Archive for February 4, 2020

Beethoven from Brexit Day

Posted in Music with tags , , on February 4, 2020 by telescoper

I may not have been able to attend the concert at the National Concert Hall in Dublin on Friday 31st January, but I did listen to it live on the Radio. Now you can experience the whole thing yourself via the Youtube recording of the live stream. The programme consisted of three pieces by Ludwig van Beethoven played by the RTÉ National Symphony Orchestra under the direction of Leonard Slatkin:

  • The Consecration of the House Overture
  • Violin Concerto (soloist Stefan Jackiw)
  • Symphony No. 7

I very much enjoyed listening to the concert, especially the up-tempo finale of the Seventh Symphony. I gather there was a problem with the live stream that meant the sound wasn’t broadcast along with the pictures, but they’ve fixed it on the recording so now you can experience both sight and sound from the NCH:

 

 

Voids, Galaxies and Cosmic Acceleration

Posted in The Universe and Stuff with tags , , , , , , on February 4, 2020 by telescoper

Time for a quick plug for a paper by Nadathur et al. that appeared on the arXiv recently with the title Testing low-redshift cosmic acceleration with large-scale structure. Here is the abstract:

You can make it bigger by clicking on the image. You can download a PDF of the entire paper here.

The particularly interesting thing about this result is that it gives strong evidence for models with a cosmological constant (or perhaps some other form of dark energy), in a manner that is independent of the other main cosmological constraints (i.e. the Cosmic Microwave Background or Type 1a Supernovae). This constraint is based on combining properties of void regions (underdensities) with Baryon Acoustic Oscillations (BAOs) to produce constraints that are stronger than those obtained using BAOs on their own. The data used derives largely from the BOSS survey.

As well as this there’s another intriguing result, or rather two results. First is that the the BAO+voids data from redshifts z<2 gives H0 = 72.3 ± 1.9, while, on the other hand adding, BAO information from the Lyman-alpha forest for from z>2 gives a value H0 = 69 \pm 1.2, favouring Planck over Riess. Once again, the `tension’ over the value of the Hubble constant appears to be related to using nearby rather than distant sources.