Hi all,
A bit new to this bitcoin currency, but already in love with it ^^
If my understanding is correct the security of the network is insured by millions of computers all over the world solving complex mathematical equations.
They really aren't all that complex. It's just a simple SHA256 hash. The tricky part is finding one that has a value lower than a target value. Since the SHA256 hash can't be done in reverse, this means everyone just keeps trying different input values until someone stumbles across an input value that will result in qualifying hash.
Those calculations are rewarded by mining. A computer that help securising the network is rewarded this way.
No. Those calculations ARE mining. They are rewarded with the block reward. The block reward is the sum of the block subsidy of brand new bitcoins plus all the transaction fees of all the transactions that are included in the block.
My question is, what will happen after all bitcoins are mined?
The block subsidy is cut in half every 210,000 blocks (approximately every 4 years). It started at 50 BTC per block back in 2009. It is currently 25 BTC per block. In 2016 it will be reduced to 12.5 BTC per block. This will continue until approximately the year
2136 when the subsidy will be cut in half from 0.00000002 BTC per block to 0.00000001 BTC per block. Four years (somewhere around 2140) later the subsidy will go from 0.00000001 BTC per block to 0.00000000 BTC per block. Since the block reward is the sum of the fees plus the subsidy, and there will no longer be a subsidy after the year 2140, the block reward will consist entirely of the transaction fees.
or when it is no more profitable to keep mining?
If mining becomes unprofitable for some, then they will quit mining and the total amount of hash power on the network will drop. In response to this, the difficulty will drop (difficulty is automatically adjusted every 2016 blocks). The reduction in difficulty will increase the revenue for those that remain mining. So long as there are transactions paying fees, and so long as bitcoin has value, there will always be someone that wants to get paid with those fees and is willing to run mining equipment to earn that revenue.
Who will ensure the security of the network then?
The miners that have access to the cheapest resources.
Thank you.
You're welcome.