Archive for the The Universe and Stuff Category

Gravitational Wave Controversy Updates

Posted in The Universe and Stuff with tags , , , on November 14, 2018 by telescoper

Following my recent post about the claims and counter-claims concerning the detection (or otherwise) of gravitational waves, I have a couple of updates.

First, a few days ago there appeared a paper on the arXiv by Nielsen et al with the abstract (which I’ve slightly edited for formatting reasons):

We use the Pearson cross-correlation statistic proposed by Liu & Jackson (2016), and employed by Creswell et al. (2017), to look for statistically significant correlations between the LIGO Hanford and Livingston detectors at the time of the binary black hole merger GW150914. We compute this statistic for the calibrated strain data released by LIGO, using both the residuals provided by LIGO and using our own subtraction of a maximum-likelihood waveform that is constructed to model binary black hole mergers in general relativity. To assign a significance to the values obtained, we calculate the cross-correlation of both simulated Gaussian noise and data from the LIGO detectors at times during which no detection of gravitational waves has been claimed. We find that after subtracting the maximum likelihood waveform there are no statistically significant correlations between the residuals of the two detectors at the time of GW150914.

The four authors of this paper are, I believe, either present or former members of the LIGO Collaboration

Meanwhile, the NBI group behind the Cresswell et al. paper challenged by the above paper has issued a statement which you can read here. The group re-iterate points made in the New Scientist article discussed in my recent post. Although the Nielsen et al. paper is not explicitly mentioned in the NBI statement but I’m given to understand that the Danish group does not agree with the conclusions in that paper.

The story continues.

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Moving Memories

Posted in Biographical, The Universe and Stuff with tags , , , on November 13, 2018 by telescoper

Yesterday evening I suddenly realized that today would be the anniversary of a significant milestone in my life. It was 20 years ago today (on 13th November 1998) that I moved from London to Beeston in Nottingham prior to starting as Professor of Astrophysics at Nottingham University on 1st January 1999. That means I’ve been a Professor for almost twenty years!

I remember it was Friday 13th November 1998 when I took possession of the house I’d bought in Marlborough Road. I picked that particular day to complete the purchase (and sale of my flat in Bethnal Green) because a removals firm offered me a very cheap deal: normally nobody wants to move house on Friday 13th, so they were happy when I turned out not to be superstitious. The move worked out very smoothly, in fact.

This picture taken in the Beeston residence that very day. You can see one of the removal men in the background:

I was still working at Queen Mary until the end of December 1998 so I had to commute to London and back for over a month after relocating, which wasn’t ideal, but bearable knowing that it wasn’t going to last forever, and that from the New Year I would be able to walk into work on the Nottingham University campus rather than trekking by train to London.

I did think leaving London would be a wrench, and that I would probably end up going back frequently to spend time with my old friends and visit regular haunts, but that didn’t really happen, and after living outside the Capital for a while I lost all inclination to ever return. Living in London is great fun when you’re young, but loses its attraction when you’re getting on a bit. That’s what I found, anyway.

It was exciting starting the new job in Nottingham. There wasn’t an Astronomy group as such prior to January 1999, but with the formation of a new group the School of Physics became the School of Physics & Astronomy, and the influx of astronomers helped the School both to expand its research portfolio and become more attractive to students. It was hard work helping to build that from scratch, but I’m glad that it worked out well. It is good to see the Astronomy group and indeed the whole School continuing to prosper, although some of my former colleagues there have now retired.

I moved to Cardiff in 2007 and eventually sold the Beeston house in 2008, after a long delay due to the Credit Crunch, and bought a house in Pontcanna which I still own.

It’s strange to think all that happened 20 years ago. I’ve just finished giving a lecture to our second-year students, most of whom weren’t even born in 1998! And I certainly never imagined back then than in twenty years I’d be living in Ireland!

R.I.P. James Stirling (1953-2018)

Posted in The Universe and Stuff with tags , , , on November 12, 2018 by telescoper

I’m sorry that this blog is once again the bearer of bad news, but it is my sad duty to pass on the news that distinguished particle physicist James Stirling (pictured above) passed away yesterday at the age of 65.

