Infall & Survival

Would you survive crossing the event horizon? Set your height and tidal acceleration tolerance, then slide the black hole mass. The answer depends entirely on the IMBH being massive enough.

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Observer
1.8 m
10 g

Human centrifuge limit ~8–12g (brief). "Survivable crossing" means tidal stretching force across your body at the horizon is below your tolerance.

Black Hole Mass
7,100 M☉
Calculating…
Schwarzschild Radius
Tidal accel at horizon
Proper time to singularity
Coordinate fall time

Critical Mass for survivable horizon crossing

At your current settings (h = 1.8 m, tolerance = 10 g = 98 m/s²), the minimum survivable black hole mass is:

Black Hole 101 Workflow → Scale Comparator

Tidal Force at the Horizon

The differential gravitational acceleration across a body of height h at distance r from a mass M: Δa = 2GMh / r³. At the Schwarzschild horizon r = r_s = 2GM/c², substituting: Δa = c⁶h / (4G²M²). This scales as M⁻², so more massive black holes have gentler tidal forces at their horizon.

Critical Mass for Survivability

Setting Δa ≤ a_tol and solving for M: M_crit = c³/(2G) × √(h/a_tol) in SI units. For h = 1.8 m and a_tol = 1g = 9.8 m/s²: M_crit ≈ 1380 M☉. For a_tol = 10g: M_crit ≈ 437 M☉.

Proper Time to Singularity

A radially infalling observer in Schwarzschild spacetime reaches the singularity in finite proper time (Misner, Thorne & Wheeler 1973, Box 31.2): τ = πGM/c³. Numerically: τ ≈ 1.545 × 10⁻⁵ × (M/M☉) seconds. For the ω Cen IMBH at 7100 M☉: τ ≈ 0.11 seconds.

Note on "coordinate time"

From the perspective of a distant observer, a falling object appears to freeze near the horizon (Schwarzschild coordinates diverge). The coordinate fall time shown is an estimate of when the signal from the infalling observer effectively ceases to reach external observers.

Tool version 1.0 · 2026-06-10 · Code: MIT · Prose: CC BY 4.0 · Part of the Black Hole 101 workflow.