Archive for January, 2015

January, 1795

Posted in Poetry with tags , , , on January 31, 2015 by telescoper

Pavement slipp’ry, people sneezing,
Lords in ermine, beggars freezing;
Titled gluttons dainties carving,
Genius in a garret starving.

Lofty mansions, warm and spacious;
Courtiers clinging and voracious;
Misers scarce the wretched heeding;
Gallant soldiers fighting, bleeding.

Wives who laugh at passive spouses;
Theatres, and meeting-houses;
Balls, where simp’ring misses languish;
Hospitals, and groans of anguish.

Arts and sciences bewailing;
Commerce drooping, credit failing;
Placemen mocking subjects loyal;
Separations, weddings royal.

Authors who can’t earn a dinner;
Many a subtle rogue a winner;
Fugitives for shelter seeking;
Misers hoarding, tradesmen breaking.

Taste and talents quite deserted;
All the laws of truth perverted;
Arrogance o’er merit soaring;
Merit silently deploring.

Ladies gambling night and morning;
Fools the works of genius scorning;
Ancient dames for girls mistaken,
Youthful damsels quite forsaken.

Some in luxury delighting;
More in talking than in fighting;
Lovers old, and beaux decrepid;
Lordlings empty and insipid.

Poets, painters, and musicians;
Lawyers, doctors, politicians:
Pamphlets, newspapers, and odes,
Seeking fame by diff’rent roads.

Gallant souls with empty purses;
Gen’rals only fit for nurses;
School-boys, smit with martial spirit,
Taking place of vet’ran merit.

Honest men who can’t get places,
Knaves who shew unblushing faces;
Ruin hasten’d, peace retarded;
Candour spurn’d, and art rewarded.

by Mary Robinson (1758-1800).

 

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The BICEP2 Bubble Bursts…

Posted in The Universe and Stuff with tags , , , , on January 30, 2015 by telescoper

I think it’s time to break the worst-kept secret in cosmology, concerning the claimed detection of primordial gravitational waves by the BICEP2 collaboration that caused so much excitement last year; see this blog, passim. If you recall, the biggest uncertainty in this result derived from the fact that it was made at a single frequency, 150 GHz, so it was impossible to determine the spectrum of the signal. Since dust in our own galaxy emits polarized light in the far-infrared there was no direct evidence to refute the possibility that this is what BICEP2 had detected. The indirect arguments presented by the BICEP2 team (that there should be very little dust emission in the region of the sky they studied) were challenged, but the need for further measurements was clear.

Over the rest of last year, the BICEP2 team collaborated with the consortium working on the Planck satellite, which has measurements over the whole sky at a wide range of frequencies. Of particular relevance to the BICEP2 controversy are the Planck mesurements at such high frequency that they are known to be dominated by dust emission, specifically the 353 GHz channel. Cross-correlating these data with the BICEP2 measurements (and also data from the Keck Array which is run by the same team) should allow the identification of that part of the BICEP2 signal that is due to dust emission to be isolated and subtracted. What’s left would be the bit that’s interesting for cosmology. This is the work that has been going on, the results of which will officially hit the arXiv next week.

However, news has been leaking out over the last few weeks about what the paper will say. Being the soul of discretion I decided not to blog about these rumours. However, yesterday I saw the killer graph had been posted so I’ve decided to share it here:

cross-correlation

The black dots with error bars show the original BICEP/Keck “detection” of B-mode polarization which they assumed was due to primordial gravitational waves. The blue dots with error bars show the results after subtracting the correlated dust component. There is clearly a detection of B-mode polarization. However, the red curve shows the B-mode polarization that’s expected to be generated not by primordial gravitational waves but by gravitational lensing; this signal is already known. There’s a slight hint of an excess over the red curve at multipoles of order 200, but it is not statistically significant. Note that the error bars are larger when proper uncertainties are folded in.

