Archive for June, 2009

Preview from Herschel

Posted in The Universe and Stuff with tags , , on June 20, 2009 by telescoper

I thought you might like to see this image from Herschel, which I got from the ESA website. The Spitzer/MIPS and the Herschel/PACS images of M51 at 160 µm are shown above. The advantage of the larger size of the Herschel telescope is clearly reflected in the much higher resolution of the image: Herschel reveals structures that cannot be discerned in the Spitzer image.

By golly, it seems to work!

Multiversalism

Posted in The Universe and Stuff with tags , , on June 17, 2009 by telescoper

The word “cosmology” is derived from the Greek κόσμος (“cosmos”) which means, roughly speaking, “the world as considered as an orderly system”. The other side of the coin to “cosmos” is Χάος (“chaos”). In one world-view the Universe comprised two competing aspects: the orderly part that was governed by laws and which could (at least in principle) be predicted, and the “random” part which was disordered and unpredictable. To make progress in scientific cosmology we do need to assume that the Universe obeys laws. We also assume that these laws apply everywhere and for all time or, if they vary, then they vary in accordance with another law.  This is the cosmos that makes cosmology possible.  However, with the rise of quantum theory, and its applications to the theory of subatomic particles and their interactions, the field of cosmology has gradually ceded some of its territory to chaos.

In the early twentieth century, the first mathematical world models were constructed based on Einstein’s general theory of relativity. This is a classical theory, meaning that it describes a system that evolves smoothly with time. It is also entirely deterministic. Given sufficient information to specify the state of the Universe at a particular epoch, it is possible to calculate with certainty what its state will be at some point in the future. In a sense the entire evolutionary history described by these models is not a succession of events laid out in time, but an entity in itself. Every point along the space-time path of a particle is connected to past and future in an unbreakable chain. If ever the word cosmos applied to anything, this is it.

But as the field of relativistic cosmology matured it was realised that these simple classical models could not be regarded as complete, and consequently that the Universe was unlikely to be as predictable as was first thought. The Big Bang model gradually emerged as the favoured cosmological theory during the middle of the last century, between the 1940s and the 1960s. It was not until the 1960s, with the work of Hawking and Penrose, that it was realised that expanding world models based on general relativity inevitably involve a break-down of known physics at their very beginning. The so-called singularity theorems demonstrate that in any plausible version of the Big Bang model, all physical parameters describing the Universe (such as its density, pressure and temperature) all become infinite at the instant of the Big Bang. The existence of this “singularity” means that we do not know what laws if any apply at that instant. The Big Bang contains the seeds of its own destruction as a complete theory of the Universe. Although we might be able to explain how the Universe subsequently evolves, we have no idea how to describe the instant of its birth. This is a major embarrassment. Lacking any knowledge of the laws we don’t even have any rational basis to assign probabilities. We are marooned with a theory that lets in water.

The second important development was the rise of quantum theory and its incorporation into the description of the matter and energy contained within the Universe. Quantum mechanics (and its development into quantum field theory) entails elements of unpredictability. Although we do not know how to interpret this feature of the theory, it seems that any cosmological theory based on quantum theory must include things that can’t be predicted with certainty.

As particle physicists built ever more complete descriptions of the microscopic world using quantum field theory, they also realised that the approaches they had been using for other interactions just wouldn’t work for gravity. Mathematically speaking, general relativity and quantum field theory just don’t fit together. It might have been hoped that quantum gravity theory would help us plug the gap at the very beginning of the Universe, but that has not happened yet because there isn’t such a theory. What we can say about the origin of the Universe is correspondingly extremely limited and mostly speculative, but some of these speculations have had a powerful impact on the subject.

One thing that has changed radically since the early twentieth century is the possibility that our Universe may actually be part of a much larger “collection” of Universes. The potential for semantic confusion here is enormous. The Universe is, by definition, everything that exists. Obviously, therefore, there can only be one Universe. The name given to a Universe that consists of bits and pieces like this is the multiverse.

 There are various ways a multiverse can be realised. In the “Many Worlds” interpretation of quantum mechanics there is supposed to be a plurality of versions of our Universe, but their ontological status is far from clear (at least to me). Do we really have to accept that each of the many worlds is “out there”, or can we get away with using them as inventions to help our calculations?

