With all that’s going on in the world right now it seems appropriate to repost this beautiful track by the great jazz pianist Bill Evans. I remember reading somewhere that Bill Evans recorded this right at the end of a session, in 1958. It was unrehearsed, entirely improvised and done in one take. It’s based on a simple two-chord progression that subsequently appeared in Flamenco Sketches, one of the tracks on the classic Miles Davis album Kind of Blue. To my ears, Peace Piece is more redolent of the composition style of Erik Satie than any other jazz musician I can think of. Although it starts out very simply it becomes more complex and fragmented as it develops, and makes effective use of dissonance in creating tension to contrast with the rather meditative atmosphere established at the beginning. Anyway, this is one of my all-time favourite tracks by one of my all-time favourite jazz musicians so I hope you don’t mind me sharing it on here.
Follow @telescoperJob Opportunity in Computer Science, Statistics or Applied Mathematics at Maynooth
Posted in mathematics, Maynooth with tags Hamilton Institute on February 21, 2022 by telescoper
Just a quick post to pass on the news that my colleagues in the Hamilton Institute at Maynooth University have a vacancy for a permanent position at Professorial level.
You can find the full advert here. Please feel free to pass it on to anyone you think might be interested.
P. S. I’m looking forward to mentioning further announcements about a number of other permanent job opportunities at Maynooth in the not-too-distant future!
New Publication at the Open Journal of Astrophysics
Posted in OJAp Papers, Open Access, The Universe and Stuff with tags arXiv:2112.08423v3, Cosmology, dark matter, The Open Journal of Astrophysics on February 21, 2022 by telescoperIt’s time yet again to announce a new publication in the Open Journal of Astrophysics! This one is the 3rd paper in Volume 5 (2022) and the 51st in all. We actually published this on Friday, byt I’ve only just got around to announcing it here now.
The latest publication is entitled Differentiable Predictions for Large Scale Structure with SHAMNet and is written by Andrew Hearin, Nesar Ramachandra and Matthew R. Becker of the Argonne National Laboratory and Joseph DeRose of the Lawrence Berkeley Laboratory (both institutions being in the USA).
Here is a screen grab of the overlay which includes the abstract:
You can click on the image to make it larger should you wish to do so. You can find the arXiv version of the paper here. This paper is in our popular Cosmology and Non-galactic Astrophysics section.
P. S. Here’s a bit of feedback from the author of this paper about the referees:
They reviewed the paper in conscientious detail, and every comment was thoughtful. We feel that our paper has materially improved in clarity as a result of their critique.”
Sins of Omission
Posted in The Universe and Stuff with tags arXiv:2202.05836v1, arXiv:astro-ph/9710154, Cosmology, dark matter, dwarf galaxies, galaxy formation on February 20, 2022 by telescoperThere’s a paper recently published in Nature Astronomy by Moreno et al, which you can find on the arXiv here. The title is Galaxies lacking dark matter produced by close encounters in a cosmological simulation and the abstract is here:
The standard cold dark matter plus cosmological constant model predicts that galaxies form within dark-matter haloes, and that low-mass galaxies are more dark-matter dominated than massive ones. The unexpected discovery of two low-mass galaxies lacking dark matter immediately provoked concerns about the standard cosmology and ignited explorations of alternatives, including self-interacting dark matter and modified gravity. Apprehension grew after several cosmological simulations using the conventional model failed to form adequate numerical analogues with comparable internal characteristics (stellar masses, sizes, velocity dispersions and morphologies). Here we show that the standard paradigm naturally produces galaxies lacking dark matter with internal characteristics in agreement with observations. Using a state-of-the-art cosmological simulation and a meticulous galaxy-identification technique, we find that extreme close encounters with massive neighbours can be responsible for this. We predict that approximately 30 percent of massive central galaxies (with at least 1011 solar masses in stars) harbour at least one dark-matter-deficient satellite (with 108 – 109 solar masses in stars). This distinctive class of galaxies provides an additional layer in our understanding of the role of interactions in shaping galactic properties. Future observations surveying galaxies in the aforementioned regime will provide a crucial test of this scenario.
It’s quite an interesting result.
I’m reminded of this very well known paper from way back in 1998, available on arXiv here, by Priya Natarajan, Steinn Sigurdsson and Joe Silk, with the abstract:
We propose a scenario for the formation of a population of baryon-rich, dark matter-deficient dwarf galaxies at high redshift that form from the mass swept out in the Intergalactic Medium (IGM) by energetic outflows from luminous quasars. We predict the intrinsic properties of these galaxies, and examine the prospects for their observational detection in the optical, X-ray and radio wavebands. Detectable thermal Sunyaev-Zeldovich decrements (cold spots) on arc-minute scales in the cosmic microwave background radiation maps are expected during the shock-heated expanding phase from these hot bubbles. We conclude that the optimal detection strategy for these dwarfs is via narrow-band Lyman-α imaging of regions around high redshift quasars. An energetically scaled-down version of the same model is speculated upon as a possible mechanism for forming pre-galactic globular clusters.
