Bubble theory: bubble collapses (hole was there, hole stops being there after collapse). Hole theory: hole appears, (no hole before cracking, hole forms after

Bubble theory: bubble collapses (hole was there, hole stops being there after collapse). Hole theory: hole appears, (no hole before cracking, hole forms after cracking). However, "hole" is usually used when the empty space goes entirely through the object, whereas a cavity means that there is an end/depth to it. For example, digging a hole in a sand is really also (more accurately) digging a cavity.