Computing the Universe: At the Intersection of Computer Science and Cosmology (16w5163)

Arriving in Oaxaca, Mexico Sunday, June 5 and departing Friday June 10, 2016

Organizers

(Institute for Theoretical Physics, University of Zurich)

(University of Victoria)

James Wadsley (McMaster University)

Fabrice Durier (University of Arizona)

(University of Toronto)

(University of Washington)

Andrew Benson (Carnegie Institution for Science)

Objectives

WORKSHOP OBJECTIVES

Some of the key issues that the workshop will address include:

How do the current simulations stack up against each other and against the mirror of reality? What are the main deficits and how can these be overcome?

What is the minimum set of physical processes that cosmological simulations must incorporate? How does one decide which of the large number of known processes can be safely neglected? How does one gauge the sensitivity of the end product to such decisions?

What is the best way to treat sub-grid processes? Do the aforementioned algorithmic, coding and technological development make it possible to implement more physical, more realistic prescriptions (or for that matter, do away with the prescriptions altogether in some cases)? Is it possible to design prescriptions that can adapt as the simulation resolution is increased or decreased, even if only over a finite range?

In order to answer this set of questions, the proposed workshop will bring together established experts as well as young, innovative computational astrophysicists, and collaborating computer scientists who work on theory and numerical modeling of physical processes operating across the full hierarchy of scales, from the very smallest to the very largest. Members of the different sub-communities rarely have an opportunity to interact closely and exchange insights even though it is becoming increasingly clear that processes on any one scale exert a strong influence on outcomes over broad range of scale.

Our specific objectives are to bring together experts on processes such as the birth and (explosive) deaths of stars, astrophysical turbulence (hydro and MHD), the physics of gas flows onto black holes, galaxy formation, etc. to :

- Pin down the most crucial physical processes at different scales within the cosmic hierarchy.

- For key processes on any one scale, the degree to which they are influenced by processes on larger and smaller scales, and the degree to which they are likely to impact processes on other scales.

- Identify novel ways, both in terms of innovative numerical techniques and more realistic physical modeling, of capturing within a numerical simulation the influence of key processes arising on scales outside the dynamic range of the simulation.

PROPOSED WORKSHOP FORMAT

Building on the collective experiences of the team proposing this workshop, which includes organizing the Victoria Computational Cosmology Conference in 2000, BIRS “hot topics” workshop in 2003, a Lorentz Center workshop in 2010 and 2011, our overarching aim is to leverage the unique features of BIRS to create enhanced opportunities for constructive dialogues, vigorous discussions and non-hostile confrontations and productive interactions that results in an agreement on what constitutes an acceptable cosmological simulation code as well as new collaborations and new synergy between different groups of researchers.

We will achieve this, first and foremost, by restricting the number of participants to no more than 35. We have learnt from prior experience that a compact group is much more willing to engage in an honest discussion of the strengths and weaknesses of various approaches. Larger conferences tend to encourage “strutting”, which we wish to avoid at all costs. The 35 participants will include a core of a highly dynamic contingent of senior researchers as well as a sizeable contingent of postdoctoral fellows and senior graduate students. In identifying our participants, we will target two or three individuals from each of the main research groups as well as individuals known to collaborate across the groups.

Additionally, we will seek to strike a balance between a limited number of “review” talks, a series of “stop the press” presentations focusing on new results, structured discussion time, and blocks of unstructured discussion/interaction time. We see the latter as opportunities for (a) collaborators to review their recent results prior to presentation; (b) competitors to compare results and thresh out points of contention; and (c) discussions that will result to new collaborations.

The above formula may come across as an experiment in social engineering but we have tried it out on at least two previous occasions with remarkable success. For example, both the 2010 and 2011 Lorentz Center workshops were organized according to this blueprint and in a follow-up survey by the Center, the participants hailed the workshop as one of the most successful and engaging that they had ever attended.