Professor James Stirling was one of the leading lights of the Institute for Particle Physics Phenomenology in Durham (of which he was the first Director) and subsequently became Jacksonian Professor of Natural Philosophy and Head of the Cavendish Laboratory at the University of Cambridge. More recently he was Provost of Imperial College, a post from which he stepped down earlier this year. He was elected to a Fellowship of the Royal Society in 1999, and awarded a CBE in the New Years Honours List in 2006.

As well as being an eminent physicist, with over 300 publications to his name including fundamental contributions to the field of hadronic interactions and perturbative QCD, Professor Stirling also gave great service to the research community, by serving on numerous important committees, including the Science Board of the Science & Technology Facilities Council (STFC).

Not being a particle physicist myself I didn’t know James as a close colleague, but I met him on several occasions during visits to Durham. Most recently, he was the external member of the appointment panel when I was interviewed for the post of Head of School of Mathematical and Physical Sciences at the University of Sussex. It says a lot for his personality that what I expected to be a fierce grilling when he led the questions on my research, turned out to he a friendly (yet challenging) discussion of some of my publications which he had clearly read extremely carefully.

James Stirling was held in extremely high regard by the scientific community and he’ll be greatly missed.I send my deepest condolences to his family, friends and colleagues.

R.I.P. Professor James Stirling (1953-2018)

Eight Papers from the Dark Energy Survey

Posted in The Universe and Stuff with tags , , , , on November 9, 2018 by telescoper

Just a quick post to point out the exciting news that this week a clutch of papers on cosmology using Type 1a Supernovae have been released by the Dark Energy Survey team. Naturally, all of them are on the arXiv. You can also read them here. For convenience I’ve provided links below to arXiv versions through their titles:

  1. Steve: A hierarchical Bayesian model for Supernova Cosmology
  2. First Cosmology Results Using Type Ia Supernovae from the Dark Energy Survey: Effects of Chromatic Corrections to Supernova Photometry on Measurements of Cosmological Parameters
  3. First Cosmology Results using Type Ia Supernova from the Dark Energy Survey: Simulations to Correct Supernova Distance Biases
  4. First Cosmology Results Using Type Ia Supernovae From the Dark Energy Survey: Photometric Pipeline and Light Curve Data Release
  5. First Cosmology Results Using Type Ia Supernovae From the Dark Energy Survey: Analysis, Systematic Uncertainties, and Validation
  6. First Cosmological Results using Type Ia Supernovae from the Dark Energy Survey: Measurement of the Hubble Constant
  7. Cosmological Constraints from Multiple Probes in the Dark Energy Survey
  8. First Cosmology Results using Type Ia Supernovae from the Dark Energy Survey: Constraints on Cosmological Parameters

Here’s a plot showing some of the cosmological constraints:

The parameter plotted on the vertical axis is the dark energy equation of state parameter, w, and w=-1 corresponds to a cosmological constant.

For those of youparticularly interested in the Hubble constant, the headline value from Paper 6 is H0 = 67.77 +/- 1.30 km s-1 Mpc-1. This closer to the value obtained from Planck and in tension with other values as I’ve blogged about before, and gives me an excuse to continue my online poll:

Lectures and Lava Lamps

Posted in Education, Maynooth, The Universe and Stuff with tags , , , on November 7, 2018 by telescoper

Teaching at Maynooth University has resumed after the Study Break, and yesterday I gave my first lecture on Astrophysics & Cosmology after a gap of a week. I still haven’t got onto the Cosmology bit yet, but am most of the way through a set of half-a-dozen lectures or so on stellar structure and evolution.

In past incarnations I’ve deployed a lava lamp as a prop to illustrate convection, one of the ways that heat can be transported from the core of a star (where it is generated by nuclear fusion) to its surface (whence it is radiated). The simple demonstration of how a temperature gradient can lead to convective motion always proved popular with students. In fact, more-or-less the only complimentary comments I ever got about my lectures on this topic were about how nice the lava lamp was.

Anyway, no longer having access to the official Cardiff University School of Physics & Astronomy Lava Lamp, I thought I’d just show a video chosen from the many available on youtube. They seem quite popular, perhaps because they are rather restful:

Unfortunately, however, the fates had it in for me yesterday. The Powers That Be decided to update the version of Windows on all the PCs in all the teaching rooms on campus during the study break. When I tried to show the video the computer crashed and would not restart. I had to run back to the office to get my laptop, which I eventually got to work, but I had lost so much time that I skipped the video. Hopefully I’ll get to show it properly at some point in the future.

