Feynman on Wine

Posted in Poetry, The Universe and Stuff with tags , on July 5, 2011 by telescoper

A poet once said, ‘The whole universe is in a glass of wine.’ We will probably never know in what sense he meant it, for poets do not write to be understood. But it is true that if we look at a glass of wine closely enough we see the entire universe. There are the things of physics: the twisting liquid which evaporates depending on the wind and weather, the reflection in the glass; and our imagination adds atoms. The glass is a distillation of the earth’s rocks, and in its composition we see the secrets of the universe’s age, and the evolution of stars. What strange array of chemicals are in the wine? How did they come to be? There are the ferments, the enzymes, the substrates, and the products. There in wine is found the great generalization; all life is fermentation. Nobody can discover the chemistry of wine without discovering, as did Louis Pasteur, the cause of much disease. How vivid is the claret, pressing its existence into the consciousness that watches it! If our small minds, for some convenience, divide this glass of wine, this universe, into parts — physics, biology, geology, astronomy, psychology, and so on — remember that nature does not know it! So let us put it all back together, not forgetting ultimately what it is for. Let it give us one more final pleasure; drink it and forget it all!

Richard Feynman (1918-1988)

 

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Cool Columbo

Posted in Columbo with tags , on July 4, 2011 by telescoper

I thought I’d post a quick update about ye olde Columbo because last week I mentioned that I was a bit concerned about his health. I’m glad to report that there’s been no re-occurrence of sickness (that I’ve seen). I started him back on the anti-inflammatory drug and that, probably together with the warm weather we’ve been having recently, has improved his mood considerably. He’s been spending most of his time outdoors lately, in the shade among the bushes at the end of the garden, emerging only to answer the call of nature or to cadge some food. Despite the fact that he’s not exactly Speedy Gonzalez these days it’s still quite difficult to take a picture of him, as he won’t look at the camera, and when I do manage to get a snap he always seems to look grumpy.

 

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False Convergence and the Bandwagon Effect

Posted in The Universe and Stuff with tags , , , , , , on July 3, 2011 by telescoper

In idle moments, such as can be found during sunny sunday summer afternoons in the garden, it’s  interesting to reminisce about things you worked on in the past. Sometimes such trips down memory lane turn up some quite interesting lessons for the present, especially when you look back at old papers which were published when the prevailing paradigms were different. In this spirit I was lazily looking through some old manuscripts on an ancient laptop I bought in 1993. I thought it was bust, but it turns out to be perfectly functional; they clearly made things to last in those days! I found a paper by Plionis et al. which I co-wrote in 1992; the abstract is here

We have reanalyzed the QDOT survey in order to investigate the convergence properties of the estimated dipole and the consequent reliability of the derived value of \Omega^{0.6}/b. We find that there is no compelling evidence that the QDOT dipole has converged within the limits of reliable determination and completeness. The value of  \Omega_0 derived by Rowan-Robinson et al. (1990) should therefore be considered only as an upper limit. We find strong evidence that the shell between 140 and 160/h Mpc does contribute significantly to the total dipole anisotropy, and therefore to the motion of the Local Group with respect to the cosmic microwave background. This shell contains the Shapley concentration, but we argue that this concentration itself cannot explain all the gravitational acceleration produced by it; there must exist a coherent anisotropy which includes this structure, but extends greatly beyond it. With the QDOT data alone, we cannot determine precisely the magnitude of any such anisotropy.

(I’ve added a link to the Rowan-Robinson et al. paper for reference). This was  a time long before the establishment of the current standard model of cosmology (“ΛCDM”) and in those days the favoured theoretical paradigm was a flat universe, but one without a cosmological constant but with a critical density of matter, corresponding to a value of the density parameter \Omega_0 =1.

In the late eighties and early nineties, a large number of observational papers emerged claiming to provide evidence for the (then) standard model, the Rowan-Robinson et al. paper being just one. The idea behind this analysis is very neat. When we observe the cosmic microwave background we find it has a significant variation in temperature across the sky on a scale of 180°, i.e. it has a strong dipole component

There is also some contamination from Galactic emission in the middle, but you can see the dipole in the above map from COBE. The interpretation of this is that the Earth is not at rest. The  temperature variation causes by our motion with respect to a frame in which the cosmic microwave background (CMB) would be isotropic (i.e. be the same temperature everywhere on the sky) is just \Delta T/T \sim v/c. However, the Earth moves around the Sun. The Sun orbits the center of the Milky Way Galaxy. The Milky Way Galaxy orbits in the Local Group of Galaxies. The Local Group falls toward the Virgo Cluster of Galaxies. We know these velocities pretty well, but they don’t account for the size of the observed dipole anisotropy. The extra bit must be due the gravitational pull of larger scale structures.

