About This Cosmology Tutorial

For some years I have been a reader of popular level books on topics cosmological. The physics describing how the universe has evolved displays some remarkable cosmic coincidences. It appears that the fundamental constants of physics have to be fine tuned to near their actual values in order to produce a universe sufficiently complex in structure to support the emergence of life. Many professionals in this field regard some of these instances of fine tuning to be accurate to an truly extreme degree (e.g. 120 places of decimals).

The question which I set out to address in November 2004 was "are these cosmic coincidences real or illusory?". The question is pressing because, if real, the implications of the coincidences are extraordinary.

The most straightfoward 'explanation' of the coincidences is to postulate a Creator. Whether this constitutes an explanation or an abdication of explanation is another matter. The religious explanation appears to be the most common adopted on the web.

The only scientific game in town - whilst it is available in many subvarieties - involves very large numbers of alternative universes. The most objectionable variety come down to this: "A means of contriving that this complex universe should arise spontaneously, despite having an apparent probability of occurrence of (say) 10^-120, is to envisage that the universe is actually just one of an ensemble of 10^120 or more universes, each arising at random. That way you'll probably get one universe like ours". This is the "anthropic" perspective. One can argue about what "at random" means. Quite what and where these alternative universes might be varies, and is most often not clearly defined. Their general characteristic is to be causally disconnected from this universe, or very nearly so. A nauseating superfluity of either parallel or precursor universes is required. As an explanation it does not impress. A more flagrant violation of Occam's Razor is hard to imagine. If the other universes in the multiverse are unobservable in principle, then one has to ask whether such ideas are scientific theories at all.

A considerably less objectionable variety of the "many universes" idea relies upon a form of natural selection. By invoking some form of Darwinian selection process, a directed means of climbing Mount Improbable could occur. This could be expected to dramatically reduce the degree of "nauseating superfluity" of other universes. Such a process might provide a more reasonable means of arriving at a complex, life-supporting, universe - in much the same way that terrestrial biological evolution occurs despite the improbability of creating life by mixing the chemical ingredients in a cosmic cocktail shaker.

The majority of cosmologists appear inclined to believe in the multiverse in some form. Probably the most respectable theories currently in vogue are the various varities of eternal inflation.

Given the weakness of the scientific position at present (my view), the Creationists must be permitted a prima facie case. Believe me, it pains me to say it. However, do we have to decide between the two at all? Are we sure that there really are any cosmic coincidences? This is the question which I set out to address. I am in the middle of doing so. My progress so far is described in "Cosmic Coincidences". The recurrent question in these investigations is "if the set of universal constants {Xi} took different values, what effect would it have on the universe?" To address such questions it is necessary first of all to be able to calculate correctly the conditions in this universe. Consequently I had firstly to teach myself enough cosmology and astrophysics to be able to carry out this programme.

The cosmology 'tutorial' is essentially just a set of notes which I compiled in the process of this self-study. The order of the Chapters represents the order in which I learnt things. The occasional interstitial 'B' Chapter indicates a topic learnt later, and inserted in a roughly logical place. Since I was attempting to explain these things to myself, the approach is idiosyncratic. Anyone out there with thought processes roughly aligned with mine (God help you) may find these notes useful.

Any comments welcome, especially any errors. Contact me from here

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Cauldron of Starbirth, Centaurus A, E.J.Schreier, 1997-8