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Dreams, Planes and Automobiles

Posted in Biographical, Covid-19, Education, Maynooth, The Universe and Stuff with tags , , , , , on November 20, 2020 by telescoper

I’ve blogged before about the strange dreams that I’ve been having during this time of Covid-19 lockdowns, but last night I had a doozy. I’ve recently been doing some examples of Newtonian Mechanics problems for my first-year class: blocks sliding up and down planes attached by pulleys to other blocks by inextensible strings; you know the sort of thing.

Anyway, last night I had a dream in which I was giving a lecture about cars going up and down hills taking particular account of the effects of friction and air resistance. The lecture was in front of a camera and using a portable blackboard and chalk, but all that was set up outside in the middle of a main road with traffic whizzing along either side and in the presence of a strong gusty wind. I had to keep stopping to pick up my notes which had blown away, dodging cars as I went.

It would undoubtedly make for much more exciting lectures if I recorded them in such a situation, but I think I’d be contravening traffic regulations by setting up in the middle of the Straffan Road. On the other hand, I could buy myself a green screen and add all that digitally in post-production…

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The End of Arecibo

Posted in The Universe and Stuff with tags , on November 19, 2020 by telescoper

I’ve just heard the news that the famous (and indeed iconic) radio telescope in Puerto Rico known as the Arecibo Observatory is to be decommissioned. The facility was badly damaged by Hurricane Maria in 2017 and it was feared it might close then, but it was saved when an agreement was reached whereby a Consortium led by the University of Central Florida took over its operations.

Unfortunately, in August 2020 an auxiliary cable broke in August and tore a 30-metre diameter hole in the reflector dish and damaged the dome above it. Then, earlier this month, one of the telescope’s main steel cables snapped, causing further damage. It has now been decided that it will be too dangerous and too expensive to repair the telescope. It is to be decommissioned and then dismantled entirely. Presumably the site will be returned to the state it was in before the telescope was built.

This will be sad news for the people who work at Arecibo Observatory and for the local economy in Puerto Rico not to mention the many astronomers who have used the facility over the years. For a time it was the largest radio telescope in the world, its 1000ft diameter dish enabling it to achieve a resolution of about 3.5 arc minutes at 21cm. Even before the Hurricane struck, however, Arecibo had been struggling to find the funds necessary to maintain its operations. Now, almost 60 years after it was built, that struggle is over.

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A Remnant Problem

Posted in Cute Problems, The Universe and Stuff with tags , , , on November 16, 2020 by telescoper

 

I haven’t posted any physics problems for a while so here’s  a quickie involving dimensional analysis. You have to assume that the supernova remnant mentioned in the question is roughly spherical, like the one shown above (SNR 0500-67.5):

As usual, answers and comments through the box below please!

Click on the `continue reading’ thing if you would like to see my worked solution:

Continue reading →

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Newton’s Laws in Words

Posted in History, Maynooth, The Universe and Stuff with tags , , , on November 13, 2020 by telescoper

I’ve been teaching my first-year Mathematical Physics students about Newton’s Laws of Motion so decided to record this little video as an aside discussing the history terminology and use of language.

Unfortunately the only microphone I have is the one built into my laptop and it tends to suffer sometimes from a crackle caused (I think) by the fan inside the machine interfering with the mike. I guess the noise appears when the CPU is working hard causing the machine to heat up so the fan works harder. The sound on video recordings I make this low budget way do break up from time to time, which is rather irritating. Obviously I need to buy an external microphone and when I do I might record this again but in the meantime you’ll just have to put up with it breaking up a couple of times!

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Memories of Philae

Posted in History, The Universe and Stuff with tags , , , on November 12, 2020 by telescoper

It seems that today is the sixth anniversary of the day (November 12th 2014) that the probe Philae, having detached from its parent spacecraft Rosetta, and subsequently landed successfully (ish) on the Comet 67P/Churyumov-Gerasimenko.

I didn’t realise it was so long ago, but who could forget the feeling of intense excitement we felt on that day as Philae approached its objective?

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Cosmology Talks: Mateja Gosença & Bodo Schwabe on Simulating Mixed Fuzzy and Cold Dark Matter

Posted in The Universe and Stuff with tags , , , , , , on November 11, 2020 by telescoper

It’s been too long since I shared one of those interesting cosmology talks on the Youtube channel curated by Shaun Hotchkiss. This channel features technical talks rather than popular expositions so it won’t be everyone’s cup of tea but for those seriously interested in cosmology at a research level they should prove interesting.

