The Hubble Constant: A Historical Review

Posted in The Universe and Stuff with tags , , , , , on May 29, 2023 by telescoper

I bookmarked this paper on arXiv a week or so ago with the intention of sharing it here, but evidently forgot about it. Anyway, as its name suggests, it’s a review by Brent Tully from a historical perspective of measurements of the Hubble Constant. I’m not sure whether it is intended for publication in a book – as it opens with the heading “Chapter 1” – but it’s well worth reading whatever its purpose. Here is the abstract:

For 100 years since galaxies were found to be flying apart from each other, astronomers have been trying to determine how fast. The expansion, characterized by the Hubble constant, H0, is confused locally by peculiar velocities caused by gravitational interactions, so observers must obtain accurate distances at significant redshifts. Very nearby in our Galaxy, accurate distances can be determined through stellar parallaxes. There is no good method for obtaining galaxy distances that is applicable from the near domain of stellar parallaxes to the far domain free from velocity anomalies. The recourse is the distance ladder involving multiple methods with overlapping domains. Good progress is being made on this project, with satisfactory procedures and linkages identified and tested across the necessary distance range. Best values of H0 from the distance ladder lie in the range 73 – 75 km/s/Mpc. On the other hand, from detailed information available from the power spectrum of fluctuations in the cosmic microwave background, coupled with constraints favoring the existence of dark energy from distant supernova measurements, there is the precise prediction that H0 = 67.4 to 1%. If it is conclusively determined that the Hubble constant is well above 70 km/s/Mpc as indicated by distance ladder results then the current preferred LambdaCDM cosmological model based on the Standard Model of particle physics may be incomplete. There is reason for optimism that the value of the Hubble constant from distance ladder observations will be rigorously defined with 1% accuracy in the near future.

Brent Tully, arXiv:2305.11950

Here is the concluding paragraph:

As the 20th century came to an end, ladder measurements of the Hubble constant were at odds with the favored cosmological model of the time of cold dark matter with Λ =0. The new favorite became the ΛCDM model with dark energy giving rise
to acceleration of space in a topologically flat universe. Yet ladder measurements, continuously improving, create doubts that this currently favorite model is complete. Yes, there is a Hubble tension.

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Premier League – Classification of Honours

Posted in Football with tags , on May 28, 2023 by telescoper

Now all the final results are in and validated the Board can now proceed to the classification of Honours for the 2022/23 Premier League.

As Chair, I will remind you of the regulations as we go through. Fortunately, this time matters are relatively straightforward.

Four candidates (Manchester City, Arsenal, Manchester United and Newcastle United) have a final score greater than or equal to 70 will therefore be awarded First Class Honours. All four can look forward to further study next year; Manchester City win this year’s Prize for getting the top mark.

The next four candidates all have scores in the range 60-69 so they are all in the Upper Second Class, i.e. II.1, category – though in the case of Tottenham Hotspur, only just. Liverpool will be disappointed to have missed out on a First, but Aston Villa and Brighton & Hove Actually will probably be satisfied.

Only two candidates are in the Lower Second Class (II.2) this year (Brentford and Fulham) while Crystal Palace, Chelsea, Wolverhanpton Wanderers and West Ham United all get clear Thirds, having marks in the range 40-49.

AFC Bournemouth, Nottingham Forest and Everton have all technically failed, but with marks in the range 35-39 they are “soft fails” and are allowed to pass by compensation. There being no extenuating circumstances, however, they do not qualify for Honours and must be content with being classified as “Ordinary”.

That leaves the three candidates at the bottom of the table – Leicester City, Leeds United and Southampton – who are all “hard fails” so will have to terminate the course and consider their options while taking some time out.

I hope this clarifies the situation.

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On Whit The Marking Boycott

Posted in Biographical, Education with tags , , , , on May 28, 2023 by telescoper

This is a bank holiday weekend in the United Kingdom, but not here in Ireland. Over here the old Whit Monday bank holiday is marked on the first Monday in June (i.e. a week tomorrow) rather than the last Monday in May as it is in the UK. Whit Sunday is another name for Pentecost, a moveable feast, which occurs on the 7th Sunday after Easter Sunday and therefore moves around in the calendar. Last year, Whit Sunday was actually June 5th; this year it is May 28th (today); and next year it will be on 19th May. So sometimes Ireland has a holiday on Whit Monday, sometimes the UK does, and sometimes neither.

