Today brought sad news of the death of artist David Hockney at the age of 88. Hockney was one of the leaders in the pop art movement, which involved assimilating and distilling ideas from popular culture and his career spanned painting, drawing, photography, printmaking and stage design. The last exhibition I saw by him consisted of wonderful drawings done on an IPad. That was about 15 years ago; he remained remarkably active and productive well into old age.
Throughout his career, Hockney’s work was often inspired by his fascination with light, especially its interplay with water, as well as his unique use of space and unusual use of colour. His most famous early expressions of these were realised in California, where he became obsessed with the bright sunshine and the plethora of swimming pools.
As Hockney’s fame grew his work became very collectible, commanding huge prices at auction, so much of it ended up in private collections. This large-scale work, A Bigger Splash, painted in 1967, followed a smaller painting, The Splash (1966). The earlier work fetched around $30M at auction and is in a private collection, but A Bigger Splash can be seen at Tate Britain. The spare composition and distinctive palette are his instantly recognisable trademarks.
A Bigger Splash by David Hockney (1967, Acrylic on Canvas, 242.5 × 243.9 cm, Tate Britain, London)
Once upon a time – in the summer of 2022 – I posted a silly little joke on Twitter (before I left there, obviously):
I thought a few people might find it funny, but it took off beyond my expectations. By my standards over 5000 “likes” counts as “going viral” (as you young people say). Most people saw the joke immediately – if you don’t get it, the image is of a slice of choriz,o not an astronomical object – and some even joined in with puns and other jokes. Even funnier, some respondents earnestly shared their devastating insight that it was chorizo (or some variant thereof). I honestly didn’t think anyone would think that I was seriously trying to pass it off as a JWST picture; it was just meant to be silly. But there you go. That’s Twitter. I should also report that some people looked at the rainbow flags in my profile and proceeded to indulge in some homophobic abuse. That’s Twitter too.
Anyway, the day after I posted the image it seems a prominent French physicist called Etienne Klein who has many times more Twitter followers than I ever did, posted an embellished version of the same joke.
To cut a long story short that led to ChorizoGate, a story which made it into numerous newspapers, from the Daily Star to The Times, and even got coverage on CNN News and the RTÉ website. More exciting and even Physics World! In nearly all the stories I’ve seen, the image, together with the JWST connection, is attributed to Étienne Klein who is apparently very well known in France as a popularizer of science in the French language. Because he writes and broadcasts in French he is not so well known outside France.
To be honest I’m quite relieved to have avoided the media notoriety surrounding ChorizoGate, especially as it means I’ve avoided being on the front page of the Daily Star! Dr Klein is welcome to the publicity, though perhaps it might backfire on him…
I’ve been slow onto a result which was announced last week concerning the detection weak gravitational lensing in the cluster Abell 2390 by the Euclid spacecraft and its use to determine the distribution of dark matter in the cluster. You can find a full discussion of the result here and the scientific paper is here.
The analysis was based on Early Release Observations of the cluster, a pretty picture of which are shown here:
Credit: ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi.
(The little blue patches are artefacts caused by internal reflections in the VIS instrument and can be dealt with in software.)
According to general relativity, the presence of any mass bends the path of light passing near it, producing gravitational lensing. The most famous examples of this are the giant arcs and multiple images associated with strong gravitational lensing, but these are very rare as they require good alignment between observer, lens and source.. Most lines of sight in the universe do not satisfy this condition so are in the weak lensing regime. Even in such cases, however, the presence of the foreground mass can be detected, by way of a systematic alignment in the orientation of background sources around the lensing mass. A circular background image would be distorted into an ellipse by this process. Unfortunately galaxies aren’t circular but are approximately elliptical, so the shape of each source is changed from an ellipse to differently shaped ellipse. The distortion is therefore impossible to detect in a single background source because we don’t know the intrinsic orientation of the galaxy, but the distortion of different sources is correlated in a particular way. Weak gravitational lensing is thus an intrinsically statistical measurement, but it provides a way to measure the masses of astronomical objects without requiring assumptions about their composition or dynamical state. Weak gravitational lensing observations are, however technically difficult to carry out and analyse, as one has to be very careful that no correlations are introduced by systematic errors in the optics.
