Archive for February, 2019

“No Erasmus please, we’re British..”

Posted in Education, Maynooth with tags , , , on February 28, 2019 by telescoper

As the ongoing Brexit fiasco systematically trashes Britain’s international reputation, the consequences for the UK University sector are becoming increasingly obvious. In particular, the realization that Britain now defines itself exclusively by its xenophobia has led to a decision by Spain to remove the UK from the list of potential destinations for students under the Erasmus scheme. I’m sure other nations will soon make the same decision.

The European Union has agreed to honour Erasmus grants this year to UK students wish to study at European universities under Erasmus regardless of whether there is a Withdrawal Agreement between the UK and EU, but this is unlikely to be anything other than a stop-gap. It’s very sad to think that British students will be denied access to the Erasmus scheme in future, along with losing all the other benefits of Freedom of Movement.

Every cloud has a silver lining, though. Irish universities are more than happy to accept Erasmus students, and the one I work in (Maynooth) has a very active involvement in the scheme. So if you’re a student based in the EU, and want to study at an English-speaking university, why not apply to study in Ireland?

What a difference a year makes

Posted in Maynooth with tags , , on February 27, 2019 by telescoper

All this week we’ve seen very nice sunny weather in Maynooth, with temperatures reaching around 16 degrees (which is unusually high for February). This is in remarkable contrast with this time last year, when Ireland was facing the Beast from the East. The roads were blocked, the airports were closed, people were panic-buying bread, and the scene on campus was this:

It’s not been quite as warm here as it has been in England and Wales, where temperatures have exceeded  20°C, but it’s still been very pleasant – apart, perhaps, from being a bit warm in the computer laboratory.

One can’t help thinking, though, that there’s something disconcerting about this weather. It’s almost as if the climate might be changing or something like that.

New Publication at the Open Journal of Astrophysics!

Posted in Open Access, The Universe and Stuff with tags , , , , , , , , on February 27, 2019 by telescoper

It’s nice to be able to announce that the Open Journal of Astrophysics has just published another paper. Here it is!

It’s by Ben Maughan of the University of Bristol (UK) and Thomas Reiprich of the University of Bonn (Germany). You can find the accepted version on the arXiv here.

This is the first paper we have published in the section called High Energy Astrophysical Phenomena.

Thanks to the Editor and referees for dealing with this one so efficiently!

We have a few other papers coming up for publication soon, and some have been sent back to authors for revise and resubmit so we will almost certainly have further announcements to make soon.

 

P.S. Nobody spotted that I put the wrong DOI on the front page. I did that deliberately to see who was paying attention. Anyway, I’ve now put the right one on.

Norman Granz Jam Session No. 6

Posted in Jazz with tags , , , , , , , , , on February 26, 2019 by telescoper

It behoves me to spend most of this evening at a postgraduate Open Evening here at Maynooth University so I thought I’d take a little tea break and post a bit of Jazz.

This recording, made in 1954, is from one of the famous `All-Star’ jam sessions organized by impresario Norman Granz. These are fascinating for jazz fans because they provide a rare opportunity to hear extended solos from great musicians, not confined to the usual three-minute 78rpm records of the period. This one is almost half an hour long altogether, and was originally issued in two parts (on either side of an LP record) so there’s a rather clumsy edit half way through. There are also a few jumps on the record, but I don’t think they spoil this classic too much.

Norman Granz liked to select contrasting musicians for these spontaneous recordings and this line-up was clearly intended to juxtapose modernist trumpeter Dizzy Gillespie with his boyhood inspiration Roy Eldridge. It is indeed fascinating to hear them play one after the other, but the star of this show for me is the great clarinettist Buddy De Franco whose solo is absolutely superb – few Jazz clarinettists are able to match his control in the upper register. The other musicians clearly enjoy his solo too; I’m pretty sure that it’s Dizzy Gillespie you can hear delivering the encouraging shouts as De Franco gets into full flood.

The soloists (in order) are: Flip Phillips (tenor sax); Bill Harris (trombone); Buddy De Franco (clarinet); Oscar Peterson (piano); Herb Ellis (guitar); Dizzy Gillespie (trumpet); and Roy Eldridge (trumpet). The other musicians providing rhythm accompaniment are Ray Brown (bass) and Louie Bellson (drums). That’s not a bad band is it?

