Sunday, January 30, 2011

Supermassive Black Holes

Two v interesting papers in Nature by John Kormendy about the growth of super-massive black holes in galaxies.

Jim Peebles in a commentary says "I would not ignore the possibility that the cosmological model requires fine adjustment to account for a relatively small detail — the galaxies."

I'm particularly interested in supermassive black holes in the middle of galaxies because it seems to me that the dependence of E[HELP] on lambda may relate to them. It seems plausible that HELPs are only likely to exist in the arms of spiral galaxies, because there are far too many violent events at and near the galactic centre for the 5bn years or so of stability that appears to be required. It's intuitively clear that increasing lambda will increase the ratio of stars in arms to stars in the centre. Thus from

#HELP = (#HELP/#ArmStars)*(#ArmStars/#SpiralGalaxies)*#SpiralGalaxies

if (#HELP/#ArmStars) doesn't depend on lambda we could get at ∂log(#HELP)/∂Λ from ∂log(#armStarts/#SpiralGalaxies)/∂Λ and ∂log(#SpiralGalaxies)/∂Λ {I am of course including barred spiral galaxies in this category}.

Spiral Galaxies are also rare at the centres of galactic clusters but these probably have too many violent events as well.

Saturday, January 29, 2011

not Evidence against fine-tuning for life

After much interesting e-correspondence Don Page has sent a revised version of his paper, which he has posted on arXiv. It is now called, quite rightly, "Preliminary Inconclusive Hint of Evidence Against Optimal Fine Tuning of the Cosmological Constant for Maximizing the Fraction of Baryons Becoming Life" and not "Evidence Against Fine-Tuning for Life". This will of course disappoint the over-excitable atheists, who have been exulting in the blogosphere that "Evidence Emerges That Laws of Physics Are Not Fine-Tuned For Life: The value of the cosmological constant suggests that the laws of nature could not have been fine-tuned for life by an omnipotent being, says a cosmologist" Ah well.

I do entirely agree that "Maximum likelihood" hypotheses of the type we have been discussing are highly interesting (especially if we can start to explore ones which involve the interaction of multiple levels) and in principle testable, and if thereby we have introduced an interesting new idea into cosmology that will be great.

BUT:
  1. These are not the same as "fine tuning" in the classic theological/apologetics sense. The point about fine tuning is "it is very unlikely that these constants would have these values by chance, and if the constants had been even slightly different intelligent life would not exist". To simplify, if L is the probability of intelligent life existing and y is the fundamental constant, which has the value 0.5 but which could in principle be uniformly distributed over the range [0,1], then L=A (y-0.5)^2 has y at MaxL, but is not fine tuned, and L= A exp(-100(y-0.501)^2) has y away from MaxL, but is fine-tuned.
  2. Nothing much hangs on them theologically. The idea that we would know the objective function that God is trying to maximise is absurd. And as Don has rightly pointed out, God could well have chosen to so love the multiverse.
  3. I'm not sure they tell us anything much about the universe vs multiverse debate. Any combination of fundamental constants by definition maximises some objective function. And unless there is some credible evidence of interaction between "pocket universes" in the multiverse, any story about an actually existing multiverse M can be re-written as one in which M is simply a set of possible universes.

Sunday, January 23, 2011

Calling of Peter and Andrew - and well done Miranda

Warmest congratulations to Miranda Hart who won two awards at the British Comedy Awards and whose brilliant series Miranda won a third.

Additive Combinatorics is a lovely book and so far I can understand it, though I'm only on Chapter One!

Sermon this morning was on the calling of Peter and Andrew. It's interesting that in Matthew Jesus says "I will make you fishers of men" and the Greek word haleeis is the ordinary word for fishermen, but Luke has "henceforth you will be catching men" and the word is zwgrwn which means "taking alive" or indeed taking into life (Mark is like Matthew but has "I will make you become fishers of men". Of course these are not "discrepencies" because the Gospels are portraits not transcripts, and anyway Jesus would have spoken in Aramaic). Life is a big theme of Luke's (he was after all a physician according to tradition) and his emphasis is clearly that the disciples are bringing people into true life.

Friday, January 21, 2011

Haldane and May Nature paper published

The Haldane and May paper in Nature has been published - it is the cover paper and references our work twice. The FT interviewed me about it and used part of the quote. FWIW the full version of what I said (though I knew very well that only part would be used) was:

This is a really important paper which will help set the agenda for scientific work on banking ecosystems for some years. It also has significant messages for the financial community. It draws attention to the dangerously flimsy foundations of derivatives pricing, to the importance of network effects, and to the fundamental problem, which we call the Regulator’s Dilemma, that reducing risks for each individual bank can increase the risks to the system as a whole, a problem which is made even worse when you consider the effect of bank failures on the wider economy.

