Pencil Code (http://pencil-code.nordita.org/) is a modular MPI public code to efficiently solve coupled systems of partial differential equations in high-performance computing architectures using high-order finite-difference schemes. Started in 2001 by A. Brandenburg and W. Dobler, its core application initially focused on magnetohydrodynamics (MHD) for solar physics. Since then, it has been continuously under development by a total of 90 contributors covering a broad range of applications.
 
In particular, it has been used for studies of early universe physics including the evolution and formation of primordial magnetic fields and chiral MHD; the production of gravitational waves and propagation of gravitational waves in modified gravity, and inflation.
 
Due to the recent and undergoing developments in cosmology applications with Pencil Code and the growing interest by the research community, this CERN TH institute will consist of:

• The 1st Pencil Code school on early Universe physics and gravitational waves (Oct 20-24)
• The 21st Pencil Code user meeting 2025 (Oct 27-31)

1st Pencil Code school on early Universe physics and gravitational waves (Oct 20-24)

The Pencil Code school on early Universe physics and gravitational waves will take place on October 20-24 as part of a two-week CERN TH institute.

The school targets early-career and senior researchers that are interested in learning and developing numerical skills applied to early Universe physics using Pencil Code.

The lectures will cover numerical aspects:

• Introduction to Pencil Code
• Finite-difference schemes for partial differential equations
• Post-processing of data with IDL and Python
• GPU acceleration of Pencil Code

as well as applications to particular physics cases with hands-on exercises on:

• Magnetohydrodynamics of the early Universe
• Generation and evolution of primordial magnetic fields
• Chiral magnetohydrodynamics
• First-order phase transitions
• Gravitational wave production
• Axion inflation

Registration is open and will close on July 31st. The school is limited to a maximum of 30 participants.

Participants of the school are encouraged to also participate in the user meeting (Oct 27-31) and need to register separately.

Lecturers:

• Axel Brandenburg (Nordita)
• Philippe Bourdin (University of Graz)
• Simon Candelaresi (University of Augsburg)
• Deepen Garg (University of Bonn)
• Frederik Gent (Aalto University & Nordita)
• Matthias Rheinhardt (Aalto University)
• Alberto Roper Pol (University of Geneva)
• Isak Stomberg (IFIC, Valencia)

21st Pencil Code user meeting PCUM2025 (Oct 27-31)

The Pencil Code user meeting will take place on October 27-31 as part of a two-week CERN TH institute.

Registration for the Pencil Code user meeting is open and will close on September 28th.