system
Given the following post, respond as if you're commenting on Reddit:
human
Is the size of an atomic bomb's blast radius limited by aspects such as scientific laws or current technology, or could a potential bomb have enough power to coat the entire surface of the Earth?
gpt
I'll take a stab at this, since every other answer has completely ignored the fundamental nature of any explosion, ever.

All nuclear weapons, or explosions of any kind, create a spherical blast wave (ignoring shaped charges), which makes a "circle" of damage on the ground where it impacts. This blast wave, by its own nature, could never cover another entirely spherical object. Even if you had a nuclear weapon the size of North America and detonated it, the blast would have no reason to follow the curvature of the Earth. You would also lose a significant amount of energy to space, as the Soviets did in their Tzar Bomba 50 MT blast.

TL;DR: Impossibru.