It’s true that the detailed mechanism for forming dwarf galaxies with low dark matter densities is different in the two papers, but it does show that the issue being addressed by Moreno et al. had been addressed before. It seems to me therefore that the Natarajan et al. paper is clearly relevant background to the Moreno et al. one. I always tell junior colleagues to cite all relevant literature. I wonder why Moreno et al. decided not to do that with this paper?
Had Moreno et al. preprinted their paper before acceptance by Nature Astronomy I’m sure someone would have told them of this omission. This is yet another reason for submitting your papers to arXiv at the same time as you submit them to a journal rather than waiting for them to be published.
Personal and Postdoctoral Choices
Posted in Biographical, Brighton on February 19, 2022 by telescoperOver the past week or so I’ve noticed quite a lot of discussion on social media about postdoctoral fellowship positions. These positions are scarce compared to the number of eligible applicants so competition is quite intense. Applications are usually required around November for a start the following year: those lucky enough to have been offered such a position to start in September or October usually have to accept or decline around this time of year; those lucky enough to receive more than one offer have to pick which one they want to accept so that those on a waiting list can be contacted. It’s a nervous time for early career researchers, particularly in the USA where there are few opportunities outside this cycle.
Seeing all these exchanges on Twitter reminded of this time of year in 1988. I was in the last the last year of my PhD DPhil at Sussex – there was only three years’ funding in those days – and had applied before Christmas 1987 for postdoc positions to start in September or October1988. I was fortunate to receive several offers, including one to stay at Sussex.
There was a big complication in my case. I have never written about this on the blog but during the last year of my PhD I was helping to care for a friend who was terminally ill. The medical people couldn’t say how long he would live but said it would be months rather than years. When it came to February 1988 and I had to make a choice, I felt I had no alternative but to make a decision that would allow me to continue to help as long as was necessary if my friend lived past September, rather than abandon him. Accordingly I accepted the position at Sussex and decline the others.
As it happened my friend passed away (peacefully) about six weeks later, but by then I’d made the decision and there was no going back.
I do generally advise younger researchers that moving away from the institute in which they did their graduate studies is generally a good idea in order to broaden your experience. Given that, people have sometimes asked me in person why I decided to stay at Sussex and I usually tell them what I’ve written above.
I have absolutely no regrets about the decision. Sussex was a very good place to be a postdoctoral researcher anyway and things worked out very well for me in the end, career-wise. I also felt I’d done the right thing based on how the situation stood at the time I made the decision.
The point of this post is that you shouldn’t be afraid of including personal considerations in your career choices. We’re all people, not robots. And if you’re that others might think your decision is strange then remind yourself that it’s your life, not theirs. In the end the only person you need to justify yourself to is yourself.
Wind, by Ted Hughes
Posted in Poetry on February 18, 2022 by telescoperThis house has been far out at sea all night,
The woods crashing through darkness, the booming hills,
Winds stampeding the fields under the window
Floundering black astride and blinding wet
Till day rose; then under an orange sky
The hills had new places, and wind wielded
Blade-light, luminous black and emerald,
Flexing like the lens of a mad eye.
At noon I scaled along the house-side as far as
The coal-house door. Once I looked up –
Through the brunt wind that dented the balls of my eyes
The tent of the hills drummed and strained its guyrope,
The fields quivering, the skyline a grimace,
At any second to bang and vanish with a flap;
The wind flung a magpie away and a black-
Back gull bent like an iron bar slowly. The house
Rang like some fine green goblet in the note
That any second would shatter it. Now deep
In chairs, in front of the great fire, we grip
Our hearts and cannot entertain book, thought,
Or each other. We watch the fire blazing,
And feel the roots of the house move, but sit on,
Seeing the window tremble to come in,
Hearing the stones cry out under the horizons.
by Ted Hughes (1930-98)
They think it’s all over…
Posted in Biographical, Covid-19, Education, Maynooth on February 18, 2022 by telescoperThis afternoon it was announced that the Government of Ireland would be accepting the latest advice from the National Public Health Emergency Team (NPHET) to wind down most of the remaining Covid-19 restrictions from 28th February 2002. The first officially recognized Covid-19 case in Ireland was reported on March 1st 2020, so that will be two years after the arrival of the pandemic here.
The decision means that face masks will no longer be required on public transport or in shops or in schools, though they will be mandatory in hospitals and other health-care settings. I assume this extends to universities too. Likewise limits on social distancing. The Chief Medical Officer has also announced that PCR testing will no longer be performed for anyone under the age of 55. It seems that even NPHET itself is to be phased out.
