From January 14-17, Oslo’s famous Holmenkollen played a fitting backdrop to the remarkable Beyond LCDM conference, an assembly of cosmologists from all over the world, working within and without the so-called standard model.
For those of us who have learned to refer to LCDM as the “standard model” of cosmology, it gave an insight into the range of alternatives out there, while those in the community hoping to slay the LCDM dragon were reminded that, outrageous and ugly as it may seem, LCDM continues to be notoriously tough to beat with observational evidence.
With a four hour lunch break and daily discussion groups, this conference truly deserved to be called a “workshop”. Rather than a never-ending series of presentations, the number of talks was limited in favour of opportunities for interactions and discussions. I got to share a working group on the small scale challenges to LCDM together with Matteo Viel and Marcel Pawloski – and while there was disagreement on the most likely solutions to the Local Group’s puzzles, it reminded me of the fact that these problems are still considered serious by many in the field, and certainly worthy of investigating.
Indeed, while much attention (and money) for stress-testing LCDM is focused on future large-scale experiments such as Euclid, the fate of the CDM part of our current model may well depend on the scales testable within our own Local Group. In his talk, Marcel showed some plots on satellite alignments within the Local Group, which taken at face value would be hard to dismiss – clearly, if all of the properties of the Local Group satellites are ubiquitous in other galaxies, LCDM is in trouble. While our own simulations (and others) indicate that satellite systems like those of the Milky Way are perfectly consistent within LCDM, the question then becomes which properties of the Local Group are rare features, and which are truly universal. As Roy Maartens reminded us in his talk, the Copernican condition that the Universe should be homogeneous and isotropic on large scales is by no means trivial – and we may already know enough about the Local Group that it should come as no surprise if some of its features turn out to be quite rare.
Perhaps the fact that my work, describing how baryons solve many of the Local Group’s puzzles, won the “best poster” prize, shows that even an audience of LCDM skeptics agrees that more work is needed in making the connection between theory and observations by studying galaxy formation – although there is a distinct possibility that they were just dazzled by the augmented reality aspects, made possible by Jascha Schewtschenko’s free DARO software.
Beyond the science (of which there was a lot) and the prize, the Holmenkollen had a lot more to offer. While we decided against staying at the (admittedly fabulous) conference hotel in favour of a cheaper B&B in town, we still got to enjoy the fantastic surroundings during the generous lunch breaks, which not only left time for discussions, but also quite a few runs up and down the Holmenkollen. Being a vegetarian in Norway turned out to be even easier than running on the snow and ice, and both are no doubt a lot less challenging (but just as enjoyable) as trying to get to the bottom of LCDM. I’m already looking forward to Beyond LCDM².