Archive for the Uncategorized Category

Dark Energy and its Discontents

Posted in Uncategorized on April 24, 2015 by telescoper

Just time for a spot of gratuitous self-promotion. I shall be giving a public lecture tonight, Friday 24th April 2015, entitled Dark Energy and its Discontents, at the very posh-sounding Bath Royal Literary and Scientific Institution.
I am just finishing the slides for the talk, and packing some dark energy in my bag to use as a demonstration.
Here is the poster for tonight’s event, which explains all…

Bath_lecture

Perhaps I’ll see the odd reader of this blog there?

Another Awayday..

Posted in Uncategorized on April 23, 2015 by telescoper

Just a quick post to say that I spent today in London with the other Heads of School at Sussex University (or most of them). We met in the British Library Conference Centre, which is next door to St Pancras station. It wasn’t in the library itself, so I wasn’t able to try out the famous echo in the British Library Reading Room…

After leaving that meeting at ten-mile I had another appointment, near this relatively well-known landmark..

image

I won’t divulge the purpose or location of Meeting B as it’s a bit hush-hush, though not in a bad way…

An Einstein Ring – Courtesy of ALMA

Posted in Uncategorized with tags , , , , , , , on April 8, 2015 by telescoper

Just back from a short Easter holiday, I thought I’d resume blogging activities by showing you this remarkable image.

 

SDP81_ALMA3bands

What you see is a near-perfect example of an Einstein Ring which is a result of a chance alignment between a background galaxy and a foreground concentration of mass, sometimes a cluster of galaxies but in this case another galaxy. A more usual effect is the formation of a number of bright arcs; here there are two bright segments, but there is enough detail to see the rest of the circle. The lensed galaxy has a redshift about 3, so that light from it was emitted when the Universe was about one-quarter its current size, about 12 billion years in the past.

This object, codenamed SDP81, was initially detected as a potential lens system by the Herschel Space Observatory, which turned out to be superb at identifying gravitational lenses. I posted about this here, in fact. Working in the far-infrared makes it impossible to resolve the detailed structure of lensed images with Herschel – even with a 3.5m mirror in space, λ/D isn’t great for wavelengths of 500 microns! However, the vast majority of sources found during the Herschel ATLAS survey with large fluxes at this wavelengths can be identified as lenses simply because their brightness tells us they’ve probably been magnified by a lens. Candidates can then be followed up with other telescopes on the ground. A quick look during the Science Demonstration Phase of Herschel produced the first crop of firmly identified gravitational lens systems published in Science by Negrello et al. This one was followed up last year by the Atacama Large Millimetre Array (ALMA), itself a remarkable breakthrough in observational technology; the image was actually made in an extended configuration during the commissioning tests of ALMA’s long-baseline interferometric capability, which gives it stunning resolving power of about 23 milli-arcseconds. It’s absolutely amazing to see such detail in an image made in the submillimetre region of the spectrum.

The press release accompanying this can be found here and the full scientific paper by Vlahakis et al. is already on the arXiv here.

For the specialists the abstract of the journal paper reads:

We present initial results of very high resolution Atacama Large Millimeter/submillimeter Array (ALMA) observations of the z=3.042 gravitationally lensed galaxy HATLAS J090311.6+003906 (SDP.81). These observations were carried out using a very extended configuration as part of Science Verification for the 2014 ALMA Long Baseline Campaign, with baselines of up to 15 km. We present continuum imaging at 151, 236 and 290 GHz, at unprecedented angular resolutions as fine as 23 milliarcseconds (mas), corresponding to an un-magnified spatial scale of ~180 pc at z=3.042. The ALMA images clearly show two main gravitational arc components of an Einstein ring, with emission tracing a radius of ~1.5″. We also present imaging of CO(10-9), CO(8-7), CO(5-4) and H2O line emission. The CO emission, at an angular resolution of ~170 mas, is found to broadly trace the gravitational arc structures but with differing morphologies between the CO transitions and compared to the dust continuum. Our detection of H2O line emission, using only the shortest baselines, provides the most resolved detection to date of thermal H2O emission in an extragalactic source. The ALMA continuum and spectral line fluxes are consistent with previous Plateau de Bure Interferometer and Submillimeter Array observations despite the impressive increase in angular resolution. Finally, we detect weak unresolved continuum emission from a position that is spatially coincident with the center of the lens, with a spectral index that is consistent with emission from the core of the foreground lensing galaxy.

