Here’s a message for Alumni of Cambridge University!
Tomorrow (18th July) is the last day registered electors can vote online for Prof. Wyn Evans as Chancellor of the University. If you’ve registered then please don’t forget to vote! You have until 5pm tomorrow.
Here’s a post outlining the reasons why you should vote for Wyn.
The word on the street in Cambridge is that the election will be won by Lord Browne. The Masters of many of the richest Colleges (Trinity, St Johns) have come out in his favour despite his tarnished reputation. The likelihood that the post of Chancellor of the University of Cambridge will be filled by someone so eminently unsuitable has prompted an open letter by academics (any academic can sign, not just Cambridge).
Why anyone would think that Lord Browne is an appropriate choice is completely beyond me. The letter clearly identifies the main reason why he would be a terrible choice; he is one of the key individuals associated with ushering in the present funding regime, which has led to students graduating with huge debts and many UK universities currently facing financial ruin.
Update: Unfortunately, Wyn didn’t win. Lord Browne didn’t either. The new Chancellor of Cambridge University is Chris Smith (currently Master of Pembroke College, Cambridge). It seems the electorate went with the tradition of electing a political has-been.
Stock viscosity image: Photo by Fernando Serrano on Pexels.com
I thought I’d mention here a paper now on arXiv that I co-wrote with my PhD student Aoibhinn Gallagher. Here is the abstract:
The Schrödinger-Poisson formalism has found a number of applications in cosmology, particularly in describing the growth by gravitational instability of large-scale structure in a universe dominated by ultra-light scalar particles. Here we investigate the extent to which the behaviour of this and the more general case of a Schrödinger-Newton system, can be described in terms of classical fluid concepts such as viscosity and pressure. We also explore whether such systems can be described by a pseudo-Reynolds number as for classical viscous fluids. The conclusion we reach is that this is indeed possible, but with important restrictions to ensure physical consistency.
arXiv:2507.08583
It is based on work that his in her now-completed PhD thesis, along with another paper mentioned here. I have been interested for many years in the Schrödinger-Newton system (or, more specifically, the Schrödinger-Poisson system in the case where self-gravitational forces are involved). In its simplest form this involves a wave-mechanical representation, in the form of an effective Schrödinger equation, of potential flow described classically by an Euler equation. More recently we got interested in the extent to which such an approach could be used to model viscous fluids represented by a Navier-Stokes equation rather than an Euler equation. That was largely because the effective Planck constant that arises in this representation has the same dimensions as kinematic viscosity (but there’s more to it than that).
In the paper we explored a limited aspect of this, by looking at situations where there is no vorticity (so still a potential flow) but there is viscosity. There aren’t many examples of fluid flow in which there is viscosity but no vorticity, and most of those that do exist are about one-dimensional flow along channels or pipes with boundary conditions that don’t really apply to astrophysics, but one example we did look at in detail was the dissipiation of longitudinal waves in such a fluid.
One upshot of this work is that one can indeed describe some aspects of quantum-mechnical fluids such as ultra-light scalar matter in terms of classical fluid properties, such as viscosity, but you have to be careful. For more information, read the paper!
There was some sad news for cosmologists last week in that the Government of the United States of America – specifically the National Science Foundation (NSF) and the Department of Energy (DOE) – has cancelled the next generation of ground-based cosmic microwave background experiments, called CMB-S4. This would have been the fourth generation This would have consisted of several dedicated telescopes equipped with highly sensitive superconducting cameras.
The plan was that these telescopes would spend about seven years listening to the microwave sky at two locations already recognized for their suitability: the South Pole, which was to host several telescopes of varying sizes to observe across a wide range of microwave frequencies; and the Atacama Plateau in Chile, a high-desert site which would have hosted two large telescopes that can also observe several different frequencies. The South Pole telescopes were to conduct an ultra-deep survey of 3% of the sky, while the Atacama telescopes would conduct a complementary ultra-wide and deep survey of 70% of the sky. Together, the two sites promised to provide a dramatic leap forward in our understanding of the fundamental nature of space and time and the evolution of the Universe.
Longstanding readers of this blog will remember that in 2014 the BICEP2 experiment at the South Pole was claimed to have detected the B-mode polarization signal that would be a diagnostic of primordial gravitational waves generated during a burst of cosmic inflation. That result was later shown to be dominated by Galactic dust emission which could not be identified from its spectral properties, as BICEP2 operated at only one frequency. With an order of magnitude more detectors than previous ground-based CMB experiments, wider frequency coverage, and better control of systematic errors, CMB-S4 would have reduced the limits on earlier observations by a factor of five, enabling either the direct detection of primordial gravitational waves or ruling out large classes of inflationary models and dramatically impacting current thought on cosmic inflation.
