Dublin Back

I’m just back from a flying visit to Dublin, where I gave a talk yesterday at a meeting of the Astronomical Science Group of Ireland (ASGI), an organization which promotes scientific collaborations between individuals and institutions on both sides of the border between Northern Ireland and the Republic of Eire. The venue for the twice-yearly meetings moves around both countries, but this time it was held in the splendid environment of Trinity College, Dublin.

It turned out to be an easy trip from Cardiff to Dublin and my first opportunity to try out Cardiff’s fine little airport. A small airline called Air Arann operates the route to Dublin from there, and it all went to schedule despite the plane having to struggle against a 70 mph head wind across the Irish sea. For our small propeller-driven plane, that made a signficant difference to the flying time.

Arriving in Dublin on Thursday I had time to have a nice dinner before settling in to my hotel in the Temple Bar region of the city. There’s a huge concentration of bars and nightclubs there and it’s a traditional area for Stag and Hen Parties. There was plenty of evidence of drunken debauchery going on into the early hours of the morning, which remind me of the way the Irish rugby fans carried on last weekend in Cardiff.

Anyway, the meeting itself was interesting with a wide range of talks most of which were given by PhD students. I enjoy meetings where the younger scientists are encouraged to speak; too many conferences involve the same people giving the same talk time after time. Solar Physics was particularly  well represented, and I learned quite a bit about about things that are far from my own province. 

There isn’t much actual cosmology done in Ireland (North or South) so my brief as invited speaker was to give an overview of the current state of the field for astronomers who are not  experts in cosmological matters. I therefore gave a summary of the concordance model which I’ve blogged about before and then made some comments about things that might point to a more complete theory of the Universe. I also mentioned some of the anomalies in the cosmic microwave background that I’ve also blogged about on here.

I usually use this piece of Hieronymus Bosch The Last Judgement to illustrate my feelings about the concordance model:

das_letzte_gericht

 

 
The top part represents the concordance cosmology. It clearly features an eminent cosmologist surrounded by postdoctoral researchers. Everything appears to be in heavenly harmony, surrounded by a radiant glow of self-satisfaction. The trumpets represent various forms of exaggerated press coverage.

But if you step back from it, and get the whole thing in a proper perspective, you realise that there’s an awful lot going on underneath that’s not so pleasant or easy to interptet. I don’t know what’s going down below there although the unfortunate figures slaving away in miserable conditions and suffering unimaginable torments are obviously supposed to represent graduate students.

The main point is that the concordance model is based on rather strange foundations: nobody understands what the dark matter and dark energy are, for example. Even more fundamentally, the whole thing is based on a shotgun marriage between general relativity and quantum field theory which is doomed to fail somewhere along the line.

Far from being a final theory of the Universe I think we should treat our standard model as a working hypothesis and actively look for departures from it. I’m not at all against the model. As models go, it’s very successful. It’s a good one, but it’s still just a model.

That reminds me of the school report I got after my first year at the Royal Grammar School. The summary at the bottom described me as a “model student”. I was so thrilled I went and looked up the word model in a dictionary and found it said “a small imitation of the real thing.”

Anyway, the talk went down pretty well (I think) and after a quick glass of Guinness (which definitely went down well) I was back to Dublin airport and home to Cardiff soon after that: Cardiff airport to my house was less than twenty minutes. I greatly enjoyed my short visit and was delighted to be asked to do a couple of seminars back there in the near future.

I was in a  good mood when I got home, which got even better when I found out that I won the latest Crossword competition in the Times Literary Supplement. And the prize isn’t even a dictionary. It’s cash!

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10 Responses to “Dublin Back”

  1. Anton Garrett Says:

    Welcome back Peter,

    Trinity College, Dublin is a great place – as is Dublin, though it’s no longer a cheap place for a night on the town. A few years ago I gave a talk on ancient Greek mathematics to a joint meeting of Trinity’s mathematics and classics societies, which was a good challenge. Do Guinness still sponsor a free glass of their product with the evening meal in Trinity’s magnificent dining hall?

    From North Shropshire it is as quick and cheap, and less hassle, to take the boat train to Holyhead as it is to fly to Dublin.

    Bosch is not, as some post-1960s art critics have supposed, a drug-crazed visionary, but a more extreme purveyor of the mediaeval Catholic view of the afterlife than other painters. They all get it wrong that God is in charge of heaven and the devil in charge of hell, though – that is a dualistic view, and according to the bible Satan will end up suffering in hell.

    I know *exactly* what dark matter and dark energy are: epicycles (ie, artifacts of the way cosmologists try to reconcile their model with increasingly conflicting data, just like geocentrists did before their model was overthrown by heliocentricity). The skill in cosmology today will be in knowing how many steps backward to take before moving forward again with a better model.

