Quote from: gavinandresen on August 15, 2010, 04:55:20 PM

I'm better at thinking through things using specific examples, so bear with me: let's use Mars as the extreme case, and say I'm on Mars and want to double-spend some bitcoins.

I talk to my cousin in New York, and send him some coins with the "Mars" locality. We agree that we'll use the same coins to buy candy bars on January 1, 2040, 10:00:00 UTC, me on Mars and him in New York.

So the New York candy machine just rejects my cousin's transaction OR makes him wait the 40 minutes for communication between Earth and Mars? Wouldn't it be more likely that the New York candy machine just accepts the transaction after seeing no double-spends after, oh, I dunno, maybe two seconds?

Not in my system, because the bitcoin nodes would not work on a transaction before it was accepted by the verifier or before a certain time out has passed if the verifier doesn't respond.

Also, there could be a lot of cpu power on Mars as well. So, the New York vending machine shouldn't accept a Mars coin within several hours.

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After all, Bitcoin+ Payment Verification Systems, Incorporated knows it is highly connected into the majority Bitcoin network with very low latency, so it knows that if it blasts a transaction into the network and doesn't see a double-spend after two seconds the chances are very, very, very good that it will be declared the first spend.

On earth, yes, but not in the Mars example. Most bitcoin nodes are far away.

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If the New York payment system accepts the transaction every time, then the Mars verifier will lose every time. I'm pretty sure the New York folks will tell the Mars folks "tough cookies, you should set up MarsCoin for low-latency transactions up there."
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I am not sure we are talking about the same setup. Are you talking about a single node on Mars and many on earth. That is a very special situation.

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I don't know much about high speed trading with millisecond latency, and, frankly, don't care much about high speed trading with millisecond latency. It wouldn't bother me at all if you can't use Bitcoin for that (and you have to set up a SpeedyCoin system for doing that sort of thing).

Why, when it is as easy as I describe (unless I am missing something). Actually, I don't think my proposal is complicated. Maybe, I just haven't expressed myself clearly enough.

Red, interesting about Antarctica. I just don't see the connection. They are certainly connecting to a bank account, and they will wait for the communication to go back to the rest of the world. So, you probably have to wait for several seconds if you withdraw at that ATM.