For more technical information about CMB-S4 see the 2021 White Paper here.
Despite its very strong science case, and the fact that it was ranked as second-highest priority in the 2020 Decadal Survey, it seems that CMB-S4 is no more. Sad.
Though not as warm as it has been over the last few days, today still found Maynooth University Library Cat in need of a siesta. There aren’t many students around these days so he’s not disturbed by so many people wanting to pet him, and was sound asleep in a shady spot when I passed by this afternoon.
About a year ago, I posted an item about a change to Employment Law in Ireland that effectively bans the use of Non-Disclosure Agreements (NDAs) in situations involving allegations of discrimination, victimisation, harassment and sexual harassment. When I posted this, the change had not come into force, but it has now. I think this is a very good move.
There aren’t many reasons to praise the current UK Government, but it seems they are proposing something similar, through an Amendment to the Employment Rights Bill, although the change has not yet come into effect and will not do so until the Bill becomes an Act.
The legislation will state that an employer shall not enter an NDA with an employee where the employee has made allegations of discrimination, harassment or sexual harassment. In my experience, NDAs are currently the default in such cases. I know of many examples in the UK where such legal instruments have been used to prevent victims of harassment from speaking publicly about their experiences, thus enabling harassers to move elsewhere without anyone knowing what they had done. This ploy is also seen by Management as a way of preventing reputational damage, although it does not seem to me to be a good way of doing that, as the truth has a way of coming out anyway and the effect of hiding the misconduct when it does causes more reputational damage than the harassment itself.
This reminds me of things I wrote a while ago in connection with a case at Leiden University where the Management decided not to name a professor involved in such a case (who was subsequently identified as Tim de Zeeuw). I thought this was a nonsense, for at least two reasons. The first is that I think people who have behaved in such a way should be named as a matter of principle, so that potential collaborators and future employers know what they have done. In previous posts on this topic I had defended confidentiality (e.g. here) during an investigation, but I still think that once it has been decided that a disciplinary offences have been committed there should be full disclosure.
The second is that failing to identify the individual concerned led to a proliferation of rumours inside and outside Leiden (none of which I am prepared to repeat here). As a result, the finger of suspicion was pointed at the wrong people until the name of the abusive Professor was revealed. That made for a very difficult working environment for everyone concerned.
Of course the new law, when passed, will only apply to cases in the United Kingdom. In Astronomy, as in many other parts of academia, there is a great deal of international mobility. The new legislation would not prevent someone who has engaged in such misconduct in, for example, The Netherlands, applying for a job in the UK without this coming to light. One could hope that other countries follow suit, but the wheels of the legislature are not known to turn quickly in any country that I know of.
I can sense many Human Resources departments getting very nervous, as the proposed change will render a major component of their modus operandi unlawful. Who knows, it may even encourage them to start tackling the culture of harassment that they have so far been content to hide.
Finally, I think it’s an important question whether or not this legislation is retroactive. If it is, and past NDAs are declared null and void then it will blow open many cases. I can imagine rather a lot of institutions and individuals getting rather nervous at the prospect of their previously concealed misconduct coming out in the open.
P.S. In related news, online voting for the Chancellorship of Cambridge University opened last week. It’s a transferable vote system. I put my first choice for Wyn Evans.
So here I am, back from a sweltering London to an almost-as-sweltering Maynooth. It was 33 degrees where I was in London yesterday and 30 degrees here in Maynooth earlier today, though it is now cooling slightly. Such a temperature is very unusual for this part of the world.
I was visiting South Kensington Technical College Imperial College for the last couple of days, working there. The surrounding area is of course looked very posh and looked resplendent in the summer sun. The area around the Museums was very busy with tourists, but it was nice to see people out and about, enjoying themselves in the sunshine.
I had hoped to publish a few OJAp papers on Wednesday morning before leaving for the airport. Unfortunately, as explained here, Crossref was offline all day Wednesday so I couldn’t do that. I caught up on Thursday morning by getting up before 6am and publishing 4 papers before heading down for a very nice hotel breakfast at 7am.
The journey to London on Wednesday didn’t get off to a very good start. My Aer Lingus flight from Dublin was delayed for an hour waiting the arrival of the aircraft from, of all places, Barcelona. Worse was to follow. I had decided to take the tried-and-trusted route from Heathrow Terminal 2 to South Kensington via the Piccadilly line. All went well until we approached Acton Town when the driver explain that there was a signal failure ahead at Covent Garden which meant the line in front was congested. Thereafter we inched along waiting for a succession of red lights to clear. The Piccadilly line has rather old trains without air conditioning, so it was like sitting in a slowly-moving sauna. Then we reached Turnham Green (where the train was not supposed to stop), and the driver opened the doors to give us a bit of fresh air. I spotted a District Line train to Upminster on the other side of the platform. That line does not go through Covent Garden so I dashed across and took it for the rest of the journey. I got to my hotel about 90 minutes later than planned, but not late enough to miss the welcome dinner at Ognisko, a very nice Polish restaurant.
