WMAP: The Last Judgement

Posted in The Universe and Stuff with tags , , , , , , on December 21, 2012 by telescoper

It seems the the Wilkinson Microwave Anisotropy Probe, or rather the estimable team of people working on it, have produced yet another set of maps and key results. I believe this will be the final release from WMAP. The paper is on the arXiv here and it represents a synthesis of no less than nine years of measurements of the cosmic microwave background radiation:

Here’s the abstract:

We present the final nine-year maps and basic results from the WMAP mission. We provide new nine-year full sky temperature maps that were processed to reduce the asymmetry of the effective beams. Temperature and polarization sky maps are examined to separate CMB anisotropy from foreground emission, and both types of signals are analyzed in detail. The WMAP mission has resulted in a highly constrained LCDM cosmological model with precise and accurate parameters in agreement with a host of other cosmological measurements. When WMAP data are combined with finer scale CMB, baryon acoustic oscillation, and Hubble constant measurements, we find that Big Bang nucleosynthesis is well supported and there is no compelling evidence for a non-standard number of neutrino species (3.26+/-0.35). The model fit also implies that the age of the universe is 13.772+/-0.059 Gyr, and the fit Hubble constant is H0 = 69.32+/-0.80 km/s/Mpc. Inflation is also supported: the fluctuations are adiabatic, with Gaussian random phases; the detection of a deviation of the scalar spectral index from unity reported earlier by WMAP now has high statistical significance (n_s = 0.9608+/-0.0080); and the universe is close to flat/Euclidean, Omega_k = -0.0027 (+0.0039/-0.0038). Overall, the WMAP mission has resulted in a reduction of the cosmological parameter volume by a factor of 68,000 for the standard six-parameter LCDM model, based on CMB data alone. For a model including tensors, the allowed seven-parameter volume has been reduced by a factor 117,000. Other cosmological observations are in accord with the CMB predictions, and the combined data reduces the cosmological parameter volume even further. With no significant anomalies and an adequate goodness-of-fit, the inflationary flat LCDM model and its precise and accurate parameters rooted in WMAP data stands as the standard model of cosmology.

The main reason for posting this is to acknowledge the remarkable impact WMAP has had on the field of cosmology. The standard model does indeed account for most available cosmological data extremely well. I’m not entirely sure about the “no significant anomalies” bit in the last sentence, in fact, but I won’t argue with it as it depends entirely upon what you mean by significant. It’s not exactly proven that the fluctuations have “random phases” either. We’ll just have to see whether data from Planck, due to be released next year, will reveal evidence of any physics beyond the standard framework WMAP did so much to establish.

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Das Letzte Gericht

Posted in Art, Astrohype, The Universe and Stuff with tags , , , on December 20, 2012 by telescoper

Apparently the world is due to end tomorrow, so I’ve saved quite a lot of money by not having done my Christmas shopping yet. Anyway, the forthcoming Apocalypse reminded me of the painting that I often use to introduce cosmology talks. I usually use this piece of Hieronymus Bosch Das letzte Gericht (The Last Judgement) to illustrate my feelings about the standard cosmological 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 large knife visible in the bottom right corner clearly symbolises budget cuts looming in the next Comprehensive Spending Review.

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.

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Astronomy Look-alikes, No. 81

Posted in Astronomy Lookalikes with tags , on December 19, 2012 by telescoper

At the Winter School I attended recently I was struck by the not inconsiderable similarity in both sound and appearance between Dr Jonathan Pritchard of Imperial College and former Prime Minister Sir John Major. Oh yes. I wonder if, by any chance, they might be related?

Presentation1

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What’s Your Lecture Face?

Posted in Biographical, Education with tags , , , on December 19, 2012 by telescoper

I was thinking the other day – it doesn’t happen that often so I try to make the most of it when it does – about what a strange situation it is when someone stands up in front of a bunch of students and lectures at them for an hour. In the course module I’ve just finished teaching I’ve had the best part of a 100 people watching, and occasionally listening to, me drone on about something or other. What’s strange is that all those people see basically the same thing, whereas the lecturer gets to see all those different facial expressions. I wonder if the students are even aware that each one has a characteristic lecture face?

I’m one of those people who finds it very difficult to give a lecture without looking at the audience. It’s partly to try to establish some kind of rapport with them, notably in order to encourage them to answer when I ask a question or to offer questions of their own, but also to try to figure out whether anyone at all is following what I’m saying. Not all students are helpful in this regard, but some have very responsive mannerisms, nodding when they understand and frowning when they don’t. When I’m teaching a class for the first time I usually look around a lot in an attempt to identify those students who are likely to help me gauge how well things are going. Usually,  there are only a few barometers like this but I would be lost without them. Fortunately most students seem to sit in the same place in the theatre for each lecture so you can usually locate the useful ones fairly easily, with a discreet look around before you  start.

Most other students seem to have a default lecture face.  The expressions range from a perpetual scowl to a vacant smile (each of which is in its own way a bit scary). There’s the “wish I wasn’t here” face of pure boredom,  not to mention those who are fast asleep; I don’t mind them as long as they don’t snore. There’s the Bookface of someone who’s not listening but messing around on Facebook, and the inscrutable ones whose faces are masks yielding no clues as to what, if anything, is going on behind. The brightest students often seem to belong to the last group, although I haven’t done a statistical study of this so that must be taken as purely anecdotal.

Anyway, I feel a Christmas Poll coming on. Please participate if you can be bothered. If you don’t know what your own lecture face is, then you could always ask….