 On the other hand, some plausible models based on quantum field theory do admit the possibility that our observable Universe is part of collection of mini-universes, each of which “really” exists. It’s hard to explain precisely what I mean by that, but I hope you get my drift. These mini-universes form a classical ensemble in different domains of a single-space time, which is not what happens in quantum multiverses.

According to the Big Bang model, the Universe (or at least the part of it we know about) began about fourteen billion years ago. We do not know whether the Universe is finite or infinite, but we do know that if it has only existed for a finite time we can only observe a finite part of it. We can’t possibly see light from further away than fourteen billion light years because any light signal travelling further than this distance would have to have set out before the Universe began. Roughly speaking, this defines our “horizon”: the maximum distance we are in principle able to see. But the fact that we can’t observe anything beyond our horizon does not mean that such remote things do not exist at all. Our observable “patch” of the Universe might be a tiny part of a colossal structure that extends much further than we can ever hope to see. And this structure might be not at all homogeneous: distant parts of the Universe might be very different from ours, even if our local piece is well described by the Cosmological Principle.

Some astronomers regard this idea as pure metaphysics, but it is motivated by plausible physical theories. The key idea was provided by the theory of cosmic inflation, which I have blogged about already. In the simplest versions of inflation the Universe expands by an enormous factor, perhaps 1060, in a tiny fraction of a second. This may seem ridiculous, but the energy available to drive this expansion is inconceivably large. Given this phenomenal energy reservoir, it is straightforward to show that such a boost is not at all unreasonable. With inflation, our entire observable Universe could thus have grown from a truly microscopic pre-inflationary region. It is sobering to think that everything galaxy, star, and planet we can see might from a seed that was smaller than an atom. But the point I am trying to make is that the idea of inflation opens up ones mind to the idea that the Universe as a whole may be a landscape of unimaginably immense proportions within which our little world may be little more than a pebble. If this is the case then we might plausibly imagine that this landscape varies haphazardly from place to place, producing what may amount to an ensemble of mini-universes. I say “may” because there is yet no theory that tells us precisely what determines the properties of each hill and valley or the relative probabilities of the different types of terrain.

Many theorists believe that such an ensemble is required if we are to understand how to deal probabilistically with the fundamentally uncertain aspects of modern cosmology. I don’t think this is the case. It is, at least in principle, perfectly possible to apply probabilistic arguments to unique events like the Big Bang using Bayesian inference. If there is an ensemble, of course, then we can discuss proportions within it, and relate these to probabilities too. Bayesians can use frequencies if they are available but do not require them. It is one of the greatest fallacies in science that probabilities need to be interpreted as frequencies.

At the crux of many related arguments is the question of why the Universe appears to be so well suited to our existence within it. This fine-tuning appears surprising based on what (little) we know about the origin of the Universe and the many other ways it might apparently have turned out. Does this suggest that it was designed to be so or do we just happen to live in a bit of the multiverse nice enough for us to have evolved and survived in?  

Views on this issue are often boiled down into a choice between a theistic argument and some form of anthropic selection.  A while ago I gave a talk at a meeting in Cambridge called God or Multiverse? that was an attempt to construct a dialogue between theologians and cosmologists. I found it interesting, but it didn’t alter my view that science and religion don’t really overlap very much at all on this, in the sense that if you believe in God it doesn’t mean you have to reject the multiverse, or vice-versa. If God can create a Universe, he could create a multiverse to0. As it happens, I’m agnostic about both.

So having, I hope, opened up your mind to the possibility that the Universe may be amenable to a frequentist interpretation, I should confess that I think one can actually get along quite nicely without it.  In any case, you will probably have worked out that I don’t really like the multiverse. One reason I don’t like it is that it accepts that some things have no fundamental explanation. We just happen to live in a domain where that’s the way things are. Of course, the Universe may turn out to be like that –  there definitely will be some point at which our puny monkey brains  can’t learn anything more – but if we accept that then we certainly won’t find out if there is really a better answer, i.e. an explanation that isn’t accompanied by an infinite amount of untestable metaphysical baggage. My other objection is that I think it’s cheating to introduce an infinite thing to provide an explanation of fine tuning. Infinity is bad.

