As can 49%, 40%, 20%, etc., they just have zero chance of succeeding.
Fixed it for ya
You seem to misunderstand now cryptocurrencies work. Read over
http://en.wikipedia.org/wiki/Variance and come back when you understand it.
Variance has nothing to do with it. You can't create the longest chain if you have less hashing power than the rest of the network. It's one of the most basic concepts of the current design of crypto-currencies actually.
*facepalm*
Yeah real useful response thanks.
Here's a more useful one:
Variance means that even with less than 51% of the hashing power you have a chance, albeit a smaller one, to disrupt the chain. For example, a bunch of people freaked out some weeks ago because the Bitcoin chain managed to get... I think it was like 3 blocks in a 10 second period? People also often freak if there's the occasional hour between blocks, but this has happened MANY times without a drop in hashing power.
Think of it this way: Take, say, a d12 for roll playing, and assume you and several players are sitting at a table, and to "win" the game you have to roll a 1. The average chance of you rolling a 1 is going to be 1 in 12, but...
You could roll that 1 result twice in a row, or, you could get 24 rolls in a row... that come up with a different number. In a large enough sample set, with a truly balanced die to roll, it'll just about always be "even" among the different numbers, but if you're looking at just a few rolls in a row...
If you play many games with dice, cards, etc, it only takes a moment of pondering that before you can realize that if you were to roll that die 12 times, it's quite possible for you to _NOT_ get each number exactly one time.
Now imagine the block chain lottery as rolling a die with 115792089237316195423570985008687907853269984665640564039457584007913129639936 sides... (Someone correct me if I'm remembering wrong and it's not a 256 bit hash in use, please.)
transactions, but still remember that shorter block times give less varience. So someone with 49% has a near-zero, close enough to zero, chance. The actual probability of getting 7 blocks in a row is less than 0.6% for a 49% holder. The actual probability is smaller, because you aren't rolling an infinite amount of dies.