Questioning LIGO

Posted in The Universe and Stuff with tags , on June 17, 2017 by telescoper

Well. Cat, meet pigeons..

A paper appeared on the arXiv this week with the following abstract:

To date, the LIGO collaboration has detected three gravitational wave (GW) events appearing in both its Hanford and Livingston detectors. In this article we reexamine the LIGO data with regard to correlations between the two detectors. With special focus on GW150914, we report correlations in the detector noise which, at the time of the event, happen to be maximized for the same time lag as that found for the event itself. Specifically, we analyze correlations in the calibration lines in the vicinity of 35 Hz as well as the residual noise in the data after subtraction of the best-fit theoretical templates. The residual noise for the two more recent events, GW151226 and GW170104, exhibits equivalent behavior with respect to each of their time lags. A clear distinction between signal and noise therefore remains to be established in order to determine the contribution of gravitational waves to the detected signals.

I’m going to tread carefully here because (a) I have a number of colleagues at Cardiff who are directly involved in the analysis of LIGO data; (b) one of the authors of the new paper (Panel Naselsky) is a longstanding collaborator of mine; and (c) the new paper has not yet been refereed.

In fact I’m planning to visit Copenhagen in July/August and will catch up with Pavel and the other authors then.

Whether or not the points raised in the new paper are correct – and I am firmly agnostic, having not done the analysis myself – I think it’s entirely reasonable of the authors to subject the LIGO data to independent analysis. That’s how science is supposed to work; the relevant data are in the public domain now. 

No doubt the LIGO consortium will respond officially in due course. Of course, if anyone would like to comment unofficially then they are free to do so through the box below.

Update: Here is a fairly detailed rebuttal post.

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June 1915, by Charlotte Mew

Posted in Poetry with tags , , on June 16, 2017 by telescoper

Who thinks of June’s first rose today?
Only some child, perhaps, with shining eyes and
rough bright hair will reach it down.
In a green sunny lane, to us almost as far away
As are the fearless stars from these veiled lamps of town.
What’s little June to a great broken world with eyes gone dim
From too much looking on the face of grief, the face of dread?
Or what’s the broken world to June and him
Of the small eager hand, the shining eyes, the rough bright head?

by Charlotte Mew (1869-1928)

 

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Week Ending

Posted in Biographical on June 16, 2017 by telescoper

I’ve spent most of today involved in interviewing prospective PhD students for our new Centre for Doctoral Training in Data-Intensive Science run jointly between the universities of Bristol and Swansea which I advertised on here just a couple of months ago. I spent most of Monday in Bristol meeting representatives of industrial and other businesses, who are offering placement opportunities for PhD students on this new scheme. This activity is taking up quite a lot of my time these days and it’s not over yet as we haven’t yet finished the process of recruiting students which has to be done in connection with our academic and business partners.

I’ll be in Cambridge for the first half of next week, on external examining duties, and then the following week we have our little workshop on Random Fields. People generally think that, once our undergraduate lecture courses are finished and associated examinations are marked, we are free to do research until October. If only. There are many other things to be done.

Anyway that’s enough for this week. I’m off to the pub for a pint. Have a good weekend!

 

 

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Cosmological Wave Mechanics

Posted in The Universe and Stuff with tags , , , , on June 15, 2017 by telescoper

As promised here are the slides I used for my talk yesterday at Imperial College. I stole some of them from an old presentation given by Chris Short, who was a PhD student of mine when I was at Nottingham. Chris now works for the Met Office, working on rather different application of fluid mechanics!

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One Day in London

Posted in Biographical, Books, Talks and Reviews with tags , , on June 15, 2017 by telescoper

As it happens, I was in London yesterday to give an Astrophysics seminar at South Kensington Technical Imperial College. In due course I’ll post the slides as I normally do on such occasions.

It was an enjoyable day, with a train journey from Cardiff nice lunch followed by a question-and-answer session with students followed by the talk followed by a cup of tea, followed by a train ride home – all (for a change) running exactly to schedule. It was also extremely hot which meant the walk between Paddington and Imperial (across Hyde Park) left me rather sweaty. Better than getting rained on I suppose.

My hosts gave me an espresso cup, with an interesting motto on the back.


Usually when I go to Imperial or thereabouts I have a minor quandary about whether to walk or take the tube, with such factors as time, weight of baggage and weather taken into consideration before making a decision. This time, however, there was no decision to make because there were problems on the Underground in the area because of the terrible fire at Grenfell Towers, which has claimed the lives of at least 17 people (and possibly many more). The fire itself was near Latimer Road station, which is not on the line I would have taken, but there were apparently fears that the building might collapse near the line (which is overground at that point) so trains were suspended all the way from Hammersmith to Edgware Road, which disrupted the running of the Circle Line.

