Thats not entirely true, since the work required to find a valid hash is random, the amount of work done can only be guesed.
I agree with you on the rest though. After thinking about the system for a while whan realizes that there is almost no alternative...

I actually like the idea of throwing in some folding. But the main point of Bitcoin is that there is no central authority, so who should decide what project is added. On the other hand, someone had to decide that there are 50 coins reward for a completed block. But the other problems of "useful work" described here still remain. I guess some energy waste is the price to pay for a decentraliced secure digital currency.

Edit: True, its not a waste! see next post.

Oh no another noob

I've now spent several hours wrapping my head about Bitcoins and Mining.

What I find quite strange is that the complexity to find a Block is (more or less) artificially increased if the computing power of the miner-collective inreases to achive one block every 10 minutes. So the Miners do more computing without any direct benfit for the system except for a lower probability that one single entity can control more than half of the processing power. Wouldn't it be more elegant to just force them "on hold" or something like that so that they don't consume more energy than necessary?

I am sure many intelligent people have thought about that and there is a very good reason why the system works as it does. Maybe smeone cares to enlighten me?