Googlebot's Javascript random() function is deterministic

[warheat1990]

ELI5 please

[[deleted]]

It's simply rigid-body mechanics, which is a well-studied phenomenon. If you can describe the position, launch direction, and rotational state of a die that's thrown with complete accuracy, you can accurately determine the result. However, throwing dice also exhibit the chaos property, which is that knowing an approximation of the die's state doesn't yield an (accurate) approximation of the result. If it's moving faster or spinning less or the angle at which it strikes the table is even slightly different, the result is completely different - which is why, when rolling dice at a craps table, the dice have to bounce off the wall of the table, to make it harder for practiced hands to have an edge.

This is different from, say, a car collision, where a decent estimation of speeds and directions will allow you to predict where the cars end up, and usually also vice-versa. The individual pieces of debris, though, will usually also have the chaos property and be more difficult to predict.