The concept of “now” — so far as we’ve been taught to understand it — is inherently flawed.
In fact, “now” doesn’t even exist. This is a reality illuminated by Einstein’s Theory of Relativity, which affirms that the way humans experience time is limited to their rate of acceleration through space. In essence, we can never collectively define “now,” since everyone’s conception of it is incontrovertibly relative.
Consider, for example, the Twin Paradox, which is a popular thought experiment in physics. As the theory goes, two twins are separated at some point in adulthood. One stays on Earth to live out his life here, and the other is sent in a spaceship to travel through the galaxy. His spaceship moves at the speed of light and comes back to Earth after what he believes to be a year of space vacation. In reality, however, what passed for a year in his speeding spaceship amounted to 50 years on Earth. When he returns home, he finds his twin has aged 50 years while he looks the same.
The Twin Paradox proves there is no such thing as “now.” But how, then, are humans to construct systems or protocols in which a shared understanding of “now” is critical?
The answer, so it goes, explains the genius behind the blockchain.
The fact that “now” doesn’t exist was an eminent challenge for the designers of the blockchain at its inception.
The key mechanism that enables the blockchain to function is consensus: the ability of multiple parties to agree that a transaction made on the blockchain is accurate and verifiable.
But if complementary servers can’t agree on what “now” is, they in effect can’t build consensus — a dilemma exemplified by something called the Byzantine Generals’ Problem.
The Byzantine Generals’ problem goes like this: there are five generals in the Byzantine Empire. They plan to attack a city at five different points along its perimeter, so they assign a general to each mark. After claiming their posts, the generals are ready to strike.
The generals know that the secret to overtaking the city is to sync their movements and their surprise attacks at the exact same time. To facilitate this, the first general — general A — writes a message to be sent to the other generals. The message says, “We will attack the city at 5 a.m.”
He gives the message to a rider on horseback, who goes off to deliver it to the second general — general B. But two minutes after the first general sends his rider, another rider from the last general — general E — arrives breathlessly into his camp carrying his own message, which says, “We will attack the city at 5:15 a.m.” The first general is dismayed, so he sends another rider to renege the previous message. But as it turns out, every general has sent a message like this, and they did so all at the same time.
Thus, the generals find themselves caught in a loop of confusion and delay.
The problem they ran into, of course, is they couldn’t build consensus around their definition of “now.”
“Now” was, in fact, different for each of them because their locations in time were unique and disparate.
The Byzantine Generals’ Problem highlights the essence of the challenge of defining “now” as it pertains to servers and nodes on the blockchain. If parties on the blockchain can’t agree on a common definition of “now” in order to confirm transactions, they risk creating a fork in which servers can’t agree that any given transaction is verifiably what it claims to be.
In such an instance, disparate servers will determine one transaction as two separate transactions — a point of confusion which creates a barbed array of debilitating problems that Einstein himself surely would have foretold.
So, how do parties on the blockchain reach consensus? The need to agree on “now” has to be eliminated entirely.
Presently, transactions made on the blockchain are not validated until the nodes on the network approve them with a super-majority of votes.
In this way, the blockchain has rendered the concept of “now” irrelevant. What really matters in building consensus on the blockchain is validating transactions to confirm they’re not counterfeited. It takes a long time, since the nodes on the network all need to conduct their validation processes, but that’s what we sacrifice in order to ensure consensus and prevent problems related to counterfeiting or double spending.
This illuminates the fact that we as participants in human systems should not think of the universe in terms of our three dimensional experience. The way we experience life on earth is not in line with the fundamentals of physics, which state that “now” cannot exist.
The designers of the blockchain accounted for this — the relevance of Einsteinian relativity and quantum physics in building consensus. They appreciated what the Byzantine Generals could not, lent credence to the limitations of our physical reality, and in turn devised a solution which not only allows for the blockchain to function, but sheds light on the way our universe actually works.
That’s the genius of the blockchain.