Anyway, tomorrow may not be a holiday here on the Emerald Isle but I’ve finished marking my examinations so one major source of stress has been removed and I can get on with other things next week. Best wishes to colleagues still ploughing through their scripts.

All of this reminded me that universities on the other side of the Irish Sea are currently gripped by a marking and assessment boycott called by the University and College Union (UCU) as part of ongoing industrial action over pay and conditions. This has already been going on for over a month.

I haven’t kept up very well with what’s been going on in UK universities but it looks like a deal has been struck over pensions which will result in benefits being restored to members of the USS scheme. Drastic and unjustifiable cuts imposed on the pension scheme were just one part of the UCU industrial dispute, however, and action continues with respect to the others. Accordingly, UCU has asked its members in higher education institutions which are part of the pay and working conditions dispute to cease undertaking all summative marking and associated assessment activities/duties. The boycott also covers assessment-related work such as exam invigilation and the processing of marks. 

The managers of some universities have reacted to this boycott with 100% salary cuts to staff participating in it. The gloves seem to be off and it doesn’t seem likely that a resolution will be reached any time soon. I support the industrial action, by the way, as I hope do colleagues in Ireland who are employed as External Examiners in UK universities and who should to carry out their duties which would be tantamount to crossing a picket line.

It remains to be seen what will happen to students who hope to graduate from UK universities this summer, especially those who need a specific grade to take their next step. These students have had a difficult time with both the pandemic and the industrial action, but something must be done to arrest the downward spiral of pay and working conditions for university teachers, otherwise there will no long be a higher education system worthy of the name.

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R.I.P. Jim Hartle (1939-2023)

Posted in The Universe and Stuff with tags , , , , on May 27, 2023 by telescoper

It’s another one of the occasions on which I have to use this blog to pass on some sad news. Renowned physicist James B. Hartle has passed away.

Jim Hartle’s scientific work was concerned with the application of Einstein’s theory of general relativity to astrophysics, especially gravitational waves, relativistic stars, black holes, and cosmology, specifically the theory of the wave function of the universe. For much of his career he was interested in the earliest moments of the big bang where the subjects of quantum mechanics, gravity theory and cosmology overlap, leading among other things to the Hartle-Hawking conjecture.

Jim Hartle was one of the speakers at the very first scientific conference I attended in Cargèse, Corsica way back in 1986. I remember his lectures very well after all these years, not least because he was so witty. I remember his response when someone asked him about the existence of large dimensionless numbers in cosmology: “…it’s a property that numbers have that some of them are larger than others.”

Condolences to his family, friends and colleagues. Rest in peace, Jim Hartle (1939-2023).

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Rachmaninov (×2) + Tubin at the National Concert Hall

Posted in Biographical, Music with tags , , , , , , , , , on May 27, 2023 by telescoper

Yesterday, after a nice walk through the sunny streets of Dublin, at the National Concert Hall for the final concert of the season by the National Symphony Orchestra, under the direction of Mihhail Gerts, who were joined, for the second half, by the National Symphony Chorus directed by David Young and three star vocalists. The progamme consisted of two pieces by Sergei Rachmaninov (who was born 150 years ago this year) and one by Eduard Tubin (an Estonian composer who was new to me before last night).

The Isle of the Dead, by Arnold Böcklin

The first item one the menu was The Isle of the Dead, Op. 29 by Sergei Rachmaninov,  inspired by a painting of the same name by Arnold Böcklin and written around 1908. The rhythms of the opening passage evoke the motion of a boat moving across the sea to the island, from which point the piece develops among a cloud of increasingly dense harmonic layers into a dark atmosphere full of foreboding.  It’s a darkly dramatic work that I’ve enjoyed every time I heard it and last night was no exception.

There then followed the Sinfonietta on Estonian Motifs by Eduard Tubin introduced by conductor Mihhail Gerts, who is himself from Estonia. It’s a work in three movements inspired by the folk songs the composer heard as a child growing up in Estonia. I knew that much before the performance started but didn’t realize it would turn out to be such a weighty composition. The two outer movements are rhythmically complex in a way that’s reminiscent of Stravinksy (especially Petrushka) and the overall mood is far from the pastoral tranquility I’d expected: the music is rather edgy, in fact. I suppose that’s not surprising given that it was written in 1940. I enjoyed this but it is strange how much it reminded me of other composers: as well as Stravinsky, there are clear nods in the direction of Sibelius and at times it also reminded me of Arnold Bax. You might say it is a little bit derivative. I couldn’t possibly comment.

