Archive for December, 2023

Two New Publications at the Open Journal of Astrophysics

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , , on December 14, 2023 by telescoper

As anticipated a couple of days ago, it’s now possible to announce another couple of new papers at the Open Journal of Astrophysics. These papers take us up to a total of 49  in Volume 6 (2023) and 114 in total since we started publishing.

It would be nice if we could make it to 50 in Volume 6 (2023), but I have already decided to close the publishing platform from 22nd December until 5th January (inclusive), so there there isn’t much time to get the single needed for our half-century.  While we will not be publishing new papers during this closure, the peer review platform will remain open for submission of new and revised manuscripts and the editorial processes will continue.

Whether or not we make 50 this year, it is worth remarking that 49 is already a significant figure, as it corresponds to the total number of papers we published in the previous three years: 15 (2020); 17 (2021); and 17 (2022). Things are definitely looking up!

Anyway, the first paper of the most recent pair – published on December 8th – is “The Million Quasars (Milliquas) Catalogue, v8”; its primary classification is Astrophysics of Galaxies and the author is Eric Wim Flesch from New Zealand. The Milliquas catalogue includes quasars from the literature to 30 June 2023, including quasars from the DESI-EDR and SDSS-DR18Q surveys.

Here is a screen grab of the overlay which includes the abstract:

You can click on the image of the overlay to make it larger should you wish to do so. You can find the officially accepted version of the paper on the arXiv here.

The second paper was published on 11th December 2023 and is also in the folder marked Astrophysics of Galaxies.

The authors are all from various institutions in the USA:  Michael Grudić (Carnegie Observatories), Stella Offner (University of Texas at Austin); Dávid Guszejnov (Harvard);  Claude-André Faucher-Giguère (Northwestern University); and Philip F. Hopkins (Caltech).  The paper presents a comparison of full radiative magnetohydrodynamics simulations of the formation of star clusters with simple stochastic modelling showing the limitations of the latter.

Here is a screen grab of the overlay which includes the abstract:

 

 

You can click on the image of the overlay to make it larger should you wish to do so. You can find the officially accepted version of the paper on the arXiv here.

Museu Picasso

Posted in Art, Barcelona with tags , , , , on December 13, 2023 by telescoper

I was delighted to receive from a certain person an early Christmas gift in the form of tickets to the Museo Picasso in Barcelona. I took this morning off so that the two of us could visit the exhibition. As well as the permanent collection, including many early works of by Picasso, we saw a special exhibition juxtaposing works by Picasso and Joan Miró (who was a great admirer of Picasso). The influence of the former on the latter is very clear when you see the works together, though they remain stylistically very separate. This part of the exhibition is shared between the Museo Picasso and the La Fundación Joan Miró, which is a clever way of getting people to visit both museums. Some works by Miró included The Farm shown in the gallery below – have been moved to the Picasso Museum in the centre of Barcelona and some works by Picasso have been moved to Montjuic where the Miro Foundation is located; my visit there will have to wait until I return after the Christmas break.

The permanent collection in Museo Picasso seems like an exhibition of work by many different artists. It starts off with paintings and drawings he did while still a teenager (like the one I posted here), an art student, and then many works done when he had moved to Paris at the end of the 19th Century. These show him absorbing many influences and mastering many techniques before he found his own original approach. Most of paintings he made becoming famous are elsewhere, but there are examples of later work (including ceramics) in this gallery. The evolution of Picasso’s art is amazing to see.

Here is a selection of what can be seen

A visit to the Picasso Museum is a feast in itself but after almost three hours wandering around we had to leave to get lunch…

New Publication at the Open Journal of Astrophysics

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , on December 12, 2023 by telescoper

I was doing some work on the Open Journal of Astrophysics site and realized that there is a paper we published last week that I haven’t advertised on here yet, so I’m remedying that now.

The paper in question is the 47th so far in Volume 6 (2023)  and it’s the 112th altogether. This one was actually published on Tuesday December 5th. Two further papers are imminent; I’m just waiting for their metadata to be registered with Crossref.

