It's technically possible, but debates surrounding how and when to do this have been circulating for years. So far, the general consensus is that it would cause

It's technically possible, but debates surrounding how and when to do this have been circulating for years. So far, the general consensus is that it would cause a lot of distrust in the system. Technically, +50% of BTC mining capacity could choose to ignore transactions, double spend coins, or even bring the network down. For a while, a shared mining pool got close to the 50% mark, but users deliberately moved away from it to bring it's share down. Here's a conversation that took place at the time: http://www.reddit.com/r/Bitcoin/comments/1bq4ia/for_the_love_of_bitcoin_stop_mining_at_btc_guild/ http://www.reddit.com/r/Bitcoin/comments/1bq4ia/for_the_love...