This has been discussed so many times already...
There are currently 329,993 addresses in the Bitcoin network. Say that this number of addresses are created every day for the next 140 years. That's 16,862,642,300 addresses.
The chance that at least two of those addresses collided is about 9.7x10
-29, using the formula
here.
Calculation.If every person on Earth makes ten addresses per second for 20 years (2x1018 total addresses), then the probability that two of these addresses collide is about 1.57x10-12.
UUIDs have 2
128 possible identifiers. They are also designed to be collision-proof. Wikipedia
says:
To put these numbers into perspective, one's annual risk of being hit by a meteorite is estimated to be one chance in 17 billion, that means the probability is about 0.00000000006 (6 × 10−11), equivalent to the odds of creating a few tens of trillions of UUIDs in a year and having one duplicate. In other words, only after generating 1 billion UUIDs every second for the next 100 years, the probability of creating just one duplicate would be about 50%. The probability of one duplicate would be about 50% if every person on earth owns 600 million UUIDs.
Compare this to Bitcoin's 2
160 possible addresses. Bitcoin has:
1461501637330902918203684832716283019655932542976 addresses
UUIDs have:
340282366920938463463374607431768211456 identifiers
And...
Bitcoin already supports OP_HASH256 in script, so it would be trivial to increase the number of addresses if it ever became a problem.
addresses, each address, on average, would have 0.0000000000105 BTC, less than a satoshi, in it.