The cosmic horizon marks the boundary beyond which light hasn’t had time to reach us. It’s roughly 46 billion light-years away. The universe could extend infinitely beyond this horizon. Observations of the horizon inform cosmic geometry and expansion. Studying it helps refine models of dark energy and inflation. It highlights how our view of the universe is fundamentally limited.
It matters because it defines the observable universe and its limits.
It also informs theoretical models about what might exist beyond our detection.
The universe’s observable edge is 46 billion light-years away.
National Aeronautics and Space Administration [nasa.gov]