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Can someone explain how old Bitcoin works post-fork? Can you sell the same old Bitcoin twice now? Is this already priced in somehow and still going up?

JoshTriplett 9y ago
Bitcoin works the same as it always did. However, anyone who had N Bitcoin on a particular time on August 1 also has N "Bitcoin Cash" using the same private keys, and can go spend that separately on the forked blockchain, without in any way affecting their existing Bitcoin. Both have their own price and market, and they don't interconvert beyond that one-time thing except by selling/buying/trading between them.
- mirimir 9y ago
  Right, but you can get yourself a BCH wallet, and import the keys from your existing BTC wallet. Then convert BCH to BTC, if you like. Using shapeshift.io perhaps, which requires no account.
  - icebraining 9y ago
    Just to make it clear to others, "convert" here means sell BCH in exchange for BTC. It's not some sort of mathematical operation.
  - kingmanaz 9y ago
    I'm having trouble wrapping my head around this. Once you use your private key to complete a transaction on the BCH blockchain, won't that reveal the private key publicly and allow others to spend the corresponding unspent bitcoin on the BTC blockchain? Sorry if I'm overlooking something obvious, but it was my understanding that once someone used their private key it should never be used again...
    - mirimir 9y ago
      Not at all. You never reveal private keys when transacting. You will reveal addresses, however. The only BTC addresses that have BCH value are those that existed at the fork. So before using them in the BCH blockchain, it would be prudent to first spend them in the BTC blockchain. Doing this is a double spend in some sense, but they happen in different blockchains, so they don't affect each other.
- wfunction 9y ago
  Thanks! Isn't this something a currency should fundamentally prevent? I don't know of any real-world currency that can be used twice.
  - markburns 9y ago
    It's not being used twice though on any individual fork. Plus the value would have to split for any fork.
  - icebraining 9y ago
    It's more like if someone created a new currency and gave each owner of an existing currency (say, the dollar) an equivalent nominal amount of the new notes.
  - AgentME 9y ago
    Bitcoin Cash is a separate project and currency from Bitcoin. You can't pay someone who is expecting Bitcoin by sending Bitcoin Cash to them or vice-versa. Bitcoin's code is open source and the balances of all addresses are public, so anyone could create a fork (a new separate currency based on it, optionally starting with the same balances).
    - wfunction 9y ago
      Right, but presumably a reasonably large merchant would find that they need to accept both though, right? And now you would have more purchasing power with them which feels a bit weird, since the old Bitcoin and the new Bitcoin would not have the same purchasing power...
      - MichaelGG 9y ago
        Maybe, maybe not. Bitcoin might have been 200$ higher without the fork. Merchants find they need to accept any popular currency their users demand. Being forked from the Bitcoin chain is beside the point.
        9y ago
markburns 9y ago
Yes you can - bitcoin held prior to the fork is valid on both chains. And yes it is still going up. An alternative scaling solution (to the big blocks proposed by the 'new' fork) Segwit will be going ahead - aiding the scalability of 'old' Bitcoin fork, which may explain some/all of the price rise. Along with the uncertainty reduction post fork. 'New' and 'old' here are somewhat arbitrary/controversial ways of thinking of the fork. Proponents of Bitcoin cash might argue having no limit was closer to Satoshi's original intention - the block limit was originally added in as a temporary measure. Lots of politics going on around that.

JoshTriplett 9y ago

Bitcoin works the same as it always did. However, anyone who had N Bitcoin on a particular time on August 1 also has N "Bitcoin Cash" using the same private keys, and can go spend that separately on the forked blockchain, without in any way affecting their existing Bitcoin. Both have their own price and market, and they don't interconvert beyond that one-time thing except by selling/buying/trading between them.

mirimir 9y ago
Right, but you can get yourself a BCH wallet, and import the keys from your existing BTC wallet. Then convert BCH to BTC, if you like. Using shapeshift.io perhaps, which requires no account.
- icebraining 9y ago
  Just to make it clear to others, "convert" here means sell BCH in exchange for BTC. It's not some sort of mathematical operation.
- kingmanaz 9y ago
  I'm having trouble wrapping my head around this. Once you use your private key to complete a transaction on the BCH blockchain, won't that reveal the private key publicly and allow others to spend the corresponding unspent bitcoin on the BTC blockchain? Sorry if I'm overlooking something obvious, but it was my understanding that once someone used their private key it should never be used again...
  - mirimir 9y ago
    Not at all. You never reveal private keys when transacting. You will reveal addresses, however. The only BTC addresses that have BCH value are those that existed at the fork. So before using them in the BCH blockchain, it would be prudent to first spend them in the BTC blockchain. Doing this is a double spend in some sense, but they happen in different blockchains, so they don't affect each other.
wfunction 9y ago
Thanks! Isn't this something a currency should fundamentally prevent? I don't know of any real-world currency that can be used twice.
- markburns 9y ago
  It's not being used twice though on any individual fork. Plus the value would have to split for any fork.
- icebraining 9y ago
  It's more like if someone created a new currency and gave each owner of an existing currency (say, the dollar) an equivalent nominal amount of the new notes.
- AgentME 9y ago
  Bitcoin Cash is a separate project and currency from Bitcoin. You can't pay someone who is expecting Bitcoin by sending Bitcoin Cash to them or vice-versa. Bitcoin's code is open source and the balances of all addresses are public, so anyone could create a fork (a new separate currency based on it, optionally starting with the same balances).
  - wfunction 9y ago
    Right, but presumably a reasonably large merchant would find that they need to accept both though, right? And now you would have more purchasing power with them which feels a bit weird, since the old Bitcoin and the new Bitcoin would not have the same purchasing power...
    - MichaelGG 9y ago
      Maybe, maybe not. Bitcoin might have been 200$ higher without the fork. Merchants find they need to accept any popular currency their users demand. Being forked from the Bitcoin chain is beside the point.
      - 9y ago

markburns 9y ago

Yes you can - bitcoin held prior to the fork is valid on both chains. And yes it is still going up. An alternative scaling solution (to the big blocks proposed by the 'new' fork) Segwit will be going ahead - aiding the scalability of 'old' Bitcoin fork, which may explain some/all of the price rise. Along with the uncertainty reduction post fork. 'New' and 'old' here are somewhat arbitrary/controversial ways of thinking of the fork. Proponents of Bitcoin cash might argue having no limit was closer to Satoshi's original intention - the block limit was originally added in as a temporary measure. Lots of politics going on around that.