I know many people will be celebrating the end of these restrictions, but in case you need reminding here are the latest figures for Covid-19 in Ireland:
PCR-confirmed new cases are still running at 4500+ per day (almost double that if you include self-reported antigen tests). That means medically vulnerable people would be at risk of infection if those around them are not wearing masks. Masks protect others more than they protect the wearer so allowing the wearing of face masks to be discretionary puts such people in danger. For this reason I for one will be continuing to wear a face covering in shops, on buses, etc for the foreseeable future.
I don’t mind this – it was widespread practice in Asia long before the Coronavirus pandemic – and just can’t understand the extreme anti-maskers who liken the wearing of a face covering to being put in a concentration camp. I just hope we don’t get situations in which those who choose to wear a mask on, say, a bus get picked on by those who don’t.
At the moment in the Department of Theoretical Physics at Maynooth the situation is that a significant fraction of our students are staying away from lectures because of illness or self-isolation and one lecturer is having to do his teaching remotely. That’s not too bad; I feared much worse. I think other Departments have worse problems, missing demonstrators and tutors who are unable to come on campus.
The logic behind scrapping these restrictions is that despite the high case numbers the vaccination programme (helped, perhaps by the ‘milder’ omicron variant) does seem to have succeeded in keeping hospitalizations and deaths at a much lower level than in previous waves. Implicitly the strategy is to let Covid-19 wash over the population without worrying that the Health Service will be overwhelmed. My main worry now is what if another variant emerges after we have let our guard down?
A Topical Nursery Rhyme
Posted in Poetry on February 17, 2022 by telescoperI’ve always been fascinated by Nursery Rhymes. Some people think these are little more than nonsense but in fact they are full of interesting historical insights and offer important advice for the time in which they were written. One such poem, for example, delivers a stern warning against the consequences of placing sleeping babies in the upper branches of trees during windy weather.
In the light of recent events I thought I would continue this old tradition by posting a nursery rhyme of topical relevance. Here it is:
Verse:
The Grand Old Duke of York
He gave twelve million quid
To a girl he never met
For a thing he never did.
Chorus:
And when he was up he **censored**
Say hello to ar5iv!
Posted in Open Access with tags ar5iv, arXiv, HTML5, PDF on February 16, 2022 by telescoperYesterday I stumbled across a new thing which I think is very cool.
Usually if you want to read a paper posted on arXiv you have to view, e.g. a PDF file. Now someone has set up a facility to view every article as a modern HTML5 page. To use this function you just need to change the “X” in the link to an arXiv paper to a “5” and you can view the whole paper, equations and all, in your browser as a web page.
You can check this out using a recent paper from the Open Journal of Astrophysics:
Here is the standard arXiv link to the paper:
https://arxiv.org/abs/2107.05639v2
Now try looking at
https://ar5iv.org/abs/2107.05639v2
I have found a few conversion errors using this facility but I assume these can be ironed out in due course. Now I have to persuade Scholastica to let us link to the ar5iv versions of OJAp papers (although I think the plan is to integrate ar5iv with arXiv at some point).
Attack of the Rooks
Posted in Biographical, Maynooth on February 15, 2022 by telescoper
In this recent spell of rather cold weather I’ve been especially careful to keep the garden birds well nourished by deploying various feeders around the place. My fat balls are proving particular popular with the birds, but I won’t dwell on that here.
A few weeks ago a solitary rook started visiting my garden. I felt a bit sorry for this bird as it seemed to be on its own and was too big and clumsy to feed off the seed and peanut dispensers. Rooks always look a big glum to me. Eventually this figured one out how to dislodge one of the feeders from its usual place so it crashed to the floor and spilled seed all over the lawn, some of which it ate.
There then followed a sort of arms race. First I attached the feeder more securely to its existing site. The rook again managed after some time to knock it down. Then I moved it somewhere else, only for it to appear on the ground once more. Then I found a place where I could hang it between two branches of a tree in such a way it would be impossible to dislodge. This clearly frustrated the rook and again I felt sorry for it, but only for a short time.
A few days later I looked out in the garden and saw not just one rook but a whole crowd of them five or six in number, no doubt the local gang had been pressed into service. They proceeded to jump up and down on the branches of the tree until both snapped off completely, again dislodging the feeder.
I know I should admire the quality of the teamwork – a characteristic of the Corvid family – but at this rate the trees in my garden are going to be reduced to stumps. I’m not sure what I can do next.
There’s no doubt that rooks are hooligans, but at least they’re not taking all the food. I have two other dispensers that are positioned in such a way that only the little critters can get at them. So far. I’ve had all kinds of tits and finches as well as sparrows and starlings and pigeons as well as the rooks’ slightly less troublesome cousins, jackdaws and magpies.
In the Dark 