Bitcoin was invented in the aftermath of the 2008 financial crisis, and the crisis was a clear motivating factor for its creation.
Numerous banks and other financial institutions failed across the world, and had to be bailed out by governments at the expense of their taxpayers. This underscored the fragility of the modern financial system, where the health of our monetary system is reliant on banks and other financial institutions that we are forced to trust to make wise and prudent decisions with the money we give them. Too often for comfort, they fail to carry out this fiduciary responsibility to an adequate degree.
Of particular note is fractional reserve banking. When you give a bank $1,000, the bank doesn’t actually keep all that money for you. It goes out and is legally allowed to spend up to $900 of your money, and keep just $100 in the off chance that you ask for your money back.
In the most simplistic case, if you are the only depositor at this bank, and you ask for more than $100 back at once, the bank won’t be able to give you your money, because it doesn’t have it any more.
Shockingly, this is actually how banks work in reality. In the United States, the reserve requirement, or the percentage of net deposits banks are actually required to keep in liquid financial instruments on hand, is generally 10% for most banks. This means that if a bank has net deposits of a billion dollars, it needs to only keep 100 million on hand at any given time.
This is fine most of the time, as generally the customers of that bank won’t all try to cash out at the same time, and the bank is able to stay liquid. However, the moment customers start to question the bank‘s financial stability, things can go south very quickly. If just a small number of customers begin asking for all their deposits back, a bank can rapidly become depleted of all its liquid funds.
The financial crisis of 2008 highlighted yet another risk of the modern banking system. When a bank goes out and spends the 90% of net deposits it holds in investments, it can often make very bad bets, and lose all that money. In the case of the 2008 crisis, banks in particular bet on high risk subprime mortgages. These were mortgages taken out by borrowers very likely to become delinquent, to purchase houses that were sharply inflated in value by the rampant ease of acquiring a mortgage.
When those mortgages were defaulted on, the artificially inflated values of the homes began to collapse, and banks were left holding assets worth far less than the amount they had lent out. As a consequence, they now had nowhere near the amount of money that customers had given them, and began experiencing liquidity crises that led to their ultimate bankruptcy and demise.
Mistrust in fiat currencies, or currencies created and backed solely by faith in a government, both because of the modern banking system and because of the inherent nature of fiat currency, has in large part been why gold has been used as such a reliable store of value over millennia.
Fiat currencies are the world’s predominant form of currency today. The US dollar or the British pound, for instance, are fiat currencies. These are currencies that are entirely controlled in their supply and creation by a national government, and are backed by nothing but faith in that government.
This has proved a mistake countless times throughout history. Zimbabwe is a classic example, where the Zimbabwean dollar, thanks to an incompetent government among other factors, experienced enormous levels of hyperinflation. At one point, inflation was estimated at almost 80 billion percent in just a single month.
Bitcoin was designed, essentially, as a better ‘digital gold’. It incorporates all of the best elements of gold — its inherent scarcity and decentralized nature — and then solves all the shortcomings of gold, in allowing it to be globally transactable in precise denominations extremely quickly.
How does it do this? In short, by emulating gold’s production digitally. Gold is physically mined out of the ground. Bitcoin is also ‘mined’, but digitally. The production of bitcoin is controlled by code that dictates you must find a specific answer to a given problem in order to unlock new bitcoins.
In technical terms, bitcoin utilizes the same proof-of-work system that Hashcashdevised in 1997. This system dictates that one must find an input that when hashed, creates an output with a specific number of preceding zeros, among a few other specific requirements.
This is where the ‘crypto’, incidentally, in cryptocurrency comes from. Cryptographic hash functions are fundamentally necessary for the functioning of bitcoin and other cryptocurrencies, as they are one-way functions. One-way functions work such that it is easy to calculate an output given an input, but near impossible to calculate the original input given the output. Hence, cryptographic one-way hash functions enable bitcoin’s proof of work system, as it ensures that it is nigh-impossible for someone to just see the output required to unlock new bitcoins, and calculate in reverse the input that created that output.
Instead, one must essentially brute-force the solution, by trying every single possible input in order to find one that creates an output that satisfies the specified requirements.
Bitcoin is further ingeniously devised to guarantee that on average, new bitcoins are only found every 10 minutes or so. It guarantees this by ensuring that the code that dictates the new creation of bitcoin automatically increases the difficulty of the proof-of-work system in proportion to the number of computers trying to solve the problem at hand.
For instance, in the very beginning of time, it was only the creator of bitcoin who was mining for bitcoins. He used one computer to do so. For simplicity’s sake, let’s assume this one computer could try 1000 different values to hash a second. In a minute, it would hash 60,000 values, and in 10 minutes, 600,000 values.
The algorithm that dictates the mining of bitcoins, therefore, would ensure that on average, it would take 600,000 random tries of hashing values to find one that would fulfill the requirements of the specified output required to unlock the next block of bitcoins.
It can do this by making the problem more or less difficult, by requiring more or less zeros at the beginning of the output that solves the problem. The more zeros that are required at the beginning of the output, the more exponentially difficult the problem becomes to solve. To understand this why this is, click here for a reasonably good explanation.
In this case, it would require just the right amount of leading zeros and other characters to ensure that a solution is found on average every 600,000 or so tries.
However, imagine now that a new computer joins the network, and this one too can compute 1000 hashes a second. This effectively doubles the rate at which the problem can be solved, because now on average 600,000 hashes are tried every 5 minutes, not 10.
Bitcoin’s code elegantly solves this problem by ensuring that every 2,016 times new bitcoin is mined (roughly every 14 days at 10 minutes per block), the difficulty adjusts to become proportional to how much more or less hashing power is mining for bitcoin, such that on average new bitcoin continues to be found roughly every ten minutes or so.
You can see the present difficulty of mining bitcoin here. It should be evident from a half-second glance that the amount of computing power working to mine bitcoin right now is immense, and the difficulty is proportionally similarly immense. As of the time of this writing right now, there are close to 5 billion billion hashes per second being run to try to find the next block of bitcoin.
This system holds a lot of advantages even over gold’s natural system of being mined out of the ground. Gold’s mining is effectively random and not dictated by any perfect computer algorithm, and is consequently much more unpredictable in its output at any given moment. If a huge supply of gold is serendipitously found somewhere, it could theoretically dramatically inflate the rate at which gold enters the existing supply, and consequently cause an unanticipated decrease in the unit price of gold.
Bitcoin, on the other hand, will always be mined on a carefully regulated schedule, because it can perfectly adapt no matter how many people begin to mine it or how technologically advanced bitcoin mining hardware becomes.
In fact, it’s already known for certain that there will only ever be a total of 21 million bitcoins in the world.
This is because the amount of bitcoin that is mined every time a hash problem is solved and a new block is created halves every 210,000 blocks, or roughly every 4 years.
The initial reward per block used to be 50 bitcoins back in 2009. After about four years, this dropped to 25 bitcoins in late 2012. The last halving occurred in July 2016, and dropped the reward per block mined to 12.5. In 2020, this should go down to 6.25, in 2024, 3.125, and so forth, all the way until the reward drops to essentially zero.
When all is said and done, there will hence be 21 million bitcoins. Exactly that, no more, no less. Elegant, no? This eliminates yet another risk with extant currencies, gold included: there are absolutely no surprises when it comes to knowing the present and future supply of bitcoin. A million bitcoin will never be found randomly in California one day and incite a digital gold rush.