ALMA will only work in long baseline mode for a small fraction of its time, and it is bound to be in very heavy demand, so it’s not clear how many of the hundreds of candidate lenses flagged up by Herschel will ever be mapped in such detail, but this is definitely one for the album!

Interlude

Posted in Biographical, Uncategorized with tags , , on April 1, 2015 by telescoper

The University of Sussex is closing down for a week to allow people to take a breather around Easter weekend. After this afternoon’s staff meeting, I will heading off for a week’s holiday and probably won’t be blogging until I get back, primarily because I won’t have an internet connection where I’m going. That’s a deliberate decision, by the way….

So, as the saying goes, there will now follow a short intermission….

PS. The suitably restful and very typical bit of 1950s  “light” music accompanying this is called Pastoral Montage, and it was written by South African born composer Gideon Fagan.

 

Tony Blair, dread creature of the forbidden swamp

Posted in Uncategorized on March 8, 2015 by telescoper

telescoper:

Withering. Wonderful. Worth reblogging.

Originally posted on Idiot Joy Showland:

In the Hegelian system the history of mankind no longer appeared as a wild whirl of senseless deeds of violence, all equally condemnable at the judgement seat of mature philosophic reason and which are best forgotten as quickly as possible, but as the process of evolution of man himself.
Engels, Socialism: Utopian and Scientific

There was meant to be progress. Slowly at first, and then with gathering confidence, human beings were supposed to be turning the world from a Hell we couldn’t understand into a finely tuned machine that we could. We would predict the weather and split the atom and put a brushed-aluminium fridge-freezer with an ice-cube dispenser in every household, whether they wanted one or not. It was all a lie. What’s been called progress was nothing more than a war of annihilation against the ghosts. At first our odds were slim: the ghosts outnumbered us several times…

View original 1,366 more words

Image of the Week: The Nutshell Studies of Unexplained Death

Posted in Uncategorized with tags , , , on February 28, 2015 by telescoper

telescoper:

I just came across this post from the Wellcome institute blog and thought I would share it here. It’s linked to a (free) exhibition that opened this week in London which I must try to see.There’s a short video about it here. It includes some disturbing but fascinating photographs of the “The Nutshell Studies of Unexplained Death” a collection of eighteen miniature crime scene models that were built in the 1940’s and 50’s by a progressive criminologist by the name of Frances Glessner Lee. The models, which were based on actual homicides, suicides, and accidental deaths, were created to train detectives to assess visual evidence.You can see a complete set of the photographs here.

Originally posted on Wellcome Trust Blog:

Dark Bathroom (Tub), Corinne May Botz, 2004. Image courtesy of the artist Dark Bathroom (Tub), Corinne May Botz, 2004. Image courtesy of Corinne Botz and Benrubi Gallery.

This unsettling image of a doll meeting her untimely end, carries a deadly serious purpose. It is a close up portrait of one the twenty miniature crime scenes created by American heiress and criminologist Frances Glessner Lee in the 1940s and 50s. Termed ‘The Nutshell Studies of Unexplained Death’, each of these macabre dollhouse scenes was based on a composite of actual crimes. Their purpose was to train police investigators in a more methodical approach when observing and collecting evidence, while encouraging better interaction between law enforcement and the medical community. The Nutshells are still used for police training in Baltimore today.

Our featured image this week was created by artist and author Corinne May Botz, who spent several years photographing the Nutshells and researching the work and life of Glessner Lee. She was particularly fascinated by…

View original 84 more words

The Lost Art of Taking Notes..

Posted in Uncategorized on February 8, 2015 by telescoper

Taking a short break from this weekend’s task of preparing notes and problem sets for the Theoretical Physics module I’m teaching this term. In  the course of putting this stuff together I remembered an old post I did some time ago about  lecture notes.