Here’s a quasi-official statement of the result (orginall issued in French) that has been floating around on Twitter:

BICEP_null

To be blunt, therefore, the BICEP2 measurement is a null result for primordial gravitational waves. It’s by no means a proof that there are no gravitational waves at all, but it isn’t a detection. In fact, for the experts, the upper limit on the tensor-to-scalar ratio  R from this analysis is R<0.13 at 95% confidences there’s actually till room for a sizeable contribution from gravitational waves, but we haven’t found it yet.

The search goes on…

UPDATE: As noted below in the comments, the actual paper has now been posted online here along with supplementary materials. I’m not surprised as the cat is already well and truly out of the bag, with considerable press interest, some of it driving traffic here!

UPDATE TO THE UPDATE: There’s a news item in Physics World and another in Nature News about this, both with comments from me and others.

Mistaken Identity

Posted in Uncategorized with tags , on January 29, 2015 by telescoper

 

wpid-wp-1422539203608.jpeg

R.I.P. Charles Townes, the physicist whose work touched all our lives

Posted in The Universe and Stuff with tags , , , , on January 28, 2015 by telescoper

Just a short post to mark the passing of a truly great physicist, Charles H. Townes, who died yesterday at the age of 99.

Charles Townes, pictured in 2013

Charles Townes, pictured in 2013

Townes came to fame for his pioneering work on the theory and applications of the maser , which he then followed up by designing the first laser. Lasers are used in many common consumer devices such as optical disk drives, laser printers, barcode scanners and fibre-optic cables. They are also used in medicine for laser surgery and various skin treatments, and in industry for cutting and welding materials.

The work of Charles Townes in physics has thus had an enormous impact on everyday life; he was awarded the Nobel Prize for is his work on quantum electronics, especially lasers and masers.

It’s very sad that he didn’t quite make his century, especially because this year is the International Year of Light, which will involve many activities and celebrations relating to his work on lasers. Much of our experimental work in Physics here in the Department of Physics and Astronomy at the University of Sussex involves lasers in various ways, and we will find an appropriate occasion to celebrate the life and achievements of a truly great physicist. Until then let me just express my condolences to the friends, family and colleagues of Charles Townes on the loss not only of an eminent scientist but of an extremely nice man.

R.I.P. Charles Townes, physicist and gentleman (1915-2015).

A whole lotta cheatin’ going on? REF stats revisited

Posted in Education, Science Politics with tags , , , on January 28, 2015 by telescoper

Here’s a scathing analysis of Research Excellence Framework. I don’t agree with many of the points raised and will explain why in a subsequent post (if and when I get the time), but I reblogging it here in the hope that it will provoke some comments either here or on the original post (also a wordpress site).

coastsofbohemia

 

1.

The rankings produced by Times Higher Education and others on the basis of the UK’s Research Assessment Exercises (RAEs) have always been contentious, but accusations of universities’ gaming submissions and spinning results have been more widespread in REF2014 than any earlier RAE. Laurie Taylor’s jibe in The Poppletonian that “a grand total of 32 vice-chancellors have reportedly boasted in internal emails that their university has become a top 10 UK university based on the recent results of the REF”[1] rings true in a world in which Cardiff University can truthfully[2]claim that it “has leapt to 5th in the Research Excellence Framework (REF) based on the quality of our research, a meteoric rise” from 22nd in RAE2008. Cardiff ranks 5th among universities in the REF2014 “Table of Excellence,” which is based on the GPA of the scores assigned by the REF’s “expert panels” to the three…

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The Map is not the Territory

Posted in History, The Universe and Stuff with tags , , , , , , , , on January 27, 2015 by telescoper

I came across this charming historical map while following one of my favourite Twitter feeds “@Libroantiguo” which publishes fascinating material about books of all kinds, especially old ones. It shows the location of London coffee houses and is itself constructed in the shape of a coffee pot:

Coffee
Although this one is obviously just a bit of fun, maps like this are quite fascinating, not only as practical guides to navigating a transport system but also because they often stand up very well as works of art. It’s also interesting how they evolve with time  because of changes to the network and also changing ideas about stylistic matters.