Old Talk

Posted in Books, Talks and Reviews, The Universe and Stuff with tags on June 16, 2009 by telescoper

I just stumbled upon a post about a talk I did last year at the Multi-Faith centre at the University of Derby. I’ll let you follow the link to see how the talk and discussion went, but here’s a copy of a photograph of me trying to talk with my mouth full.

The Cat and the Rat

Posted in Columbo on June 16, 2009 by telescoper

I was just about to go to work this morning when I heard a screaming sound from the garden. Thinking that Columbo had suffered another funny turn, I raced back into the house. There he was, sitting in the kitchen, pleased as punch, with a small wriggling animal in his mouth. He dropped it at my feet and it tried to escape by running up my leg. That took me a bit my surprise and I kicked out, sending the furry thing flying against the wall. Stunned, it fell to the ground and Columbo got hold of it again.

A few seconds later he let it go and, using my forensic skills to establish that it was dead (separation of the head from the body is quite a good indicator of death), I took it away before he could dismember it any further. This could have been the small creature that led him a merry dance under the decking some time ago. However, it wasn’t a mouse. The scaly tail proved beyond all doubt that what he’d caught was in fact a baby rat.

I hope its mother doesn’t come looking for it.

Anyway, this is the second remarkable thing that Columbo has experienced in the last few days. The other is that he seems to have acquired a girlfriend. A very pretty lady cat has started calling for him and, unlike all other cats that have entered his domain, Columbo doesn’t mind her at all. There’s not going to be any rumpy-pumpy of course – Columbo was “done” when he was a youngster – but they hang out together quite comfortably, and he cries when she goes away. She can easily jump up and climb over the fence at the back of the garden, whereas Columbo is too old. Still, it’s nice for him to have some company. She’s been here most days. Perhaps he was hoping to impress her with the rat he caught.

The cat that visits Columbo wears a collar and is friendly enough to let me look for her name on it, but there isn’t one there. I’ve decided to call her Maud, because she comes into the garden.

Days of Wine and Roses

Posted in Jazz, Poetry with tags , , , on June 15, 2009 by telescoper

Today I finished all my exam marking, and decided to celebrate by drinking a glass or two of wine while I sat in my garden. The lovely roses that have recently been in bloom are already starting to fade and drop their petals. For obvious reasons, this reminded me of this little poem by Ernest Dowson.

The title is Vitae Summa Brevis Spem Nos Vetat Incohare Longam, which I translate from my half-remembered schoolboy Latin as something like “the brief span of Life forbids us from conceiving an enduring hope”. It’s a quotation from one of the Odes of Horace (Book I, Ode 4, line 15).

They are not long, the weeping and the laughter,
Love and desire and hate:
I think they have no portion in us after
We pass the gate.

They are not long, the days of wine and roses:
Out of a misty dream
Our path emerges for a while, then closes
Within a dream.

The phrase “days of wine and roses” became the title of an excellent film dealing with the effects of alcoholism on family life, for which Henry Mancini wrote a song with the same title that went on to become a Jazz standard. Here is a lovely version played live by the great Bill Evans (who featured in another recent post of mine).

In the rather melancholy spirit of this post, I’ll add that Bill Evans died in 1980 just about a month after this performance.

Telescope Wars

Posted in Science Politics, The Universe and Stuff with tags , , , on June 13, 2009 by telescoper

Over the last few months the Science and Technology Facilities Council has been setting up a review of its ground-based astronomy programme. The panel conducting the review has produced a consultation document, and is asking for input via an online questionnaire. There will also be a (rather short) public meeting in London on July 9th. The consultation period closes on July 31st.

Reviews of this kind would be necessary in the best of times in order to establish long-term scientific priorities and try to align the provision of facilities with those strategic objectives. Unfortunately, we don’t live in the best of times so the backdrop to the current review is a shrinking pot of money available for “traditional” ground-based astronomy and the consequent need to target planned programmes for the chop.

Andy and Sarah have already blogged about this -and they both know a lot more than me about ground-based astronomy – so I won’t try to cover the same ground as them. I would however, like to make a  couple of points.

