Skip to main content

The Goldilocks Enigma – Paul Davies ****

The anthropic principle, depending on whom you believe, is either the most profound idea in cosmology or a load of old hokum. Essentially the principle says that the universe has to be the way that it is otherwise we would not be here to observe it in the first place. This may at first glance appear to stating the obvious – but this idea has very deep implications about our universe.
In particular, some cosmologists have appealed to the principle to help explain what is know as the fine tuning problem. The constants of nature such as Planck’s constant, the speed of light, the universal gravitational constant, etc. have very precise values, in fact if some of these constants were even slightly different (i.e. to the nth decimal place) then the physical nature of our universe would be radically different to what it is. Stars, galaxies and in fact life itself would not be able to exist in such conditions. The problem is, of course, why these constants should have values that have made our universe so hospitable to life.
This is a question that science authors have written about before, most notably Martin Rees’ two superb books: Just Six Numbers, and Our Cosmic Habitat. These two books put forward the hypothesis that we live in a multiverse – where the constants of nature have all possible values – leading to some universes being hospitable to life like ours, and others being completely unfriendly to life.
Davies’ book is far more ambitious and sweeping in providing an overview of the anthropic principle than Rees’ work. He considers several explanations including the possibility that we live in a computer simulation, an infinite sea of ‘habitable regions’ in a single universe as predicted by inflation theory, and the possibility of the universe obeying a self organizing principle. The most remarkable suggestion though is Davies own idea that revolves around the delayed choice experiment.
A thought experiment first proposed by John Wheeler, this is a variation of the famous double-slit experiment, except that the detector screen can be removed at the last moment, directing light into two remote telescopes, each focused on one of the slits. In a conventional double-slit experiment, the light acts as waves, causing interference patterns, if no check is made as to which slit a photon goes through, but acts as individual, non-interacting photons if the photons’ paths are checked. In Wheeler’s version there is a ‘delayed choice’ for the observer, not making the decision on which way to observe until after the light has passed the slits. Physicists are currently working on a real version of this experiment, and in fact Wheeler himself suggested an astronomical equivalent of his delayed choice set up – which may give observational weight to his idea.
Davies suggests that our universe may well operate in a similar ‘delayed choice’ manner and that the observations we make now have retroactively fixed into place the constants of nature which existed in a ‘fluid’ state shortly after the big bang.
Unfortunately the material that gets to the heart of the book’s subject matter only takes up its second half. The first half is a very readable account of the current state of big bang cosmology and how it leads to the anthropic principle, but readers who are familiar with these ideas may find the first half of the book a little long winded. Nevertheless this is an excellent read, though some might find Davies’ own ideas at the end of the book a bit impenetrable and improbable.
Paperback:  
Review by Scotty_73

Comments

Popular posts from this blog

Cosmology for the Curious - Delia Perlov and Alex Vilenkin ***

In the recently published The Little Book of Black Holes we saw what I thought was pretty much impossible - a good, next level, general audience science title, spanning the gap between a typical popular science book and an introductory textbook, but very much in the style of popular science. Cosmology for the Curious does something similar, but coming from the other direction. This is an introductory textbook, intended for first year physics students, with familiar textbook features like questions to answer at the end of each chapter. Yet by incorporating some history and context, plus taking a more relaxed style in the writing, it's certainly more approachable than a typical textbook.

The first main section, The Big Bang and the Observable Universe not only covers basic big bang cosmology but fills in the basics of special and general relativity, Hubble's law, dark matter, dark energy and more. We then move onto the more speculative (this is cosmology, after all) aspects, brin…

Astrophysics for People in a Hurry – Neil deGrasse Tyson *****

When I reviewed James Binney’s Astrophysics: A Very Short Introduction earlier this year, I observed that the very word ‘astrophysics’ in a book’s title is liable to deter many readers from buying it. As a former astrophysicist myself, I’ve never really understood why it’s considered such a scary word, but that’s the way it is. So I was pleasantly surprised to learn, from Wikipedia, that this new book by Neil deGrasse Tyson ‘topped The New York Times non-fiction bestseller list for four weeks in the middle of 2017’.

Like James Binney, Tyson is a professional astrophysicist with a string of research papers to his name – but he’s also one of America’s top science popularisers, and that’s the hat he’s wearing in this book. While Binney addresses an already-physics-literate audience, Tyson sets his sights on a much wider readership. It’s actually very brave – and honest – of him to give physics such prominent billing; the book could easily have been given a more reader-friendly title such …

Once upon and Algorithm - Martin Erwig ***

I've been itching to start reading this book for some time, as the premise was so intriguing - to inform the reader about computer science and algorithms using stories as analogies to understand the process.

This is exactly what Martin Erwig does, starting (as the cover suggests) with Hansel and Gretel, and then bringing in Sherlock Holmes (and particularly The Hound of the Baskervilles), Indiana Jones, the song 'Over the Rainbow' (more on that in a moment), Groundhog Day, Back to the Future and Harry Potter.

The idea is to show how some aspect of the story - in the case of Hansel and Gretel, laying a trail of stones/breadcrumbs, then attempting to follow them home - can be seen as a kind of algorithm or computation and gradually adding in computing standards, such as searching, queues and lists, loops, recursion and more.

This really would have been a brilliant book if Erwig had got himself a co-author who knew how to write for the public, but sadly the style is mostly heavy…