The Voice of Niels Bohr

Posted in History, The Universe and Stuff with tags , , on December 28, 2025 by telescoper

The other night I watched the 2023 film Oppenheimer on TV. I had seen it before, on a plane flight, and enjoyed it, though I thought it was overlong. Fortunately it was a long flight. Watching it again a couple of days ago reminded me of something that struck me first time, and that was the cameo performance by Kenneth Branagh as Niels Bohr. You can see him at the start of the trailer here:

Niels Bohr was born in Copenhagen, a place I visited many times in the past and can recognize the local accent, though had never heard the speaking voice of Niels Bohr himself. I was a underwhelmed by Branagh’s rendition because he doesn’t sound very Danish to me. I assumed that because it was a relatively small part, Branagh didn’t put much effort into it. He doesn’t look like Niels Bohr, either.

But what did Niels Bohr actually sound like? Here is a lecture by him given in 1957 so you can decide for yourself.

Having heard this recording I think Kenneth Branagh’s version is not too far off, in fairness, though there are clear vocal mannerisms he did not capture.

The thing that strikes me most about the lecture, however, is that his delivery is very pedestrian, not to say rambling. People say he was like that in ordinary conversation too…

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Weekly Update from the Open Journal of Astrophysics – 27/12/2025

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , , , , , , , , , , , , , , , , on December 27, 2025 by telescoper

I wasn’t planning to do another update this week but I thought it would be best to complete the publications for 2025  at the Open Journal of Astrophysics, so that I don’t have to do a bigger update in the new year, and I have a bit of time this morning, so here we go.

Since the last update we have published four papers which brings the number in Volume 8 (2025) up to 201. Adding the 12 papers in the Supplement, this brings the final total for the year up to 213, and the total so far published by OJAp up to 448. In 2023 we published just 50 papers, so we have more than quadrupled in two years.

The first paper this week is “Transverse Velocities in Real-Time Cosmology: Position Drift in Relativistic N-Body Simulations” by Alexander Oestreicher (University of Southern Denmark), Chris Clarkson (QMUL, UK), Julian Adamek (Universität Zürich, CH) and Sofie Marie Koksbang (U. Southern Denmark). This study uses a general relativistic N-body simulation code to explore how cosmological structures affect position drift measurements, a new method for studying cosmic structure formation and velocity fields. This was published on Tuesday 23rd December 2025 in the folder Cosmology and Nongalactic Astrophysics.

The overlay is here:

 

You can find the officially accepted version on arXiv here and this is the announcement on Mastodon (Fediscience):

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "Transverse Velocities in Real-Time Cosmology: Position Drift in Relativistic N-Body Simulations" by Alexander Oestreicher (University of Southern Denmark), Chris Clarkson (QMUL, UK), Julian Adamek (Universität Zürich, CH) and Sofie Marie Koksbang (U. Southern Denmark)

doi.org/10.33232/001c.154744

December 23, 2025, 9:33 am 1 boosts 0 favorites

 

The second paper of the week is “On the statistical convergence of N-body simulations of the Solar System” by Hanno Rein, Garett Brown and Mei Kanda (U. Toronto, Canada). This study presents numerical experiments to determine the minimum timestep for long-term simulations of the Solar System, finding that timesteps up to 32 days yield physical results.  It was published on Tuesday December 23rd in the folder Earth and Planetary Astrophysics.

The overlay is here:

 

You can find the official version of this one on arXiv here. The federated announcement on Mastodon is here:

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "On the statistical convergence of N-body simulations of the Solar System" by Hanno Rein, Garett Brown and Mei Kanda (U. Toronto, Canada)

doi.org/10.33232/001c.154745

December 23, 2025, 9:50 am 6 boosts 9 favorites

Next, published on 24th December 2025 in the folder High-Energy Astrophysical Phenomena, we have “The explosion jets of the core-collapse supernova remnant Circinus X-1” by Noam Soker and Muhammad Akashi (Technion, Haifa, Israel). This paper suggests that the rings in the Circinus X-1 supernova remnant resulted from jet-driven explosions, supporting the jittering-jets explosion mechanism theory for core collapse supernovae.