After the interval

After the wine break we had The Bells, a choral symphony for soprano, tenor, bass-baritone, chorus and large symphony orchestra by Sergei Rachmaninov (Op. 35). The words are based on a Russian translation of the poem The Bells by Edgar Allan Poe which was very popular in Russia in the early 20th century and which clearly resonated with Rachmaninov:

The sound of church bells dominated all the cities of Russia I used to know, they accompanied every Russian from childhood to the grave and no composer could escape their influence. Most of my life was lived amid vibrations of of the bells of Moscow.

Sergei Rachmaninov

The Bells is in four movements, echoing the four stanzas of the poem, and representing the journey “from childhood to the grave”, the last movement being a Lento subtitled The Mournful Iron Bells. The three soloists sing in one part each; the third movement involves orchestra and chorus only. Ukrainian tenor Valentyn Dytiuk sang in the first movement, Estonian soprano Mirjam Mesak the second and Ukrainian baritone Andrei Bondarenko the fourth. All three soloists were superb but particularly enjoyed the sinewy muscularity of Bondarenko’s baritone which gave a sense of rawness to his performance.

It was a fitting finale to the season. Congratulations to the National Symphony Orchestra for a great performance, and to the National Symphony Orchestra who were outstanding too.

Walking back to Pearse Station to get the train for Maynooth I found myself wondering when my next visit to the National Concert Hall will be. I’ll be away on sabbatical most of next year. Still, there’ll be plenty of music where I’m going…

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Terms Ending

Posted in Biographical, Education, Maynooth with tags , , , on May 26, 2023 by telescoper

So here I am, on a fine early summer evening, waiting for the train into Dublin for the last performance of the season by the National Symphony Orchestra at the National Concert Hall. I’m looking forward to it very much, as the second half is a piece I’ve never heard before. I’ll write more about it tomorrow.

There’s an end of term feeling in other ways, too. The examination period ended earlier this week, and most students have now vanished for the summer. Quite a few staff members will be marking scripts at home too. Campus has been very quiet for the last few days. The train I’m now on, the 17.10 from Maynooth to Connolly, usually very busy on a Friday, is almost empty today.

The one exception to the general lack of activity on campus happened on Wednesday when a mysterious ferret appeared on Campus. It even tried to get into the Science Building, but failed (I suppose) because it didn’t have a swipe card. It seems this critter was a family pet that had got out and went on an adventure. It was spotted at various locations around the town before being collected by its owner and returned safely home.

Artist’s impression of the ferret.

Despite that flurry of excitement, I managed to finish marking my examinations and other assessments, but the grades still need to be checked. They then have to be approved by the Departmental Exam Board in early June. They then get a final dose of scrutiny at the University Examination Board. Students will have to wait almost another month to get their results. It’s quite a slow process, but it’s right to be careful.

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New Publication at the Open Journal of Astrophysics

Posted in OJAp Papers, The Universe and Stuff with tags , , , , , on May 26, 2023 by telescoper

It’s time to announce yet another new paper at the Open Journal of Astrophysics. This one was published yesterday (25th May).

The latest paper is the 18th paper so far in Volume 6 (2023) and the 83rd in all. With this one we have now published more papers in 2023 than we did in all of last year. With significantly less than half the year gone, and a large number of papers in the pipeline, I think it’s quite likely we will exceed a total of 100 papers by the end of 2023.

The primary classification for this paper is Cosmology and Nongalactic Astrophysics and its title is “The Effect of Splashback on Weak Lensing Mass Estimates of Galaxy Clusters and Groups”. For the uninitiated  “Splashback” of infalling material produces features in the radial density profile of galaxy clusters. This paper discusses the effect of this on cluster masses derived from weak lensing measurements.

The authors, most of whom have multiple affiliations, are: Yuanyuan Zhang (NOIRLab, Tucson, AZ, USA), Susmita Adhikari (IISER, Pune, India), Matteo Costanzi (Univ. Trieste, Italy) and Josh Frieman, Jim Annis & Chihway Chang (Univ. Chicago, IL, USA).

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, along with all other astrophysics and cosmology research papers worth reading, on the arXiv here.