 

Chemists against Plan S..

Posted in Open Access, The Universe and Stuff with tags , , , , on November 6, 2018 by telescoper

There’s an `Open Letter’ doing the rounds which rails against the European Plan S for open access to research papers . You can find it here on Google Docs. It is apparently initiated by some chemists, and there are very few signatories who are not chemists, though the language used in the letter suggests that the authors are talking for a much broader group.

My own thoughts on Plan S can be found here. I’m basically supportive of it. I suggest you read the letter for yourself and decide what you think. I think there are many rather inaccurate statements in it, including the idea that the journals run by Learned Societies are not profit-making. In my experience some of the most exploitative publishing practice comes from these organizations, though it takes something to beat the likes of Elsevier and Springer in that regard.

I share the concern about some researchers being driven to expensive `Gold’ Open Access modes of publication,  which is why I started the Open Journal of Astrophysics which I think offers a viable route to peer-reviewed publication that’s not only low-cost, but entirely free for authors and readers. Open Access publication is really not expensive to do. It’s just that some organizations see it as an opportunity to make enormous profits.

Incidentally, I just came across this summary of different routes to open access and their implications here:

In my opinion, Column H is the place to be!

I’ve given quite a few talks about Open Access recently and one of the things that struck me in the Q & A sessions after them is the extent to which attitudes differ in different disciplines. My own research area, astrophysics and cosmology, embraced open access over twenty-five years ago. Virtually every paper published in this discipline can be found for free on the arXiv, as is the case for particle physics. More recently, condensed matter physics and some branches of mathematics have joined in.

Chemistry, by contrast, is conspicuous by its absence from the arXiv. I don’t know why. Moreover, those who have expressed the most negative attitudes to Open Access whenever I’ve given talks about it have always been chemists. And now there’s this letter. It’s definitely part of a pattern. If any chemists out there are reading this, perhaps they could tell me why there’s such an enormous cultural difference between physics and chemistry when it comes to research publication?

The Letter states (paragraph 4):

Plan S has (probably) a much larger negative effect on chemistry than on some other fields.

Maybe so, but isn’t that just another way of saying that chemistry is more in need of cultural change than other disciplines?

P.S. I’d be happy to advise anyone interested in setting up an Open Journal of Chemistry, but if you want it to run like the Open Journal of Astrophysics you will have to set up a chemistry arXiv first – and that’s a much bigger job!

P.P.S. Thanks to a comment below I now know that there is a Chemistry archive, but it only has a small number (hundreds) of papers on it. Moreover, it does not host final refereed versions of papers. It is run by the American Chemical Society, German Chemical Society, and the Royal Society of Chemistry all learned societies who are opposed to Open Access no doubt because it threatens their funding models.

Stokes, Lonsdale and DCU

Posted in Cosmic Anomalies, Maynooth, Talks and Reviews, The Universe and Stuff with tags , , , on November 2, 2018 by telescoper

On Wednesday I took a trip from Maynooth into Dublin to give a talk at the Centre for Astrophysics and Relativity at Dublin City University (DCU). I’ve stolen the above picture, which someone took near the start of the talk, from Twitter.

My talk was very general, as it was not a specialist cosmology audience, and was similar to the talks I was giving a few years ago about the Axle of Elvis Axis of Evil. If anyone is interested in the slides, here they are.

Confusingly, Dublin City University (DCU) consists of the same combination of quarks as University College Dublin (UCD), but I managed to find my way to the correct campus via Drumcondra Railway Station (which is next to historic Croke Park). Anyway, there was quite a big audience and not all of them fell asleep (even though I did go on too long) so by that measure at least the talk was moderately successful. Thanks to everyone there for their hospitality during the afternoon!

Incidentally, my talk was in the Lonsdale Building which is right next to the Stoke Building. Both are named in honour of famous Irish-born scientists. physicist George Stokes (who was born in Skreen, in County Sligo, but spent most of his adult life in Cambridge) and crystallographer Kathleen Lonsdale (who was born in Newbridge, County Kildare, but moved to England when she was only five).