Archive for the The Universe and Stuff Category

Solar Corona?

Posted in Bad Statistics, Covid-19, mathematics, The Universe and Stuff on December 8, 2021 by telescoper

A colleague pointed out to me yesterday that  evidence is emerging of a four-month periodicity in the number of Covid-19 cases worldwide:

The above graph shows a smoothed version of the data. The raw data also show a clear 7-day periodicity owing to the fact that reporting is reduced at weekends:

I’ll leave it as an exercise for the student to perform a Fourier-transform of the data to demonstrate these effects more convincingly.

Said colleague also pointed out this paper which has the title New indications of the 4-month oscillation in solar activity, atmospheric circulation and Earth’s rotation and the abstract:

The 4-month oscillation, detected earlier by the same authors in geophysical and solar data series, is now confirmed by the analysis of other observations. In the present results the 4-month oscillation is better emphasized than in previous results, and the analysis of the new series confirms that the solar activity contribution to the global atmospheric circulation and consequently to the Earth’s rotation is not negligeable. It is shown that in the effective atmospheric angular momentum and Earth’s rotation, its amplitude is slightly above the amplitude of the oscillation known as the Madden-Julian cycle.

I wonder if these could, by any chance, be related?

P.S. Before I get thrown into social media prison let me make it clear that I am not proposing this as a serious theory!

New Publication at the Open Journal of Astrophysics

Posted in Open Access, The Universe and Stuff with tags , , , , , , , on December 6, 2021 by telescoper

Time to announce yet another publication in the Open Journal of Astrophysics. This one is the 15th paper in Volume 4 (2021) and the 46th in all.

The latest publication is entitled  Interplanetary Dust as a Foreground for the LiteBIRD CMB Satellite Mission by Ken Ganga (Paris), Michele Maris (Trieste) and Mathieu Remazeilles (Santander) on behalf of the LiteBIRD collaboration. For information about the LiteBIRD mission see here.

Here is a screen grab of the overlay which includes the abstract:

You can find the paper on the Open Journal of Astrophysics site here and can also read it directly on the arXiv here.

Creating art from your thesis title

Posted in Art, The Universe and Stuff with tags , , on December 5, 2021 by telescoper

Looking for displacement activities to enable me to avoid working I noticed that people are having fun on social media by using AI apps to generate art from thesis titles. I thought I’d give it a go, and this is what I got for my thesis title Stochastic Fluctuations in the Early Universe:

Stochastic fluctuations in the early Universe

Actually, I rather like it! It’s much better than I’d expected. I’ve been told it looks like Christmas wrapping paper which gives it a seasonal twist too!

There are several apps that will create images inspired by text you type in. The one I used for the example above was this one. Why not try it yourself?

Top Ten JWST Facts!

Posted in The Universe and Stuff with tags , , on December 4, 2021 by telescoper

The James Webb Space Telescope looks nothing like the Hubble Space Telescope shown here.

As excitement mounts ahead of the launch of the James Webb Space Telescope (JWST) later this month I thought I would, as a service to the community, for the edification of the public at large, and despite popular demand, present my list of Top Ten JWST Facts.

  1. The JWST spacecraft will orbit the Sun near the Second Lagrange Point, L2, because it took so long to get built that tickets were no longer available for L1.
  2. JWST cost $10bn but its telescope is so sensitive that it can see back to redshifts greater than ten, meaning that it sees light that was emitted when its budget was less than $1 bn.
  3. To provide secure backup storage of the complete JWST data set, NASA has commandeered the world’s entire stock of 3½ inch floppy disks.
  4. As well as observing the Universe’s first galaxies and revealing the birth of stars and planets, JWST will look for signs that there might be intelligent life somewhere in the Universe.
  5. JWST’s unique 6.5m deployable mirror was  especially designed by experts from the IKEA company in Sweden who are famous for making items for ‘easy self-assembly’.
  6. The angular resolution of JWST is  0.1 arc seconds, which means  it could resolve a football at a distance of 550 km (or even further if it had Sky Sports).
  7. The Near-Infrared Spectrograph on JWST will be able to make simultaneous measurements of up to 100 sources while at the same time making a cup of coffee and washing the dishes.
  8. The BBC will be shortly be broadcasting a new 26-part TV series about JWST. Entitled WOW! JWST! That’s Soo Amaazing… it will be presented by Britain’s leading expert on infra-red astronomy, Professor Brian Cox.
  9. Er…
  10. That’s it.

