How close a sibling are we talking about? Would a sibling attacker have, say, private keys known only to it's sibling? I don't mean to be circular, but how a node's "identity" is defined would be some persistent property of the node when disconnected from the network and verifiable by other nodes during the time the first node is connected. Other nodes must a recollection of the identity, such as a public key, to validate a signature exchange. Consensus of all participants validating each other on an ongoing basis with changing keys would probably be a part of it, as it would make flooding the network with confederates who would validate an attacker ineffective.

Handling failure of consensus is an implementation issue I would have to break down to use cases. If there's an overarching simple answer, I'm not seeing it.

The property of identity itself need only persist between connections, not forever. Although I dislike the SecureID system for various reasons, their implementation of object authentication requires that an object's identity be "freshened" by occasional connection to the network, it is not a static property. Now if only their token database wasn't centralized maybe they wouldn't have gotten hacked so easily this past year.

Claiming to have an "inside line" with a supernatural world is the world's oldest confidence scheme. Such silly games are for silly children to play with each other.

That's only because BOINC does interesting and useful computing work from many fields, hence it's actually connected to reality and not a self contained game simulation featuring performance of the same simple operation over and over like the computing done in bitcoin. Spin those wheels, little hamster, spin! 

I understand completely. Thank you.

Which version of the Quran? The copies that were interred in the walls of mosques hundreds of years ago are at variance with the stuff that is passed around these days. What to do, what to do?

It's really much better just to outgrow all this sunstroked Semitic nonsense, why go through life as a superstitious child?

Too funny! Ok, sonny, I won't trot out the string of degrees I have in mathematics, economics, and law. I won't cite my 30 years of experience in the financial services industry with 20 of that on Wall Street. I won't even discuss my role as one of the earliest implementors of the RSA cryptosystem in that industry. All that was a long time ago, I would pay people to do that stuff for me now had I not done so well as to be out of it completely. None of that is relevant in a world born yesterday.

In any case, the only practical value I see in bitcoin is as a transactional system.

I am sufficiently experienced to recognize that in the worst case a black box behavioral emulation of bitcoin as a transactional system could be built, perhaps out of as little as hamster wheels and rubber bands, perhaps more. Decentralized distributed data models are very common, there are many solutions to maintaining coherency in them. So on and so on. Yawn, been there, done that.

A really good way to not get sucked into the paradigms of a given tool set is to start with requirements. Rather than retype the work of others, I would suggest you take at look, FOR EXAMPLE ( just like BOINC is an EXAMPLE, you dingbat ) at this refined set of proposed requirements posted elsewhere on this forum:

https://bitcointalk.org/index.php?topic=54222.msg647423#msg647423

You shouldn't be surprised that the adults in the room are not taking bitcoin as seriously as it takes itself, many of them have seen a lot more than you have. Did I mention I knew some of the implementors of Flooz? 

By default, the Bitcoin client accepts whichever chain is the longest as the "correct" blockchain.

No shit? To borrow a phrase from the mayor of Chicago, that's fucking retarded. Are you suggesting that this preposterous business of spinning wheels at ever increasing rates is necessary to maintain the security of the blockchain? If so, failure is inevitable. So many flaws, thanks for pointing this one out.

Give the technical details.
The means of benchmarking GPUs, FPGAs, or whatever are too obvious to waste space on, in fact the more heterogeneous the platforms, the better for having them cross-check each other. Besides, existence proofs are always compelling, witness the BOINC project does this for CPUs and GPUs as well and it is not centralized other than as a matter of recordkeeping convenience. Of course, the BOINC project generates work of tangible value, whereas bitcoin asks for unbounded resources just to barely keep itself going, so there's a shared interest in central recording in BOINC.

It's been said before, but Nakamoto was very prudent not to burn his real identity on a 1.0 prototype. He's obviously much more clever than the folks who have internalized his work as gospel, a silly thing to do with a wholly synthetic mathematical game.

Compared to what?

Why is that? Please elaborate. Peers benchmarking each other could do the verification. Once again, you are only telling us how Bitcoin works, it seems you are having trouble thinking outside that tiny little Bitcoin Box. ROTFLMFAO, what's the weather like in 2008?

Thanks, no. Paul would bring far too many anachronistic crazy people with him as baggage. A larger scale version of what happened when the U.S. House of Representatives got stuffed with Tea Party retards last election is not needed.

Hey, I know, let's see if Paul and Ralph Nader would consider a 3rd party run together. Nader's still alive, at least as much as Paul, isn't he?

