A universe fine-tuned for life?

I recently came across this summary of four elements of the fine-tuning argument.  It occurs in the printed text of Alister McGrath’s 2009 Gifford Lectures, delivered at the University of Aberdeen, in Scotland:

1. If the strong coupling constant were slightly smaller, hydrogen would be the only element in the universe.  Since the evolution of life as we know it is fundamentally dependent on the chemical properties of carbon, that life could not have come into being without some hydrogen being converted to carbon by fusion.  On the other hand, if the strong coupling constant were slightly larger (even by as much as 2%), the hydrogen would have been converted to helium, with the result that no long-lived stars would have been formed.  Since such stars are regarded as essential to the emergence of life, such a conversion would have led to life as we know it failing to emerge.

2. If the weak fine constant were slightly smaller, no hydrogen would have formed during the early history of the universe.  Consequently, no stars would have been formed.  On the other hand, if it was slightly larger, supernovae would have been unable to eject the heavier elements necessary for life.  In either case, life as we know it could not have emerged.

3.  If the electromagnetic fine-structure constant were slightly larger, the stars would not be hot enough to warm planets to a temperature sufficient to maintain life in the form in which we know it.  If smaller, the stars would have burned out too quickly to allow life to evolve on these planets.

4.  If the gravitational fine-structure constant were slightly smaller, stars and planets would not have been able to form, on account of the gravitational constraints necessary for coalescence of their constituent material.  If stronger, the stars thus formed would have burned out too quickly to allow the evolution of life.

Alister E. McGrath, A Fine-Tuned Universe: The Quest for God in Science and Theology (Louisville, KY: Westminster John Knox Press, 2009), 92-93.

At the time this book appeared, Alister McGrath was Professor of Theology, Ministry, and Education and Head of the Centre for Theology, Religion, and Culture at King’s College, London.  Currently, he holds the Andreas Idreos Professorship in Science and Religion in the Faculty of Theology and Religion at England’s University of Oxford.

He holds a Doctor of Divinity degree, as well as a doctorate (D.Litt.) in intellectual history.  Prior to those two doctorates, though, he had already earned a doctorate (D.Phil.) in molecular biophysics.  All three of his doctoral degrees are from the University of Oxford.