Bitcoin is for Everyone, page 11
All great breakthroughs begin with a question. Satoshi Nakamoto wasn’t the first to ask, “How can strangers across the world agree on a single, trustworthy digital record without relying on a central authority?”
Others had posed the question, but Satoshi decisively answered it. The solution not only addressed the problem, but also exposed the deep flaws in our financial system while offering a path to fixing them.
Satoshi’s achievement wasn’t just theoretical: it was practical, elegant, and profoundly egalitarian. At its core lies a system of ownership and verification that relies exclusively on decentralized consensus secured by math and cryptography.
Your bitcoin isn’t just numbers on a screen—it represents something revolutionary. A verifiable, finite piece of digital property backed by the most powerful computer network on Earth.
If you own a bitcoin—or even a fraction of one—you hold a share of the only 21 million bitcoins that will ever exist.
The entire network collectively verifies and attests to your ownership until you decide to transfer your bitcoin to someone else. (We’ll cover the logistics of buying and selling bitcoin in Chapter Fifteen.)
For now, think of your bitcoin as sitting in a “digital P.O. box,” a secure space on the network to which only you hold the key.
At this point, it’s perfectly reasonable to wonder, “If Bitcoin is worth trillions, why can’t a clever hacker just rewrite the ledger for their own benefit?” The answer boils down to something you can’t fake or shortcut: an open-source ledger secured by real world energy.
Every ten minutes, thousands of specialized computers worldwide engage in a high-stakes race called proof-of-work mining. Think of each machine as a sprinter running on electricity instead of muscle—burning watts the way our sprinter burns calories—trying to guess a winning number that will seal the next “page” of Bitcoin’s ledger. The first miner to land on that number broadcasts its solution to the world and earns freshly minted bitcoin plus the transaction fees in that block.
Crucially, every wrong guess costs just as much electricity as a right one, so the race is brutally expensive. If someone wanted to tamper with past transactions, they would have to redo not just one race but every race all the way back to the block they want to change—and do it faster than all honest miners combined. The electric bill alone would dwarf the potential reward, turning energy into a near-impenetrable firewall around the ledger.
Running alongside the miners is also a second layer of defense: a global constellation of independent computers known as nodes. These machines aren’t trying to win any race; their only job is to act as uncompromising referees. Each node keeps a complete copy of the blockchain and checks every proposed block against Bitcoin’s rulebook—verifying digital signatures, confirming that no coins are double-spent, and ensuring the block’s math is sound.
If even one rule is broken, nodes simply refuse to accept the block, no matter how much electricity was expended to create it. As long as just one honest copy of the ledger exists, the rules hold firm.
Together, miners and nodes form Bitcoin’s security loop. Miners pour real energy into locking in each new layer of history, while nodes stand guard to ensure every layer was built correctly.
This self-governing system needs no central authority. With these two interlocking systems, Bitcoin removes financial power dynamics and replaces them with distributed verification and thermodynamics—the unforgeable cost of energy—to keep the system honest. Your bitcoin remains safe because breaking the rules would require not only extraordinary computing power, but also a river of electricity so vast that network participants would detect and outspend an attack long before it could succeed.
In other words, Bitcoin turns the traditional financial system on its head.
In Chapter Ten, we explored how Bitcoin solved the long-standing “double-spend” problem that had plagued attempts at digital cash.
Remember, unlike physical cash, which visibly changes hands when spent, digital cash posed a unique challenge for cryptographers: how could they ensure that a digital token wasn’t simply duplicated—like a photo being copied and texted to multiple friends—allowing the same money to be spent more than once?
Before Satoshi’s innovation, there was no way to prevent double-spending without relying on a trusted intermediary, like a bank, to keep track of all transactions and ensure no one spent the same money twice.
Satoshi’s breakthrough was to create a distributed ledger shared equally among all participants in the network. Every node holds a live, synchronized copy of this ledger, updating it in real time. Meanwhile, those mining computers—known as ASICs or miners—compete in a reward-driven lottery to solve complex cryptographic puzzles. As with a traditional lottery, miners can’t simply print their own tickets and expect to win; their way of “purchasing a ticket” is through expending real-world energy for a chance to add new blocks of transactions to the blockchain and earn the mining reward.
In Bitcoin’s system, there’s nobody overseeing this process—no person or company running the lottery. Instead, the cryptographic puzzles are intentionally designed to require real-world energy as the entry fee. This energy acts as a verifiable cost of participation, ensuring that miners can’t fake their way into the competition or manipulate the results (because you can’t print energy any more than you can make it rain!).
This is the proof-of-work that keeps the network secure and prevents fraud. It’s the ingenious mechanism, grounded in the laws of physics and enforced by a set of unchangeable rules, that enables the competition—and therefore the entire network—to manage itself.
When a miner solves the cryptographic puzzle and earns the right to propose a new block, it broadcasts the block and its solution—including the transactions waiting to be inscribed within it—to the entire Bitcoin network. Every node then independently verifies the block, checking that all transactions follow Bitcoin’s consensus rules—confirming, for example, that the sender has sufficient funds to cover their expenditures and that no double-spending has occurred.