Anyway, they say that a picture paints a thousand words so here are two pictures. On the left we see the shear axes as extracted from the above image and on the right the inferred dark matter distribution. You can slide the bar backwards and forwards to see how the two images relate.
Shear map (left) and inferred dark matter distribution (right)
You can see that the shear tends to be aligned tangentially to a line connecting the image to the cluster centre (in the plane of the sky), which is what theory would predict.
There’ll be much more of this sort of analysis in the full Euclid Survey. I hope to be able to give an update about this reasonably soon.
I just watched a nice documentary programme on the Irish language channel TG4 in the series Scéalta Grá na h’Éireann (Ireland’s Greatest Loves). This one was about Lady Eleanor Charlotte Butler and the Honourable Sarah Ponsonby, often called The Ladies of Llangollen. The programme is available on the TG4 Player, actually, and it is possible I think to watch the whole thing anywhere in the world for free here. There’s also a little trailer on Youtube:
There’s an entire wikipedia page devoted to the Ladies of Llangollen, so there’s no need to reproduce it all here. However, for the sake of you who haven’t heard of them, they were. They were of Anglo-Irish extraction, both born in Ireland, and had been brought up just a few miles away from each other. They met in 1768 and immediately hit it off. They ran off together to avoid being forced into unwanted marriages, and moved to Wales in order to set up home at Plas Newydd, near Llangollen in Denbighshire, in 1780.
They lived together for the best part of 50 years in Plas Newydd, in relative seclusion, devoting their time to private studies of literature and languages and improving their estate, comprehensively redesigning the house in a Gothic style, and adding a superb garden. They did not actively socialise and town-dwellers of Llangollen seem to have regarded them as eccentrics, simply referring to them as “The Ladies”.
Gradually, their life attracted the interest of the outside world. Their house became a haven for all manner of visitors, mostly writers such as Wordsworth, Robert Southey, Shelley, Byron and Scott, but also the military leader Duke of Wellington and industrialist Josiah Wedgwood; aristocratic novelist Caroline Lamb, who was born a Ponsonby, came to visit too. Even travellers from continental Europe had heard of the couple and came to visit them, for instance Prince Hermann von Pückler-Muskau, the German nobleman and landscape designer who wrote admiringly about them.
The story of the “romantic friendship” between these two ladies is both charming and moving, but it’s also fascinating to learn how their lifestyle was accepted and even celebrated by wider society. One might have thought their relationship would have been regarded as scandalous by their contemporaries, rather than being widely admired as it turned out to be. One is tempted to assume that their “marriage” had a sexual dimension, which it may well have done, but it could have been a platonic, yet still romantic, friendship. As far as I’m concerned, that doesn’t really matter; what I find inspiring about them is that they dared to be different.
Anyway, here is the beautiful sonnet that William Wordsworth wrote after meeting the Ladies of Llangollen in 1824, although I believe the Ladies took exception to the description of their magnificent house as a “low-roofed cot”!
A stream, to mingle with your favourite Dee, Along the vale of meditation flows; So styled by those fierce Britons, pleased to see In Nature's face the expression of repose; Or haply there some pious hermit chose To live and die, the peace of heaven his aim; To whom the wild sequestered region owes At this late day, its sanctifying name. Glyn Cafaillgaroch, in the Cambrian tongue, In ours, the Vale of Friendship, let 'this' spot Be named; where, faithful to a low-roofed Cot, On Deva's banks, ye have abode so long; Sisters in love, a love allowed to climb, Even on this earth, above the reach of Time!
Over the last few days we have been having our annual meetings of the Board of Examiners in the Department of Physics at Maynooth. This process began last Friday with a preliminary meeting of those involved in the theoretical side of the Department, continued on Monday with another preliminary meeting for the experimentalists, continued yesterday with a final meeting with both sides of the house and a visit by two External Examiners, and ended this morning with a meeting I couldn’t attend with feedback. This is the first time since the Departments of Theoretical Physics and Experimental Physics merged that we have run the process like this. I think one of the primary purposes of the merger was to streamline the bureaucracy, but it seems to have had the opposite effect, with everything taking much longer. It was ever thus.