If one can map the distribution of galaxies over the whole sky, as was first done with the QDOT galaxy redshift survey, then one can compare the dipole expected from the distribution of galaxies with that measured using the CMB. We can only count the galaxies – we don’t know how much mass is associated with each one but if we find that the CMB and the galaxy dipole line up in direction we can estimate the total amount of mass needed to give the right magnitude. I refer you to the papers for details.

Rowan-Robinson et al. argued that the QDOT galaxy dipole reaches convergence with the CMB dipole (i.e. they line up with one another) within a relatively small volume – small by cosmological standards, I mean, i.e. 100 Mpc or so- which means that  there has to be quite a lot of mass in that small volume to generate the relatively large velocity indicated by the CMB dipole. Hence the result is taken to indicate a high density universe.

In our paper we questioned whether convergence had actually been reached within the QDOT sample. This is crucial because if there is significant structure beyond the scale encompassed by the survey a lower overall density of matter may be indicated. We looked at a deeper survey (of galaxy clusters) and found evidence of a large-scale structure (up to 200 Mpc) that was lined up with the smaller scale anisotropy found by the earlier paper. Our best estimate was \Omega_0\sim 0.3, with a  large uncertainty. Now, 20 years later, we have a  different standard cosmology which does indeed have \Omega_0 \simeq 0.3. We were right.

Now I’m not saying that there was anything actually wrong with the Rowan-Robinson et al. paper – the uncertainties in their analysis are clearly stated, in the body of the paper as well as in the abstract. However, that result was widely touted as evidence for a high-density universe which was an incorrect interpretation. Many other papers published at the time involved similar misinterpretations. It’s good to have a standard model, but it can lead to a publication bandwagon – papers that agree with the paradigm get published easily, while those that challenge it (and are consequently much more interesting) struggle to make it past referees. The accumulated weight of evidence in cosmology is much stronger now than it was in 1990, of course, so the standard model is a more robust entity than the corresponding version of twenty years ago. Nevertheless, there’s still a danger that by treating ΛCDM as if it were the absolute truth, we might be closing our eyes to precisely those clues that will lead us to an even better understanding.  The perils of false convergence  are real even now.

As a grumpy postscript, let me just add that Plionis et al. has attracted a meagre 18 citations whereas Rowan-Robinson et al. has 178. Being right doesn’t always get you cited.

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Lucia’s Mad Scene

Posted in Opera with tags , , on July 2, 2011 by telescoper

I came across this little clip of the great Maria Callas on youtube, and couldn’t resist sharing it for the benefit of those (apparently many) people out there who think she was an overrated singer. I’m a devout Callas fan, but I also freely admit that many of the performances she recorded later in her career (especially in the 60s) weren’t all that good and it’s unfortunate that most of her famous performances were in an era when audio technology wasn’t really up to the task of recording live opera.

However, you can get an idea of how very special Maria Callas was in this little clip recorded live at La Scala in Milan in 1954. It’s a poor quality recording but her voice has a stunning radiance to it despite the distortions. This is the very end of the lengthy Act III “Mad Scene” from Donizetti‘s Opera Lucia di Lammermoor. It’s a tremendously demanding piece, which Callas sings with flawless technical accuracy and extraordinary expressive power leading up to a ringing top E♭ at the end. Her approach to the vocal gymnastics required by the bel canto repertoire was uniquely full-on and, without a safety net, the sense of danger surrounding these performances made them truly electrifying.

Only some of the music  made it onto the recording, but there’s enough there to convince the doubters that this was a very special artist. And, listening to the applause at the end, the notoriously demanding audience at La Scala were clearly convinced too!

Incidentally, some argue that Callas’ voice was in decline after her substantial weight loss (she lost 80lbs between 1953 and 1954), but this was the slim Callas and her voice sounds pretty good to me!

