Hash Collision Probability

The hash space is atoms-in-the-universe range; this is a collision in a much, much smaller subset of that space

Yes, there's always a negligible chance of collision.

You'd have to be able to generate some pretty fantastically unique hash collisions!

It'd be great if it was something like a hash or uuid collision. Such things are super unlikely but not impossible.

You are not taking the entire hash, you are only taking the first 33 bits of the hash. Since there are only about 8.5 billion different values for the 33 bits and there are about 7 billion people, the odds are astronomically low that each of those 7 billion people will receive a different one of those 8.5 billion possibilities.This is the birthday paradox with instead of 365 days you have 2^33 possible answer values and instead of 23 people you have 7 billion people. I leave it as an exercise

The hash collision chance is extremely low.

Using the formula on wikipedia and checking random numbers it looks like the number required for 50% chance of collision is around 1200.https://www.wolframalpha.com/input?i=1-%28999999%2F1000000%2...https://en.wikipedi

No number of bits is large enough to _prevent_ collisions.

Hmm, how many bits of entropy are in one of these things? Can we calculate the likelihood of collision?

This number may be even lower if you take the birthday problem into account. I’m not a statistics guy to confirm that or to make proper calculations, but I believe it applies to this case as well, because first few bits of a hash are like what a birthday is to an otherwise unique person.https://en.wikipedia.org/wiki/Birthday_problem