What is preventing me from simply constructing a hash that's lower than the current target? I just started learning about Bitcoin, and something I can figure out is why miners have to use a random process (hashing a nonce) to get lower than the target. For example, if the target is

00000000000001ae00000000000000


why not just produce

000000000000000000000000000001


to become the winner? I have no practical experience mining, I'm guessing my ignorance lies in the requirements of how a hash is produced. If so, where can I find about those requirements? Thanks.



EDIT: For clarity, I mean this in the sense of what part of the technology requires me to use a hash function? Rather than in the sense of just constructing something that looks like a valid hash.
Hash functions are unpredictable.

You can't simply find an input to the hash function that produces such an output. The only way to accomplish that is by trying lots and lots of candidate blocks as input. If the target is 1000 times smaller, it requires 1000 times as many tries.