At Earth's surface, you're already trapped in a deep energy well — every kilogram of your mass holds about –63 MJ of gravitational potential energy. To escape to infinity where GPE equals zero, you must add energy to climb out of the negative. Drag the slider to lift a 1 kg mass away from Earth and watch how GPE increases toward zero.
The universal formula E = –GMm/r works everywhere in a gravitational field, not just near Earth's surface. The negative sign is crucial: it means you're in an energy deficit relative to infinity. At infinity, r approaches ∞ and E approaches zero — that's the reference point. Closer to the mass, r is smaller, so E becomes more negative. To escape completely requires adding exactly |E| joules of energy to climb from your current negative value up to zero. This is why orbital mechanics uses negative energies: bound orbits have E < 0, and only objects with E ≥ 0 can escape.