No changes to the ledger are finalized until the network reaches agreement on the state of the blockchain. This distributed consensus preserves an immaculate record of transactions.
ASICs and nodes, then, are like two hands locked in an iron grip, creating and reinforcing one of the most secure and resilient networks ever conceived.
All without anyone in charge.
With that, let’s take a closer look at how this “lottery” actually works.
At any given moment (and as of this writing), approximately one million70 ASICs—those highly specialized computers designed solely for Bitcoin mining—are racing to solve cryptographic puzzles and earn valuable bitcoin.
If you’ve ever been asked to “guess a number between one and ten,” you have a rough idea of the challenge. But in Bitcoin mining, it isn’t a number between one and ten—it’s closer to a number between one and the total number of atoms in the known universe. Needless to say, finding the right one takes immense computational effort (and luck!).
Each attempt at solving this puzzle therefore requires significant energy expenditure, which is costly. But the reward is worth it: the computer that guesses correctly gets to add the next batch of transactions to the blockchain. Its owner earns fees from those transactions, but they’re really going after a bitcoin reward known as the block subsidy or block reward—the prize that serves as an economic incentive for miners to keep the network secure and operational.
The rest of the network is also deeply invested in ensuring that every block is accurate and immutable, because the value of Bitcoin depends on its impeccable status as a shared, tamper-proof record of truth. Remember: “Don’t trust, verify.”
To appreciate the simple elegance of how this is achieved—how the solution to the unfathomably complex “guess a number” puzzle is instantaneously corroborated all over the world, without any help from a judge or referee—it helps to envision a bike lock.
As any would-be bicycle thief knows, guessing a five-digit combination is hard enough, especially under pressure. Now imagine trying to crack a combination so astronomically large that it surpasses human comprehension.
This is essentially what Bitcoin miners are doing: submitting trillions of guesses per second in a high-stakes race to crack the code before anyone else.
Once there’s a winner, though, verification is remarkably simple. Just as a bike lock pops open with the correct combination, the winning solution is immediately recognizable and easily confirmed by anyone—in this case, every node on the network. (More on that step in a moment.)
But here’s where it gets interesting. If all mining computers were simply trying to crack identical bike locks, you’d expect the results to be predictable: more powerful equipment and increased energy usage would mean the code gets cracked faster and more frequently.
It’d be like digging for gold with a hydraulic pump instead of a shovel: in such a scenario, the supply of bitcoins would be exhausted in no time, disproportionately favoring those with the most advanced technology and deepest pockets. In such a scenario, the entire blockchain would be at risk of being dominated—or even manipulated—by a handful of powerful players.
Preventing this outcome is one of Satoshi’s most brilliant achievements, and it brings us to the elegant solution at the heart of Bitcoin mining: the difficulty adjustment.
To understand how the difficulty adjustment works, let’s take a step back for a moment.
When I described Bitcoin mining as guessing a number somewhere between “one” and “the number of atoms in the known universe,” I was introducing the basic idea. But let’s refine that analogy.
Miners aren’t actually searching for a single, precise number, like cracking a bike lock combination. Instead, they’re aiming for a range of acceptable numbers—a constantly shifting target defined by the network.
Yan Pritzker, author of Inventing Bitcoin, offers a helpful image to bring this into focus: Bitcoin mining is like throwing darts at an enormous dartboard. The bullseye represents that target range, and to “win,” a miner must use a valid cryptographic process to generate a guess (using the data from the newly-forming block plus a random number) that lands within the range. The catch? This target range isn’t static: it widens or shrinks based on both the amount of computing power currently within the network and how quickly valid guesses are being made.
Whether it’s compared to a bike lock with a flexible combination range or a dartboard with a dynamic bullseye, the key takeaway is this: Bitcoin’s network is designed to adapt.
This built-in adaptability works in real time. If computers are winning too quickly, it means the target is too large, making it too easy to land guesses inside the bullseye. In response, the bullseye automatically shrinks, making it harder to hit and slowing down the pace of wins.
If computers are struggling to find a winning guess, it means the target is too small. In this case, the bullseye expands, making it easier to hit and speeding up the discovery of new blocks.
No matter how many miners join or how much computing power they throw at the problem, the network ensures that new blocks are produced, on average, every ten minutes.
Bitcoin is like an orchestra that’s found a way to keep perfect time without a conductor.
So here we have millions of contestants on some sort of global game show, all racing to crack an impossibly complex code. There’s no host, no moderator, just a million computers relentlessly guessing at astronomical speeds. When one miner finally lands on the winning guess, the rest of the network must agree that it’s legitimate.
Now the rubber meets the road: how do they verify the winner? How do they know the “bike lock” really popped open?
Validating the winner involves a bit of computer science known as hashing. In Bitcoin, hashing serves two purposes: it allows miners to generate their guesses during the competition, and it enables every node on the network to instantly verify whether the winning guess is valid.
