Astronomy and cosmology at Birr Castle

Yesterday, I travelled to historic Birr Castle in the centre of Ireland in order to catch the end of the annual meeting of the Astronomical Science Group of Ireland. Birr Castle is a great setting for an astronomy meeting -  not only is it a beautiful castle with fantastic grounds, it is also an important landmark in the history of astronomy. The castle was the home of the famous Leviathan, a reflecting telescope that was the largest instrument of its kind in the world for many years. The telescope was built in the 1840s by Lord Parsons, the third Earl of Rosse, and featured  a 72-inch mirror, a marvel of engineering at the time.  He made many important discoveries with the instrument, not least the first observation of the spiral structure of some of the distant nebulae and the detection of stars within the nebulae. Indeed, the Earl was one of the first to propose that the nebulae were entire galaxies distinct from our own, a hypothesis that was not definitely established until Hubble’s measurements with the 100-inch Hooker telescope at Mt Wilson in California.

Birr Castle in Co.Offaly

The Leviathan telescope at Birr castle

There were a great many interesting talks over the two days of the meeting (see program here), but I was there to catch ‘The Search for Polarization Fluctuations in the Cosmic Microwave Background’ by Creidhe O’Sullivan of NUI Maynooth. Creidhe started with a basic overview of the cosmic microwave background (CMB), explaining its importance as evidence in support of the big bang model and describing the measurements of temperature fluctuations in the radiation by the COBE and WMAP satellites. (The CMB is the primordial radiation left over from the time that atoms first began to form. Cosmologists and astronomers spend a great deal of time studying the tiny temperature fluctuations imprinted in the CMB, as this gives information on the density and geometry of the early universe, see the Cosmology 101 section of this blog.)

Creidhe then moved on to explain the study of polarization in the background radiation. The CMB radiation is expected to be polarized because it comprises light that has been scattered by many particles; when light is scattered, it gets polarized into different planes of vibration. (Polaroid sunglasses operate on the same principle; they cut down on light by allowing only light polarised in one plane to pass through). Hence cosmologists search for fluctuations in polarization as well as temperature in the CMB, although the polarization fluctuations are much smaller. Mathematically speaking, the polarization is divided into two modes: electric (E –mode) and magnetic (B-mode) polarisation. E-modes have been detected since 2003; the analysis of these modes has become a major area of research in cosmology. Creidhe gave a superb overview of the instruments used to analyse the E- modes, including the work of her own group with the QuaD experiment at the South Pole.

The QUaD experiment at the South Pole

She finished the talk by explaining that the next big challenge in cosmology is the detection of B–mode polarization in the background radiation. B-modes present a great challenge as they are yet more difficult to detect. The great hope here is that the PlANCK satellite telescope, with its improved resolution. Just as the COBE satellite results were a watershed in our view of the early universe, the resolution of B-mode polarization in the CMB by PLANCK would give yet more support for the big bang model and cosmic inflation, and even offer evidence for the existence of gravity waves.

The Planck satellite telescope

That is not to say terrestrial experiments will not have their place. After Creidhe’s talk, another member of the Maynooth group, Stephen Scully, gave a brief overview of the team’s work on the QUBIC experiment. This is a new type of the bolometric interferometer that will be used in the next generation of terrestrial measurements at the South Pole.

All in all, a most informative afternoon. After the talks, we were shown the site in the castle grounds where a new radiotelescope is to be situated. This will form the Irish node of the international LOFAR astronomy project, bringing Birr castle up to date with modern astronomy – more on this in the next post.

The Royal College of Surgeons and the Institute of Physics

I attended a very enjoyable blacktie dinner at the posh Royal College of Surgeons in Dublin on Friday. The occasion was the annual meeting of the Institute of Physics in Ireland, the Irish branch of the umbrella group for physics in the UK in Ireland. I always enjoy these occasions, it’s a great way to catch up with colleagues from schools and colleges around the country. This year was no exception and the evening also featured a very enjoyable pre-dinner lecture by Nobel laureate Bill Phillips.

The Royal College of Surgeons on Stephen’s Green in Dublin

In previous years, the IoP meeting stretched over a weekend but we decided to try a single-day meeting this year. Events included an overview of current research in the different colleges, the Rosse poster competition for postgraduate students, and a ‘physicist in the chair’ interview with Bill Phillips. The meeting went on all day but I only caught the dinner and talk due to teaching commitments.

Bill’s lecture was very entertaining. Entitled ‘Time, Einstein and the coolest stuff in the universe’, he gave a simple overview of the hows and whys of laser cooling (the cooling of atoms to extremely low temperature in order to study them in slow motion). From a description of the Heisenberg Uncertainty Principle to Bose -Einstein condensates, the talk was clearly accessible to students yet worked well with a roomful of professionals. I have often noticed this before; people love being told what they already know (and we are all on the lookout for tips in science communication). My only complaint was that the lights were too bright during the during the lecture and too dim during the meal, wrong way round!

Cool atoms: a Bose-Einstein condensate

At dinner, my nearest neighbour turned out to be a climate skeptic. I was intrigued as one rarely encounters skeptics of the theory of man-made global warming amongst professional physicists nowadays. However, I didn’t hear any new arguments, merely a discussion of our ignorance of the role of cloud formation in weather. (A valid point, but hardly a reason to disregard the well-established correlation between greenhouse gas emissions and temperature rise). Indeed, my neighbour seemed unaware of the excellent research being done in this area by several physicists in his own department.

After dinner, a few of us retired to a nearby hotel bar to catch up on the latest in physics, not least, the breaking news of the resignation of the head of the OPERA neutrino experiment. All in all, an interesting night out for a nerdy physicist..