Fortunately the hotel the Imperial staff had booked for me was very nice, and had good airconditioning. The rest of my stay was very pleasant, if intense. I even got back to Dublin on schedule yesterday evening and had time to go to the shops to get something for dinner last night and breakfast this morning.
Now that I’m back I have a report to write, but that can wait until tomorrow. Today I have to attend to a thirsty garden.
It’s Saturday morning again, so it’s time again for an update of papers published at the Open Journal of Astrophysics. Since the last update we have published seven new papers, which brings the number in Volume 8 (2025) up to 92, and the total so far published by OJAp up to 327.
This was a slightly strange week, starting with the fact that there were no new arXiv announcements on Monday 7th July because of the 4th July holiday in the USA on Friday so no papers were published that day. We were not able to publish any papers on Wednesday 9th July either because Crossref was offline for 24 hours that day while its data was migrated into the cloud. Our publishing process requires a live connection with Crossref to deposit metadata upon publication so we can’t publish while that service is down. Fortunately the update seems to have gone well and normal services resumed the following day. That partially accounts for the fact that four of this week’s papers were published on 10th July.
Anyway, The papers published this week, with their overlays, are as follows. You can click on the images of the overlays to make them larger should you wish to do so.
The officially-accepted version can be found on arXiv here.
The second paper is “Low redshift post-starburst galaxies host abundant HI reservoirs” by Sara Ellison (U. Victoria, Canada) and 10 others based in China, UK, Spain, USA and Canada. This one was also published oon Tuesday 8th July but in the folder Astrophysics of Galaxies. This paper uses 21cm observations of a sample of post-starburst galaxies, to show that they contain large reservoirs of neutral hydrogen. Here is the overlay:
You can find the final version of the manuscript on arXiv here.
You can find the officially-accepted version of the paper on arXiv here.
The penultimate paper for this week, and the last of the batch published on 10th July, is “Systematically Measuring Ultra-Diffuse Galaxies. VIII. Misfits, Miscasts, and Miscreants” by Dennis Zaritsky, Richard Donnerstein, and Donghyeon J. Khim (Steward Observatory, U. Arizona, USA). This paper presents a morphological study of weird and wonderful galaxies as part of an effort to Systematically Measure Ultra-Diffuse Galaxies (the SMUDGes survey). It is in the folder marked Astrophysics of Galaxies. The overlay is here:
You can find the officially-accepted version of the paper on arXiv here.
The last article published this week is “Differential virial analysis: a new technique to determine the dynamical state of molecular clouds” by Mark R. Krumholz (ANU, Australia), Charles J. Lada (Harvard, USA) & Jan Forbrich (U. Herts, UK). This paper presents simple analytic models of supported and collapsing molecular clouds, tested using full 3D simulations and applied to observed clouds in Andromeda. It is in the folder marked Astrophysics of Galaxies and was published yesterday, i.e on Friday 11th July 2025. Here is the overlay
You can find the officially-accepted version on arXiv here.
And that’s all the papers for this week. I will, however, take this opportunity to mention that a while ago I was interviewed about the Open Journal of Astrophysics by Colin Stuart on behalf of the Foundational Questions Institute; the write-up of the interview can be found here.
Posted in Uncategorized on July 9, 2025 by telescoper
I am going to be away until the weekend, and in any case I’ve been a bit overwhelmed with things over the last few days, so I’m going to take a short break from blogging. I’ll (probably) start again on Saturday. Normal service will be resumed as soon as possible.
At the Social Dinner at the EAS in Cork I got talking to a young postgraduate student while we were both in the queue for burgers. We chatted about the trials and tribulations of doing a PhD and about the general perception that it is a very hard slog. What I said was that, although at times it was definitely tough going, I had the best time of my life doing my PhD – well, DPhil actually – and I know many others who feel the same. I think you need work hard, but also enjoy it.
Me having received my Doctorate in 1989.
The main point is that a postgraduate research degree is very different from a programme of undergraduate study. For one thing, as a research student you are expected to work on your own a great deal of the time. That’s because nobody else will be doing precisely the same project so, although other students will help you out with some things, you’re not trying to solve the same problems as your peers as is the case with an undergraduate. Your supervisor will help you of course and make suggestions (of varying degrees of helpfulness), but a PhD is still a challenge that you have to meet on your own.