Breakout explanation: hashing
Imagine hashing like making a smoothie. You start with a specific set of ingredients—let’s say a banana, strawberries, and yogurt. You blend them together, and the result is a unique smoothie. Once blended, you can’t reverse the process to get the original banana or strawberries back; all you have is the final smoothie.
In Bitcoin, the “ingredients” are transaction data, and the “smoothie” is the hash—a unique digital fingerprint created by running that data through a cryptographic formula (the blender). Every tiny change to the ingredients (the data) creates an entirely different smoothie (or hash).
For miners, hashing is like blending millions of smoothies per second, each with slightly different ingredients, hoping to match a secret recipe set by the network. When a miner finally gets the perfect smoothie (winning hash), they share the recipe with the entire network, and everyone else can quickly check to confirm it’s the right one.
Of course, the real process is far more precise than making smoothies—hashing is pure math, not subjective judgments about flavor. But the metaphor helps show just how sensitive and irreversible the process really is.
Hashing ensures that the winning guess is valid, secure, and impossible to fake, because no one can tamper with the smoothie once it’s blended. That’s the magic of hashing: it’s incredibly hard to guess the right combination, but incredibly easy for everyone to verify once it’s found.
Imagine after 2.3 trillion dart throws, your dart finally lands in the bullseye. Lucky you! On a game show, the host would walk up, inspect your dart, and hand you the prize money on the spot.
But in Bitcoin’s system, as we know, there’s no host to inspect the dartboard and validate your hit. Instead, every computer on the network leans in, like a global team of math teachers, and asks you to “show your work.”
If you legitimately won—by “blending the perfect smoothie,” so to speak—each computer can instantly verify it, earning you the right to record transactions into the next block on the blockchain.
Any attempt to cheat will be immediately obvious and result in the automatic rejection of your claim. All the energy you’d spent mining will have been wasted. In this system of “rules without rulers,” there’s no loophole, no workaround, nobody to whom you can plead your case. You either follow the rules, validate your work, and earn the reward, or you burn money on electricity and walk away empty-handed.
This is the essence of Bitcoin’s proof-of-work. It’s a system that keeps the network secure by making cheating both costly and impractical. Just as you and I can’t print money at home to pay off our credit card bills, miners must invest real resources—electricity, computing power, and hardware—to be financially rewarded. By ensuring that every guess comes with a tangible cost, Bitcoin turns real-world energy expenditure into the foundation of its strength and security. As we’ll explore in Chapter Twelve, where we unpack criticisms of Bitcoin’s energy use, this requirement isn’t a flaw, it’s the feature that makes the system trustworthy and tamper-resistant.
So that’s what the mining computers are up to! They’re solving complex puzzles and competing for block rewards. But, as we noted at the start of this chapter, they only account for half of the Bitcoin ecosystem.
This is where nodes come in: while blocks are being mined, nodes continuously verify and secure every transaction recorded on the ledger. In fact, it’s thanks to nodes that Bitcoin can rightfully claim the mantle of “the people’s money.”
A node is simply a computer running the open-source Bitcoin software while storing the entire blockchain. Installing one is about as straightforward as downloading a desktop app—if you can set up Microsoft Word, you can spin up a node—so anyone with a modest computer and internet connection can join the network.
Picture a node as a smart security camera. Instead of watching a single doorway, it peers into every corner of Bitcoin’s ledger. Each node independently validates every transaction and every block, line by line, against Bitcoin’s unchanging rulebook. No payment or block reward becomes part of the permanent record unless thousands of these digital inspectors reach unanimous consensus that it obeys the rules.
In this way, nodes form a worldwide chorus of truth-tellers, continuously auditing the work of miners and preserving the integrity of the entire blockchain.
The fact that everyone can verify the entire system from their own machine is the key to Bitcoin’s decentralization. This truth is revealed in Bitcoin’s design: in order to make sure that absolutely anyone, anywhere can run a node and help keep the network honest, block size was deliberately set at a level everyday computers could manage.
If blocks were too large, the hardware requirements to run a node—storage, processing power, and bandwidth—would become prohibitively expensive. This would naturally limit participation to those with significant financial resources, concentrating power in the hands of the wealthy and undermining Bitcoin’s core principles of decentralization and universal access.
Instead, Bitcoin’s lightweight design allows anyone with an internet connection and a modest, affordable device to download the entire blockchain, validate transactions, and secure the network from home.
Imagine if ordinary people could “look over the shoulder” of our traditional financial system and see what the banks are really up to. At the moment, the most consequential decisions—decisions that affect all of us, like how much money to print—happen behind closed doors, among a small group of people with varying interests and incentives.
Ordinary people have no way to challenge (or even see!) what they’re doing.
Now imagine a system where every monetary action is public—where anyone, anywhere, can verify the rules are being followed, and no one can secretly change them.
Bitcoin is that system. And it’s working.
A common criticism of Bitcoin is its perceived “slowness” due to the ten-minute intervals between those blocks. As we now know, that timing is determined by the difficulty adjustment. But this isn’t a weakness; it’s one of Bitcoin’s most important features. This deliberate pace also ensures that people all over the world can run their nodes using modest household computers.