I won’t repeat the entire content of my earlier discussion, but one of the main points I made in that was about how inefficient many students are at taking notes during lectures, so much so that the effort of copying things onto paper must surely prevent them absorbing the intellectual content of the lecture (assuming that there is any).

I dealt with this problem when I was an undergraduate by learning to write very quickly without looking at the paper as I did so. That way I didn’t waste time moving my head to and fro between paper and screen or blackboard. Of course, the notes I produced using this method weren’t exactly aesthetically pleasing, but my handwriting is awful at the best of times so that didn’t make much difference to me. I always wrote my notes up more neatly after the lecture anyway. But the great advantage was that I could write down everything in real time without this interfering with my ability to listen to what the lecturer was saying.

An alternative to this approach is to learn shorthand, or invent your own form of abbreviated language. This approach is, however, unlikely to help you take down mathematical equations quickly.

My experience nowadays is that students simply aren’t used to taking notes like this – I suppose because they get given so many powerpoint presentations or other kinds of handout –  so they struggle to cope with the old-fashioned chalk-and-talk style of teaching that some lecturers still prefer. That’s probably because they get much less practice at school than my generation. Most of my school education was done via the blackboard..

Nowadays,  most lecturers use more “modern” methods than this. Many lecturers using powerpoint, and often they give copies of the slides to students. Others give out complete sets of printed notes before, during, or after lectures. That’s all very well, I think, but what are the students supposed to be doing during the lecture if you do that? Listen, of course, but if there is to be a long-term benefit they should take notes too.

Even if I hand out copies of slides or other notes, I always encourage my students to make their own independent set of notes, as complete as possible. I don’t mean copying down what they see on the screen and what they may have on paper already, but trying to write down what I say as I say it. I don’t think many take that advice, which means much of the spoken illustrations and explanations I give don’t find their way into any long term record of the lecture.

And if the lecturer just reads out the printed notes, adding nothing by way of illustration or explanation, then the audience is bound to get bored very quickly.

My argument, then, is that regardless of what technology the lecturer uses, whether he/she gives out printed notes or not, then if the students can’t take notes accurately and efficiently then lecturing is a complete waste of time. In fact for the Theoretical Physics module I’m doing now I don’t hand out lecture notes at all during the lectures, although I do post lecture summaries and answers to the exercises online after they’ve been done.

As a further study aid, most lectures at Sussex University are recorded and made available to students to view shortly after the event. In most cases this is video as well as audio but in some smaller rooms only audio capture is available. I checked the attendance at my lecture last week (the third week of Term) and found over 95% of those enrolled were at the lectures. There’s no evidence that availability of recorded lectures has lowered the attendance. It appears that students use the recordings for revision and/or to clarify points raised in the notes they have taken.

I would actually like to put my lectures online, e.g. on YouTube, so they could be viewed freely by anyone who wanted but I am told this is against University policy as the campus trade union, UCU, had objected to the suggestion. I don’t know why.

I do like lecturing, because I like talking about physics and astronomy, but as I’ve got older I’ve become less convinced that lectures play a useful role in actually teaching anything. I think we should use lectures more sparingly, relying more on problem-based learning to instil proper understanding. When we do give lectures, they should focus much more on stimulating interest by being entertaining and thought-provoking. They should not be for the routine transmission of information, which is far too often the default.

I’m not saying we should scrap lectures altogether. At the very least they have the advantage of giving the students a shared experience, which is good for networking and building a group identity. Some students probably get a lot out of lectures anyway, perhaps more than I did when I was their age. But different people benefit from different styles of teaching, so we need to move away from lecturing as the default option and ensure that a range of teaching methods is available.

I don’t think I ever learned very much about physics from lectures – I found problem-based learning far more effective – but I’m nevertheless glad I learned out how to take notes the way I did because I find it useful in all kinds of situations. Effective note-taking is definitely a transferable skill, but it’s also in danger of becoming a dying art. If we’re going to carry on using lectures, we old fogeys need to stop assuming that students learnt it the way we did and start teaching it as a skill.

Follow

Get every new post delivered to your Inbox.

Join 4,113 other followers