user109458: If the target hash were artificially low, i.e. 3, how do miners know if there will ever be a nonce that produces such a hash?

user13866: 
If the target hash were artificially low, i.e. 3, how do miners know if there will ever be a nonce that produces such a hash?

They don't.
However if the difficulty were ever such that miners were unable to mine new blocks at the expected rate (1 every 10 minutes approximately), the difficulty algorithm would reduce the difficulty after a while (up to 2 weeks if I remember correctly)

109458: <p>If the target hash were artificially low, i.e. 3, how do miners know if there will ever be a nonce that produces such a hash?</p>
 13866: <blockquote>
<p>If the target hash were artificially low, i.e. 3, how do miners know if there will ever be a nonce that produces such a hash?</p>
</blockquote>
<p>They don't.</p>
<p>However if the difficulty were ever such that miners were unable to mine new blocks at the expected rate (1 every 10 minutes approximately), the difficulty algorithm would reduce the difficulty after a while (up to 2 weeks if I remember correctly)</p>