(Incidentally, I don’t think it is good supervisory practice to look over a research student’s shoulder all the time. It’s part of the purpose of a PhD that the student learns to go it alone. There is a balance of course, but my own supervisor was rather “hands off” and I regard that as the right way to supervise. I’ve always encouraged my own students to do things their own way rather than try to direct them too much.)
That loneliness is tough in itself, but there’s also the scary fact that you do not usually know whether your problem even has a solution, let alone whether you yourself can find it. There is no answer at the back of the book; if there were you would not be doing research. A good supervisor will suggest a project that he or she thinks is both interesting and feasible, but the expectation is that you will very quickly be in a position where you know more about that topic than your supervisor.
I think almost every research student goes through a phase in which they feel out of their depth. There are times when you get thoroughly stuck and you begin to think you will never crack it. Self-doubt, crisis of confidence, call it what you will, I think everyone who has done a postgraduate degree has experienced it. I certainly did. A year into my PhD I felt I was getting nowhere with the first problem I had been given to solve. All the other research students seemed much cleverer and more confident than me. Had I made a big mistake thinking I could this? I started to panic and began to think about what kind of job I should go into if I abandoned the idea of pursuing a career in research.
So why didn’t I quit? There were a number of factors, including the support and encouragement of my supervisor, staff and fellow students in the Astronomy Centre at Sussex, and the fact that I loved living in Brighton, but above all it was because I knew that I would feel frustrated for the rest of my life if I didn’t see it through. I’m a bit obsessive about things like that. I can never leave a crossword unfinished either…
What happened was that after some discussion with my supervisor I shelved that first troublesome problem and tried another, much easier one. I cracked that fairly quickly and it became my first proper publication. Moreover, thinking about that other problem revealed that there was a way to finesse the difficulty I had failed to overcome in the first project. I returned to the first project and this time saw it through to completion. With my supervisor’s help that became my second paper, published in 1987.
I know it’s wrong to draw inferences about other people from one’s own particular experiences, but I do feel that there are some general lessons. One is that if you are going to complete a research degree you have to have a sense of determination that borders on obsession. I was talking to a well-known physicist at a meeting not long ago and he told me that when he interviews prospective physics students he asks them “Can you live without physics?”. If the answer is “yes” then he tells them not to do a PhD. It’s not just a take-it-or-leave-it kind of job being a scientist. You have to immerse yourself in it and be prepared to put long hours in. When things are going well you will be so excited that you will find it as hard to stop as it is when you’re struggling. I’d imagine it is the just same for other disciplines.
The other, equally important, lesson to be learned is that it is essential to do other things as well as your research. Being “stuck” on a problem is part-and-parcel of mathematics or physics research, but sometimes battering your head against the same thing for days on end just makes it less and less likely you will crack it., I’m sure that I’m not the only physicist who has been unable to sleep for thinking about their research or who has spent hours sitting at their desk achieving nothing at all. The human brain is a wonderful thing, but it can get stuck in a rut. One way to avoid this happening is to have more than one thing to think about.
I’ve lost count of the number of times I’ve been stuck on the last clue in a crossword. What I always do in that situation is put it down and do something else for a bit. It could even be something as trivial as making a cup of tea, just as long as I don’t think about the clue at all while I’m doing it. Nearly always when I come back to it and look at it afresh I can solve it.
It can be difficult to force yourself to pause in this way, but I think it is essential to learn how to effect your own mental reboot. In the context of my actual research this involved simply turning to a different research problem, but I think the same purpose can be served in many other ways: taking a break, going for a walk, playing sport, listening to or playing music, reading poetry, doing a crossword, or even just taking time out to socialize with your friends. Back in Brighton in the 1980s I spent most evenings in bars and nightclubs. I never felt the slightest bit of guilt for having so much fun. Without the nightlife and all that I’m not sure I would have finished my PhD.
So, for what it’s worth, here is my advice to new or prospective postgraduate students: work hard but enjoy the challenges. Listen to advice from your supervisor, but remember that the PhD is your opportunity to establish your own identity as a researcher. So take ownership of it. And never feel guilty about establishing a proper work-life balance. Having more than one dimension to your life will not only improve your well-being but may also make you a better researcher.
The views presented here are personal and not necessarily those of my employer (or anyone else for that matter).
Feel free to comment on any of the posts on this blog but comments may be moderated; anonymous comments and any considered by me to be vexatious and/or abusive and/or defamatory will not be accepted. I do not necessarily endorse, support, sanction, encourage, verify or agree with the opinions or statements of any information or other content in the comments on this site and do not in any way guarantee their accuracy or reliability.
In the Dark 