The tune played here is the swing era standard Stomping at the Savoy which is a good choice for this kind of jam session because (a) everyone knows it (b) the melody is quite simple, and (c) it has interesting chords for the musicians to improvise over. It is in standard 32-bar AABA format with a relatively simple A section (Db6, Ab9, Db6, Ddim, Ebm7, Ab7, Db, Db) but has a B section (bridge) with considerable chromatic embellishment (Gb9/G9, Gb9, B13/F#m6, B13, E9/F9, E9, A13, Ab9b); these are assuming that it is played in Db. It’s fascinating to hear how each of the soloists navigates the middle eight on this record.

Stomping at the Savoy is usually played a bit faster than it is here, but I like this beautifully relaxed and comfortably swinging tempo.

UPDATE: By an amazing coincidence*, Part 1 of this session was played by Bernard Clarke last night on The Blue of the Night (at about 10.30).

*It’s not a complete coincidence, as we had an exchange on Twitter about it a while ago and he said he would try to play it sometime – it was nevertheless a surprise that he played it on exactly the same day as I posted this!

The Negative Mass Bug

Posted in Astrohype, Open Access, The Universe and Stuff with tags , , , , , on February 25, 2019 by telescoper

You may have noticed that some time ago I posted about  a paper by Jamie Farnes published in Astronomy & Astrophysics but available on the arXiv here which entails a suggestion that material with negative mass might account for dark energy and/or dark matter.

Here is the abstract of said paper:

Dark energy and dark matter constitute 95% of the observable Universe. Yet the physical nature of these two phenomena remains a mystery. Einstein suggested a long-forgotten solution: gravitationally repulsive negative masses, which drive cosmic expansion and cannot coalesce into light-emitting structures. However, contemporary cosmological results are derived upon the reasonable assumption that the Universe only contains positive masses. By reconsidering this assumption, I have constructed a toy model which suggests that both dark phenomena can be unified into a single negative mass fluid. The model is a modified ΛCDM cosmology, and indicates that continuously-created negative masses can resemble the cosmological constant and can flatten the rotation curves of galaxies. The model leads to a cyclic universe with a time-variable Hubble parameter, potentially providing compatibility with the current tension that is emerging in cosmological measurements. In the first three-dimensional N-body simulations of negative mass matter in the scientific literature, this exotic material naturally forms haloes around galaxies that extend to several galactic radii. These haloes are not cuspy. The proposed cosmological model is therefore able to predict the observed distribution of dark matter in galaxies from first principles. The model makes several testable predictions and seems to have the potential to be consistent with observational evidence from distant supernovae, the cosmic microwave background, and galaxy clusters. These findings may imply that negative masses are a real and physical aspect of our Universe, or alternatively may imply the existence of a superseding theory that in some limit can be modelled by effective negative masses. Both cases lead to the surprising conclusion that the compelling puzzle of the dark Universe may have been due to a simple sign error.

Well there’s a new paper just out on the arXiv by Hector Socas-Navarro with the abstract

A recent work by Farnes (2018) proposed an alternative cosmological model in which both dark matter and dark energy are replaced with a single fluid of negative mass. This paper presents a critical review of that model. A number of problems and discrepancies with observations are identified. For instance, the predicted shape and density of galactic dark matter halos are incorrect. Also, halos would need to be less massive than the baryonic component or they would become gravitationally unstable. Perhaps the most challenging problem in this theory is the presence of a large-scale version of the `runaway’ effect, which would result in all galaxies moving in random directions at nearly the speed of light. Other more general issues regarding negative mass in general relativity are discussed, such as the possibility of time-travel paradoxes.

Among other things there is this:

After initially struggling to reproduce the F18 results, a careful inspection of his source code revealed a subtle bug in the computation of the gravitational acceleration. Unfortunately, the simulations in F18 are seriously compromised by this coding error whose effect is that the gravitational force decreases with the inverse of the distance, instead of the distance squared.

Oh dear.