The title of this one is “The SPHINX Public Data Release: Forward Modelling High-Redshift JWST Observations with Cosmological Radiation Hydrodynamics Simulations” and it represents  public data release of Sphinx20, a full box cosmological radiation-hydrodynamics simulation that provides a statistical sample of galaxies for comparison with those observed by JWST. It is in the folder marked Astrophysics of Galaxies.

There are 10 authors: Harley Katz (Oxford, UK); Joki Rosdahl (Lyon, France); Taysun Kimm (Seoul, Korea); Jeremy Blaizot (Lyon, France);  Nicholas Choustikov (Oxford, UK); Marion Farcy  and Thibault Garel (Geneva, Switzerland);  Martin G. Haehnelt (Cambridge, UK); Leo Michel-Dansac (Lyon, France); and Pierre Ocvirk (Strasbourg, France).

Here is the overlay of the paper containing the abstract:

 

 

You can click on the image of the overlay to make it larger should you wish to do so. You can find the officially accepted version of the paper on the arXiv here.

The Return of Halley’s Comet…

Posted in Art, Literature, The Universe and Stuff with tags , , , on December 11, 2023 by telescoper

I was reminded at the weekend that Halley’s Comet has just passed its aphelion (furthest distance from the Sun) and is now falling back into the Solar System towards its next perihelion (closest distance to the Sun) in 2061, by which time I will almost certainly be retired.

Halley’s Comet last visited us in 1986 when I was 23 and living in Brighton. It will next appear in 2061, when I shall be 98 and lucky to be living at all.

This reminded me of a rather poignant cartoon I found a while ago on Facebook. I don’t know the name of the artist. If anyone does please let me know.

The comet’s orbital period of 75 years or so is brief by astronomical standards, as is the duration of a human life. As Quintus Horatius Flaccus (Horace to you and me) put it in one of his Odes (Book I, Ode 4, line 15):

Vitae summa brevis spem nos vetat incohare longam

Two weeks to go..

Posted in Barcelona, Biographical, Maynooth with tags , on December 10, 2023 by telescoper

It’s Sunday 10th December, which means I am about to embark on the penultimate week of this stint in Barcelona. I’ve got quite a few things to finish in the next fortnight, and the inevitable glut of telecons to get through, but I also plan to take a little time off to visit a couple of cultural attractions I haven’t got round to yet. I’ll be spending Christmas and New Year elsewhere and returning to Barcelona in 2024 but these will be the last two weeks I spend this nice apartment. For various reasons I don’t yet know precisely when I’ll be coming back after the break so I’ll have to find another place to live when I do. That will be during off season though so I’m not worried. I toyed with the idea of keeping this place on, but thought better of it. It is quite expensive, and I can’t really afford to pay weeks in rent to keep an empty apartment. Since I will be returning, I can leave some of my things with friends here, which leaves plenty of space in my luggage for goodies to be consumed during the holiday.

The entrance to La Rambla from La Plaza de Cataluña

The weather here has changed a bit recently, getting much warmer. It feels a bit strange to be going round in shirt sleeves on 10th December but it was warm enough for that. It’s done my arthritis a power of good anyway. I picked up a bit of a cold last week which has now vanished too. It wasn’t anything serious but generated enough brain fog to make concentration difficult for a couple of days. The unusually warm spell is of course worrying for other reasons, as is the fact that there has been virtually no rain in Barcelona all the time I’ve been here. Drought restrictions are still in place. It seems the weather is a very different story in Ireland!

Here in Barcelona teaching carries on until Thursday 21st December, which is the end of term. Back in Maynooth, teaching term officially continues until Friday 22nd, though I don’t think there will be many students in classes on that day, just three days before Christmas, which also happens to be the day I fly out from Barcelona…

Bravo, Sorbonne University!