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In July

Posted in Poetry with tags , on July 2, 2011 by telescoper

Why do I make no poems? Good my friend
Now is there silence through the summer woods,
In whose green depths and lawny solitudes
The light is dreaming; voicings clear ascend
Now from no hollow where glad rivulets wend,
But murmurings low of inarticulate moods,
Softer than stir of unfledged cushat broods,
Breathe, till o’er drowsed the heavy flower-heads bend.
Now sleep the crystal and heart-charmed waves
Round white, sunstricken rocks the noontide long,
Or ‘mid the coolness of dim lighted caves
Sway in a trance of vague deliciousness;
And I,–I am too deep in joy’s excess
For the imperfect impulse of a song.

by Edward Dowden (1843-1913)

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Yesterday, when I was young…

Posted in Biographical, The Universe and Stuff with tags , on July 1, 2011 by telescoper

Looking for some old papers on my ancient laptop this afternoon I came across these pictures. I think they are stills taken from a series of video lectures I did a while ago (around 1996) called Topics of Modern Cosmology with a company called EUROPACE 2000. The course vanished without trace – although I still have the unedited footage in a box in my office – leaving only these  relics of a bygone era:

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Thought for the Day

Posted in The Universe and Stuff with tags , , , on July 1, 2011 by telescoper

For naturalism, fed on recent cosmological speculations, mankind is in a position similar to that of a set of people living on a frozen lake, surrounded by cliffs over which there is no escape, yet knowing that little by little the ice is melting, and the inevitable day drawing near when the last film of it will disappear, and to be drowned ignominiously will be the human creature’s portion. The merrier the skating, the warmer and more sparkling the sun by day, and the ruddier the bonfires at night, the more poignant the sadness with which one must take in the meaning of the total situation.

From The Varieties of Religious Experience by William James, first published in 1902…

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Linking to Data – Effect on Citation Rates in Astronomy (via Meters, Metrics and More)

Posted in Uncategorized with tags , , , , on June 30, 2011 by telescoper

I’m not a big fan of bibliometricism …but this is definitely Quite Interesting. I wonder if my linking to it will increase its readership?

Linking to Data - Effect on Citation Rates in Astronomy In the paper Effect of E-printing on Citation Rates in Astronomy and Physics we asked ourselves the question whether the introduction of the arXiv e-print repository had any influence on citation behavior. We found significant increases in citation rates for papers that appear as e-prints prior to being published in scholarly journals. This is just one example of how publication practices influence article metrics (citation rates, usage, obsolesc … Read More

via Meters, Metrics and More

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Bright and Early

Posted in The Universe and Stuff with tags , , , , , , on June 29, 2011 by telescoper

Some interesting astronomy news emerged this evening relating to a paper published in 30th June issue of the journal Nature. The press release from the European Southern Observatory (ESO) is quite detailed, so I’ll refer you there for the minutiae, but in a nutshell:

A team of European astronomers has used ESO’s Very Large Telescope and a host of other telescopes to discover and study the most distant quasar found to date. This brilliant beacon, powered by a black hole with a mass two billion times that of the Sun, is by far the brightest object yet discovered in the early Universe.

and the interesting numbers are given here (with links from the press release):

The quasar that has just been found, named ULAS J1120+0641 [2], is seen as it was only 770 million years after the Big Bang (redshift 7.1, [3]). It took 12.9 billion years for its light to reach us.

Although more distant objects have been confirmed (such as a gamma-ray burst at redshift 8.2, eso0917, and a galaxy at redshift 8.6, eso1041), the newly discovered quasar is hundreds of times brighter than these. Amongst objects bright enough to be studied in detail, this is the most distant by a large margin.

When I was a lad, or at least a postdoc, the most distant objects known were quasars, although in those days the record holders had redshifts just over half that of the newly discovered one. Nowadays technology has improved so much that astronomers can detect “normal” galaxies at even higher redshifts but quasars remain interesting because of their extraordinary luminosity. The standard model for how a quasar can generate so much power involves a central black hole onto which matter falls, liberating vast amounts of gravitational energy.

