0
I've heard anecdotally that the ability to find nonces is much harder than it once was. This implied that there was a fixed number of nonces in the Bitcoin system, and a large number of them have been found.
My question is: Is there a way to estimate the number of unfound nonces?
1
Nonces are not 'found' or 'unfound'. A nonce is simply a little bit of data in the block header which can be changed by the miner to change the resulting hash of the block header (this is how mining works, they try lots of nonce values for their block to find one which has a hash less than some target). But because the difficulty of mining bitcoin is now so high, because there are so many powerful miners, the small nonce field can not be changed enough to find blocks any more, so miners have to change other data in the block too such as data in the coinbase transaction, or the timestamp. I believe that's what you heard.
Is the difficulty high because of the powerful miners? (Your sentence has a couple of 'because's' in it. – hawkeye – 2017-09-19T11:40:09.000
Yes, the difficulty keeps adjusting to ensure that blocks are found on average once every 10 minutes. So more powerful miners = harder difficulty to keep that time toughly constant – MeshCollider – 2017-09-19T11:41:13.293
3
This question is based on a false premise. Mining doesn't work like that - it isn't a matter of finding nonces in a finite pool that eventually gets used up. See https://bitcoin.stackexchange.com/a/1291/5757 for a better explanation, and other questions tagged [tag:mining-theory].
– Nate Eldredge – 2017-09-18T13:35:04.287