Anyway, although I’ve been too busy to check out the talks much recently I couldn’t resist sharing this one not only because it’s on a topic I find interesting (and have worked on) but also because one of the presenters (Mateja Gosença) is a former PhD student of mine from Sussex! So before I go fully into proud supervisor mode, I’ll just say that the talk is about AxioNyx, which is a new public code for simulating both ultralight (or “Fuzzy”, so called because its Compton de Broglie wavelength is large enough to be astrophysically relevant) dark matter (FDM) and Cold dark matter (CDM) simultaneously. The code simulates the FDM using adaptive mesh refinement and the CDM using N-body particles.

P. S. The paper that accompanies this talk can be found on the arXiv here.

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Debating the Cosmological Principle

Posted in The Universe and Stuff with tags , , , , on November 5, 2020 by telescoper

Whether you need something to distract you from world events or are just interested in the subject I thought I’d share something cosmological today.

You may recall that I recently posted about a paper by Subir Sarkar and collaborators.  Here is the abstract and author list:

In that post I mentioned that Subir would be taking part in an online debate about this issue. Well, although I wasn’t able to watch it live there is a recording of it which is available here:

It’s rather long, but there are many interesting things in it…

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Phosphine on Venus, Water on the Moon, and Hype Everywhere

Posted in Astrohype, The Universe and Stuff with tags , , on October 28, 2020 by telescoper

To continue the ongoing saga of Phosphine in the atmosphere of Venus there’s a very strongly worded paper on the arXiv with the following abstract:

It’s one thing to question or refute another group’s result, but there’s no need to be so aggressive about it. The last sentence of the abstract is particularly unnecessary and reprehensible.

Update: the abstract has now been changed.

There has been a lot of reaction on social media from astronomers and others to the perceived “hype” of the initial discovery by the authors. I watched the press conference at the time and I think the authors spoke very sensibly about their work. Of course just because scientists are sensible that’s no reason to suppose the press will also be sensible and there was undoubtedly a great deal of hype about that result. In my experience hype is more likely to be a result of journalists wanting a sensational story and/or institutional press offices wanting to promote their institution that scientists over-egging their own puddings (though that does happen too).

I don’t mind individual scientists or groups of scientists making fools of themselves. It’s the damage to public trust in science that is the real danger here.

The hostile reaction we see in the above paper is an inevitable manifestation of an environment which encourages runaway self-publicity. This is not the only area in which this sort of toxic behaviour happens. I suppose it is mildly reassuring that it’s not only cosmologists that behave in such a way, but is this really what we want astrophysics to be like? I think we’d be better off leaving the petty point-scoring to the politicians.

Another example of hype this week – also involving a paper in Nature Astronomy – was the discovery of water on the Moon (again). The NASA publicity machine pulled out all the stops in advance of this announcement, only for the actual result to be a damp squib. Water is one of the most abundant molecules in space and I’ve lost track of how many times it has been detected on the Moon already. I suppose it is moderately reassuring that hasn’t suddenly disappeared, but from a scientific point of view it’s not all that interesting. I was particularly disappointed when the result turned out to be water, as I had bet on phosphine…

Could it be that the Stratospheric Observatory for Infrared Astronomy (SOFIA) is up for a funding review?

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Eye on Burlington House

Posted in The Universe and Stuff with tags , , on October 27, 2020 by telescoper

Having been forewarned of this story as soon as my copy of Private Eye arrived (this morning, owing to the Bank Holiday weekend) I headed straight to this:

It sounds rather alarming for the Royal Astronomical Society, which is currently accommodated in Burlington House in Piccadilly, but I do remember something similar being in the air not too long ago when I was a Member of RAS Council. The Government of the time threatened to increased rents and everyone involved with the RAS, including its Fellows, was a bit worried but an agreement was struck. Presumably now the leases are up for negotiation again?

It’s worth pointing out a few inaccuracies in the Eye piece.

