Lorentz Center - New Challenges for Early Universe Cosmologists from 5 Aug 2013 through 9 Aug 2013
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    New Challenges for Early Universe Cosmologists
    from 5 Aug 2013 through 9 Aug 2013


The aim of the workshop was to bring together a group of scientist that work in the field of theoretical and observational cosmology, and discuss the status of cosmology after Planck. Theoretically, it is important to obtain a complete understanding of the various predictions that different models of the early Universe make, e.g. how unique is a set of predictions made by any single model. Hence, our goal was to gain a clear picture of model space and to what extend model space had been reduced by Planck. In addition, we hoped to discuss the future of precision cosmology. On the theoretical side, this includes the measure problem, the importance of the landscape and effective description of the early Universe as well as the large scale structure. From the observational side, we wanted to fully probe the potential of existing data, as well as discuss the probes of the future, including future Microwave Background (CMB) experiments as well as measures of large scale structure (LSS). We also aimed to devote time to discuss alternative measures and discuss the impact of large collaborative efforts in future experiments.


We organized the format of the workshop to maximize output, allowing to answer the questions outlined above. Here is a short summary of the main outcomes, which are mostly driven by the discussion sessions:

-       Planck analysis probably needs to be improved, which could bring it closer to previous results and relax some tension with other experiments. A completely blind analysis is very challenging for most CMB and LSS, but some steps in that direction can be made.

-       There are still several analyses that can be done with current data, including galaxy bispectrum, various CMB trispectra, cross correlations among e.g. CMB, CMB lensing, weak lensing, quasars and lyman α.

-       There is important theoretical work that is needed to interpret observations right now, including analytical tools for LSS with particular emphasis on the Effective Field Theory approach, a theoretically motivate parameterization of models of modified gravity, chart the landscape of predictions from multifield inflation and systematically derive second order effects in cosmological perturbation theory.

-       There is a need to establish what we want to test and how. This has specific implications for inflation, the landscape, anthropic reasoning and practical issues, such as funding.


The format of the workhop proved excellent for discussion. We reserved plenty of time for discussion, which were the most productive and insightful of all events. We produced a short report of the workshop discussions, which we shared with all participants through the Lorentz Center website. We also like to stress that the format did encourage everyone to participate. The group size of the group was ideal for lively but effective discussions.


Overall, the organization was pretty good and we have always had the feeling we could immediately and effectively discuss problems and/or issues with one of the Lorentz Center staff members. Practical things that could be improved include:


-       It would be way more efficient if organizers could edit things like the website, the schedule and the list of participants without passing through the workshop coordinator. Many changes for example to the schedule need to be done quickly, sometimes from one evening to the next morning and of course there is not enough time for the information to travel all the way through the workshop coordinator. Also this is quite inefficient since it takes much longer to explain what need to be changed, for example in the participant list, than to just change it. There are many effective and typically free options to choose from for sharing files (e.g. google docs, just to mention one).

-       We did not feel completely satisfied with the process that lead to the poster. We had to go through intermediaries rather than discussing directly with the graphic designer. The final edits to the poster from the graphic designer were minimal and did not really improve the outcome.