would soon fall into line with at least one of those already characterized. However, SN 2005ap proved to be a very troublesome supernova indeed – and soon it wasn’t alone.

Electron-Capture Supernovae

What have some stars got in common with gamblers? Admittedly the answer may not seem obvious at first. However, the clue to solving this riddle lies with the fate of a class of transitional stars. These celestial bodies demarcate an evolutionary fence, separating the core-collapse supernovae and the formation of planetary nebulae. They present huge computational headaches for astrophysicists. Their fate is determined by two competing forces: core growth and mass loss from the bloated envelope of the star. Both forces are acting at very similar rates in these finely balanced stars, and the outcome depends on which of the two forces wins out.