Part of philosophy’s oddity lies in its unwavering fueling of the desire of each and every one of its practitioners to put an end to it. The path to fulfillment ends in the revelation of a version of the truth that reigns supreme over any version that preceded it and any that would otherwise follow it.
Against this backdrop, many philosophers thoroughly investigated and debated the nature of the universe. In doing so, different truths emerged on a spectrum bounded by two extremes that were vehemently defended by some of humanity’s brightest. On one end, a Parmenidean view of a static universe and its absolutely eternal reality. On the other, a Heraclitean representation of a changing universe in an eternal state of flux.
It is not my intent nor is it within the extent of my capabilities to resolve this dichotomy. However, there seems to be substantial empirical evidence that movement is inherently linked to existence. Be it microscopic or macroscopic, a certain notion of change appears to be intimately tied to the very fabric of reality. This flow is particularly noticeable at the level of the various interactions that happen among individuals or groups.
A significant part of these exchanges is succinctly encapsulated in what we refer to as a transaction. In its most general setting, a transaction refers to that which is “driven through”, “accomplished” or “settled”. It is derived from the pairing of the Latin words trans and agere which respectively mean “through” and “driving forward”. Implicit to this etymology is the notion of a movement, the subject of which could be a physical good or an intangible (e.g., a service, a right, a piece of information) originating at one or multiple sources and destined to one or multiple recipients.
A Bitcoin transaction is no exception as it fundamentally consists of transferring spending control from one entity to another. In this context, control refers to the authority that a given entity benefits from in order to unlock a certain value. As such, a Bitcoin transaction of Satoshi from Alice to Bob is an activity that ensures that the control over spending these Satoshis has moved from Alice to Bob who can now spend them (or a portion of them) at will. A Satoshi is the smallest transact-able unit of a bitcoin (the currency, also denoted BTC) and is equal to BTC In light of this description, one can define a Bitcoin transaction as a data structure that essentially includes:
- A set of unspent previous Bitcoin transaction outputs commonly known as UTXOs. Each one of them contains a specific amount of Satoshis, the control over which has been transferred from a previous entity to the one initiating the current Bitcoin transaction. UTXOs become inputs to the current Bitcoin transaction.
- One or more recipients who will be given spending control over UTXOs.
- An amount specifying the value of Satoshis to be transferred to each recipient.
- Cryptographic signatures and relevant scripts used to verify the authenticity of the sender(s) as well as to codify and observe any spending rule(s) imposed by them.