Still, at least I got a nice dinner with the Externals.
Since we have reached the end of the academic year, we looked yesterday at the final grades of those students who are completing their studies this year in order to consider the classification of their degrees. Another (pleasant) duty of our Examination Board was to award prizes for the best performance, not just for finalists but for students at every stage, including the first year. These will be announced in due course.
But that’s not quite the end of it – there is an overall University Examination Board that covers all courses in the University to formally bring an end to the examination process. It is not until after all the Boards have done their business that the students get their marks. If all goes to plan, students will receive their final marks onThursday 25th June, a couple of weeks from now.
In previous years this would have been followed by a Consultation Day on which:
Staff will be available in all Departments to discuss results with students. Students are entitled to see their examination scripts if they wish, these will be generally available on this day or at another mutually convenient time.
In its drive to scrap everything that could possibly be useful to students, however, Maynooth University has now ditched the formal Consultation Day. Well, you can’t expect a University running an €11M surplus to put any resources into processes for advising students can you?
If I had my way we would actually give all students their marked examination scripts back as a matter of routine. Obviously examination scripts have to go through a pretty strict quality assurance process involving the whole paraphernalia of examination boards (including External Examiners), so the scripts can’t be given back immediately but once that process is complete there doesn’t seem to me any reason why we shouldn’t give their work, together with any feedback written on it, back to the students in its entirety. I have heard it argued that under the provisions of the Data Protection Act students have a legal right to see what’s written on the scripts – as that constitutes part of their student record – but I’m not making a legalistic point here. My point is purely educational, based on the benefit to the student’s learning experience, so this is unlikely to be adopted.
So that’s my internal examination duties here at Maynooth done and dusted. In a month or so I have to travel abroad to be an external examiner at another institution.
Interesting to see, that according to Openalex data, diamond open access is the most frequently used model among OA models recent papers were published under. From about 26,170,000 articles and reviews published between 2020 and 2025, over 8.7M are diamond OA, more than any other OA model. And even this is likely an underestimation, as OA type detection for diamond is DOAJ based, that many diamond journals have not registered with.
The results were obtained using the excellent OpenAlex catalog(ue). It shows that of the over 25 million articles published as Open Access in the years 2020-2025 (inclusive), over 8.6 million (around 35%) were Diamond Open Access publications, i.e. free to authors and readers alike (without APC). Far from being the fringe model that many people think, these figures demonstrate that Diamond Open Access is the most frequently used form of OA. I predict that its use will increase with time.
As I mentioned a few days ago, examinations for the 2026 school Leaving Certificate are under way. One of the interesting things about the Irish system is that the examination papers are put up online immediately after the examinations. Students took their first paper in Mathematics (either Ordinary or Higher level) on Friday and the second was this morning. There has been some reaction in the news here and here.
Anyway, I thought I’d share the Mathematics papers here so you can see what you think of them.
I posted this little optical illusion yesterday on BlueSky and it proved so popular I thought I’d repeat it here.Whichever of the purple dots you look directly at turns more purple:
I find the effect is stronger on a smaller screen (e.g. on a phone).
In a nutshell, this happens because your eyes have reduced sensitivity to blue light at the centre of your field of view so the purple (which is a mixture of red and blue) changes hue if you look directly at it. For more details see here and the following blog post:
Broom out the floor now, lay the fender by, And plant this bee-sucked bough of woodbine there, And let the window down. The butterfly Floats in upon the sunbeam, and the fair Tanned face of June, the nomad gipsy, laughts Above her widespread wares,the while she tells The farmer’s fortunes in the fields, and quaffs The water from the spider-peopled wells.
The hedges are all drowned in green grass seas, And bobbing poppies flare like Elmo’s light While siren-like the pollen-stained bees Drone in the clover depths. And up the height The cuckoo’s voice is hoarse and broke with joy. And on the lowland crops the crows make raid, Nor fear the clappers of the farmer’s boy, Who sleeps, like drunken Noah, in the shade.
