HASHING THE UNIVERSE

It’s one thing to know that Bitcoin’s hashrate is astronomical. It’s quite another to transform this raw number into a memorable metric. Huge numbers on their own are hard to envisage, but this task becomes easier when they can be compared to other, equally numerous phenomena with which we are more familiar.

And how better to depict Bitcoin’s soaring hashrate than by likening it to celestial phenomena – to the stars that have long been a source of wonder, prompting humans since the dawn of civilisation to ponder their number? In 2024, getting a handle on Bitcoin’s rising hashrate was attempted by comparing it to the number of stars in the observable universe.

The most widely cited figure, often quoted by astronomical bodies like NASA, places the upper bound at one septillion stars, or 1×1024 – that’s a one followed by 24 zeroes. Our own Milky Way contains over 100 billion stars alone, and there are thousands of other galaxies out there, many multiples larger. The number of stars in the observable universe – which has a radius of about 46.5 billion light-years – is an estimate, then, albeit a carefully modelled one.

Hashing It Out

A more precise estimate, meanwhile, can be placed on the number of hashes that the Bitcoin network performs every 21 minutes. A hash is the output of a cryptographic one-way function, which in Bitcoin's case entails the SHA-256 algorithm taking input data – the information contained in a block of transactions – and producing a unique, fixed-length 256-bit string. The process is deterministic, meaning the same input will always produce the same output, but it is computationally infeasible to reverse the process to find the input from the output.

Bitcoin miners must repeatedly hash the block's data, each time altering a small piece of that data called a nonce until they produce a hash that is numerically below a target value set by the network's difficulty algorithm. The process is akin to a lottery where miners are constantly guessing numbers by changing the nonce until one of them finds a “winning” number that meets the criteria. Hashrate therefore refers to the total number of these guesses, or hashes, that all miners on the network are collectively performing per second and is the primary measure of the network's total computational power.

In 2024, an alluring idea was popularised concerning Bitcoin’s hashrate. The network’s collective computational rate was so high, it was reckoned, that every 21 minutes it produced the same number of hashes as there are stars in the observable universe.

A figure like one septillion hashes every 21 minutes may be numerically precise but it is cognitively empty for most people. By comparing the hashrate to another incomprehensibly large but more familiar concept, the scale becomes graspable and awe-inspiring. Bitcoiners had long aimed for the moon. Now, with the aid of a memorable analogy, they could reach for the stars.