Archive for the Books Category

What’s a good Cosmological Model?

Posted in Books, The Universe and Stuff with tags , , , on April 2, 2023 by telescoper

Some years ago – actually about 30! – I wrote a book with George Ellis about the density of matter in the Universe. Many of the details in that book are of course out of date now but the main conclusions still stand. We started the book with a general discussion of cosmological models which I think also remains relevant today so I thought I’d do a quick recap here.

Anyone who takes even a passing interest in cosmology will know that it’s a field that’s not short of controversy, sometimes reinforced by a considerable level of dogmatism in opposing camps. In understanding why this is the case, it is perhaps helpful to note that much of the problem stems from philosophical disagreements about which are the appropriate criteria for choosing a “good” (or at least acceptable) theory of cosmology. Different approaches to cosmology develop theories aimed at satisfying different criteria, and preferences for the different approaches to a large extent reflect these different initial goals. It would help to clarify this situation if one could make explicit the issues relating to choices of this kind, and separate them from the more `physical’ issues that concern the interpretation of data.

The following philosophical diversion was intended to initiate a debate within the cosmological community. Some cosmologists in effect claim that there is no philosophical content in their work and that philosophy is an irrelevant and unnecessary distraction from their work as scientists. I would contend that they are, whether they like it or not, making philosophical (and, in many cases, metaphysical) assumptions, and it is better to have these out in the open than hidden.

To provide a starting point for, consider the following criteria, which might be applied in the wider context for scientific theories in general, encapsulating the essentials of this issue:

One can imagine a kind of rating system which judges cosmological models against each of these criteria. The point is that cosmologists from different backgrounds implicitly assign a different weighting to each of them, and therefore end up trying to achieve different goals to others. There is a possibility of both positive and negative ratings in each of these areas.

Note that such categories as “importance”, “intrinsic interest” and “plausibility” are not included. Insofar as they have any meaning apart from personal prejudice, they should be reflected in the categories above, and could perhaps be defined as aggregate estimates following on from the proposed categories.

Category 1(c) (“beauty”) is difficult to define objectively but nevertheless is quite widely used, and seems independent of the others; it is the one that is most problematic . Compare, for example, the apparently “beautiful” circular orbit model of the Solar System with the apparently ugly elliptic orbits found by Kepler. Only after Newton introduced his theory of gravitation did it become clear that beauty in this situation resided in the inverse-square law itself, rather than in the outcomes of that law. Some might therefore wish to omit this category.

One might think that category 1(a) (“logical consistency'”) would be mandatory, but this is not so, basically because we do not yet have a consistent Theory of Everything.

Again one might think that negative scores in 4(b) (`confirmation’) would disqualify a theory but, again, that is not necessarily so, because measurement processes, may involve systematic errors and observational results are all to some extent uncertain due to statistical limitations. Confirmation can therefore be queried. A theory might also be testable [4(a)] in principle, but perhaps not in practice at a given time because the technology may not exist to perform the necessary experiment or observation.

The idea is that even when there is disagreement about the relative merits of different models or theories, there is a possibility of
agreement on the degree to which the different approaches could and do meet these various criteria. Thus one can explore the degree to which each of these criteria is met by a particular cosmological model or approach to cosmology. We suggest that one can distinguish five broadly different approaches to cosmology, roughly corresponding to major developments at different historical epochs:

These approaches are not completely independent of each other, but any particular model will tend to focus more on one or other aspect and may even completely leave out others. Comparing them with the criteria above, one ends up with a star rating system something like that shown in the Table, in which George and I applied a fairly arbitrary scale to the assignment of the ratings!

To a large extent you can take your pick as to the weights you assign to each of these criteria, but my underlying views is that without a solid basis of experimental support [4(b)], or at least the possibility of confirmation [4(a)], a proposed theory is not a ‘good’ one from a scientific point of view. If one can say what one likes and cannot be proved wrong, one is free from the normal constraints of scientific discipline. This contrasts with a major thrust in modern cosmological thinking which emphasizes criteria [2] and [3] at the expense of [4].

Another Riddle in Mathematics

Posted in Books, mathematics on December 3, 2022 by telescoper

The little paradox in probability that I posted earlier in the week seemed to go down quite well so I thought I’d try a different paradox on a different topic from the same book of paradoxes, which is this one:

It’s quite old. I have the first edition, published in 1945, but many of the “riddles” are still interesting.

Here is one which you might describe as being about “knot theory”…

It’s probably best not to ask why, but the two gentlemen in the picture, A and B, are tied together in the following way: one end of a piece of rope is tied about A’s right wrist, the other about his left wrist. A second rope is passed around the first and its ends are tied to B’s wrists.

Can A and B free each other without cutting either rope, performing amputations,  or untying the knots at either person’s wrists?

If so, how?

