New horizons in cosmology with spectral distortions of the cosmic microwave background

Voyage 2050 White Paper highlighting the unique science opportunities using spectral distortions of cosmic microwave background (CMB). CMB probe many processes throughout history Universe. Precision spectroscopy, possible with existing technology, would provide key tests for expected within cosmological standard model and open an enormous discovery space to new physics. This offers scientific furthering our understanding inflation, recombination, reionization structure formation as well dark matter particle A dedicated experimental approach could this window early Universe in decades come, allowing us turn long-standing upper distortion limits obtained COBE/FIRAS some 25 years ago into clear detections signals.