You can understand how efficient this is by imagining a mass m falling onto a black hole of Mass M from a large distance to the horizon of the black hole, which is at the Schwarzschild radius R=2GM/c^2. Since the gravitational potential energy at a radius R is -GMm/R the energy involved in bringing a mass m from infinity to the horizon is a staggering \frac{1}{2} mc^2, i.e. half the rest mass energy of the infalling material. This is an overestimate  for various reasons but it gives you an idea of how much energy is available if you can get gravity to do the work; doing the calculation properly still gives an answer much higher than the amount of energy that can be released by, e.g., nuclear reactions.

The point is, though, that black holes aren’t built in a day, so if you see one so far away that its light has taken most of the age of the Universe to reach us then it tells us that its  black hole must have grown very quickly. This one seems to be a particularly massive one, which means it must have grown very quickly indeed. Through observations like this  we learn something potentially very interesting about the relationship between galaxies and their central black holes, and how they both form and evolve.

On the lighter side, ESO have also produced the following animation which I suppose is quite illustrative, but what are the sound effects all about?

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Tosca

Posted in Opera with tags , , , , , on June 29, 2011 by telescoper

After yesterday’s examiners meeting at Queen Mary  I downed a quick beer and took the tube to the West End in order to meet up with  a couple of friends (Joao and Kim) to see last night’s production of Tosca at the Royal Opera House at Covent Garden.

Just over a year ago I posted about Welsh National Opera’s Tosca here in Cardiff, so I’ll refer you there for details about the plot synposis and background. Let me just say even though the WNO production was very good, it’s very difficult to match the special atmosphere of Covent Garden. It’s such a famous venue but at the same time is so intimate. I’d forgotten just how close you get to the stage.  The prices were special prices too! Our tickets were £220 each and drinks in the two intervals were eye-wateringly expensive. But then you don’t go to Covent Garden for a cheap night out.

This was the only night that I could make it to this run, and as a result we actually saw the “second” cast: no Bryn Terfel, no Angela Gherghiou, and as it happens to Marcello Giordani either (owing to illness). In the performance we saw, Floria Tosca was Martina Serafin, Baron Scarpia was Juha Uusitalo, and making his Covent Garden debut as understudy thanks to Giordiani’s indisposition was  was the young tenor Giancarlo Monsalve as Cavaradossi. I wasn’t too disappointed not to see Angela Gheorghiou, as I think she’s quite overrated, but I would have loved to have seen Bryn Terfel’s Scarpia. Perhaps some other time.

Anyway, it was a thoroughly enjoyable production if perhaps lacking that extra sparkle that the headline cast might have supplied. Serafin took a while to get going but from Act II onwards was very good, although she never quite managed to get across the fiery unpredictable side of her character’s persona. Uusitalo was a brutish Scarpia with a strong stage presence; the dashing Monsalve took his opportunity well and was warmly received by the full house.

I’ve often wondered how this Opera, which on the face of it is a straightforward melodrama, manages to work so well. I think part of its magic is that the characters, as is often the case with Puccini, are not quite what they seem. Tosca is the heroine but she’s far from Snow White. She’s jealous and temperamental and in many ways quite unattractive. In this production, after initially stabbing Scarpia in self-defence, she carries on stabbing him in a kind of bloodlust which is quite scary. Cavaradossi is the hero, but he’s not a particularly heroic hero because he crumbles under the strain of his imminent execution in Act III. And then there’s Scarpia, the baddy. I find him the most fascinating of all because, although he’s evil,  there are flashes of loneliness and contrition. I think he’s monstrous because something in his past has made him monstrous. A prequel to Tosca based on Scarpia’s earlier biography would make a very interesting opera indeed..

I know it’s deeply unfair to make comparisons, but I thought nevertheless I’d include this clip of a live broadcast of  Tosca from the same venue, way back in 1964, featuring perhaps the greatest Scarpia, Tito Gobbi, and perhaps the greatest Tosca, Maria Callas.  I heard the composer Michael Berkeley talking about what a revelation it was to see Callas at Covent Garden in this role; he simply hadn’t imagined that acting in the opera could be so good. Even in black-and-white you can get idea of the mesmerising stage presence that was Maria Callas and what a fine actress she was. Here she is, with hatred burning in her eyes, plunging the knife into Scarpia, standing over him willing him to die, then realising what she has done, turning back into a frightened, vulnerable and remorseful woman then doing the best she can to pay respect to his dead body. Magnificent.

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