The review has to help STFC strike a balance between current facilities and projects for the future. The largest elements of the current ground-based programme include the subscription to ESO (including associated costs for ALMA, which amounts to over £200 Million), the twin 8m telescopes known as Gemini (North and South, about £60 Million), E-Merlin (about £24 Million), UKIRT and JCMT (about £34 Million); figures represent costs over the next 10 years or so. The two biggest projects that the UK would like to get involved in are a European Extremely Large Telescope (E-ELT), an optical telescope currently aimed to be about 42m in diameter, and the Square Kilometre Array, a futuristic radio telescope. Each of these would cost the UK over £100 Million over the next decade.

The consultation document puts it quite succintly:

It would be unrealistic to imagine that in 2020 the UK would have a large stake in large facilities like E-ELT and SKA, and would also retain all its current ground-based facilities. It is always hard to forego a workhorse facility that has supported an active and successful science programme, in order to start construction of some future facility many years hence. But our bid for the capital costs for E-ELT and/or SKA would not be credible if we do not show that we are willing to do this.

 

I agree that it maintaining the current programme as well as acquiring an interest in both E-ELT and SKA is completely implausible. The more relevant question though is how deep we have to cut the ongoing astronomy programme in order to afford either of these, or whether we can do that at all. It seems quite likely to me that future funding of the ground-based programme is likely to suffer drastically, both because of cuts to the overall STFC grant that appear inevitable in the next comprehensive spending review and also the current STFC leadership’s bias in favour of space technology at the expense of science. On the latter point, it is worth noting that it is specifically the ground-based astronomy programme that is being lined up against the wall here; space-based projects of negligible scientific value, such as Moonlite and BEPI-Columbo are not to going be weighed in the same balance. At the very least, future involvement in a next-generation X-ray telescope  should certainly have been in the mixer with other observatory-type facilities on the ground. I fear that the STFC Executive sees the current UK ground-based programme as significantly too large, and would like to squeeze it all into the box marked ESO. I would like to be able to sound more optimisitic, but I think that the most likely outcome of this review is therefore that the only current facilities that will survive into the medium term will be those provided through ESO  membership. JCMT and UKIRT are nearing the end of their useful life anyway, but the writing is definitely on the wall for both Gemini and E-Merlin. Not that it hasn’t been before now…

If this the way things go, then the remaining issue is whether we can afford to be involved in both E-ELT and  SKA, which seems to me to be most unlikely. If we have to pick one, which should it be? That is clearly going to be the topic of much debate. In the spirit of the drive for rationalisation I touched on above, it may well be that we don’t do anything at all outside the ESO umbrella. In that case the United Kingdom ends up with a ground-based astronomy programme consisting of the ESO facilities plus a share in the E-ELT (itself an ESO proposal). I think this would be a tragedy because  I find the scientific case for SKA much stronger than that for E-ELT; it would have been a closer call if the ELT were still the 100m optical telescope as originally proposed many years ago (and which I used to call the FLT). I’m sure many will disagree for legitimate scientific reasons (rather than the desire to play “mine’s bigger than yours” with the Americans, who are currently developing a 30m telescope).

I’m sure there will also be many astronomers who would rather have neither SKA nor E-ELT if it means losing access to the suite of smaller telescopes that continue to produce many interesting scientific results. If it came to a vote I’m not sure what the result would be, which is why I want to encourage anyone who has any input to fill in the questionnaire!

A final little wrinkle on this question is the following. Suppose STFC decides  not to support future involvement in SKA – I hope this isn’t the way things turn out, but in our dire financial circumstances it might be – does this make continued funding for E-Merlin more likely or less likely? Answers on a postcard (or even via the comments box)..

In the Dark

Posted in Jazz with tags , , on June 13, 2009 by telescoper

A while ago I posted an item about Bix Beiderbecke during which I mentioned that, as well as being a star trumpeter,  he had also written a suite of four pieces for solo piano. I just found out that about a month ago somebody posted this lovely version of one of them on Youtube. It’s called – you guessed it – In the Dark.

This version is by Dick Hyman, and I think it’s lovely. This is my official theme tune from now on!