A lot of work is needed to develop the insights from these theoretical models into practical regulatory tools, and we’re working on this with leading investors, regulators and academics. But at least we’re now able to ask some of the right questions, which previously had been overlooked due to a lack of basic theoretical understanding.

As for making a detailed micro-foundations model of bank behaviour, this is a long way beyond the state of the art. Economists like Ned Phelps fully understand that
rational expectations models cannot really describe financial markets, but no-one yet really knows what to put in their place. And in reality banks are highly complex social systems, where people behave in accordance with complex incentives and belief systems that cannot be captured mathematically. The only certainty is that any explicit model of bank behaviour that became part of a regulatory system would then be gamed by the banks trying to circumvent it. We don’t prevent collisions in yacht races by making behavioural models of crew, but by having robust rules for the prevention of collisions at sea.

I met up with my Cambridge contemporary Robert MacKay and now I'm trying to learn a bit about Additive Combinatorics - which sounds fascinating though I'm sure the maths is way way beyond me. There is a book by Terence Tao whose review by Ben Green has been enough to get me to order it.

Wednesday, January 19, 2011

Cosmology, Lifeboat and McGilchrist

Interesting discussion with Very Distinguished Cosmologist on Don's paper and the MaxHELP hypothesis. I rather hope a joint paper will emerge. Though it needs to be stressed that, while these explorations are interesting at a scientific level, nothing very much hangs on them theologically. God's idea of what constitutes a "better" universe will certainly be very different, and much better informed than ours! And there is no reason to suppose that we can order universes in some linear quality scale.

Lifeboat Foundation appointment has now been announced - it will be interesting to discuss these issues with my new colleagues. I know some of them, and most of them by reputation. Quite a wide divergence of views as well. Curiously none of them seem to be based in Boston, or I would visit them on my next trip.

The Master and His Emissary is really good! I'm only on p125 but it fizzes with interesting ideas. The chapier is "language, truth and music" and Iain is suggesting, very plausibly, that language comes from music. After all many other species have music and even more can recognise it (he reports a fascinating experiment of carp who can distinguish Muddy Waters from The Trout Quintet). He also suggests that language is strongly connected with manipulation, both philosophically, biologically and from an evolutionary PoV.

Some quotes I have highlighted:
  • Music doesn't symbolise emotional meaning ... it metaphorises it.
  • Jung said that 'all cognition is akin to recognition'.... we come to know...(wissen) something only by recognisind (erkennen) something we already knew (kennen).
  • If we assume a purely mechanical universe and take the machine as our model we will uncover the view that - suprise, suprise - the body, and the brain with it, is a machine.
  • Despite the fact that there is no culture anywhere in the world that does not have music... we have relegated music to the sidelines of life
  • There are extant tribes ... such as the Piraha... whose language is effectively a kind of song.
  • Even 'theory of mind' ... which has become the shibboleth of complex, multilayered thought - since children are commonly said not to acquire it till about the age of four... is intact in human subjects who have lost language. {Iain will no doubt have been interested in this Science paper}

Sunday, January 16, 2011

Polkinghorne #1,2 and 6 in Science & Religion




John's radio appearance on Christa Tippett has caused sales to go through the roof in the US. QoT is #2 in Science and Religion and #3,654 in Books on Amazon.com, the Kindle Edition is #6 and #1 is John's Quarks, Chaos and Christianity, which is #655 in Books (ahead of The God Delusion which is #1,115. There are well over 5M titles on Amazon.com, so QoT is in the top 0.01% and QCC in the top 0.001%. And FWIW Quantum Physics and Theology: An Unexpected Kinship is #16 so that's 4 in the top 20.

Maximising E[Habitable Earth-Like Planets]

Fascinating e-correspondence (now about 23 emails) with Don Page and two other cosmologists, one immensely distinguished, around Don Page's paper suggested by the remark in Questions of Truth. I hope to discuss this with one of them tomorrow so things may become clearer.

Although Don’s paper is (of course) interesting I don't think it establishes the conclusion he seeks. Arguably the data he presents shows that the observed value of Λ is well within ε of the value that would be maximal for (the probability of intelligent) life developing, where ε is our margin of uncertainty about where such a maximal value might be. But the other hand I think that the idea could be developed into a potentially powerful, testable and tractable hypothesis.