I don’t think I need go any further into this particular case, which would just rub salt into the wounds of Farnes (2018) but I will make a general comment. Peer review is the best form of quality stamp that we have but, as this case demonstrates, it is by no means flawless. The paper by Farnes (2018) was refereed and published, but is now shown to be wrong*. Just as authors can make mistakes so can referees. I know I’ve screwed up as a referee in the past so I’m not claiming to be better than anyone in saying this.

*This claim is contested: see the comment below.

I don’t think the lesson is that we should just scrap peer review, but I do think we need to be more imaginative about how it is used than just relying on one or two individuals to do it. This case shows that science eventually works, as the error was found and corrected, but that was only possible because the code used by Farnes (2018) was made available for scrutiny. This is not always what happens. I take this as a vindication of open science, and an example of why scientists should share their code and data to enable others to check the results. I’d like to see a system in which papers are not regarded as `final’ documents but things which can be continuously modified in response to independent scrutiny, but that would require a major upheaval in academic practice and is unlikely to happen any time soon.

In this case, in the time since publication there has been a large amount of hype about the Farnes (2018) paper, and it’s unlikely that any of the media who carried stories about the results therein will ever publish retractions. This episode does therefore illustrate the potentially damaging effect on public trust that the excessive thirst for publicity can have. So how do we balance open science against the likelihood that wrong results will be taken up by the media before the errors are found? I wish I knew!

The Morning After

Posted in Biographical, Cardiff, Rugby with tags , , on February 24, 2019 by telescoper

So it’s not even 8am and I’m already sitting in Cardiff Airport waiting for my flight back to Ireland.

On the way to the bus stop in the City Centre I had to pick my way through the mess created by yesterday’s rugby crowd: empty beer bottles, plastic glasses and fast food containers lay all around, the pavements were sticky with spilt booze and massed formations of seagulls wheeled and shrieked looking for leftovers to scavenge.

No doubt there will be an organised cleanup but it hadn’t started when I walked through town around 7am.

I didn’t see any of yesterday’s match, but when Wales pulled the score back from 10-3 to 10-9 I got restless listening to the radio and went outside for a walk.

The thing about having a huge stadium right in the city centre is that the sounds coming from it permeate all of Cardiff. Sometimes they are recognisably human: cheers, jeers, applause, singing and stadium public address announcements. Often though, they are indistinct primordial murmurings, as if Gandalf were giving battle to a Balrog in the bowels of the Earth somewhere under Westgate Street.

But there was no mistaking the din a couple of minutes before the end when Wales scored the try that killed off the game and sent the home supporters into ecstasy. No doubt there’ll be more than a few hangovers in Cardiff this morning!

Wales play Ireland at the Principality Stadium on 16th March, with a possible Grand Slam in the offing. If that comes about the celebrations will no doubt make last night seem like a vicarage tea party!

Anyway, hopefully I will be back in Maynooth in a few hours to get next week’s lectures ready.

In Cardiff on Match Day

Posted in Cardiff, Rugby with tags , , , , on February 23, 2019 by telescoper

I’m in Cardiff today and have just been for a walk into town and back. It’s a lovely sunny springlike day with a temperature of around 13 degrees. There’s an abundance of daffodils in Bute Park.

Today is of course the occasion for the Wales versus England match in this year’s Six Nations Rugby tournament. This excerpt from a piece by Tom Fordyce on the BBC website is spot on:

Although the match doesn’t start for several hours, all the main roads are already closed so you can stroll around the City without worrying about cars. There’s a lot of people crammed into town, but a very good atmosphere around the place. I haven’t got a ticket for the match and don’t feel like watching in a packed pub either so I’ll just follow it on the radio.

After two impressive performances so far this year, England are probably favourites but you never know! They have also won the last five Six Nations matches between these two teams. But with their home crowd behind them Wales might well bring England’s run to an end.

I’ll make only one prediction: it will be a very physical game.

P. S. On my way home I passed two clearly inebriated England fans trying to find a way into the empty cricket ground at Sophia Gardens. It took quite some time to explain to them that it was not the rugby ground, despite the fact that the Principality Stadium was in clear view about half a mile away…

UPDATE: I was certainly right about it being a physical game! But a strong second-half comeback against a tiring England gave Wales victory by 21 to 13. Diolch, Cymru!