Potato Head Blues

Posted in Biographical, Jazz with tags , , on June 12, 2009 by telescoper

I’ve just spent several hours ploughing through yet more examination scripts – first year ones, not needed before the finals Examination Board. By way of a bit of refreshment I thought I’d listen to this, and enjoyed it so much I thought I’d share it on here.

At one point in the film Manhattan, the character played by Woody Allen makes a list of the things that make life worth living. This record is one of them. Potato Head Blues was recorded on May 10th 1927 in the Okeh Studios in Chicago by Louis Armstrong and the Hot Seven. It’s not actually a blues, but we won’t quibble about that because whatever it is not it is definitely a timeless Jazz masterpiece.

The other members of the band are Johnny Dodds (clarinet, heard to good effect in the solo before Louis Armstrong), Johnny’s brother Warren “Baby” Dodds (drums), Louis Armstrong’s first wife Lil Armstrong (née Hardin, piano), Johnny St Cyr (banjo), Pete Briggs (brass bass or tuba) and John Thomas on trombone. But the star of the performance is, of course, Satchmo himself, who was at the absolute peak of his powers when this record was made. If you have any doubts about what a musical genius he was, go straight to the point (at about 1:50) where he launches into his famous stop-time solo chorus which is just breathtaking in its power and inventiveness. Built from a succession of dazzling impromptu phrases, it explodes into a joyous climax which is beautifully sustained into the final ensemble chorus that follows.  Enjoy!

Examination Matters

Posted in Biographical, Education with tags , , on June 10, 2009 by telescoper

I made it safely back to Blighty last night and have spent the day catching up on a few things. I wasn’t really planning to post anything today, but after looking through the comments on my previous item I thought it was probably a good idea to move on!

My trip to Copenhagen was carefully timed to miss the mammoth examiners’ meeting that took place yesterday in the Cardiff School of Physics & Astronomy, at which decisions were made about the degree classes of the graduating students. Final results have to be confirmed by the University but, following a longstanding tradition, provisional pass lists went up on the boards immediately after the meeting.

When I came in this morning I was delighted to hear that the meeting went off fairly smoothly and also delighted to see the pass lists had very good news for many of the students I know quite well personally. Particular congratulations to all the students who got First Class Honours, some of whom will be taking another step on the academic treadmill and going on to do PhDs here and there. I’m not really sorry I missed the examiners’ meeting, but I am sorry I wasn’t here to congratulate the soon-to-be-graduates in person.

I remember that when I finished my degree and got the result I didn’t actually feel much euphoria, only exhaustion. When I was younger, exams were always times of enormous stress for me. I guess that’s because, when I first went to School, I was very far behind everyone else and, as one of the “slow” kids, I was almost thrown in the educational wastebin. I gradually caught up but for a long time felt that I was still regarded as a bit of a dunderhead so, to prove I wasn’t a fake,  to myself as much as anyone else, I worked very hard at all the examinations I had to take. It was only when I got to University that I realised all the stress wasn’t worth it. It’s nice to pass but you shouldn’t become obsessed with grades and certificates. Examinations seem to have an almost overwhelming significance when they’re the only thing on your horizon, but years later you will look back on them as being of very little real importance (regardless of whether you did well or not).

My feelings about examinations agree pretty much with William Wordsworth, who studied at the same University as me, as expressed in this quotation from The Prelude:

Of College labours, of the Lecturer’s room
All studded round, as thick as chairs could stand,
With loyal students, faithful to their books,
Half-and-half idlers, hardy recusants,
And honest dunces–of important days,
Examinations, when the man was weighed
As in a balance! of excessive hopes,
Tremblings withal and commendable fears,
Small jealousies, and triumphs good or bad–
Let others that know more speak as they know.
Such glory was but little sought by me,
And little won.