R.I.P. Jon Davies

Posted in Biographical, Cardiff, The Universe and Stuff on December 1, 2021 by telescoper

Once again I find myself having to pass on some bad news. I was shocked and saddened last night to hear of the death of former colleague at Cardiff University, astronomer Prof. Jonathan Davies (shown left).  I understand he had been ill for some time, but had preferred to keep his illness private.

Jon followed an interesting route into astronomy. He left school at 16 to become an apprentice car mechanic and did a few other jobs before deciding to study for a degree in Physics at the University of Bristol in 1986, following that up with a PhD at Cardiff University where he spent the rest of his academic career teaching and doing research in extragalactic astronomy.

Jon’s main research interests involved low surface brightness galaxies and cosmic dust which he studied using observations at a range of wavelengths, using radio and infra-red as well as optical facilities.

Jon was always helpful and supportive to other staff in the School of Physics & Astronomy, especially new arrivals. For example, when I was arrived in Cardiff in 2007 I inherited a part of a module from Jon (the “Nuclear” part of “Nuclear and Particle Physics”) and he was very helpful in getting me started on it. I remember also having interesting discussions with him about the physics of the hyperfine transition in atomic hydrogen which produces the 21cm much exploited by astronomers but for some reason not covered in much detail by many quantum mechanics texts.

Jon Davies was a fine colleague and an excellent astronomer who will be greatly missed in Cardiff and beyond. I send my heartfelt condolences to his wife Anne and their family on their loss.

 

On Fourier Series

Posted in mathematics, Maynooth, The Universe and Stuff with tags , , , , , , on November 30, 2021 by telescoper

So here we are, in the antepenultimate week of the Autumn Semester, and once again I find myself limbering up for the “and” bit of my second-year module on Vector Calculus and Fourier Series, i.e. Fourier Series.

As I have observed periodically, I don’t like to present the two topics mentioned in the title of this module as completely disconnected, so I linked them in a lecture in which I used the divergence theorem of vector calculus to derive the heat equation, the solution of which led Joseph Fourier to devise his series in Mémoire sur la propagation de la chaleur dans les corps solides (1807), a truly remarkable work for its time that inspired so many subsequent developments.

 

Anyway I was looking for nice demonstrations of Fourier series to help my class get to grips with them when I remembered this little video recommended to me some time ago by esteemed Professor George Ellis. It’s a nice illustration of the principles of Fourier series, by which any periodic function can be decomposed into a series of sine and cosine functions.

This reminds me of a point I’ve made a few times in popular talks about astronomy. It’s a common view that Kepler’s laws of planetary motion according to which which the planets move in elliptical motion around the Sun, is a completely different formulation from the previous Ptolemaic system which involved epicycles and deferents and which is generally held to have been much more complicated.

The video demonstrates however that epicycles and deferents can be viewed as the elements used in the construction of a Fourier series. Since elliptical orbits are periodic, it is perfectly valid to present them in the form a Fourier series. Therefore, in a sense, there’s nothing so very wrong with epicycles. I admit, however, that a closed-form expression for such an orbit is considerably more compact and elegant than a Fourier representation, and also encapsulates a deeper level of physical understanding.

Great News for Astrophysics & Cosmology at Maynooth!

Posted in Education, Maynooth, Science Politics, The Universe and Stuff with tags , , , on November 29, 2021 by telescoper

I couldn’t resist a quick post in reaction to the announcement by the Irish Government of ten new senior professorial positions under the Strategic Academic Leadership Initiative (SALI). I blogged about this scheme here. Among the positions just announced is a new Chair in Observational Astrophysics or Cosmology at Maynooth University. You can find Maynooth University’s official response to the announcement here.