The overlay is here:

The officially accepted paper can be found on arXiv here and the announcement on Mastodon is here

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "The explosion jets of the core-collapse supernova remnant Circinus X-1" by Noam Soker and Muhammad Akashi (Technion, Haifa, Israel)

doi.org/10.33232/001c.154770

December 24, 2025, 9:15 am 2 boosts 1 favorites

Finally for 2025 we have “Quantifying the Fermi paradox via passive SETI: a general framework” by Matthew Civiletti (City University of New York, USA). This was published on Wednesday 24th December in the folder Instrumentation and Methods for Astrophysics. The author uses SETI observations and the Drake Equation to calculate the probability of detecting at least one extraterrestrial signal, highlighting the model’s limitations and potential improvements. The overlay is here:

The officially accepted version can be found on arXiv here and the Mastodon announcement here:

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "Quantifying the Fermi paradox via passive SETI: a general framework" by Matthew Civiletti (City University of New York, USA)

doi.org/10.33232/001c.154771

December 24, 2025, 9:27 am 1 boosts 1 favorites

And that concludes the updates for 2025. I’ll be back in a week with the first update of 2026, which will include the first paper(s) of Volume 9.

I’d like to thank everyone who has supported the Open Journal of Astrophysics this year – Editors, Reviewers, Authors and the excellent Library staff at Maynooth – and who have made it such a bumper year. In 2023 we published just 50 papers, so we have more than quadrupled in two years. How many will we publish in 2026?

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Nollaig shona daoibh go léir!

Posted in Uncategorized on December 25, 2025 by telescoper

Here we are then, Christmas Day. I thought I’d do a quick yule blog in between finishing a rather late breakfast and starting the preparations for dinner*.

Let me just wish you all a Merry Christmas, Nollaig Shona, Nadolig Llawen, Fröhliche Weihnachten, Joyeux Noël, Buon Natale, Feliz Navidad, Feliç Nadal, Glædelig Jul, etc…

And in the words of a traditional Irish toast:

Go mbeirimid beo ar an am seo arís!

(“May we live to see this time next year”)

*Roast beef Chateaubriand, with red wine gravy, honey-roast carrots and parsnips, sprouts, and roast potatoes. Preceded by smoked salmon with asparagus and followed by Christmas pudding and, later on, cheese and port.

Update:  et voilà

P.S. I couldn’t resist sharing this cartoon from the Christmas issue of Private Eye:

P.P.S. I find it interesting, from a linguistic point of view, how the French “Noel” (or “Noël”) and Irish “Nollaig” evolved from the Latin “Natalis”.

The spelling of “Noël” with a diaeresis over the “e” indicates that the two vowels are pronounced separately rather than as a diphthong. This may be a relic of the missing consonant in “Natalis”.

Perhaps the Welsh “Nadolig” is some sort of Celtic missing link…

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A Christmas Eve Message

Posted in Uncategorized on December 24, 2025 by telescoper

Since Christmas Eve – Oíche Nollaig in Ireland and variously known elsewhere in Europe as Nochebuena, Heiligabend, Veille de Noël, Vigilia di Natale, Juleaften, etc – is upon us, I wonder if I might crave the momentary indulgence of all readers of this weblog, in order to discharge a by no means disagreeable obligation which has, over the years, become more or less established practice as we approach the terminal period of the year — calendar, of course, not financial, nor indeed academic — in fact, not to put too fine a point on it, the interregnum between the First Semester Teaching Block and the First Examination Period — and submit to you, with all appropriate deference, for your consideration at a convenient juncture, a sincere and sanguine expectation — perhaps even confidence — indeed one might go so far as to say hope — that the aforementioned period may be, at the end of the day, when all relevant factors have been taken into consideration, susceptible to being deemed to be such as to merit a final verdict of having been by no means unsatisfactory in its overall outcome and, in the final analysis, to give grounds for being judged, on mature reflection, to have been conducive to generating a degree of gratification which will be seen in retrospect to have been significantly higher than the general average. I hope this clarifies the situation.

