# Challenges for Cosmic-ray Experiments

## TL;DR

This paper discusses the unresolved questions in cosmic-ray, gamma-ray, and neutrino research, emphasizing the challenges and open issues highlighted during the ISVHECRI 2016 conference.

## Contribution

It provides a synthesis of current challenges and unanswered questions in high-energy astrophysics based on recent conference discussions.

## Key findings

- Identifies key open questions in cosmic-ray sources.
- Highlights the complexity of particle relations in astrophysics.
- Emphasizes need for further experimental and theoretical work.

## Abstract

This paper is a commentary on presentations at ISVHECRI 2016 related to cosmic rays, gamma rays and neutrinos. Its goal is to highlight the unanswered questions raised during the conference about the sources of these cosmic particles and the relations among them.