It seems to me a great a pity that our system of education – both at School and University – places such a great emphasis on examination and assessment, to the detriment of real learning. The biggest bane of physics education is the way modular degrees have been implemented. Don’t get me wrong. I’m not opposed to modularisation in principle. I just think the way we teach modules in British university fails to develop any understanding of the interconnection between different aspects of the subject. That’s an educational disaster because what is most exciting and compelling about physics is its essential unity. Splitting it into little boxes, taught on their own with no relationship to the other boxes, provides us with no scope to nurture the kind of lateral thinking that is key to the way physicists attempt to solve problems. The small size of each module makes the syllabus very “bitty” and fragmented. No sooner have you started to explore something at a proper level than the module is over. More advanced modules, following perhaps the following year, have to recap a large fraction of the earlier modules so there isn’t time to go as deep as one would like even over the whole curriculum.

Our students take 120 “credits” in a year, split into two semesters. These are usually split into 10-credit modules with an examination at the end of each semester. Laboratories and other continuously-assessed work does not involve a written examination, but the system means that a typical  student will have 5 written examination papers in January and another 5 in May. Each paper is two hours.

These factors mean that the ratio of assessment to education has risen sharply over the last decades with the undeniable result that academic standards have fallen in physics. The system encourages students to think of modules as little bit-sized bits of education to be consumed and then forgotten. Instead of learning to rely on their brains to solve problems, students tend to approach learning by memorising chunks of their notes and regurgitating them in the exam. I find it very sad when students ask me what derivations they should memorize to prepare for examinations. A brain is much more than a memory device. What we should be doing is giving students the confidence to think for themselves.

You can contrast this diet of examinations with the regime when I was an undergraduate. My entire degree result was based on six three-hour written examinations taken at the end of my final year, rather than something like 30 examinations taken over 3 years. Moreover, my finals were all in a three-day period. Morning and afternoon exams for three consecutive days is an ordeal I wouldn’t wish on anyone so I’m not saying the old days were better, but I do think we’ve gone far too far to the opposite extreme. The one good thing about the system I went through was that there was no possibility of passing examinations on memory alone. Since they were so close together there was no way of mugging up anything in between them. I only got through  by figuring things out in the exam room.

I don’t want to denigrate the success of our high achievers. They have taken the course we have given them and done extremely well. They deserve admiration and praise. What I’m saying is that I don’t think the education we provide does justice to their talents. That’s our fault, not theirs…

Notes from the North

Posted in Biographical, The Universe and Stuff with tags , , on June 8, 2009 by telescoper

Just time for a quick post today. I’m in Copenhagen for a short meeting entitled “Cosmology and Astroparticle Physics from the LHC to Planck“. The meeting only lasts today and tomorrow morning, but it’s been a lot of fun so far and has offered me the chance to chat with a lot of people I don’t often get the chance to talk to.

I suppose the only thing from the meeting I really want to mention in this short post is the  current status of Planck, which is currently about a million km from Earth. Both instruments (the High Frequency Instrument HFI and Low Frequency Instrument LFI) are still performing fine and the satellite,  having now been injected into its rather large orbit around L2, is  cooling down to its operating temperature. So far so good. There will be more tests at the beginning of July, after which it will start its real business of scanning the sky to make maps of the primordial temperature  fluctuations.

Today I gave my (usual) talk about cosmic anomalies (which I’ve blogged about before), but there were also interesting talks about possible interpretation of the positron excess observed in the direction of the Galactic Centre,  on a model of anisotropic dark energy  and a wacky contribution by Igor Novikov about semi-traversible wormholes.

Meanwhile, over lunch and dinner the various European participants of the meeting mulled over the results from the elections to the European parliament which completed yesterday.

The results generally showed a move to the right across Europe. In the United Kingdom this also happened, as the Labour Party’s share of the vote collapsed to just under 16%. I’m not going to shed any tears for them, but I am shamed to admit that my country will now be represented in the European Parliament by two members of the British National Party – a bunch of neo-Nazi thugs who are doing the best they can for their own ends to exploit peoples’ discontent with the mainstream parties. Fortunately their share of the vote (about 6%, on a very low turnout) remained relatively small and was, in fact, less than that of the Green Party. Nevertheless with the 65th anniversary of D-Day only a few days ago, it is depressing that so many people have forgotten the sacrifices that previous generations made to save this country from exactly that  kind of fascist. I hope this disaster is not repeated at the next general election. This kind of monstrosity makes the arcane world of cosmology suddenly seem so irrelevant.