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The Counties of the United Kingdom (according to ChatGPT)

Posted in Artificial Intelligence with tags , , , , on December 23, 2025 by telescoper

Regular readers will know that I sometimes use this blog to educate the Great Unwashed about the facts of British geography (including where the North begins). I have decided to enlist the help of Generative AI to support me with this task so, with a little help from social media, here is a response from ChatGPT to a prompt requesting a map showing all the counties of the United Kingdom with their names. The result, as you can see, is truly spectacular:

I began my research career at the University of Bulgaria, by the way.

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O Tannenbaum – Vince Guaraldi Trio

Posted in Jazz, Television with tags , , , on December 22, 2025 by telescoper

A jazz version of an old song from an album called A Charlie Brown Christmas may not seem a very promising concept but I like it, so there. The original lyrics of O Tannenbaum don’t refer to Christmas at all, incidentally, but it has become a Christmas standard. This version is by the Vince Guaraldi Trio and it was recorded 60 years ago in 1965. Vince Guaraldi was a fine jazz pianist who had an interesting solo career as well as playing with bands led by Woody Herman and Carl Tjader, among others. He is best remembered, however, for composing the music that went with TV adaptations of the Peanuts cartoons written and illustrated by Charles M. Schulz of which this is a nice example.

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The Winter Solstice 2025

Posted in Maynooth, The Universe and Stuff with tags , , , , on December 21, 2025 by telescoper
Sunlight at dawn on the Winter Solstice at Newgrange

Just a quick note to point out that the Winter Solstice in the Northern hemisphere happens today, Sunday 21st December 2025, at 15.03 UT (GMT).

In Dublin, sunrise yesterday (20th December) was at 8.37 am and sunset at 4.07 pm, while today the sunrise was at 8.38 am and sunset at 4.08 pm. Both sunrise and sunset happen later tomorrow than today, so the Solstice marks neither the latest sunrise nor the earliest sunset. We have to wait until January for the latest sunrise (8.40am) and the earliest sunset (4.06pm) actually happened over a week ago. The interval between the two events will, however, be about 2 seconds longer tomorrow than today; and yesterday the gap was about 4 seconds longer than today. Taking a day to be the interval between sunrise and sunset, today is the shortest.

For a full explanation of this, see this older Winter Solstice post.

P.S. In the Southern Hemisphere this is of course the summer solstice. In Australia it was marked by the ritual of a victory in the Ashes against England.

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R.I.P. Yannick Mellier (1958-2025)

Posted in Euclid, R.I.P., The Universe and Stuff with tags , , , , on December 21, 2025 by telescoper

Last night I received a message via the Euclid Consortium conveying the very sad news of the death, at the age of 67, of the French astrophysicist and cosmologist Yannick Mellier (pictured left). Among many other things, Yannick was the Euclid Consortium Lead in which role he took on enormous responsibility for getting the project started and, with his team, keeping everything running. His loss is incalculable.

Yannick’s research work focussed on cosmology and the search for dark matter using gravitational lensing. Back in 1987 he was part of the observational team that discovered the first giant arc produced by strong gravitational lensing. He also did pioneering work in the field of weaking gravitational lensing with the Canada-France Hawaii Telescope in that regard starting back in 2000.

For well over a decade now Yannick had been involved with the European Space Agency’s Euclid mission. He was a major force right from the beginning, making the proposal, and after it was accepted leading the Consortium assembled to bring the project into being, preparing for launch, and dealing with the first data. The Euclid Consortium is a huge collaboration and it is impossible to overestimate the scale of the task facing the Lead. The first full data release (DR1) from Euclid will take place towards the end of next year (2026). It is sad beyong words that he did not live to see this.

During the period when I was Chair of the Euclid Consortium Diversity Committee I had a number of interactions with Yannick, sometimes dealing with difficult and confidential matters. I found him to be a man of great wisdom and sensitivity. Despite having many other things to deal with, including a long-term illness, he was unfailingly supportive and his advice was always sound.

The following is an excerpt from the message sent out yesterday:

Yannick’s death leaves a huge void within the consortium and our community. Those of us who have been here the longest know how hard he worked to make the Euclid project a success. He became its embodiment, working tirelessly to ensure its success; we owe him an immense debt of gratitude, and we will surely have the opportunity to reflect in detail on all that we owe him.

Indeed. I hope the Euclid Consortium – and the international cosmological community generally – will, at some stage, organize an appropriate tribute to Yannick.

