The edge of locality: visualizing a black hole from the inside

TL;DR

This paper explores the visual perspective of an observer inside a Schwarzschild black hole's horizon, highlighting the effects of extreme gravity on perception and discussing the concept of locality at the edge of the observer's lightcone.

Contribution

It provides a detailed visualization of the inside-horizon view and introduces the concept of affine and perceptual distances in highly curved spacetime.

Findings

Observer's view is aberrated into a horizontal plane near the singularity.

Horizontal directions are highly blueshifted, others are redshifted.

Affine distance is a key measure, and trinocular perception could estimate it in curved spacetime.

Abstract

We illustrate and discuss the view seen by an observer inside the horizon of a Schwarzschild black hole. The view as the observer approaches the central singularity is of particular interest because, according to ideas arising from "observer complementarity," points in opposite directions along the observer's past lightcone are at "the edge of locality," where standard flat-space quantum-field-theory commutation rules may be at the brink of failure. Near the singularity, the observer's view is aberrated by the diverging tidal force into a horizontal plane. The view in the horizontal plane is highly blueshifted, but all directions other than horizontal appear highly redshifted. We argue that the affine distance provides a canonical measure of distance along a light ray from emitter to observer. Since the affine distance is not directly measurable by the observer, we also consider perceptual distances, and argue that the trinocular distance (binocular distance is inadequate) provides an estimate of affine distance that would allow tree-leaping apes to survive in highly curved spacetime.