At such a minute scale, everyday forces such as gravity are not the main obstacles to be overcome.

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His main characters include G, the strength of gravity, h, Planck's constant, which governs the quantum nature of reality at small scales, e, the charge of the electron, and c, the speed of light itself.

ECONOMIST: Modern physics

The gravity assist would allow a safe return to Earth even if the spacecraft's main rocket engine failed, Professor Longuski said.

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