Posted in Education, Open Access with tags , , , on December 10, 2023 by telescoper

Here’s some good news for advocates of open research. Sorbonne University (Paris) has made an important announcement. I quote:

Sorbonne University has been deeply committed to the promotion and the development of  open science for many years. According to its commitment to open research information, it has decided to discontinue its subscription to the Web of Science publication database and Clarivate bibliometric tools in 2024. By resolutely abandoning the use of proprietary bibliometric products, it is opening the way for open, free and participative tools.

That’s the way to do it! Such a decision requires real intellectual leadership, so I’m not sure how many other universities will follow suit. Those paralyzed by managerialism probably won’t.

The Sorbonne statement goes on to explain:

This decision is in line with the University’s overall policy of openness, and it is now working to consolidate a sustainable, international alternative, in particular by using OpenAlex.

Both Web of Science and Clarivate are, of course, fronts for the academic publishing industry and are just as pointless, as they sell to subscribers a biased subset of information which is already in the public domain through services such as CrossRef.

While I’m congratulating Sorbonne for its leadership, I should do likewise (though in a different context) for Utrecht University, which refused to participate in this year’s Times Higher World Rankings. Among their reasons are

  • Rankings put too much stress on scoring and competition, while we want to focus on collaboration and open science.
  • The makers of the rankings use data and methods that are highly questionable, research shows. 

I hope more institutions join the fight back against the box-tickers in this regard too, although I’m not particularly hopeful here either.

Value versus Values

Posted in Biographical, Politics with tags , , , , , on December 9, 2023 by telescoper

I noticed last week that the United Kingdom has a new Home Secretary, the ironically-named James Cleverly, who has taken over the task of making the country even more xenophobic. Among the measures he is proposing is hiking the minimum salary needed for skilled overseas workers from £26,200 to £38,700. That figure has come as a shock to scientific researchers, as the entry level for a new postdoctoral researcher in the UK is about £36-37K. No foreign postdocs, please, we’re British! I wonder how this squares with the recent (belated) decision to join Horizon 2020? I don’t see this latest bout of small-mindedness doing much to repair the damage done by a two-year absence from the programme.

Anyway, the decision to set a high salary threshold for skilled migrants, reminded me of something that struck me when I read David Graeber’s book Bullshit Jobs. It’s really just a side issue in the context of that book, and it’s probably something well known to students of ethics, but I found it interesting:

In English, as currently spoken, we tend to make a distinction between “value” in the singular, as in the value of gold, pork bellies, antiques, and financial derivatives, and “values” in the plural: that is, family values, religious morality, political ideals, beauty, truth, integrity, and so on. Basically, we speak of “value” when talking about economic affairs, which usually comes own to all those human endeavors in which people are getting paid for the work or their actions are otherwise directed at getting money. “Values” appear when that is not the case. For instance, housework and child care are, surely, the single most common forms of unpaid work, Hence we constantly hear about the importance of “family values”.

Bullshit Jobs, David Graeber, p. 203

The point of relevance here is that defining the “value” of a job only in the sense of how large the salary is misses the fact that the financial reward isn’t the only sort of value that a job has; there is social value too. As far as I am aware, though, there is no really satisfactory theory of social value. On the other hand, it does seem that many jobs with the highest social value (care worker, nurse, primary school teacher, etc) are poorly paid, i.e. have low financial value. Nevertheless, people still do them. Why is that? It’s because people are motivated by things other than money – values. It’s possible to find work rewarding in a way that’s not primarily financial. That’s yet another reason why it is daft to measure the success of a University course in terms of the salaries of those who graduate from it.

One thing that confuses me is that there seem to be people – perhaps many of them – who actively resent those who find their work enjoyable or fulfilling. This sometimes manifests itself as exploitation. Take nurses, for example. I think we all agree that health services would fall apart without them, but the are routinely denied decent monetary reward for their work. One can’t live off values. A system that drives nurses out of the profession due to financial hardship is truly rotten.

As a University Professor, I’m well off financially, but that’s not the reason I chose a career as an academic. I don’t think the reason is simple, actually, among the factors are: (a) I think science is important and wanted to make a contribution; (b) I enjoy teaching; and (c) I didn’t want to be bored (in other words I didn’t want a bullshit job).