The Self on the Shelf

Posted in Biographical, Books with tags , on September 12, 2021 by telescoper
Financial Times Weekend Edition

In this Weekend’s Financial Times there is an article (above) about why some of us find it hard to throw away old books. This range home to me because the work involved in packing and shipping my possessions to Ireland recently would have been considerably reduced had I thrown away my books, all 25 boxes of them. The removers who did the packing mentioned that they dislike packing books because it takes so long. You have to use small boxes otherwise they are too heavy to shift but mainly it’s because books aren’t all the same size so it can be awkward to pack them efficiently.

Anyway, it would have been a lot easier not to have bothered moving them and , but I just find it very difficult throw books away. So there they are on my shelves (or part of them).

They’re arranged somewhat randomly because I just put them wherever they would fit. This is the packing problem in reverse: it’s hard to organize books by theme or author when they can differ so much in dimension that they don’t fit. For this reason I tend to arrange books by height but I can usually remember the size and cover colour so I can find them quite quickly.

The various gaps are because some books are currently on loan friends while another is on my bedside cabinet (as I realized when I was unpacking that I hadn’t read it yet and am now doing so).

My house in Maynooth came equipped with a large selection of bookshelves. Above you see half the shelves in my sitting room. The hallway is also lined with built-in bookcases; the spare room has a set of similar shelves and my study has four standalone bookcases (of the ‘Billy’ variety, for those of you familiar with Ikea). I also have a small bookcase unit in the kitchen in which I keep cookery and gardening books. All of these are full (or nearly full). That amounts to well over a thousand books altogether – and no, they’re not mainly dictionaries.

So why do I have so many books?

The FT article hits on some of the reasons. There are definitely some that I consult regularly, for different reasons. Reference books such as dictionaries are obvious examples. I also have quite a few old maths and physics textbooks which I keep because they’re useful sources of homework problems and exam questions. I dip into poetry books quite regularly too as one can read a couple of poems at a time; I have a habit of putting a volume of poetry in my pocket when I travel on the bus or train. Quite a few of these and other books have scribbles in the margins, another habit of mine.

Other books I keep because they remind me of the experience of reading them. Just as you might keep a souvenir of a visit to a foreign land, a book is a memento of a journey of the mind. That doesn’t explain however why I tend to keep books I’ve read but didn’t enjoy!

Among the other ideas suggested in the FT article is that a library of books is that they are statement of identity or even a form of bragging: you display them to impress visitors to your house with your intellect and erudition. I don’t think that works for me, though, as I don’t have many visitors and didn’t even before the pandemic. In any case I think most people aren’t likely to be “impressed” by stacks of books – they’re more likely to think you’re a weirdo.

But there’s another reason missed by the analysis in the Financial Times and that is that books actually look quite nice on shelves. Covering a wall in that way saves you the bother of having to paint it!

Found in Translation…

Posted in Books, Books, Talks and Reviews, Maynooth with tags , on August 7, 2019 by telescoper

Here I am, back in Maynooth, after taking the early flight back to Dublin from rainy Cardiff. By way of a gentle re-introduction to the habit of blogging after a gap of a week or so I thought I’d mention something I discovered when I returned:

This pleasant surprise was a package from Oxford University Press containing five copies of the new Turkish edition of my book  Cosmology: A Very Short Introduction.I don’t know if there are any staff or students in Maynooth who (a) can read Turkish and (b) are interested in cosmology but if there are please contact me and you can have a copy!

(I’m particularly intrigued by how the first two words of the sub-title are to be pronounced…)

Anyway, I thought it would be nice to show some of the other translations of this book. This one is in Arabic. I was a bit confused when I first saw this edition, because books in Arabic open the opposite way to books in English, as Arabic is read from right to left rather than from left to right.


The following are in Korean, Bulgarian, Bosnian, Dutch and Czech, respectively:






Anyway, I’m due to finish the 2nd Edition  – which will be a completely new book rather than an update – by the end of next month so hopefully there will be translations of the new version in due course!

On Bumfodder

Posted in Books, History with tags , , on June 21, 2019 by telescoper

It’s not quite the end of the week for me, as I am on duty all day tomorrow for the Summer Open Day at Maynooth University, but I thought I’d end the penultimate working day of this week with a post about a piece I read in the Times Literary Supplement a few weeks ago. I subscribe to this mainly for the crossword, but also because some of the reviews are extremely interesting.

In the May 31st issue of said organ, I came across a review of a book charmingly entitled Bellies, bowels and entrails in the eighteenth century, which is published by Manchester University Press. I’m not planning to buy a copy as it costs £96, but it I was intrigued by the review, which includes such vivid insights as

Stomachs and bellies, hiccups and flatulence dominate the last third of the book…

The thing that really caught my attention however was the issue of toilet paper. As far as I am aware, paper in a form specifically designed for the use of wiping one’s bits clean after defecation wasn’t introduced until the middle of the 19th century, but waste paper was commonly used for that purpose much earlier. In the 18th century it was apparently commonplace to tear pages out of cheap books to use as lavatory tissue, and it appears some people would buy books both to read when on the job and for cleaning up afterwards.

This practice gave rise to the word bumfodder, which the Oxford English Dictionary defines as:

  1. Toilet paper. Also occasionally: a piece of this.

  2. attributive and allusively. Worthless or inferior literature; any written or printed material that is perceived as useless, tedious, or unnecessary.

