What is the simplest possible building block? What is the simplest possible component of change we could apply to that building block? — Treatid
An electron is not composed of other particles. ... If an electron is 'composed' of position, momentum, spin, charge and mass; aren't these properties more fundamental than the electron? — Treatid
Well an electron is an emergent composite and not fundamentally simple in some reductionist/atomistic sense. It exists as the result of a chain of symmetry-breaking events that leave it as a particle that has indeed hit its lowest possible mass state, so exists"fundamentally" as it can't decay further, while also representing the specific world-building property of "a negative charge". It has a property that is cosmically meaningful because it can stand in relation with its partner-in-crime, the proton.
So to think about it in a holistic, structural, emergent, evolutionary, thermodynamic and systems sense, the Big Bang is a cosmic dissipative structure that organises itself to dispose of its entropy by expanding and cooling. It undergoes a whole series of phase changes – like steam to water to ice – as it globally restructures in ways that minimise its entropy. Like a cooling iron bar, it can suddenly lock in a global field that creates an emergent state which then has its own second-order excitations or "particles" doing their own second-order entropic thing.
An electron is what you get left with at this stage of the Universe when it has cooled and expanded to almost zero in energy density and almost unbound in effective distance scale. A baked-in defect like you find topologically trapped in a crystal.
To exist as the distinct and fundamental thing it is, an electron had to be produced by the Higgs symmetry breaking. Before the temperature of the Universe fell to the 160 GeV range, electrons were chirally broken, left and right, Weyl particles. Gaining mass from the Higgs field glued the two halves together to make a whole electron – turn it into a Dirac particle, along with creating electromagnetism with its photons as part of the whole reorganisation of the cosmic topological order.
This only got us as far as a hot soup of electrons and positrons though. A stew of matter and antimatter creation and annihilation which lacked any great particularity of the kind we would associate with "a particle". Location and momentum were just an averaged blur within the general thermal confusion of a charged plasma, not really anything individual.
But more symmetry breaking saw a slight excess of electrons (as the negatively charged matter particle) being left over and positrons (as the positively charged antimatter) being eliminated from the cosmic topological order (being wasted to hot photons that made up the fast-fading CMB radiation background).
So we have this fundamental kind of thing that we call "electron-ness" which only emerges as everything else gets more crisply and counterfactually suppressed. The Weyl left-right difference has to be welded together to create a Dirac particle which is now divided at the higher topological level of being a matter or antimatter particle. Then the electron must outlive the positron to create a general negative charge difference – the one that the proton on its own symmetry breaking story is heading towards to become the positively charged “fundamental particle” that is its counterpart in turning the Universe into a realm dominated by electromagnetic radiation as its most visible thermalising characteristic.
Even when we get to electrons as the negative charge stamped out as material form, we still have to have it decay through its three mass generations – taus, muons, then electrons – to arrive at the thermal bottom rung simplicity of a particle that can decay no further ... at least not until black holes eventually sweep up all mass particles and themselves evaporate to leave an empty Heat Death void.
So the holistic or structural take on this is that we have the general thing of a heat sink cosmos winding its way down its entropic gradient. That is the fundamental relation, the fundamental thermal context. Then as it cools, it also goes through major phase changes that each throw up the local topological features – the excitations that obey the symmetries – which characterise that stage of organisation.
The reason the rather mixed and complex brew of radiation, electrons and protons seems such a "fundamental" state of order is that these indeed proved to be a suitable ground for the nuclear chemistry of atoms, the atomic chemistry of materials science, the material chemistry of biological life, etc.
By comparison to the lifetimes of stars, planets, mountain ranges and haircuts, photons, electrons and protons do fit the ontological bill of "atomistic materials existing in an acausal, large and frigid, cosmic void".
But photons, electrons and protons are all topologically composite particles that happened to land in a place where they formed an electromagnetic level of entropic organisation. They are only fundamental to the degree they are Platonically inevitable mathematical structure – a place a cooling cosmos had to arrive at because thermodynamics can't avoid being self-organised by the maths of its own symmetry breaking.
A ton of other "particle stories" also condensed out of the Big Bang, but add so little further to the complexity and wonder of nature that even if they contribute much more actual entropification to the total dissipation budget, we don't think of them as being "fundamental" it the same way. They don't carve a history of individuated and counterfactual events. Stuff like the CMB, dark matter, dark energy, blackhole evaporation, are just background stuff to us, given our very human concerns when it comes to metaphysical story telling.
So in summary, our very notion of "fundamental" is rather screwed by our natural psychological prejudices. But physics does tell us about dissipative structure, topological order, gauge symmetry and all the stuff we need to be able to see through to what is really going on. The Universe is a heat sink rattling through a series of phase changes on the way to its eventual heat death. The present moment is an especially complexified mid-stage with its stars, planets and life.
But even that accounts for a few percent – a round-up error – in the matter budget of the Cosmos. And if we include all that exists, then black holes are already the dominant "particles of being" and themselves on the way to be shown the door as they are swept up and exported over the cosmic event horizon, leaving a pure void near absolute zero apart from the faintest rustle of dark energy blackbody radiation – the least interesting fluctuations possible in the most empty spacetime possible.
Given your interest in nodes and edges, or information-centric, accounts of all this, this is a way of telling the thermodynamic story using a topological mathematics. There is a reason to think this way for the practical purpose of modelling.
But then you have to dig into the logical atomism being built into the models to be able to step back to the larger metaphysics you might want to frame. Atomism succeeds by simplifying – by severing the immediate from its evolutionary history and self-organising tendencies.
Reality is a fabric of relations. But the simplicity of nodes and edges is the constructive simplicity that emerges from self-constraint. It is what you get – like photons, electrons and protons clattering about in an electromagnetic void – when a heck of a lot of other possibility has been cut away to leave only that as the material stuff you want explained.
The deeper question becomes how does causality and logical counterfactuality even arise as something so apparently simple and inevitable? That is the where systems thinking and other forms of holistic metaphysics comes in.