PREM SEISMIC EARTH · ETOPO 2022 · 881 WORLD CITIES & 3,181 ROMANIAN LOCALITIES
Falling through Earth takes 38 minutes, not 42
Textbooks claim every gravity tunnel through Earth takes 42 minutes because they treat the planet as a uniform sphere. On the real seismic Earth, a dense iron core lifts gravity to 10.69 m/s² at 2,891 km depth, cutting a pole-to-pole fall to 38m 11s—and leaving a straight Bucharest–London chord behind at 42m 04s.
01 · SEISMIC PROFILE
Why the textbook 42-minute formula fails inside a real iron-core planet
The textbook calculation assumes Earth has a constant density of 5.51 g/cm³, making gravity fall linearly to zero and producing an identical 42m 12s harmonic oscillation for every straight chord. In reality, seismology (the Preliminary Reference Earth Model, Dziewonski & Anderson 1981) shows density leaping from 5.57 to 9.90 g/cm³ at the core–mantle boundary (2,891 km deep) and reaching 13.09 g/cm³ at the centre. Gravity does not drop as you descend—it climbs to a planetary peak of 10.69 m/s² before plunging through the core, pulling a capsule past 9.92 km/s (35,708 km/h) and finishing a diameter in 38m 11s.
02 · OPTIMAL CURVE
Curving down first makes Bucharest–London faster than flying: 18m 26s
Along a straight tunnel from Bucharest to London (2,091 km apart), most of Earth’s gravitational pull acts perpendicular to the rails rather than pushing forward, so the journey crawls to 42m 04s—nearly four minutes slower than falling straight through the planet’s centre. Bending the track along the exact Euler–Lagrange gravity brachistochrone plunges the capsule ~690 km into the upper mantle early on, reaching London in 18m 26s and New York in 28m 02s without engines. Click anywhere on the chart to inspect any angular span.
03 · EARTH’S SPIN
Why you cannot drop without rails: 213.2 km Coriolis miss from Bucharest, 185.8 km from London
Nothing on Earth starts from rest. At Bucharest (44.43° N), Earth carries you eastward at 331.7 m/s; at London (51.51° N), at 289.2 m/s. As you drop toward the core, that angular momentum is conserved: after only 32.5 s in London (or 31.0 s in Bucharest), the eastern wall of a 10 m shaft slices into your path. Even inside a hollow frictionless planet without walls, you would swing past the centre by 185.8 km (London) or 213.2 km (Bucharest)—meaning frictionless guide rails have to absorb Coriolis accelerations everywhere outside the poles.
—
04 · ETOPO 2022 ANTIPODES
Only 4.00% of Earth has land at both ends—and zero towns in Romania do
Integrating all 233 million 1-arcminute cells of NOAA’s ETOPO 2022 relief grid shows that 50.17% of Earth pairs land with ocean, 45.83% pairs ocean with ocean, and just 4.00% of the globe (13.76% of all dry land) reaches dry land on the opposite side—mainly Spain↔New Zealand (Madrid, 625 m ↔ rural New Zealand, +234 m) and eastern China↔Argentina. In the United Kingdom, London’s antipode drops to −4,767 m under the Southern Ocean, just 212.3 km from the uninhabited Antipodes Islands. Meanwhile, every single municipality and commune in Romania—all 3,181 local authorities (19,053,815 residents)—exits underwater in the South Pacific, at a mean depth of −4,742 m.
Blue points mark −4,000 to −4,900 m Pacific depths; amber points mark abyssal plains below −4,900 m (deepest: Bucharest at −5,388 m; shallowest: Obreja seamount at −658 m).
05 · COMPLETE DATA & LIMITS
Browse all 881 global cities & 3,181 Romanian localities
| Place | Pop. | Antipode | Elev./Depth | Status | Nearest land | Coriolis miss |
|---|
- Interior Earth gravity: numerical integration (Δr = 100 m) of the 11 polynomial density layers of Dziewonski & Anderson (1981), Preliminary Reference Earth Model (PREM); equatorial radius R = 6,371 km, G = 6.6743×10⁻¹¹ m³ kg⁻¹ s⁻².
- Elevation & ocean depth: NOAA NCEI ETOPO 2022 Global Relief Model at 60 arc-seconds (233.28 million grid cells), paired cell-by-cell at exact antipodes (−φ, λ ± 180°) with cos(φ) spherical area weighting.
- Romanian localities & global cities: INS / ANCPI SIRUTA 2026 & UAT polygons 2025, Romanian 2021 Census (19,053,815 population across 3,181 UATs), GeoNames seat coordinates and cities15000, plus Natural Earth 1:10m boundaries.
- Physical limits: all travel times assume an evacuated, frictionless tunnel in a spherical non-oblate PREM planet. An unlined shaft in Earth’s real outer/inner core faces 364.1 GPa (~3.6 million atmospheres) and ~5,000–6,000 K; Earth’s deepest actual borehole (Kola, 12.26 km) stopped at 0.19% of Earth’s radius.