Limited number of bitcoin addresses

[cohnhead]

that 2^160 possible addresses is too big to fathom...but I kind of can get my head around the fact that we basically will never run out of addresses, but being truly random....it is possible for addresses to collide...although infinitesimal, yes?
and I guess the probability of that address either holding any or any significant amount of btc is even more infinitesimal?
but those possibilities exist?

[1715375482]

1715375482

[1715375482]

1715375482

[virtualx]

The number of base pairs in a human genome is about 3 billion base pairs.  (10^12)
The bitcoin address search space is 2^160  (10^48)

Think about the scale of that. You are not able to count to 10^48 in your lifetime, let alone generate all bitcoin addresses.
At the time when all bitcoin addresses are collected, we are long dead.

[skierchewing]

it'll take millions of years to have address collisions, so many possibilities

[zetaray]

The address space is unimaginably large, address collision is extremely unlikely. I understand that ever since I first know about bitcoin. But there is still a worrying thought in my mind that this is possible and there is no protection to my coins when that happens. I have got used to using bitcoin without this insecurity because I think if a collision happened, mine won't be the first to collide. 

[enthus]

You must be joking.  I hope you are joking.  This is a joke, right?

must be joking, i hope he is joking.... but sadly i do not think he is joking  

[cohnhead]

The address space is unimaginably large, address collision is extremely unlikely. I understand that ever since I first know about bitcoin. But there is still a worrying thought in my mind that this is possible and there is no protection to my coins when that happens. I have got used to using bitcoin without this insecurity because I think if a collision happened, mine won't be the first to collide. 

i guess it is just another reason (although low on the list) for spreading out your bitcoins across multiple addresses.

[DannyHamilton]

10^77 possible bitcoin addresses, 10^80 atoms in the universe. So there are only 1000 times as many atoms in the universe as possible bitcoin addresses.

Nope.

Currently only 10⁴⁸ possible bitcoin addresses. So there are 10³² times as many atoms in the universe as possible bitcoin addresses.

It's possible that additional bitcoin address types may be introduced in the future, but its impossible to predict just how many potential bitcoin addresses those future versions may enable.

[DannyHamilton]

I thought there were as many possible addresses as possible private keys, is this not so?

Nope. Not so.

Bitcoin addresses are calculated with a RIPEMD160 hash.  That's a 160 bit value.  Therefore, there are only 2¹⁶⁰ possible bitcoin addresses.

(Actually there are both P2PKH, starting with a "1", and P2SH addresses, starting with a "3", so that doubles the number of potential addresses to 2¹⁶¹)

That would make 2^256 or roughly 10^77 possible addresses.

2¹⁶¹ is approximately

2.9 X 10⁴⁸ possible addresses.

[BurtW]

I also learn something new every time I visit these forums.

For example, this interesting thread:  https://bitcointalk.org/index.php?topic=1166928.msg13097839#msg13097839