And loop this red rose in that hazel ring That snares your little ear, for June is short And we must joy in it and dance and sing, And from her bounty draw her rosy worth. Ay! soon the swallows will be flying south, The wind wheel north to gather in the snow Even the roses spilt on youth’s red mouth Will soon blow down the road all roses go.
Ledwidge was born in Slane, County Meath, in Ireland. He served in the British Army in the First World War and was killed at Passchendaele during the Third Battle of Ypres, just a few weeks before his 30th birthday. I’ve posted this poem before but was reminded of it when I saw some roses in my garden had died while I was away last week.
Another Saturday, another update of activity at the Open Journal of Astrophysics. Since the last update we have published a further five papers, bringing the number in Volume 9 (2026) to 119 and the total so far published by OJAp up to 567.
I will continue to include the posts made on our Mastodon account (on Fediscience); these announcements also show the DOI for each paper.
The first paper to report this week, published on Tuesday 2nd June, is “The impact of the formation channel on gravitational-wave-galaxy cross-correlations” by Kabir Chakravarti (Chennai Mathematical Institute, India) and Federico R Urban (CEICO-FZU, Czech Republic). This article, published in the folder Cosmology and Nongalactic Astrophysics, explores how uncertainties in binary formation affect the cross-correlation signal between gravitational wave events and galaxy catalogues, finding that time-delay distribution significantly impacts the signal.
The overlay for this paper is here
You can find the officially accepted version on arXiv here and the announcement on Fediverse here:
New Publication at the Open Journal of Astrophysics: "The impact of the formation channel on gravitational-wave-galaxy cross-correlations" by Kabir Chakravarti (Chennai Mathematical Institute, India) and Federico R Urban (CEICO-FZU, Czech Republic)
New Publication at the Open Journal of Astrophysics: "Transient X-ray Sources as Extremely Eccentric Mass-Transfer Binaries with Compact Companions" by Jonathan I Katz and Michael A Nowak (Washington University, USA)
Next one up, the third paper of the week, also published on Tuesday 2nd June in the folder High-Energy Astrophysical Phenomena is “Resolving the (Debate About) Nozzle Shocks in Tidal Disruption Events” by Zachary L. Andalman & Eliot Quataert (Princeton U., USA), Eric R. Coughlin (Syracuse U. USA) and C. J. Nixon (U. Leeds, UK). This paper presents a model to understand the role of nozzle shocks in the circularization of stellar debris during a tidal disruption event when a star approaches a supermassive black hole (SMBH)
The overlay for this one is here:
The final, accepted version can be found on arXiv here and the Mastodon announcement is here:
New Publication at the Open Journal of Astrophysics: "Resolving the (Debate About) Nozzle Shocks in Tidal Disruption Events" by Zachary L. Andalman & Eliot Quataert (Princeton U., USA), Eric R. Coughlin (Syracuse U. USA) and C. J. Nixon (U. Leeds, UK)
The fourth paper this week, published on Wednesday 3rd June in the folder Cosmology and Nongalactic Astrophysics, is “Validating Digital Twins of the Local Universe with the Thermal Sunyaev-Zel’dovich Signal” by Richard Stiskalek (University of Oxford, UK) and Harry Desmond (University of Portsmouth, UK). The thermal Sunyaev-Zel’dovich effect and constrained simulations are used to analyze the thermal pressure of ionized gas in galaxy clusters and produce a set of digital twins for cosmological study.
The overlay is here:
The officially accepted version can be found on arXiv here and here is the Mastodon announcement:
New Publication at the Open Journal of Astrophysics: "Validating Digital Twins of the Local Universe with the Thermal Sunyaev-Zel’dovich Signal" by Richard Stiskalek (U. Oxford, UK) and Harry Desmond (U. Portsmouth, UK)
New Publication at the Open Journal of Astrophysics: "Photon (Non)Conservation in the Reduced Speed of Light Approximation and How to (Almost) Fix It" by Nickolay Y. Gnedin (U. Chicago, USA)
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In the Dark 