Marking Scheme

Posted in mathematics with tags , , , on December 8, 2023 by telescoper

With Christmas looming and the January examination period getting closer, I thought I’d help (?) those involved in such assessments by sharing this model of an elegant marking scheme from a Mathematics examination.

What could be simpler?

Do Black Holes have Singularities?

Posted in mathematics, The Universe and Stuff with tags , , , on December 7, 2023 by telescoper

A paper appeared on arXiv this week that has ruffled a few feathers. It’s by Roy Kerr (yes, him) and it has the abstract:

There is no proof that black holes contain singularities when they are generated by real physical bodies. Roger Penrose claimed sixty years ago that trapped surfaces inevitably lead to light rays of finite affine length (FALL’s). Penrose and Stephen Hawking then asserted that these must end in actual singularities. When they could not prove this they decreed it to be self evident. It is shown that there are counterexamples through every point in the Kerr metric. These are asymptotic to at least one event horizon and do not end in singularities.

arXiv:2312.00841

I don’t think this paper is as controversial as some people seem to find it. I think most of us have doubts that singularities – specifically curvature singularities – are physically real rather than manifestations of gaps in our understanding. On the other hand, this paper focusses on an interesting technical question and provides a concrete counterexample. The point is that the famous Penrose-Hawking singularity theorems don’t actually prove the existence of singularities; they prove geodesic incompleteness, i.e. that there are geodesics that can only be extended for a finite time as measured by an observer travelling along one. Geodesic incompleteness does imply the existence of some sort of boundary, often termed a trapped surface, but not necessarily that anything physical diverges there at that boundary. Though a singularity will result in geodesic incompleteness, the assertion that geodesic incompleteness necessarily implies the existence of a singularity is really just a conjecture.

For more details, read the paper. It’s technical, of course, but well written and actually not all difficult to understand.

El Puente

Posted in Barcelona, Biographical with tags , , on December 7, 2023 by telescoper

So here I am on Thursday 7th December, the day between two public holidays. In fact I attended, and gave a brief presentation at, a three-hour Zoom meeting (related to Euclid) yesterday afternoon, so it wasn’t really a holiday for me, and I’ll be working tomorrow too. Most shops are closed on public holidays, though

Today being an example of a Puente (‘bridge’, slang for a day bridging two holidays); at first I thought it was a day for playing Bridge. Many businesses close for a puente and some workers take a holiday even if their place of work is not closed. This is a rather splendid puente, actually, as it joins Wednesday to Friday and thus creates a (very) long weekend. I suppose the best one would be when public holidays are on a Tuesday and Thursday so then one can take Monday, Wednesday and Friday off to make a week-long holiday. I’m told this is called not a puente but an acueducto!

Anyway, I had planned to spent today’s puente working from home like I did yesterday. Unfortunately I had to change plan. There has been construction work going on in my apartment block more-or-less continually since I moved in. This hasn’t really bothered me much, as I have been out during most weekdays and the work never happens at night, at weekends, or on public holidays (such as yesterday). On the occasions when I have been in during the work, however, it has been very irksome. I had assumed that the builders would regard today as a puente but alas this is not the case. No sooner had I eaten my breakfast when the dreaded drilling and banging began. Knowing I wouldn’t be able to get much work done in such an environment, I decided to relocate to the University after all.

The University of Barcelona is actually open today (although not all entrances to the Physics Department are accessible) but there are no classes for students. The Metro coming here to Zona Universitaria was, unsurprisingly, pretty empty. The café downstairs is closed. The only other people are staff members, so It is very quiet and I should be able to put few useful hours of work in…

P.S. Apologies for getting the gender of puente wrong in the original title.It’s interesting that the Welsh word for “bridge” is “pont”, like French (from Latin pons cf puente), whereas in Irish it is “droichead”. The English word “bridge” is of Germanic origin.