We don’t remotely know enough about the overall possibilities of intelligent life. But we do know that life like ours requires the existence of what we might call a Habitable Earth-Like Planet (HELP). It’s hard to be sure exactly what characteristics of a HELP are vital, but we might try:

  1. stable average temperatures* somewhere between say 280-350K
  2. not too much ionising radiation or
  3. bombardment by large meteors
  4. M/MEarth >0.1 and <>stability for at least (say) 2bnYr, and
  5. an abundance of key elements (esp H,O,C,N) within a factor of 2 of their observed values.
We could then formulate an in-principle-testable hypothesis (MaxHELP) that the fundamental constants of nature locally maximise E[HELP] the expected number of HELPs in the universe. In particular that, within experimental error and the uncertainly of our calculations, ∂E[HELP]/∂y = 0 for any fundamental constant y. There is a weak statistical argument in favour of MaxHELP (if the only thing we can be sure about is that there exists at least one HELP, and we think all other astronomical observations may be corrigible in the long run) and a methodological argument that if it turned out to be true it would provide an interesting insight into why the fundamental constants had the values they do. It also seems to go with the grain of much of the work on exoplanets.
My basic problem with Don’s current paper is that, even assuming life is made of baryons, the quantity we are trying to maximise (let's call it L and work in logs) is presumably B + F + P where

  • B = ln(number of baryons produced during a time where the universe could form life)
  • F = ln(fraction of such baryons that become structures large enough for suitable living observers)
  • P = ln(average number of such living observers formed per baryon in such structures).

Don observes that in his ref [11] ∂F/∂Λ < 0 for the observed value of Λ and infers that ∂L/∂Λ < 0. But of course ∂L/∂y = ∂B/∂y + ∂F/∂y + ∂P/∂y, and without upper bounds on the other terms, the inference doesn’t follow. It seems most improbable that we can currently calculate an “optimal” value of Λ to better than 1E-121 so all that we can say is that the rough hypothesis Don derives from QoT is within Margin of Error.

However the more modelling there is of planetary formation, the easier it will be to test MaxHELP. At least this theist “would not be surprised” if it were true, though equally unsurprised if it turned out to be only approximate. But it seems worth discussing and then perhaps publishing in collaboration.

* by which of course I mean not just that the average of the temperatures over the surface of the planet is about this, but that for a large fraction of the planet's surface temperatures are in this range almost all the time. A situation like that of Mercury wouldn't do.

Thursday, January 13, 2011

Two interesting citations

Amazed and delighted to learn that the front cover paper of Nature for 20 Jan will be a paper that cites our work (as Beale & al, forthcoming).

Also amazed and delighted to be sent a draft paper by a cosmologist that is inspired by a remark in Questions of Truth. He claims that his paper is evidence against the hypothesis that is suggested by the remark, but in fact he shows that the hypothesis conforms to the evidence well within the margin of error, which in this case is about 10^-121.

Tuesday, January 11, 2011

Rochester Roundabout: What was happening?

Saw The King's Speech on Sat - excellent. Though of course the story is greatly compressed in its timescale for dramatic purposes. Colin Firth is of course superb - so is Geoffrey Rush, a role curiously reminiscent of his brilliant Walsingham in Elizabeth.