In case you didn’t know, this is also the origin of the word bumf, which the OED gives as

  1. slang (originally in British public schools). Paper (of any kind). Now rare.

  2. Toilet paper. Now somewhat archaic.

  3. orig. Military slang. Written or printed material that is perceived as useless, tedious, or unnecessary, as bureaucratic paperwork, advertising, etc. Also occasionally: worthless or inferior literature.

I have to admit I’ve used the word `bumf’ in the third sense on a number of occasions without realizing quite how indelicate is its origin.

The first instances of `bumfodder’ quoted in the OED date from the mid-17th Century, which surprises me a little because I was under the impression that paper was an expensive commodity then. By the 18th century, however, it was obviously much cheaper, presumably because of mass production, and so consequently books and newspapers were much less expensive. Waste paper was then used quite frequently not only as toilet paper but also for wrapping groceries and other goods. I should mention, however, that paper was used at toilet tissue in China as far back as the 6th Century AD, so Europe was obviously a bit behind on the matter.

Anyone who has read any 18th Century literature – the humour in which is often rather coarse – will not be surprised by the number of scatalogical jokes about bumfodder going around. Obviously I couldn’t repeat any here.

P.S. Now wash your hands please.

The Russell Library, Maynooth

Posted in Books, Education, Literature, Maynooth with tags , on August 29, 2018 by telescoper

For those of you who like lovely old libraries filled with lovely old books, here’s a picture of the Russell Library, which is on the South Campus of Maynooth University:

Library Picture

According to the website:

The Russell Library houses the historical collections of St Patrick’s College, Maynooth which was founded in 1795 as a seminary for the education of Irish priests. The reading room was designed by renowned British architect and designer Augustus Welby Northmore Pugin (1812-1852) and completed in the year 1861. The Russell Library contains approximately 34,000 printed works dating from the 16th to the mid-19th century across a range of subjects including: theology, mathematics, science, geography and history. Other important collections include: medieval and Gaelic manuscripts, archival material and incunabula (pre-1501 printing).

Precision Cosmology!

Posted in Books, The Universe and Stuff with tags , , on April 28, 2017 by telescoper

Well, look what the postman brought me today!

Hot off the press, here is a textbook by my friend and erstwhile collaborator Bernard Jones. As you will see, it even has an endorsement by me on the back cover. I think its a very fine book indeed and it will be immensely useful for cosmologists young and old alike!

Sono arrivato a Pisa

Posted in Biographical, Books with tags , , , , on August 30, 2015 by telescoper

En route to a workshop in the picturesque village of Castiglioncello, which is on the coast of Tuscany on a promontory sticking out into the Ligurian Sea, I decided to travel a day early and stay over in Pisa. I flew direct from London Gatwick to Pisa and it’s not far from the airport by train to my final destination, but despite travelling to Italy many times over the years I’ve never actually visited Pisa so I thought I’d take the opportunity to have a look around before making the short journey to Castiglioncello in the morning. In any case the cost of the flight was much lower to travel on a Sunday and the hotel I’m in is quite cheap so it seemed like a good deal. It’s lovely and warm here – 32 degrees in fact, at 7pm local time, so I had a pleasant stroll among the tourists.

Here are a few pictures to prove I was here! The first is the main road nearest to my hotel, brought back a lot of memories of my days as a student:


Now a couple of obligatory shots of the Leaning Tower. It was difficult to photograph because of the setting sun, so they’re not perfect but I was in a bit of a rush to get something to eat and, well you know, that there is little point in having the inclination if you haven’t got the time..


The final one is of the Scuola Normale Superiore in the Piazza dei Cavalieri.


I rather like the shadow of the statue, which seems to be creeping up the stairs!

Anyway, I wish you all a pleasant bank holiday back in Blighty. I hope to blog from the conference, but if I don’t get time or the wifi craps out, I’ll be back online when I return at the end of the week.

Dark Energy and its Discontents – the Talk

Posted in Biographical, Books, The Universe and Stuff with tags , , , on April 28, 2015 by telescoper

Yet another very busy day, so I just have time to post the slides of the talk I gave last week, on  Friday 24th April 2015, entitled Dark Energy and its Discontents, at the very posh-sounding Bath Royal Literary and Scientific Institution. Here is the poster




And here are the slides – though I didn’t get through them all on the night!…

A Happy Hubble Coincidence

Posted in Biographical, Books, The Universe and Stuff with tags , , , on April 25, 2015 by telescoper


Preoccupied with getting ready for my talk in Bath  I forgot t post an item pointing out that yesterday was the 25th anniversary of the launch of the Hubble Space Telescope. Can it really be so long?

Anyway, many happy returns to Hubble. I did manage to preempt the celebrations however by choosing the above picture of the Hubble Ultra Deep Field as the background fo the poster advertising the talk.

Anyway it went reasonably well. There was a full house and questions went on quite a while. Thanks to Bath Royal Literary and Scientific Institution for the invitation!