A familiar example is the London Underground or Tube map. There is a fascinating website depicting the evolutionary history of this famous piece of graphic design. Early versions simply portrayed the railway lines inset into a normal geographical map which made them rather complicated, as the real layout of the lines is far from regular. A geographically accurate depiction of the modern tube network is shown here which makes the point:

tubegeo

A revolution occurred in 1933 when Harry Beck compiled the first “modern” version of the map. His great idea was to simplify the representation of the network around a single unifying feature. To this end he turned the Central Line (in red) into a straight line travelling left to right across the centre of the page, only changing direction at the extremities. All other lines were also distorted to run basically either North-South or East-West and produce a regular pattern, abandoning any attempt to represent the “real” geometry of the system but preserving its topology (i.e. its connectivity).  Here is an early version of his beautiful construction:

Note that although this a “modern” map in terms of how it represents the layout, it does look rather dated in terms of other design elements such as the border and typefaces used. We tend not to notice how much we surround the essential things, which tend to last, with embellishments that date very quickly.

More modern versions of this map that you can get at tube stations and the like rather spoil the idea by introducing a kink in the central line to accommodate the complexity of the interchange between Bank and Monument stations as well as generally buggering about with the predominantly  rectilinear arrangement of the previous design:

I quite often use this map when I’m giving popular talks about physics. I think it illustrates quite nicely some of the philosophical issues related with theoretical representations of nature. I think of theories as being like maps, i.e. as attempts to make a useful representation of some  aspects of external reality. By useful, I mean the things we can use to make tests. However, there is a persistent tendency for some scientists to confuse the theory and the reality it is supposed to describe, especially a tendency to assert there is a one-to-one relationship between all elements of reality and the corresponding elements in the theoretical picture. This confusion was stated most succintly by the Polish scientist Alfred Korzybski in his memorable aphorism :

The map is not the territory.

I see this problem written particularly large with those physicists who persistently identify the landscape of string-theoretical possibilities with a multiverse of physically existing domains in which all these are realised. Of course, the Universe might be like that but it’s by no means clear to me that it has to be. I think we just don’t know what we’re doing well enough to know as much as we like to think we do.

A theory is also surrounded by a penumbra of non-testable elements, including those concepts that we use to translate the mathematical language of physics into everday words. We shouldn’t forget that many equations of physics have survived for a long time, but their interpretation has changed radically over the years.

The inevitable gap that lies between theory and reality does not mean that physics is a useless waste of time, it just means that its scope is limited. The Tube  map is not complete or accurate in all respects, but it’s excellent for what it was made for. Physics goes down the tubes when it loses sight of its key requirement: to be testable.

In any case, an attempt to make a grand unified theory of the London Underground system would no doubt produce a monstrous thing so unwieldly that it would be useless in practice. I think there’s a lesson there for string theorists too…

Now, anyone for a game of Mornington Crescent?

 

Luqman Onikosi

Posted in Education, Politics with tags , on January 27, 2015 by telescoper

Yesterday my attention was drawn to the case of Luqman Onikosi, a postgraduate student at the University of Sussex, who is originally from Nigeria. Luqman has been granted temporary permission to reside in the United Kingdom based on his medical circumstances; he is suffering from Hepatitis B, for which far better treatment is available in the UK than in his home country. His immigration status is yet to be definitely resolved and in the meantime he is being treated, entirely according to established policy and practice, as an Overseas Student. He is therefore  liable to pay full Overseas Fees if he is to continue on his course, an MA in Global Political Economy, and currently can not afford to pay them.

It would be inappropriate for me to comment in further detail on Luqman’s case – not least because I don’t have much in the way of further detail to comment on – but I am happy to use the medium of this personal blog to draw the attention of readers to a crowdsourcing appeal that has started with the aim of collecting sufficient funds to enable him to continue his studies. You can find the website where you can find more information about the issues surrounding his case, and instructions on how to make a donation, here.