The pandemic has played havoc with my sense of the passage of time so I had to check my documents folder to see when we completed the application. It turns out to have been January this year; the deadline was 29th January 2021. It has taken much longer than expected to for the outcome of this, the second, round to emerge but I suppose it’s better late than never!

The key rationale for these SALI positions is clear from the statement from Simon Harris, the Minister responsible for Third Level education in Ireland:

“Championing equality and diversity is one of the key goals of my department. The Senior Academic Leadership Initiative (SALI) is an important initiative aimed at advancing gender equality and the representation of women at the highest levels in our higher education institutions.

We have a particular problem with gender balance among the staff in Physics in Maynooth, especially un Theoretical Physics where all the permanent staff are male, and the lack of role models has a clear effect on our ability to encourage more female students to study with us.

The wider strategic case for this Chair revolves around broader developments in the area of astrophysics and cosmology at Maynooth. Currently there are two groups active in research in these areas, one in the Department of Experimental Physics (which is largely focussed on astronomical instrumentation) and the other, in the Department of Theoretical Physics, which is theoretical and computational. We want to promote closer collaboration between these research strands. The idea with the new position is that the holder will nucleate and lead a new research programme in the area between these existing groups as well as getting involved in outreach and public engagement.

The next step will be to launch a recruitment campaign, and more details will be available when the position is formally advertised. Let me just say for now that we intend the position to appeal not only to people who have their own observational programmes (e.g. using facilities provided by ESO, which Ireland recently joined) but also working on data from space missions, multi-messenger astrophysics, gravitational waves, and so on.

A Pembrokeshire Dangler

Posted in Biographical, Maynooth, The Universe and Stuff on November 28, 2021 by telescoper

I checked the weather app on my phone last night and noticed the unmistakable cloud formation over the Irish Sea known as a Pembrokshire Dangler:

The Dangler is the strip of rain  over the Irish Sea extending North from the Pembrokeshire coast in Wales. I knew I had mentioned this phenomenon before on this blog and when I check it turns out to have been almost exactly four years ago. That’s not very surprising as winter is definitely the season for dangling. There has been a northerly airflow over Ireland for a few days now, which is why it has been so cold here, though in relatively sheltered Maynooth we have been spared the worst of the effects of Storm Arwen.

The situation required for the formation of a Pembrokeshire Dangler (which quite often involves snow rather than rain) is a cold northerly airflow down into the Irish Sea from the Arctic. This combines with slightly warmer air in the form of land breezes from the Irish coast to the North West and the Scottish coast to the North East, funneling the airflow into a narrow channel over the Irish Sea in which convection cells form, leading to precipitation. The configuration is quite stable as long as the dominant northerly airflow continues so although the strip of cloud tends to persist for some time once it has formed.

A Free Online Course in Cosmology from SISSA

Posted in Education, The Universe and Stuff with tags , , , , on November 25, 2021 by telescoper

The nice people at the Scuola Internazionale Superiore di Studi Avanzati (known to its friends as SISSA for short) have made available a free online course in cosmology. You can get all of it on Youtube.

The course comprises 16 professionally edited video-lectures delivered by lecturers of the SISSA Astrophysical and Cosmology and Astroparticle PhD Programs and some of their collaborators. I know some of the participants personally, including Paulo Salucci (who introduces the course though I haven’t met him in person for ages so it was nice to see him on camera.

Cosmology is a big subject, of course, and a short-ish course can’t cover everything so there is an emphasis on the research topics covered by SISSA scientists. I haven’t watched all the videos but those I have seen are pretty good. There are actually 17 videos in the playlist below but that includes a very short prelude to introduce the series. The others are between about 25 and 45 minutes in length so you probably don’t want to watch them all in one sitting!

Clusters and Superclusters of Galaxies 1991

Posted in Biographical, The Universe and Stuff with tags , , on November 23, 2021 by telescoper

As part of an occasional series of blasts from the past down memory lane of days gone by I present this, which was taken in Cambridge in July 1991 – 30 years ago!!! – at the NATO ASI Clusters and Superclusters of Galaxies:

Picture Credit: Alberto Fernandez Soto

There are no prices for putting names to faces because the names are all along the bottom but it’s still fun to try doing it without looking at the answers!