Alan Guth’s ‘A Golden Age of Astronomy’ appropriately presents this golden age through the lens of the inflationary theory. Paul Steinhardt then poses a case for a cyclic universe, pulling a rabbit out of a hat with a neat application of string theory. Guth goes on to contrast these theories, accounting for the universe’s smoothness (stirred with a little complexity) and flatness through the inflationary model, drawing on much evidence and the fudge factors of dark energy and dark matter. Andrei Linde’s conversationally presented discussion on the inflationary model, leading to his eternal chaotic inflation model and anthropic considerations, is a triumph of exposition. His peppering of events over the last few decades and Soviet era science optimistically collates different perspectives in cosmology and is instructive and refreshing. Lisa Randall pulls together the current state of string theory and its relevance to the standard quantum model and cosmology. Checking edge.org indicates this was written in 2003 and some developments, for instance at the LHC, have moved on, but it is nevertheless a good synopsis. Neil Turok also employs an appropriate conversational style to invoke a role for branes in a cyclic universe which shoves aside the anthropic principle and offers an extended and very neat role for dark energy. Sean Carroll challenges theories (relativity, standard model, and Big Bang), examining their incompatibilities and extensions such as inflation, using the common sense direction of entropy. His discussion reads well, and I will follow up his publications.
The discussion then broadens with Martin Rees making a gentle and reflective appraisal of the prospects for humanity. Ranging from religion to ‘is our universe a simulation?’, his coverage includes technology, exobiology, geopolitics, exoplanets and some informed insights into scientific endeavour. His insights on targeted research are immediately challenged by Lee Smolin who examines scientific paradigms, in particular teasing out the contradictions in our perceptions of time. Leonard Susskind’s entertaining account of his contribution to string theory gaining relevance is followed by Brockman’s introduction of Susskind’s email stoush with Lee Smolin over the credibility of the Anthropic Principle. This slightly erratic discussion, inevitably so due to the reference to papers not available to the reader, coalesces into fascinating final statements advocating baby universes formed through black hole singularities (Smolin) and pocket universes evolving though eternal inflation (Susskind). Brockman exceeds Edge’s expository goal with this exchange alone, few readers will resist consulting each theorist’s background works. Carlo Rovelli argues for a constructive approach to science where adaptation of existing theories achieves better progress than capitulation of existing science, contending string theory to be an example of the latter approach. Lawrence Krauss always entertains with his blat against trendy or teleological thinking, but he is a fair man, acknowledging the overall usefulness of anything, “even string theory”, in tackling mysteries such as dark energy.
Brockman introduced a 2007 discussion between Brian Greene, Walter Isaacson and Paul Steinhardt regarding Einstein’s contribution to modern physics. This insightful discussion was dogged slightly by unconstructive point scoring on string theory. This discussion is ably extended by Peter Galison introducing his recently published (then) comparison of Einstein and Poincare. The insights on Einstein’s scientific approach are excellent, but this reader would be less generous regarding Poincare’s motives when criticising Einstein. This appraisal of broader issues is extended by Raphael Bousso to weigh up many existing theories of the universe. This exercise puts many earlier contributions into perspective and sparks the imagination as to how such a grand ‘weighing-up’ would be done.
Seth Lloyd sifts through a mosaic of steam-punk ideas, from monkeys typing to algorithmic evolution, to show how a complex universe computes. This is a fabulous concept which perhaps needed a little more teasing out from metaphor to theory in this conversation. Frank Wilczek offers some of this background, albeit more specifically a great ‘how to’ on quantum computing. Wilczek’s appraisal of physical breakthroughs so far is apt, fresh and his tone cannot help but remind one of the view that, during university lectures, a minority of students are focussing on the topic and a majority are having musings about sex. Steven Strogatz discusses his study of synchrony and its importance in biology and science generally – this might be a book plug, but I’m hooked and will be looking for it. David Deutsch’s thoughts about constructor theory seemed important but needed more than a few hints – I thought it was opaque and had to look it up elsewhere. Benoit Mandelbrot discusses ‘roughness’ with his characteristic Gallic confidence.
This thematic set of conversations is inspiring, as Brockman would intend. His assembly of ideas from key thinkers into a conversational format is effective. An index would have been helpful, probably so would ‘Further Reading’ and ‘Notes’, but more importantly, the introduction of readers to the works of these key thinkers, works which will have these helpful reference features, is the grander goal.