  1.  “..the six Learned Societies complacently assumed they would continue to pay a peppercorn rent forever”. This is untrue as the rents have been renegotiated before (see above).
  2.  “The Royal Academy is still relatively flush….but the other five are effectively broke”. I don’t know anything about the others but I’d be very surprised if the Royal Society of Chemistry is “effectively broke” given the income from its academic publishing wing. It also has sizeable industrial income, as does the Geological Society. The Royal Astronomical Society has sizeable reserves in the form of a portfolio of long-term investments built up over the 200 years of its existence but it tends not to use them to fund expenditure; its main cash flow is provided again by academic publishing, especially Monthly Notices of the Royal Astronomical Society. This year – the bicentenary of its foundation – is a bit of an exception because it has dipped into reserves to fund a series of celebratory outreach activities.
  3. The description of “vast clubbable tearooms” is inaccurate too. The RAS occupies rather cramped accommodation in one corner of Burlington house. There is a Fellows’ Room but it is rather small. There are staff offices, a (small) lecture theatre and an important historical library. There are also the President’s Apartments (which I have of course never seen).

I wouldn’t put it past this particular Government to kick out the Learned Societies and outsource Burlington House to Serco but even if this does happen, it wouldn’t be the end of the world.  In my view the RAS needs to shake off the fusty image that its current accommodation in what looks like an old museum tends to perpetuate.  It has always been the case that most of the regulars at the monthly Open Meetings in Burlington House are based in or near London, which means many Fellows don’t get the chance to be involved. Would it really be all that bad for the Royal Astronomical Society had to move? They may have to overhaul their finances anyway if their publishing revenues dry up…

Why not use the opportunity to move the Society out of London altogether to a place with a strong astronomical connection, Bath for example, although that would admittedly make it difficult to get to the Athenaeum in time for dinner…

And if “commercial rates” are going to be the thing for Government-owned buildings, shouldn’t the occupant of 10 Downing Street be charged for his accommodation?

 

 

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Lá Saoire i mí Dheireadh Fómhair

Posted in Beards, Biographical, Covid-19, Irish Language, Maynooth, The Universe and Stuff with tags on October 26, 2020 by telescoper

Today being the last Monday of October, it’s a Bank Holiday here in Ireland so I’m having the day off (well, at least the morning: I have a telecon this afternoon). This week is Study Week too so there are no lectures or tutorials – real or virtual – until next Monday. Now that I have a broadband connection at home I’ll be working from here much more as the Level 5 restrictions require me to. It won’t be ideal because a lot of my work stuff is still in the office on campus, but at least I’ll be more comfortable than first time round, when I was in the flat.

Normally, most students go home for some or all of Study Week and return to campus the following week. This year I suppose most will stay where they are, although some might go home and stay there until the end of term since virtually all their teaching is online this term. They won’t even have to come back for the examinations after Christmas as these will be online too. It’s anyone’s guess whether we will have teaching on campus next Semester.

Coincidentally, the first campus closure started just before a Bank Holiday too. That was St Patrick’s Day. It seems like an eternity ago. The news of my award of the St Patrick’s Day Beard of Ireland would surely have made front pages across the Republic had it not been for the Covid-19 Pandemic. I think I’ll refrain from trimming my beard for the duration of the new restrictions like I did during the original lockdown.

Incidentally, the Irish word for beard is Féasóg. Also incidentally, I’ve signed up to have Irish language lessons this term; they start in November.

As I’ve mentioned before, this Bank Holiday (as others of its type in Ireland) has a sort of astronomical connection. In the Northern hemisphere, from an astronomical point of view, the solar year is defined by the two solstices (summer, around June 21st, and winter around December 21st) and the equinoxes (spring, around March 21st, and Autumn, around September 21st). These four events divide the year into four roughly equal parts each of about 13 week. If you divide each of these intervals in two you divide the year into eight pieces of six and a bit weeks each. The dates midway between the astronomical events mentioned above are (roughly) :

1st February: Imbolc (Candlemas)
1st May: Beltane (Mayday)
1st August: Lughnasadh (Lammas)
1st November: Samhain (All Saints Day)

The names I’ve added are taken from the Celtic/neo-Pagan (and Christian) terms for these cross-quarter days. These timings are rough because the dates of the equinoxes and solstices vary from year to year. Imbolc is often taken to be the 2nd of February (Groundhog Day) and Samhain is sometimes taken to be October 31st, Halloween.
Another name for the present Bank Holiday is Lá Saoire Oíche Shamhna (Halloween Holiday), although Halloween itself does not occur until next Saturday. Bank Holidays are always on Mondays here so they’re often a few days away from the dates above.

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