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MSc in Theoretical Physics & Mathematics at Maynooth

Posted in Education, Maynooth, The Universe and Stuff with tags , , on May 25, 2023 by telescoper

Now that the exams are over I thought I’d take the opportunity to promote our new MSc in Theoretical Physics & Mathematics. The existence of this was only announced in April and it was fully opened to applications just a couple of weeks ago. The University’s social media people have been pushing it very hard recently with, so I’m told, some success! Here are a few examples of the images that have been used in the ads:

Anyway, this (new) postgraduate course will be run jointly between the Departments of Theoretical Physics and Mathematics & Statistics, with each contributing about half the material. The duration is one calendar year (full-time) or two years (part-time) and consists of 90 credits in the European Credit Transfer System (ECTS). This will be split into 60 credits of taught material (split roughly 50-50 between Theoretical Physics and Mathematics) and a research project of 30 credits, supervised by a member of staff in a relevant area from either Department.

This new course is a kind of follow-up to the existing undergraduate BSc Theoretical Physics & Mathematics at Maynooth, also run jointly. We think the postgraduate course will appeal to many of the students on that programme who wish to continue their education to postgraduate level, though applications are very welcome from suitably qualified candidates who did their first degree elsewhere.

Postgraduate admissions in Ireland operate differently from the UK, in that there is a central system in Ireland (called PAC) that is similar to the undergraduate admissions system; in the UK PG courses are dealt with by individual institutions. You will need to apply online via PAC after the following the instructions here. The requisite PAC code for the full-time version of the course is MHQ56.

If you apply by 30th June you may be eligible for one of the University’s Taught Masters Scholarships!

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The End of the Irish Civil War

Posted in History with tags , , on May 24, 2023 by telescoper
An injured Anti-Treaty soldier is supported by a fellow fighter in the Battle for Dublin that started the Irish Civil War; over 500 Anti-Treaty fighters were taken as prisoners after the battle died down in the city.

Just a very quick post to mark the fact that it was on this day a century ago, May 24th 1923, that the terrible Irish Civil War came to an end. The conflict had been stuttering to a close for some time, but the final act was a communique issued by Éamon de Valera, the political leader of the Anti-Treaty forces, which said

Soldiers of the Republic. The Republic can no longer be successfully defended by your arms. Further sacrifice on your part would now be in vain and the continuance of the struggle in arms unwise in the national interest and prejudicial to the future of our cause. Military victory must be allowed to rest for the moment with those who have destroyed the Republic. Other means must be sought to safeguard the nation’s right.

Éamon de Valera, May 24th 1923

The Irish Free State created by the Anglo-Irish Treaty lasted until 1937, when a new constitution, largely written by de Valera, was adopted. Ireland (minus the Six Counties retained by the United Kingdom in the Treaty) became a full republic in 1949.

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Open Access: the Future is Diamond

Posted in Open Access with tags , , , on May 24, 2023 by telescoper

As it was foretold the Council of Europe has now released a document (PDF) that calls for “transparent, equitable, and open access to scholarly publications”.  In its conclusions, the Council calls on the Commission and the member states to support policies towards a scholarly publishing model that is not-for-profit, open access and multi-format, with no costs for authors or readers. In other words, it calls for Diamond Open Access. The covering press release includes:

If we really believe in open science, we need to make sure that researchers can make their findings available and re-usable and that high-quality scientific articles are openly accessible to anyone that needs to read them. This should be particularly the case for research that benefits from public funding: what has been paid by all should be accessible to all.

Mats Persson, Swedish Minister for Education, Ministry of Education and Research

This is clearly how Open Access should be, though I am still worried that the sizeable publishing lobby will still try to persuade research agencies and institutions to pay the existing fees on behalf of authors, which does not solve the problem but merely hides it.

I know I’m not alone in thinking that the current publishing ecosystem is doomed and will die a natural death soon enough. The replacement should be a worldwide network of institutional and/or subject-based repositories that share research literature freely for the common good. Universities and research centres should simply bypass the grotesque parasite that is the publishing industry. Indeed, I would be in favour of hastening the demise of the Academic Journal Racket by having institutions make it a disciplinary offence for any researcher to pay an APC to any journal.

We are lucky in physics and astronomy because arXiv has already done the hard work for us. With the existence of arXiv, old-style journals are no longer necessary. It is great that arXiv is being joined by similar ventures in other fields, such as BiorXiv and EarthArxiv. A list of existing repositories can be found here. I’m sure many more will follow. The future is Diamond.

What is needed is a global effort to link these repositories to each other and to peer review mechanisms. One way is through overlays as demonstrated by the Open Journal of Astrophysics, there being no reason why the idea can’t be extended beyond arXiv. Other routes are possible, of course, and I would love to see different models developed. I hope the European Council call will result in more support for Diamond Open Access. But whether this happens or not, I think the next few years are going to be very exciting.

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