    Provided that the limitations of today’s attempts to marry general relativity and quantum field theory are honestly and explicitly acknowledged, we should obviously welcome attempts to do so. Too bad that failure to observe this caveat has led to a large amount of ‘science fiction’ in the learned journals.

    Anton

  2. telescoper Says:

    Anton,

    I didn’t mention the fact that since I last went there, for the National Astronomy Meeting in 2003, prices seem to have rocketed and it’s definitely not a place for a cheap holiday any more.

    I didn’t dine in Trinity College this time, but have done so on several occasions and did get a free glass of Guiness each time. As far as I know the tradition still stands.

    I also once stayed in a splendid guest apartment on the campus. The deal there is you write what you want for breakfast on a piece of paper the night beforehand and the housekeeper comes in and cooks it for you in the morning. How the other half lives!

    I can accept that the dark matter could well be real – there are many plausible candidates and it is a testable idea in principle. Direct evidence may come from the LHC or the particles may be found in underground experiments.

    I think Dark Energy is a different kettle of fish. To me the failure to reconcile calculations of the vacuum energy arising from quantum physics (which basically diverge) with the very low but non-zero value inferred from cosmological evidence is a fundamental problem on the same scale as the “ultraviolet catastrophe” of black-body radiation that ushered in quantum theory a century ago. The resolution is likely to be equally radical.

    I’d wager that years from now, people will look back on this era with some amusement. But that’s how science goes. It’s only by getting things wrong that you really make progress.

    And let me put in a good word for epicycles. In a sense they are right. Epicycles added to a circular orbit give you a Fourier series representation of an elliptical orbit around a different origin. Mathematically, therefore, there’s nothing wrong with them. It’s the interpretation that counts!

    Peter

  3. Anton Garrett Says:

    Peter,

    Funny that while you were defending epicycles (sort of), I was rewriting my popular talk on Ockham’s Razor, that we choose the simplest theory to fit the facts well, and that there is a trade-off between closeness of fit and simplicity of theory (a trade-off which can be made precise in Bayesian probability theory, as we both accept).

    About that cooked breakfast: I was elected onto the Fellowship of Magdalene College, Cambridge immediately before the retirement of a man who polished Fellows’ shoes, and I admit that I didn’t quite know how to treat people like that. I don’t mean treat badly, but treat at all. I am not against the concept of serving somebody (it’s the basis of my faith) but unless you are brought up with it, it’s not easy.

    Your comments that dark matter make more sense than dark energy are based on a lot more expertise than I have – thanks.

    Finally, back to Bayesianism. Isn’t it rather Popperian to say that “It’s only by getting things wrong that you really make progress”? I thought science progressed by getting things right! In practice that means finding a new theory which trounces the old in an Ockham-style analysis, as relativity trounced Newtonian mechanics for instance. Popper ultimately rejected inductive logic, which means rejecting probability (though he would have disagreed), which is in turn the only way of objectively comparing theories.

    Anton

    • telescoper Says:

      I take your point. I wasn’t meaning to be Popperian about it. What I meant to say is the most exciting stage of scientific progress seems to me when things start to go pear-shaped with a well-accepted theory. But that’s not the only kind of change that counts as progress…

      I suppose I was trying to justify the making of mistakes because I make so many myself!

  4. Anton Garrett Says:

    Totally agree Peter, there is no better time to be in a field of science than when a revolution is going on. (The opposite of society?) We physicists should tell today’s biochemists to enjoy themselves, because it is a pity to be in the midst of an exciting time and only realise it afterwards.
    Anton

  5. Hi Peter, hear I missed an excellent talk. (They could have advertised it better, was there a good turnout?).
    Re DM, I’m relieved to see your clear distinction between the status of the postulate of DM the rather more speculative Dark Energy. However, I’m puzzled by your comment “Direct evidence may come from the LHC or the particles may be found in underground experiments”. Of course – but does the bullet cluster observation not give a strong pointer to the existence of DM (if not it’s nature ?). I’m surprised there is not much discussion of these results in the media

  6. telescoper Says:

    Cormac,

    What I meant was direct evidence as the particular nature of the dark matter, i.e. whether it is a supersymmetric particle, axion or whatever. Astronomical evidence can tell us that it is there and maybe whether it is hot or cold, but not how it was produced or precisely what it is.

    Peter

  7. Thanks – Im personally hoping that it willl be a SUSY particle ! What I mean about the bullet cluster is that you don’t hear too much about it. Of course, I agree it doesn’t tell one much about the *nature* of DM, but from the initial reports, I thought the debate concerning the existence of DM was over…evidently not

  8. [...] my talk in Dublin last Friday, somebody in the audience asked me what I thought about Dark Energy. There’s some [...]

  9. [...] The other day I decided to visit a few bookshops in Cardiff in order to spend the money I won in the TLS Crossword competition. It seemed only right to use it that way. These days I seem to [...]

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