The venue for my talk was two or three miles away from Grenfell Towers, but in mid-afternoon you could still see smoke in the distance. It was a grim sight. I think I’ll remember yesterday afternoon very well, not because I gave a seminar, but because of the terrible events that happened earlier the same day.

There are many questions that urgently require answers. How did the fire start? Why did it spread so rapidly? Did the smoke alarms work (and if not why not)? Did the cladding on the outside of the building play a role? Did the fact that there was only a single stairwell – astonishing to my mind for a 20-storey residential building – cost lives?

I hope we’ll find the answers to these questions through a proper public inquiry. In the meantime all I can do is express my deepest condolences to those bereaved by this disaster, and wish a speedy recovery for those injured. They will need to understand what happened, urgently.

On the train home yesterday I looked at Twitter and saw this picture, of grim-faced and exhausted firefighters taking a break. I found it almost unbearably moving. We take these people for granted so much of the time, but they’re heroes – every single one of them:

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KCTMO – Playing with fire!

Posted in Uncategorized on June 14, 2017 by telescoper

This blog post was written in November 2016. Today the building went up in flames. We can only hope that no lives were lost.

http://www.bbc.co.uk/news/uk-england-london-40269625

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Take Five with Joe Morello

Posted in Jazz with tags , , , , on June 13, 2017 by telescoper

Not long ago I posted a clip of a drum solo by the great Joe Morello which has proved to be extremely popular. Since a meeting I thought I had this afternoon has been cancelled I’ve decided to take five minutes out to post another terrific drum solo.

The tune Take Five, composed by alto saxophonist Paul Desmond and recorded by the Dave Brubeck Quartet in 1959, became a hit at the second attempt when it was re-released in 1961. It proved so popular that the band performed many versions of it live, manu of which can be found on youtube. This one is not unusual in that it is performed at a faster tempo than the version that was released as a single. I read an interesting blog post a while ago that explains how Joe Morello’s arrival almost broke up the Dave Brubeck Quartet, as Paul Desmond and he had clashing personalities. I think Part of that was Morello’s predilection for tempos that were a bit faster than Desmond was comfortable with; Paul Desmond had a beautiful tone, but in contrast to many of his Jazz contemporaries on the instrument, he was never a speed merchant on alto saxophone. He seems to be less fluent than usual on this track, at least at first, probably because of the speed.

Joe Morello’s drum solo, on the other hand, is characteristically wonderful. Just watch his superb left-hand technique, from a relatively gentle opening to when he turns down the strainer on the snare drum he starts to build up to a stunning climax in which his hands are far too fast for the camera. It’s a great solo, not only because of it’s technical brilliance but because it’s so beautifully constructed. All in 5/4 time too…

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Cosmology at a Crossroads – Poll

Posted in The Universe and Stuff with tags , , , on June 13, 2017 by telescoper

A short comment piece by Wendy Freedman has appeared in Nature Astronomy; there’s a free version on the arXiv here. It gives a nice perspective on the current debate about the value of the Hubble constant from the point of view of an expert on cosmological distance scale measurements.

The abstract is here:

We are at an interesting juncture in cosmology. With new methods and technology, the accuracy in measurement of the Hubble constant has vastly improved, but a recent tension has arisen that is either signaling new physics or as-yet unrecognized uncertainties.

For the record, I’d go for `as-yet unrecognized uncertainties’, primarily because this field has a long history of drastically underestimated error-bars!

However, the publication of this piece gives me the excuse to resurrect the following poll, in which I invite you to participate:

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Tory MP author of ‘How To Win a Marginal Seat’ … lost his marginal seat on Thursday

Posted in Politics on June 11, 2017 by telescoper

Sometimes irony is too delicious for words…

Tom Pride's avatarPride's Purge

Gavin Barwell’s book ‘How To Win a Marginal Seat‘ was heavily praised by top Tories as a textbook on effective campaigning:

Boris Johnson wrote highly of the book:

Unfortunately for poor Gavin such hubris didn’t help him on Thursday – he lost his marginal Croydon seat to Labour’s Sarah Jones.

And even more hilariously – Gavin has just been put in charge of Theresa May’s campaigning.

Although I’m not sure May needs advice from anyone on how to f*ck up election campaigns …

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Poster Syndrome 

Posted in Uncategorized on June 10, 2017 by telescoper

I’ve taken these posters down from my window, now that the General Election is over, but I haven’t thrown them away. Something tells me I might be needing them again before too long..

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