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Talking about Winterreise

Posted in Music with tags , , , on December 18, 2012 by telescoper

Well, here’s a find! A fascinating bit of film featuring Benjamin Britten and Peter Pears discussing and performing Franz Schubert‘s great song cycle, Winterreise.

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Passo del Tonale Winter School 2012

Posted in Biographical, Books, Talks and Reviews with tags , , on December 18, 2012 by telescoper

I’m having a restful morning at home because (a) it was our Departmental Christmas Lunch yesterday meaning that I’m feeling a bit fragile and (b) there’s a planned electrical shutdown in our building this morning meaning that there’s not much point going in until it’s all back up anyway.

Anyway, since various people made the odd facetious comment accusing me of skiving off last week, I thought I’d take the opportunity to reflect a little on the Winter School that I was lecturing at last week. This took place at Passo del Tonale, in the Italian Alps and was the Sixth in a series of schools for graduate students and postdocs held there annually. When I was invited to take part, I was asked to give five lectures as a sort of overview of the current state of cosmology. Subsequently one of the other speakers dropped out so instead of inviting a replacement, the remaining four were given an extra lecture each. Then one of those was taken ill during the summer school so I stepped in at short notice to give another one. And so it came to pass that I gave seven lectures altogether, in the space of five days. That’s considerably more lecturing than I would have done had I stayed in Cardiff.

Anyway, here’s a picture of me during one of the lectures (taken by one of the participants, Chris Crowe).

Tonale

Afternoons were kept free for skiing and snowboarding, but my dodgy knees don’t allow me to participate in such activities. I am not shap’d for sportive tricks nor made to court an amorous looking-glass. I had lectures to prepare anyway.

However the hosts looked after us well and there was a fine conference dinner on Wednesday evening,

IMG-20121212-00008

the main course featuring a roast pig brought into the room by the chefs with some aplomb:

IMG-20121212-00009

Everything was eaten. I was given the honour of having one of the ears, in fact. A bit chewy, but quite tasty in case you were wondering. I don’t know what the vegetarians did.

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Anyway, at the end of the school the lecturers were presented with bottles of fine Grappa. I’ll no doubt be sampling mine over the Christmas vacation!

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Debt

Posted in Poetry with tags , , on December 17, 2012 by telescoper

What do I owe to you
Who loved me deep and long?
You never gave my spirit wings
Or gave my heart a song.

But oh, to him I loved,
Who loved me not at all,
I owe the open gate
That led through heaven’s wall.

by Sara Teasdale (1884-1933)

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Kettles, pots and metonymic shifts….

Posted in Uncategorized on December 17, 2012 by telescoper

As our Departmental Christmas lunch is looming I only have time for a brief reblog of this nice discussion of boiling water in pots. It might strike you as as a bit obsessive to write about the physics of such an everyday phenomenon, but I think a bit of an obsession about physics is a very good thing indeed.

P.S. As a fully paid-up member of Pedants Anonymous I couldn’t resist drawing attention to the metonymic shift involved in the title “Watching pots boil”. Of course the pot doesn’t boil – the water in it does….

Michael de Podesta's avatarProtons for Breakfast

My previous article about kettles left me wondering: Can gas hobs really waste more than half of the calorific energy in the gas? I decided to try a few more experiments and finally I think I have an answer: ‘Yes’. Gas hobs really do fail to transfer a great deal of the calorific energy in the gas to the pan or kettle they are heating.

Experiment#1 Rather than measuring the total time to reach 100 °C, I measured the rate of temperature rise. Because the heat capacity of water is well known, this allowed me to estimate how much thermal power was entering the water. So I spent a happy hour or so heating up various amounts of water: first 200g, then 400 g, 600g and finally 800g and I measured the temperature every 20 seconds.

I knew the burner power was 1.75 kW, and after a little jiggery pokery with a…

View original post 639 more words

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Another Refusal to Mourn

Posted in Poetry with tags , , , , on December 17, 2012 by telescoper

I posted this poem after the terrible events in Norway last year. Sadly the awful killings in Newton, Connecticut make it relevant again.

The full title is A Refusal to Mourn the Death by Fire of a Child in London  and it was written  by Dylan Thomas. Published just after the end of the Second World War, it was written some time earlier when Thomas heard news of a young girl who had burned to death when the house she was in was set on fire during an air raid. Here is the poet himself reading it.

The idea behind the poem is complex, and its message double-edged,  but Thomas finds a perfect balance between horror and sadness, and between indignation and heartbreak. Children shouldn’t have to die, and neither should anyone else whose life is cut short by another’s hand, but we have to accept that they can and do.  There’s no consolation to be found in mourning  and in any case it’s hypocritical to favour one death with elegies, when suffering is so widespread. The best we can do is allow the dead some dignity and their families and loved ones some time to grieve.

Never until the mankind making
Bird beast and flower
Fathering and all humbling darkness
Tells with silence the last light breaking
And the still hour
Is come of the sea tumbling in harness

And I must enter again the round
Zion of the water bead
And the synagogue of the ear of corn
Shall I let pray the shadow of a sound
Or sow my salt seed
In the least valley of sackcloth to mourn

The majesty and burning of the child’s death.
I shall not murder
The mankind of her going with a grave truth
Nor blaspheme down the stations of the breath
With any further
Elegy of innocence and youth.

Deep with the first dead lies London’s daughter,
Robed in the long friends,
The grains beyond age, the dark veins of her mother,
Secret by the unmourning water
Of the riding Thames.
After the first death, there is no other.

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God sent the shooter….

Posted in Uncategorized with tags on December 16, 2012 by telescoper

Sometimes I just despair. Watch this and weep. If this is your God, I weep for you too.

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