# Cosmological Lightcone Reconstruction

Moving along a cosmological lightcone's line of sight also moves through cosmic time, so the lightcone can be read as a video of structure forming. ViViViT recasts reconstruction of the matter density field from 21 cm brightness-temperature lightcones as video-to-video translation, using attention factorized into transverse frames and radial evolution. On held-out 21cmFAST lightcones it keeps spectral power and phase alignment within a few percent of the ground truth and outperforms the tested 3D U-Net baseline across all measured statistics.

Moving along a cosmological lightcone's line of sight also moves through cosmic time, so the lightcone can be read as a video of structure forming. ViViViT recasts reconstruction of the matter density field from 21 cm brightness-temperature lightcones as video-to-video translation, using attention factorized into transverse frames and radial evolution. On held-out 21cmFAST lightcones it keeps spectral power and phase alignment within a few percent of the ground truth and outperforms the tested 3D U-Net baseline across all measured statistics.