Just finished Rochester Roundabout which is great fun and very illuminating. At the end, after Polkinghorne has recounted the key events of the 20 "Rochester" conferences he is covering, he has a very interesting chapter called "What Was Happening?" in which he engages with various philosophies of science. Points I have highlighted:
  • Imre Latakos: "Philosophy of science without history of science is empty: History of science without Philosophy of science is blind"
  • The development of a mature, well-winnowed scientific theory is comparable to our inspection of a figure approaching us across the moors: a dark blob - a matchstick man - a person in a kilt - Fergus.
  • Maxwell had described [the aether] as better confirmed than any other entity in natural philosophy. Now it is no more...but...Maxwell's equations [remain] fundamental to the description of the electromagnetic field [and] the aether was a mechanical way of thinking about the enduring concept of a field and...the quantum-mechanical vacuum is also an all-pervading medium of subtle property in which excitations of energy...occur.
  • Judgements of verismillitude require tacit skills, not specifiable in advance according to some success-counting algorithm {in the light of The Master and His Emissary I'd be tempted to say, right-brain skills as well as left-brain skills}
  • No-one believes that hadrons are really bags of quarks...but quantum chromodynamics is a serious candidate for providing a fundamental, widely applicable, understanding of quark dynamics.
  • Social influences play a part in scientific investigation...Yet...the stubborn facticity of nature imposes ineluctable constraint.
  • [Some] Philosophers of science ... are so obsessed with what is logically demonstrable that they fail to recognise what is philosophically interesting.
  • Philosophers of science seldom exhibit any understanding of how difficult it is to preduce even a passable shot at a credible explanation of a wide range of phenomena... In the actual scientific enterprise, the problem is not the embarassing riches of a superfluity of theories but the extraordinary difficulty of finding one that is at all believable.
  • the Popperian account... will not do... the emphasis on refutation...gives a curiously cockeyed view of the scientific endeavour....A further difficulty ... is to give a clear account, in realistic circumstances, of when refutation takes place. Very general and powerful principles are not to be discared at the first suggestion of an adverse result.
  • Science is an act of judgement, involving tacit skills. In Polanyi's oft-repeated phrase, 'we know more than we can tell'.
  • Dirac once said of himself and Schrodinger..."It was a sort of act of faith with us that the equations which describe fundamental laws of Nature must have great mathematical beauty in them. It was a very profitable religion to hold and can be considered the basis of much of our success."
He concludes with the following:
The universe is marvellously rationally transparent to our inquiry. The instinct of a scientist to seek an explanation through and through will not allow him to say 'that's just the way it is, and good luck for those of us who are mathematically able'. He will want to go beyond his science (with its assumption of cosmic intelligibility) to a wider setting in which that intelligibility will find its own explanation. In my view, that search will take him in the direction of theology. But that is another story.

Saturday, January 08, 2011

Histories of Christianity and High Energy Physics

Ferociously busy so no time to blog. Have been reading the History of Christianity with enjoyment and interest, although he takes a secular and sceptical line, but with acknowledgement that there may be forces as work which are beyond the ability of historians.

I've also obtained a copy of John Polkinghorne's wonderful Rochester Roundabout: The Story of High Energy Physics which I'm reading with great interest: lovely anecdotes about the development of particle physics from the heady days of the 50s to 1980. Gives an interesting additional perspective to the "unexpected kinship" he finds between quantum physics and theology.

Economics Editor of The Guardian has asked for a short piece, we'll see if they publish it!

Unusual experience yesterday of hearing two acquaintances on successive items in the Today programme: Shami Chakrabarti speaking on Control Orders and Ioanna Sitaridou on this fascinating Greek dialect.

Saturday, January 01, 2011

Happy New Year!

An amazing Christmas and New Year. Elder Daughter came over with husband and their daughter MJ. Son and entire family arrived on Christmas Eve and stayed until the 27th so we had the entire family (11 in total) together for 3 days. Then due to some happy mistakes ED & family just missed their flight on the 28th and stayed until the 1st, a wholly unexpected and delightful extension which gave us much more quality time together. The only sadness was that my mother was stuck in Cornwall, but in partial compensation the brilliant friend of ED whom I regard as an "honorary daughter" visited twice, together with a few other very close friends. MJ is now 7 months old and an utter delight. I can well believe this fascinating paper in Science showing that even children of 7 months have some understanding of other people's beliefs and a Theory of Mind.

Was given The Big Short, A History of Christianity: the first 3,000 years and Sisters of Sinai for Chrismas. Have devoured the first, and am in process with the 2nd.

Continuing violence against Christians because of their faith in Nigeria, Egypt, Iraq, Pakistan and elsewhere is extremely deplorable. Deeply unfortunate that the ghastly Polly Toynbee apparently merely laughed when Christina Odone suggested that persecution of Christians was a problem. How Toynbee (whose sole academic qualificiation is 1 A-level) gets away with pointificating so extensively is beyond me.

I've been invited (along with John Polkinghorne and Bob Pollack) to join the Religion/Spirituality Advisory Board of the Lifeboat Foundation which should be very interesting - this is a result of my paper with Bob for the USQR (which doesn't yet seem to have come out but there is an almost-final draft online on Bob's website here).

A very Happy New Year to all readers of this blog: visitors came from 96 countries in 2010 (top 10 countries: US, UK, Canada, Australia (G'day!), Philippines (Hola!), Germany (Hallo!), Finland (Hei!), Turkey (Merhaba!), Poland (Witam!) and S Africa)