BTW, the American electorate is really fucking stupid, superstitious, and has an attention span roughly equal to the length of a beer commercial, even worse than only 30 or 40 years ago. The 1980s were a watershed time for the "Let's Get Stupid" movement, now we are stuck with them until they die, hopefully sooner than they expect 

Good thinking inside the Bitcoin Box there. If all you have is a hammer, everything looks like cryptography.

Why not a capacity-based mining metric as used in the distributed project software BOINC? "Earnings" are based on your percentage of commitment of a benchmarked resource as well as total capacity contributed. If capacity is really not needed in the aggregate, you could level the playing field between the cell phone processor used at 99% and the energy-wasting dedicated red hot pig breath generator running at 99% or for that matter dial in any skewing of reward you might want to achieve.

The whole weird hack of the difficulty level makes it clear whats really going on. Set it to minimum and rework the mining block creation rate meter, which could be amenable to something as simple as a consensus-based peer to peer counter.

Right now the mining hack is a lovely illustration of the fallacy of composition. The more it's done the less is the return to each participant for their investment. At the other end, where everyone recognizes pointlessly compute-intensive mining just costs everyone more individually so that no one should do it, bitcoins aren't created. It's a truly ludicrous situation.

The whole mining thing is the most elaborate and wasteful means of trickling out a new block every ten minutes or so that the human mind could devise, so far anyway  
As you rightly point out, the exchanges thwart the concept of decentralization.

So, there's two requirements for Bitcoin 2.0, or the replacement for Bitcoin 1.0
1. Eliminate wasteful mining driven by computing capacity.
2. Decentralize the currency exchange function.

#1 is easy, #2 not so...

+1

Bitcoin is neither fish nor fowl, desert topping or floor wax.

On the one hand it trades like the cheesiest sub-penny stock ever, offering a combination of tiny total market capitalization, lack of transparency, and very few interested participants of size that takes me back to when the "pink sheets" were really listed on pink pieces of paper that got physically passed around. In this regard it's a toy for all practical purposes, an amusing diversion.

As a medium of exchange it offers a requirement of unusual determination to actually use it for its own sake, the wide acceptance and universal recognition associated with cowrie shells, and an ability to store a relatively fixed value for hours at a time. Thank goodness for the drug trade which generates enough volume for the speculators to have something to play with, for otherwise the "bitcoin economy" would likely be much, much smaller.

However, let's not overlook it's utility for money laundering, transaction fees for placement of many small amounts filtering through a number of addresses are much better than old-fashioned vehicles like Cayman banks and single premium life insurance policies. Too bad it's not big enough to absorb the demand and still keep laundering somewhat hidden.

So, all in all, bitcoin is a pretty interesting online game/simulation. Isn't that good enough?

Thanks all. Sell 'em if you got 'em.

Be careful what you ask for 
http://www.youtube.com/watch?v=UNttHtP2Dtk

Returns to mining should be in the aggregate near zero over the long term, your mileage may vary depending on your incremental electrical cost of mining. The energy efficiency of mining from least to most efficient generally goes: CPU mining, GPU mining, FPGA mining.

The most tenuous aspect is whether or not you will be able to recover an initial hardware investment, due to both the expected near-zero returns over time and that any payback period could quite possibly exceed the lifetime of bitcoins actually being of value. Of course, lots of folks will tell you the latter will *never* happen.

If your only cost is the additional electricity to mine on a video card in a system that is left on anyway ( say a 7x24 firewall box ) your only initial investment would be your time setting up the software. Beyond that point any outlay for hardware should probably incorporate FPGA hardware, which is unlikely to ever be of any use for anything else. I suppose if you were to buy a video card for gaming you could also choose one that could be used for mining.

Setting up a CPU miner program is easiest, cheapest in initial outlay, and would give you a feel for what takes place.

Some people might tell you mining is a sucker's game since the return to mining is rigged to begin with by the difficulty level, which is adjusted every 2016 blocks to result in one block being solved every ten minutes or so, thus the difficulty changes every two weeks or so. The more capacity ( hardware and electricity ) that is thrown at mining, the less the return per unit of mining capacity. From this one might conclude the best way to mine is not to mine, although there are evidently big galvanized steel tubs of Kool Aid from which you are encouraged to drink in order to help you believe otherwise 

Yeah, the U.S. concurrently arming both sides in the Iran-Iraq war in the 1980s was indeed classic, but I'm not sure it did anyone much good long term. Dammit, they quit fighting before they had completely destroyed themselves, what's the fun in that?

On the other hand, getting the Iranians and the Israelis to smoke each other for good is an idea with legs.

+1