Rest in Peace, Yannick Mellier (1958-2025)

Ar dheis Dé go raibh a anam

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Weekly Update from the Open Journal of Astrophysics – 20/12/2025

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , , , , , , , , , , , , on December 20, 2025 by telescoper

Christmas is coming, but it’s still time for the usual update of the week’s new papers at the Open Journal of Astrophysics. Since the last update we have published two more regular papers, described below, which brings the number in Volume 8 (2025) up to 197, as well as the 12 papers in yesterday’s Supplement, and the total published for the year up to 209, and the total so far published by OJAp up to 444.

Please note that we will be pausing publishing activity from 24th December 2025 until Monday 5th January 2026. Submissions will remain open, but no more papers will be published in Volume 8 (2025) after Christmas Eve. We will resume in the New Year with Volume 9.

Now for this week’s update. Since I blogged about the contents of the Supplement yesterday I won’t repeat them here and will instead just include the two regular papers.

The first regular paper this week is “Optimal intrinsic alignment estimators in the presence of redshift-space distortions” by Claire Lamman (Harvard-Smithsonian CfA, USA), Jonathan Blazek (Ohio State U., USA) and Daniel J. Eisenstein (Northeastern U., USA). This was published on Monday December 15th 2025 in the folder  Cosmology and Nongalactic Astrophysics. The authors present estimators for quantifying intrinsic alignments in large spectroscopic surveys intended to inprove the constraints they provide for weak gravitational lensing and other cosmological applications.

The overlay is here:

You can find the officially accepted version on arXiv here and this is the announcement on Mastodon (Fediscience):

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "Optimal intrinsic alignment estimators in the presence of redshift-space distortions" by Claire Lamman (Harvard-Smithsonian CfA), Jonathan Blazek (Ohio State U.) and Daniel J. Eisenstein (Northeastern U.); all based in the USA

doi.org/10.33232/001c.154373

December 15, 2025, 8:57 am 1 boosts 0 favorites

The second regular paper of the week is “What is the contribution of gravitational infall on the mass assembly of star-forming clouds? A case study in a numerical simulation of the interstellar medium” by Noé Brucy (Universite Claude Bernard Lyon 1, France), Enrique Vázquez-Semadeni (Universidad Nacional Autónoma de México, Mexico), Tine Colman (Universite Claude Bernard Lyon 1, France), Jérémy Fensch (Universite Claude Bernard Lyon 1, France) and Ralf S. Klessen (Universität Heidelberg, Germany). This was published in the folder Astrophysics of Galaxies on Friday 19th December 2025. This paper describes research using numerical simulations to quantify how much of the mass inflow into a star-forming cloud is driven by the self-gravity of the gas and the gravity from the stellar disk.

The overlay is here:

You can find the official version of this one on arXiv here. The federated announcement on Mastodon is here:

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "What is the contribution of gravitational infall on the mass assembly of star-forming clouds? A case study in a numerical simulation of the interstellar medium" by Noé Brucy (Universite Claude Bernard Lyon 1, France), Enrique Vázquez-Semadeni (Universidad Nacional Autónoma de México, Mexico), Tine Colman (Lyon), Jérémy Fensch (Lyon) and Ralf S. Klessen (Universität Heidelberg, Germany)

doi.org/10.33232/001c.154637

December 19, 2025, 8:30 am 0 boosts 0 favorites

And that concludes the update for this week, which will be the last Saturday update for 2025.

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Art in Bruges

Posted in Art, Film with tags , , , , , on December 19, 2025 by telescoper

For various reasons I find myself thinking about this little clip from the 2016 film In Bruges, starring Brendan Gleason and Colin Farrell. It’s set in the Groeningemuseum in the city of Bruges.

You can read an interesting post about the art in the film here.

You will see that the only painting that Ray (Colin Farrell) likes is a triptych called The Last Judgment, a version of which coincidentally featured in my post on Monday. The one I posted was by Hieronymous Bosch and is in Vienna; the one in Bruges is of doubtful attribution. It may be by Bosch, but experts think it is more likely to be by members of his workshop.

P.S. If you like black comedies then In Bruges is definitely for you! I wouldn’t say it was really a Christmas movie though…

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