What makes double-spending unlikely, though, is the size of the Bitcoin network. A so-called 51% attack, in which a group of miners theoretically control more than half of all network power, would be necessary. By controlling a majority of all network power, this group could dominate the remainder of the network to falsify records. However, such an attack on Bitcoin would require an overwhelming amount of effort, money, and computing power, thereby rendering the possibility extremely unlikely.